一个移植十分方便的malloc函数族的实现
2024-05-15 14:29:28
相信学习过c语言的人都知道malloc、free函数，这里就不多说怎么用了。这里要说的是：提供它们的实现。
该实现方法由uboot中malloc等函数的实现改编而来。已经过验证，没有问题。 ------多说一句，该实现支持物理地址malloc、free。。。，不支持虚拟地址的映射
该malloc的源码实现，很方便移植。特别是在BootLoader或者单片机开发过程中，想要实现malloc、free、realloc等函数时，只需要将下面提供的dlmalloc.c和malloc.h拷贝到你的工程的同一个目录下，编译链接进去即可。
编译出错处理：
该实现分2个文件：dlmalloc.c、malloc.h。由于dlmalloc.c中含有除法运算，在添加入你的工程中，当使用makefile去做gcc编译时，倘若编译出错。请尝试连接gcc库：libgcc.a,libm.a,libc.a三个库，在连接时按顺序加入。倘若不知道它们存在哪？那运行下：
arm-none-linux-gnueabi-gcc -print-libgcc-file-name【举例】看下路径
arm-linux-gcc -print-search-dirs【举例】看下gcc的搜索范围
另外，通过执行 arm-linux-gcc –dumpspecs【举例】 命令可以看到很多有用的信息，如指定软硬浮点，指定处理器。
下面贴代码（dlmalloc.c和malloc.h），malloc函数族的实现：
//dlmalloc.c：
#if 0 /* Moved to malloc.h */
/* ---------- To make a malloc.h, start cutting here ------------ *//*A version of malloc/free/realloc written by Doug Lea and released to thepublic domain. Send questions/comments/complaints/performance datato dl@cs.oswego.edu* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)Note: There may be an updated version of this malloc obtainable atftp://g.oswego.edu/pub/misc/malloc.cCheck before installing!* Why use this malloc?This is not the fastest, most space-conserving, most portable, ormost tunable malloc ever written. However it is among the fastestwhile also being among the most space-conserving, portable and tunable.Consistent balance across these factors results in a good general-purposeallocator. For a high-level description, seehttp://g.oswego.edu/dl/html/malloc.html* Synopsis of public routines(Much fuller descriptions are contained in the program documentation below.)malloc(size_t n);Return a pointer to a newly allocated chunk of at least n bytes, or nullif no space is available.free(Void_t* p);Release the chunk of memory pointed to by p, or no effect if p is null.realloc(Void_t* p, size_t n);Return a pointer to a chunk of size n that contains the same dataas does chunk p up to the minimum of (n, p's size) bytes, or nullif no space is available. The returned pointer may or may not bethe same as p. If p is null, equivalent to malloc. Unless the#define REALLOC_ZERO_BYTES_FREES below is set, realloc with asize argument of zero (re)allocates a minimum-sized chunk.memalign(size_t alignment, size_t n);Return a pointer to a newly allocated chunk of n bytes, alignedin accord with the alignment argument, which must be a power oftwo.valloc(size_t n);Equivalent to memalign(pagesize, n), where pagesize is the pagesize of the system (or as near to this as can be figured out fromall the includes/defines below.)pvalloc(size_t n);Equivalent to valloc(minimum-page-that-holds(n)), that is,round up n to nearest pagesize.calloc(size_t unit, size_t quantity);Returns a pointer to quantity * unit bytes, with all locationsset to zero.cfree(Void_t* p);Equivalent to free(p).malloc_trim(size_t pad);Release all but pad bytes of freed top-most memory backto the system. Return 1 if successful, else 0.malloc_usable_size(Void_t* p);Report the number usable allocated bytes associated with allocatedchunk p. This may or may not report more bytes than were requested,due to alignment and minimum size constraints.malloc_stats();Prints brief summary statistics.mallinfo()Returns (by copy) a struct containing various summary statistics.mallopt(int parameter_number, int parameter_value)Changes one of the tunable parameters described below. Returns1 if successful in changing the parameter, else 0.* Vital statistics:Alignment: 8-byte8 byte alignment is currently hardwired into the design. Thisseems to suffice for all current machines and C compilers.Assumed pointer representation: 4 or 8 bytesCode for 8-byte pointers is untested by me but has workedreliably by Wolfram Gloger, who contributed most of thechanges supporting this.Assumed size_t representation: 4 or 8 bytesNote that size_t is allowed to be 4 bytes even if pointers are 8.Minimum overhead per allocated chunk: 4 or 8 bytesEach malloced chunk has a hidden overhead of 4 bytes holding sizeand status information.Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)8-byte ptrs: 24/32 bytes (including, 4/8 overhead)When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byteptrs but 4 byte size) or 24 (for 8/8) additional bytes areneeded; 4 (8) for a trailing size fieldand 8 (16) bytes for free list pointers. Thus, the minimumallocatable size is 16/24/32 bytes.Even a request for zero bytes (i.e., malloc(0)) returns apointer to something of the minimum allocatable size.Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes8-byte size_t: 2^63 - 16 bytesIt is assumed that (possibly signed) size_t bit values suffice torepresent chunk sizes. `Possibly signed' is due to the factthat `size_t' may be defined on a system as either a signed oran unsigned type. To be conservative, values that would appearas negative numbers are avoided.Requests for sizes with a negative sign bit when the requestsize is treaded as a long will return null.Maximum overhead wastage per allocated chunk: normally 15 bytesAlignnment demands, plus the minimum allocatable size restrictionmake the normal worst-case wastage 15 bytes (i.e., up to 15more bytes will be allocated than were requested in malloc), withtwo exceptions:1. Because requests for zero bytes allocate non-zero space,the worst case wastage for a request of zero bytes is 24 bytes.2. For requests >= mmap_threshold that are serviced viammap(), the worst case wastage is 8 bytes plus the remainderfrom a system page (the minimal mmap unit); typically 4096 bytes.* LimitationsHere are some features that are NOT currently supported* No user-definable hooks for callbacks and the like.* No automated mechanism for fully checking that all accessesto malloced memory stay within their bounds.* No support for compaction.* Synopsis of compile-time options:People have reported using previous versions of this malloc on allversions of Unix, sometimes by tweaking some of the definesbelow. It has been tested most extensively on Solaris andLinux. It is also reported to work on WIN32 platforms.People have also reported adapting this malloc for use instand-alone embedded systems.The implementation is in straight, hand-tuned ANSI C. Among otherconsequences, it uses a lot of macros. Because of this, to be atall usable, this code should be compiled using an optimizing compiler(for example gcc -O2) that can simplify expressions and controlpaths.__STD_C (default: derived from C compiler defines)Nonzero if using ANSI-standard C compiler, a C++ compiler, ora C compiler sufficiently close to ANSI to get away with it.DEBUG (default: NOT defined)Define to enable debugging. Adds fairly extensive assertion-basedchecking to help track down memory errors, but noticeably slows downexecution.REALLOC_ZERO_BYTES_FREES (default: NOT defined)Define this if you think that realloc(p, 0) should be equivalentto free(p). Otherwise, since malloc returns a unique pointer formalloc(0), so does realloc(p, 0).HAVE_MEMCPY (default: defined)Define if you are not otherwise using ANSI STD C, but stillhave memcpy and memset in your C library and want to use them.Otherwise, simple internal versions are supplied.USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)Define as 1 if you want the C library versions of memset andmemcpy called in realloc and calloc (otherwise macro versions are used).At least on some platforms, the simple macro versions usuallyoutperform libc versions.HAVE_MMAP (default: defined as 1)Define to non-zero to optionally make malloc() use mmap() toallocate very large blocks.HAVE_MREMAP (default: defined as 0 unless Linux libc set)Define to non-zero to optionally make realloc() use mremap() toreallocate very large blocks.malloc_getpagesize (default: derived from system #includes)Either a constant or routine call returning the system page size.HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)Optionally define if you are on a system with a /usr/include/malloc.hthat declares struct mallinfo. It is not at all necessary todefine this even if you do, but will ensure consistency.INTERNAL_SIZE_T (default: size_t)Define to a 32-bit type (probably `unsigned int') if you are on a64-bit machine, yet do not want or need to allow malloc requests ofgreater than 2^31 to be handled. This saves space, especially forvery small chunks.INTERNAL_LINUX_C_LIB (default: NOT defined)Defined only when compiled as part of Linux libc.Also note that there is some odd internal name-mangling via defines(for example, internally, `malloc' is named `mALLOc') neededwhen compiling in this case. These look funny but don't otherwiseaffect anything.WIN32 (default: undefined)Define this on MS win (95, nt) platforms to compile in sbrk emulation.LACKS_UNISTD_H (default: undefined if not WIN32)Define this if your system does not have a <unistd.h>.LACKS_SYS_PARAM_H (default: undefined if not WIN32)Define this if your system does not have a <sys/param.h>.MORECORE (default: sbrk)The name of the routine to call to obtain more memory from the system.MORECORE_FAILURE (default: -1)The value returned upon failure of MORECORE.MORECORE_CLEARS (default 1)true (1) if the routine mapped to MORECORE zeroes out memory (whichholds for sbrk).DEFAULT_TRIM_THRESHOLDDEFAULT_TOP_PADDEFAULT_MMAP_THRESHOLDDEFAULT_MMAP_MAXDefault values of tunable parameters (described in detail below)controlling interaction with host system routines (sbrk, mmap, etc).These values may also be changed dynamically via mallopt(). Thepreset defaults are those that give best performance for typicalprograms/systems.USE_DL_PREFIX (default: undefined)Prefix all public routines with the string 'dl'. Useful toquickly avoid procedure declaration conflicts and linker symbolconflicts with existing memory allocation routines.*//* Preliminaries */#ifndef __STD_C
#ifdef __STDC__
#define __STD_C 1
#else
#if __cplusplus
#define __STD_C 1
#else
#define __STD_C 0
#endif /*__cplusplus*/
#endif /*__STDC__*/
#endif /*__STD_C*/#ifndef Void_t
#if (__STD_C || defined(WIN32))
#define Void_t void
#else
#define Void_t char
#endif
#endif /*Void_t*/#if __STD_C
#include <stddef.h> /* for size_t */
#else
#include <sys/types.h>
#endif#ifdef __cplusplus
extern "C" {
#endif#include <stdio.h> /* needed for malloc_stats *//*Compile-time options
*//*Debugging:Because freed chunks may be overwritten with link fields, thismalloc will often die when freed memory is overwritten by userprograms. This can be very effective (albeit in an annoying way)in helping track down dangling pointers.If you compile with -DDEBUG, a number of assertion checks areenabled that will catch more memory errors. You probably won't beable to make much sense of the actual assertion errors, but theyshould help you locate incorrectly overwritten memory. Thechecking is fairly extensive, and will slow down executionnoticeably. Calling malloc_stats or mallinfo with DEBUG set willattempt to check every non-mmapped allocated and free chunk in thecourse of computing the summmaries. (By nature, mmapped regionscannot be checked very much automatically.)Setting DEBUG may also be helpful if you are trying to modifythis code. The assertions in the check routines spell out in moredetail the assumptions and invariants underlying the algorithms.*//*INTERNAL_SIZE_T is the word-size used for internal bookkeepingof chunk sizes. On a 64-bit machine, you can reduce mallocoverhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'at the expense of not being able to handle requests greater than2^31. This limitation is hardly ever a concern; you are encouragedto set this. However, the default version is the same as size_t.
*/#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif/*REALLOC_ZERO_BYTES_FREES should be set if a call torealloc with zero bytes should be the same as a call to free.Some people think it should. Otherwise, since this mallocreturns a unique pointer for malloc(0), so does realloc(p, 0).
*//* #define REALLOC_ZERO_BYTES_FREES *//*WIN32 causes an emulation of sbrk to be compiled inmmap-based options are not currently supported in WIN32.
*//* #define WIN32 */
#ifdef WIN32
#define MORECORE wsbrk
#define HAVE_MMAP 0#define LACKS_UNISTD_H
#define LACKS_SYS_PARAM_H/*Include 'windows.h' to get the necessary declarations for theMicrosoft Visual C++ data structures and routines used in the 'sbrk'emulation.Define WIN32_LEAN_AND_MEAN so that only the essential MicrosoftVisual C++ header files are included.
*/
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif/*HAVE_MEMCPY should be defined if you are not otherwise usingANSI STD C, but still have memcpy and memset in your C libraryand want to use them in calloc and realloc. Otherwise simplemacro versions are defined here.USE_MEMCPY should be defined as 1 if you actually want tohave memset and memcpy called. People report that the macroversions are often enough faster than libc versions on manysystems that it is better to use them.*/#define HAVE_MEMCPY#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif#if (__STD_C || defined(HAVE_MEMCPY))#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
#else
#ifdef WIN32
/* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
/* 'windows.h' */
#else
Void_t* memset();
Void_t* memcpy();
#endif
#endif
#endif#if USE_MEMCPY/* The following macros are only invoked with (2n+1)-multiples ofINTERNAL_SIZE_T units, with a positive integer n. This is exploitedfor fast inline execution when n is small. */#define MALLOC_ZERO(charp, nbytes) \
do { \INTERNAL_SIZE_T mzsz = (nbytes); \if(mzsz <= 9*sizeof(mzsz)) { \INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \*mz++ = 0; \if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \*mz++ = 0; \if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \*mz++ = 0; }}} \*mz++ = 0; \*mz++ = 0; \*mz = 0; \} else memset((charp), 0, mzsz); \
} while(0)#define MALLOC_COPY(dest,src,nbytes) \
do { \INTERNAL_SIZE_T mcsz = (nbytes); \if(mcsz <= 9*sizeof(mcsz)) { \INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; \if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; \if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; }}} \*mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; \*mcdst = *mcsrc ; \} else memcpy(dest, src, mcsz); \
} while(0)#else /* !USE_MEMCPY *//* Use Duff's device for good zeroing/copying performance. */#define MALLOC_ZERO(charp, nbytes) \
do { \INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \switch (mctmp) { \case 0: for(;;) { *mzp++ = 0; \case 7: *mzp++ = 0; \case 6: *mzp++ = 0; \case 5: *mzp++ = 0; \case 4: *mzp++ = 0; \case 3: *mzp++ = 0; \case 2: *mzp++ = 0; \case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \} \
} while(0)#define MALLOC_COPY(dest,src,nbytes) \
do { \INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \switch (mctmp) { \case 0: for(;;) { *mcdst++ = *mcsrc++; \case 7: *mcdst++ = *mcsrc++; \case 6: *mcdst++ = *mcsrc++; \case 5: *mcdst++ = *mcsrc++; \case 4: *mcdst++ = *mcsrc++; \case 3: *mcdst++ = *mcsrc++; \case 2: *mcdst++ = *mcsrc++; \case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \} \
} while(0)#endif/*Define HAVE_MMAP to optionally make malloc() use mmap() toallocate very large blocks. These will be returned to theoperating system immediately after a free().
*/#ifndef HAVE_MMAP
#define HAVE_MMAP 1
#endif/*Define HAVE_MREMAP to make realloc() use mremap() to re-allocatelarge blocks. This is currently only possible on Linux withkernel versions newer than 1.3.77.
*/#ifndef HAVE_MREMAP
#ifdef INTERNAL_LINUX_C_LIB
#define HAVE_MREMAP 1
#else
#define HAVE_MREMAP 0
#endif
#endif#if HAVE_MMAP#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif#endif /* HAVE_MMAP *//*Access to system page size. To the extent possible, this mallocmanages memory from the system in page-size units.The following mechanics for getpagesize were adapted frombsd/gnu getpagesize.h
*/#ifndef LACKS_UNISTD_H
# include <unistd.h>
#endif#ifndef malloc_getpagesize
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
# ifndef _SC_PAGE_SIZE
# define _SC_PAGE_SIZE _SC_PAGESIZE
# endif
# endif
# ifdef _SC_PAGE_SIZE
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
# else
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)extern size_t getpagesize();
# define malloc_getpagesize getpagesize()
# else
# ifdef WIN32
# define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
# else
# ifndef LACKS_SYS_PARAM_H
# include <sys/param.h>
# endif
# ifdef EXEC_PAGESIZE
# define malloc_getpagesize EXEC_PAGESIZE
# else
# ifdef NBPG
# ifndef CLSIZE
# define malloc_getpagesize NBPG
# else
# define malloc_getpagesize (NBPG * CLSIZE)
# endif
# else
# ifdef NBPC
# define malloc_getpagesize NBPC
# else
# ifdef PAGESIZE
# define malloc_getpagesize PAGESIZE
# else
# define malloc_getpagesize (4096) /* just guess */
# endif
# endif
# endif
# endif
# endif
# endif
# endif
#endif/*This version of malloc supports the standard SVID/XPG mallinforoutine that returns a struct containing the same kind ofinformation you can get from malloc_stats. It should work onany SVID/XPG compliant system that has a /usr/include/malloc.hdefining struct mallinfo. (If you'd like to install such a thingyourself, cut out the preliminary declarations as described aboveand below and save them in a malloc.h file. But there's nocompelling reason to bother to do this.)The main declaration needed is the mallinfo struct that is returned(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains abunch of fields, most of which are not even meaningful in thisversion of malloc. Some of these fields are are instead filled bymallinfo() with other numbers that might possibly be of interest.HAVE_USR_INCLUDE_MALLOC_H should be set if you have a/usr/include/malloc.h file that includes a declaration of structmallinfo. If so, it is included; else an SVID2/XPG2 compliantversion is declared below. These must be precisely the same formallinfo() to work.*//* #define HAVE_USR_INCLUDE_MALLOC_H */#if HAVE_USR_INCLUDE_MALLOC_H
#include "/usr/include/malloc.h"
#else/* SVID2/XPG mallinfo structure */struct mallinfo {int arena; /* total space allocated from system */int ordblks; /* number of non-inuse chunks */int smblks; /* unused -- always zero */int hblks; /* number of mmapped regions */int hblkhd; /* total space in mmapped regions */int usmblks; /* unused -- always zero */int fsmblks; /* unused -- always zero */int uordblks; /* total allocated space */int fordblks; /* total non-inuse space */int keepcost; /* top-most, releasable (via malloc_trim) space */
};/* SVID2/XPG mallopt options */#define M_MXFAST 1 /* UNUSED in this malloc */
#define M_NLBLKS 2 /* UNUSED in this malloc */
#define M_GRAIN 3 /* UNUSED in this malloc */
#define M_KEEP 4 /* UNUSED in this malloc */#endif/* mallopt options that actually do something */#define M_TRIM_THRESHOLD -1
#define M_TOP_PAD -2
#define M_MMAP_THRESHOLD -3
#define M_MMAP_MAX -4#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif/*M_TRIM_THRESHOLD is the maximum amount of unused top-most memoryto keep before releasing via malloc_trim in free().Automatic trimming is mainly useful in long-lived programs.Because trimming via sbrk can be slow on some systems, and cansometimes be wasteful (in cases where programs immediatelyafterward allocate more large chunks) the value should be highenough so that your overall system performance would improve byreleasing.The trim threshold and the mmap control parameters (see below)can be traded off with one another. Trimming and mmapping aretwo different ways of releasing unused memory back to thesystem. Between these two, it is often possible to keepsystem-level demands of a long-lived program down to a bareminimum. For example, in one test suite of sessions measuringthe XF86 X server on Linux, using a trim threshold of 128K and ammap threshold of 192K led to near-minimal long term resourceconsumption.If you are using this malloc in a long-lived program, it shouldpay to experiment with these values. As a rough guide, youmight set to a value close to the average size of a process(program) running on your system. Releasing this much memorywould allow such a process to run in memory. Generally, it'sworth it to tune for trimming rather tham memory mapping when aprogram undergoes phases where several large chunks areallocated and released in ways that can reuse each other'sstorage, perhaps mixed with phases where there are no suchchunks at all. And in well-behaved long-lived programs,controlling release of large blocks via trimming versus mappingis usually faster.However, in most programs, these parameters serve mainly asprotection against the system-level effects of carrying aroundmassive amounts of unneeded memory. Since frequent calls tosbrk, mmap, and munmap otherwise degrade performance, the defaultparameters are set to relatively high values that serve only assafeguards.The default trim value is high enough to cause trimming only infairly extreme (by current memory consumption standards) cases.It must be greater than page size to have any useful effect. Todisable trimming completely, you can set to (unsigned long)(-1);*/#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif/*M_TOP_PAD is the amount of extra `padding' space to allocate orretain whenever sbrk is called. It is used in two ways internally:* When sbrk is called to extend the top of the arena to satisfya new malloc request, this much padding is added to the sbrkrequest.* When malloc_trim is called automatically from free(),it is used as the `pad' argument.In both cases, the actual amount of padding is roundedso that the end of the arena is always a system page boundary.The main reason for using padding is to avoid calling sbrk sooften. Having even a small pad greatly reduces the likelihoodthat nearly every malloc request during program start-up (orafter trimming) will invoke sbrk, which needlessly wastestime.Automatic rounding-up to page-size units is normally sufficientto avoid measurable overhead, so the default is 0. However, insystems where sbrk is relatively slow, it can pay to increasethis value, at the expense of carrying around more memory thanthe program needs.*/#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
#endif/*M_MMAP_THRESHOLD is the request size threshold for using mmap()to service a request. Requests of at least this size that cannotbe allocated using already-existing space will be serviced via mmap.(If enough normal freed space already exists it is used instead.)Using mmap segregates relatively large chunks of memory so thatthey can be individually obtained and released from the hostsystem. A request serviced through mmap is never reused by anyother request (at least not directly; the system may just sohappen to remap successive requests to the same locations).Segregating space in this way has the benefit that mmapped spacecan ALWAYS be individually released back to the system, whichhelps keep the system level memory demands of a long-livedprogram low. Mapped memory can never become `locked' betweenother chunks, as can happen with normally allocated chunks, whichmenas that even trimming via malloc_trim would not release them.However, it has the disadvantages that:1. The space cannot be reclaimed, consolidated, and thenused to service later requests, as happens with normal chunks.2. It can lead to more wastage because of mmap page alignmentrequirements3. It causes malloc performance to be more dependent on hostsystem memory management support routines which may vary inimplementation quality and may impose arbitrarylimitations. Generally, servicing a request via normalmalloc steps is faster than going through a system's mmap.All together, these considerations should lead you to use mmaponly for relatively large requests.*/#ifndef DEFAULT_MMAP_MAX
#if HAVE_MMAP
#define DEFAULT_MMAP_MAX (64)
#else
#define DEFAULT_MMAP_MAX (0)
#endif
#endif/*M_MMAP_MAX is the maximum number of requests to simultaneouslyservice using mmap. This parameter exists because:1. Some systems have a limited number of internal tables foruse by mmap.2. In most systems, overreliance on mmap can degrade overallperformance.3. If a program allocates many large regions, it is probablybetter off using normal sbrk-based allocation routines thatcan reclaim and reallocate normal heap memory. Using asmall value allows transition into this mode after thefirst few allocations.Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,the default value is 0, and attempts to set it to non-zero valuesin mallopt will fail.
*//*USE_DL_PREFIX will prefix all public routines with the string 'dl'.Useful to quickly avoid procedure declaration conflicts and linkersymbol conflicts with existing memory allocation routines.*//* #define USE_DL_PREFIX *//*Special defines for linux libcExcept when compiled using these special defines for Linux libcusing weak aliases, this malloc is NOT designed to work inmultithreaded applications. No semaphores or other concurrencycontrol are provided to ensure that multiple malloc or free callsdon't run at the same time, which could be disasterous. A singlesemaphore could be used across malloc, realloc, and free (which isessentially the effect of the linux weak alias approach). It wouldbe hard to obtain finer granularity.*/#ifdef INTERNAL_LINUX_C_LIB#if __STD_CVoid_t * __default_morecore_init (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;#elseVoid_t * __default_morecore_init ();
Void_t *(*__morecore)() = __default_morecore_init;#endif#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
#define MORECORE_CLEARS 1#else /* INTERNAL_LINUX_C_LIB */#if __STD_C
extern Void_t* sbrk(ptrdiff_t);
#else
extern Void_t* sbrk();
#endif#ifndef MORECORE
#define MORECORE sbrk
#endif#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE -1
#endif#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif#endif /* INTERNAL_LINUX_C_LIB */#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)#define cALLOc __libc_calloc
#define fREe __libc_free
#define mALLOc __libc_malloc
#define mEMALIGn __libc_memalign
#define rEALLOc __libc_realloc
#define vALLOc __libc_valloc
#define pvALLOc __libc_pvalloc
#define mALLINFo __libc_mallinfo
#define mALLOPt __libc_mallopt#pragma weak calloc = __libc_calloc
#pragma weak free = __libc_free
#pragma weak cfree = __libc_free
#pragma weak malloc = __libc_malloc
#pragma weak memalign = __libc_memalign
#pragma weak realloc = __libc_realloc
#pragma weak valloc = __libc_valloc
#pragma weak pvalloc = __libc_pvalloc
#pragma weak mallinfo = __libc_mallinfo
#pragma weak mallopt = __libc_mallopt#else#ifdef USE_DL_PREFIX
#define cALLOc dlcalloc
#define fREe dlfree
#define mALLOc dlmalloc
#define mEMALIGn dlmemalign
#define rEALLOc dlrealloc
#define vALLOc dlvalloc
#define pvALLOc dlpvalloc
#define mALLINFo dlmallinfo
#define mALLOPt dlmallopt
#else /* USE_DL_PREFIX */
#define cALLOc calloc
#define fREe free
#define mALLOc malloc
#define mEMALIGn memalign
#define rEALLOc realloc
#define vALLOc valloc
#define pvALLOc pvalloc
#define mALLINFo mallinfo
#define mALLOPt mallopt
#endif /* USE_DL_PREFIX */#endif/* Public routines */#if __STD_CVoid_t* mALLOc(size_t);
void fREe(Void_t*);
Void_t* rEALLOc(Void_t*, size_t);
Void_t* mEMALIGn(size_t, size_t);
Void_t* vALLOc(size_t);
Void_t* pvALLOc(size_t);
Void_t* cALLOc(size_t, size_t);
void cfree(Void_t*);
int malloc_trim(size_t);
size_t malloc_usable_size(Void_t*);
void malloc_stats();
int mALLOPt(int, int);
struct mallinfo mALLINFo(void);
#else
Void_t* mALLOc();
void fREe();
Void_t* rEALLOc();
Void_t* mEMALIGn();
Void_t* vALLOc();
Void_t* pvALLOc();
Void_t* cALLOc();
void cfree();
int malloc_trim();
size_t malloc_usable_size();
void malloc_stats();
int mALLOPt();
struct mallinfo mALLINFo();
#endif#ifdef __cplusplus
}; /* end of extern "C" */
#endif/* ---------- To make a malloc.h, end cutting here ------------ */
#endif /* 0 */ /* Moved to malloc.h */#include "malloc.h"
#ifdef DEBUG
#if __STD_C
static void malloc_update_mallinfo (void);
void malloc_stats (void);
#else
static void malloc_update_mallinfo ();
void malloc_stats();
#endif
#endif /* DEBUG *//*Emulation of sbrk for WIN32All code within the ifdef WIN32 is untested by me.Thanks to Martin Fong and others for supplying this.
*/#ifdef WIN32#define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
~(malloc_getpagesize-1))
#define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1))/* resrve 64MB to insure large contiguous space */
#define RESERVED_SIZE (1024*1024*64)
#define NEXT_SIZE (2048*1024)
#define TOP_MEMORY ((unsigned long)2*1024*1024*1024)struct GmListElement;
typedef struct GmListElement GmListElement;struct GmListElement
{GmListElement* next;void* base;
};static GmListElement* head = 0;
static unsigned int gNextAddress = 0;
static unsigned int gAddressBase = 0;
static unsigned int gAllocatedSize = 0;static
GmListElement* makeGmListElement (void* bas)
{GmListElement* this;this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));assert (this);if (this){this->base = bas;this->next = head;head = this;}return this;
}void gcleanup ()
{BOOL rval;assert ( (head == NULL) || (head->base == (void*)gAddressBase));if (gAddressBase && (gNextAddress - gAddressBase)){rval = VirtualFree ((void*)gAddressBase,gNextAddress - gAddressBase,MEM_DECOMMIT);assert (rval);}while (head){GmListElement* next = head->next;rval = VirtualFree (head->base, 0, MEM_RELEASE);assert (rval);LocalFree (head);head = next;}
}static
void* findRegion (void* start_address, unsigned long size)
{MEMORY_BASIC_INFORMATION info;if (size >= TOP_MEMORY) return NULL;while ((unsigned long)start_address + size < TOP_MEMORY){VirtualQuery (start_address, &info, sizeof (info));if ((info.State == MEM_FREE) && (info.RegionSize >= size))return start_address;else{/* Requested region is not available so see if the *//* next region is available. Set 'start_address' *//* to the next region and call 'VirtualQuery()' *//* again. */start_address = (char*)info.BaseAddress + info.RegionSize;/* Make sure we start looking for the next region *//* on the *next* 64K boundary. Otherwise, even if *//* the new region is free according to *//* 'VirtualQuery()', the subsequent call to *//* 'VirtualAlloc()' (which follows the call to *//* this routine in 'wsbrk()') will round *down* *//* the requested address to a 64K boundary which *//* we already know is an address in the *//* unavailable region. Thus, the subsequent call *//* to 'VirtualAlloc()' will fail and bring us back *//* here, causing us to go into an infinite loop. */start_address =(void *) AlignPage64K((unsigned long) start_address);}}return NULL;}void* wsbrk (long size)
{void* tmp;if (size > 0){if (gAddressBase == 0){gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));gNextAddress = gAddressBase =(unsigned int)VirtualAlloc (NULL, gAllocatedSize,MEM_RESERVE, PAGE_NOACCESS);} else if (AlignPage (gNextAddress + size) > (gAddressBase +
gAllocatedSize)){long new_size = max (NEXT_SIZE, AlignPage (size));void* new_address = (void*)(gAddressBase+gAllocatedSize);do{new_address = findRegion (new_address, new_size);if (new_address == 0)return (void*)-1;gAddressBase = gNextAddress =(unsigned int)VirtualAlloc (new_address, new_size,MEM_RESERVE, PAGE_NOACCESS);/* repeat in case of race condition *//* The region that we found has been snagged *//* by another thread */}while (gAddressBase == 0);assert (new_address == (void*)gAddressBase);gAllocatedSize = new_size;if (!makeGmListElement ((void*)gAddressBase))return (void*)-1;}if ((size + gNextAddress) > AlignPage (gNextAddress)){void* res;res = VirtualAlloc ((void*)AlignPage (gNextAddress),(size + gNextAddress -AlignPage (gNextAddress)),MEM_COMMIT, PAGE_READWRITE);if (res == 0)return (void*)-1;}tmp = (void*)gNextAddress;gNextAddress = (unsigned int)tmp + size;return tmp;}else if (size < 0){unsigned int alignedGoal = AlignPage (gNextAddress + size);/* Trim by releasing the virtual memory */if (alignedGoal >= gAddressBase){VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal,MEM_DECOMMIT);gNextAddress = gNextAddress + size;return (void*)gNextAddress;}else{VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,MEM_DECOMMIT);gNextAddress = gAddressBase;return (void*)-1;}}else{return (void*)gNextAddress;}
}#endif/*Type declarations
*/struct malloc_chunk
{INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */struct malloc_chunk* fd; /* double links -- used only if free. */struct malloc_chunk* bk;
} __attribute__((__may_alias__)) ;typedef struct malloc_chunk* mchunkptr;/*malloc_chunk details:(The following includes lightly edited explanations by Colin Plumb.)Chunks of memory are maintained using a `boundary tag' method asdescribed in e.g., Knuth or Standish. (See the paper by PaulWilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for asurvey of such techniques.) Sizes of free chunks are stored bothin the front of each chunk and at the end. This makesconsolidating fragmented chunks into bigger chunks very fast. Thesize fields also hold bits representing whether chunks are free orin use.An allocated chunk looks like this:chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Size of previous chunk, if allocated | |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Size of chunk, in bytes |P|mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| User data starts here... .. .. (malloc_usable_space() bytes) .. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Size of chunk |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Where "chunk" is the front of the chunk for the purpose of most ofthe malloc code, but "mem" is the pointer that is returned to theuser. "Nextchunk" is the beginning of the next contiguous chunk.Chunks always begin on even word boundries, so the mem portion(which is returned to the user) is also on an even word boundary, andthus double-word aligned.Free chunks are stored in circular doubly-linked lists, and look like this:chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Size of previous chunk |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+`head:' | Size of chunk, in bytes |P|mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Forward pointer to next chunk in list |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Back pointer to previous chunk in list |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| Unused space (may be 0 bytes long) .. .. |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+`foot:' | Size of chunk, in bytes |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+The P (PREV_INUSE) bit, stored in the unused low-order bit of thechunk size (which is always a multiple of two words), is an in-usebit for the *previous* chunk. If that bit is *clear*, then theword before the current chunk size contains the previous chunksize, and can be used to find the front of the previous chunk.(The very first chunk allocated always has this bit set,preventing access to non-existent (or non-owned) memory.)Note that the `foot' of the current chunk is actually representedas the prev_size of the NEXT chunk. (This makes it easier todeal with alignments etc).The two exceptions to all this are1. The special chunk `top', which doesn't bother using thetrailing size field since there is nonext contiguous chunk that would have to index off it. (Afterinitialization, `top' is forced to always exist. If it wouldbecome less than MINSIZE bytes long, it is replenished viamalloc_extend_top.)2. Chunks allocated via mmap, which have the second-lowest-orderbit (IS_MMAPPED) set in their size fields. Because they arenever merged or traversed from any other chunk, they have nofoot size or inuse information.Available chunks are kept in any of several places (all declared below):* `av': An array of chunks serving as bin headers for consolidatedchunks. Each bin is doubly linked. The bins are approximatelyproportionally (log) spaced. There are a lot of these bins(128). This may look excessive, but works very well inpractice. All procedures maintain the invariant that noconsolidated chunk physically borders another one. Chunks inbins are kept in size order, with ties going to theapproximately least recently used chunk.The chunks in each bin are maintained in decreasing sorted order bysize. This is irrelevant for the small bins, which all containthe same-sized chunks, but facilitates best-fit allocation forlarger chunks. (These lists are just sequential. Keeping them inorder almost never requires enough traversal to warrant usingfancier ordered data structures.) Chunks of the same size arelinked with the most recently freed at the front, and allocationsare taken from the back. This results in LRU or FIFO allocationorder, which tends to give each chunk an equal opportunity to beconsolidated with adjacent freed chunks, resulting in larger freechunks and less fragmentation.* `top': The top-most available chunk (i.e., the one bordering theend of available memory) is treated specially. It is neverincluded in any bin, is used only if no other chunk isavailable, and is released back to the system if it is verylarge (see M_TRIM_THRESHOLD).* `last_remainder': A bin holding only the remainder of themost recently split (non-top) chunk. This bin is checkedbefore other non-fitting chunks, so as to provide betterlocality for runs of sequentially allocated chunks.* Implicitly, through the host system's memory mapping tables.If supported, requests greater than a threshold are usuallyserviced via calls to mmap, and then later released via munmap.*//* sizes, alignments */#define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
#define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ)
#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
#define MINSIZE (sizeof(struct malloc_chunk))/* conversion from malloc headers to user pointers, and back */#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))/* pad request bytes into a usable size */#define request2size(req) \(((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \(long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \(((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))/* Check if m has acceptable alignment */#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)/*Physical chunk operations
*//* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */#define PREV_INUSE 0x1/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */#define IS_MMAPPED 0x2/* Bits to mask off when extracting size */#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)/* Ptr to next physical malloc_chunk. */#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))/* Ptr to previous physical malloc_chunk */#define prev_chunk(p)\((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))/* Treat space at ptr + offset as a chunk */#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))/*Dealing with use bits
*//* extract p's inuse bit */#define inuse(p)\
((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)/* extract inuse bit of previous chunk */#define prev_inuse(p) ((p)->size & PREV_INUSE)/* check for mmap()'ed chunk */#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)/* set/clear chunk as in use without otherwise disturbing */#define set_inuse(p)\
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE#define clear_inuse(p)\
((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)/* check/set/clear inuse bits in known places */#define inuse_bit_at_offset(p, s)\(((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)#define set_inuse_bit_at_offset(p, s)\(((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)#define clear_inuse_bit_at_offset(p, s)\(((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))/*Dealing with size fields
*//* Get size, ignoring use bits */#define chunksize(p) ((p)->size & ~(SIZE_BITS))/* Set size at head, without disturbing its use bit */#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))/* Set size/use ignoring previous bits in header */#define set_head(p, s) ((p)->size = (s))/* Set size at footer (only when chunk is not in use) */#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))/*BinsThe bins, `av_' are an array of pairs of pointers serving as theheads of (initially empty) doubly-linked lists of chunks, laid outin a way so that each pair can be treated as if it were in amalloc_chunk. (This way, the fd/bk offsets for linking bin headsand chunks are the same).Bins for sizes < 512 bytes contain chunks of all the same size, spaced8 bytes apart. Larger bins are approximately logarithmicallyspaced. (See the table below.) The `av_' array is never mentioneddirectly in the code, but instead via bin access macros.Bin layout:64 bins of size 832 bins of size 6416 bins of size 5128 bins of size 40964 bins of size 327682 bins of size 2621441 bin of size what's leftThere is actually a little bit of slop in the numbers in bin_indexfor the sake of speed. This makes no difference elsewhere.The special chunks `top' and `last_remainder' get their own bins,(this is implemented via yet more trickery with the av_ array),although `top' is never properly linked to its bin since it isalways handled specially.*/#define NAV 128 /* number of bins */typedef struct malloc_chunk* mbinptr;/* access macros */#define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))/*The first 2 bins are never indexed. The corresponding av_ cells are insteadused for bookkeeping. This is not to save space, but to simplifyindexing, maintain locality, and avoid some initialization tests.
*/#define top (av_[2]) /* The topmost chunk */
#define last_remainder (bin_at(1)) /* remainder from last split *//*Because top initially points to its own bin with initialzero size, thus forcing extension on the first malloc request,we avoid having any special code in malloc to check whetherit even exists yet. But we still need to in malloc_extend_top.
*/#define initial_top ((mchunkptr)(bin_at(0)))/* Helper macro to initialize bins */#define IAV(i) bin_at(i), bin_at(i)static mbinptr av_[NAV * 2 + 2] = {0, 0,IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
};unsigned long mem_malloc_start = 0;
unsigned long mem_malloc_end = 0;
unsigned long mem_malloc_brk = 0;void *sbrk(int increment)
{unsigned long old = mem_malloc_brk;unsigned long new = old + increment;/** if we are giving memory back make sure we clear it out since* we set MORECORE_CLEARS to 1*/if (increment < 0)memset((void *)new, 0, -increment);if ((new < mem_malloc_start) || (new > mem_malloc_end))return (void *)MORECORE_FAILURE;mem_malloc_brk = new;return (void *)old;
}void mem_malloc_init(unsigned long start, unsigned long size)
{mem_malloc_start = start;mem_malloc_end = start + size;mem_malloc_brk = start;memset((void *)mem_malloc_start, 0, size);
}/* field-extraction macros */#define first(b) ((b)->fd)
#define last(b) ((b)->bk)/*Indexing into bins
*/#define bin_index(sz) \
(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \126)
/*bins for chunks < 512 are all spaced 8 bytes apart, and holdidentically sized chunks. This is exploited in malloc.
*/#define MAX_SMALLBIN 63
#define MAX_SMALLBIN_SIZE 512
#define SMALLBIN_WIDTH 8#define smallbin_index(sz) (((unsigned long)(sz)) >> 3)/*Requests are `small' if both the corresponding and the next bin are small
*/#define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)/*To help compensate for the large number of bins, a one-level indexstructure is used for bin-by-bin searching. `binblocks' is aone-word bitvector recording whether groups of BINBLOCKWIDTH binshave any (possibly) non-empty bins, so they can be skipped overall at once during during traversals. The bits are NOT alwayscleared as soon as all bins in a block are empty, but instead onlywhen all are noticed to be empty during traversal in malloc.
*/#define BINBLOCKWIDTH 4 /* bins per block */#define binblocks_r ((INTERNAL_SIZE_T)av_[1]) /* bitvector of nonempty blocks */
#define binblocks_w (av_[1])/* bin<->block macros */#define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH))
#define mark_binblock(ii) (binblocks_w = (mbinptr)(binblocks_r | idx2binblock(ii)))
#define clear_binblock(ii) (binblocks_w = (mbinptr)(binblocks_r & ~(idx2binblock(ii))))/* Other static bookkeeping data *//* variables holding tunable values */static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
static unsigned long top_pad = DEFAULT_TOP_PAD;
static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;/* The first value returned from sbrk */
static char* sbrk_base = (char*)(-1);/* The maximum memory obtained from system via sbrk */
static unsigned long max_sbrked_mem = 0;/* The maximum via either sbrk or mmap */
static unsigned long max_total_mem = 0;/* internal working copy of mallinfo */
static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };/* The total memory obtained from system via sbrk */
#define sbrked_mem (current_mallinfo.arena)/* Tracking mmaps */#ifdef DEBUG
static unsigned int n_mmaps = 0;
#endif /* DEBUG */
static unsigned long mmapped_mem = 0;
#if HAVE_MMAP
static unsigned int max_n_mmaps = 0;
static unsigned long max_mmapped_mem = 0;
#endif/*Debugging support
*/#ifdef DEBUG/*These routines make a number of assertions about the statesof data structures that should be true at all times. If anyare not true, it's very likely that a user program has somehowtrashed memory. (It's also possible that there is a coding errorin malloc. In which case, please report it!)
*/#if __STD_C
static void do_check_chunk(mchunkptr p)
#else
static void do_check_chunk(p) mchunkptr p;
#endif
{INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;/* No checkable chunk is mmapped */assert(!chunk_is_mmapped(p));/* Check for legal address ... */assert((char*)p >= sbrk_base);if (p != top)assert((char*)p + sz <= (char*)top);elseassert((char*)p + sz <= sbrk_base + sbrked_mem);}#if __STD_C
static void do_check_free_chunk(mchunkptr p)
#else
static void do_check_free_chunk(p) mchunkptr p;
#endif
{INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;mchunkptr next = chunk_at_offset(p, sz);do_check_chunk(p);/* Check whether it claims to be free ... */assert(!inuse(p));/* Unless a special marker, must have OK fields */if ((long)sz >= (long)MINSIZE){assert((sz & MALLOC_ALIGN_MASK) == 0);assert(aligned_OK(chunk2mem(p)));/* ... matching footer field */assert(next->prev_size == sz);/* ... and is fully consolidated */assert(prev_inuse(p));assert (next == top || inuse(next));/* ... and has minimally sane links */assert(p->fd->bk == p);assert(p->bk->fd == p);}else /* markers are always of size SIZE_SZ */assert(sz == SIZE_SZ);
}#if __STD_C
static void do_check_inuse_chunk(mchunkptr p)
#else
static void do_check_inuse_chunk(p) mchunkptr p;
#endif
{mchunkptr next = next_chunk(p);do_check_chunk(p);/* Check whether it claims to be in use ... */assert(inuse(p));/* ... and is surrounded by OK chunks.Since more things can be checked with free chunks than inuse ones,if an inuse chunk borders them and debug is on, it's worth doing them.*/if (!prev_inuse(p)){mchunkptr prv = prev_chunk(p);assert(next_chunk(prv) == p);do_check_free_chunk(prv);}if (next == top){assert(prev_inuse(next));assert(chunksize(next) >= MINSIZE);}else if (!inuse(next))do_check_free_chunk(next);}#if __STD_C
static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
#else
static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
#endif
{INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;long room = sz - s;do_check_inuse_chunk(p);/* Legal size ... */assert((long)sz >= (long)MINSIZE);assert((sz & MALLOC_ALIGN_MASK) == 0);assert(room >= 0);assert(room < (long)MINSIZE);/* ... and alignment */assert(aligned_OK(chunk2mem(p)));/* ... and was allocated at front of an available chunk */assert(prev_inuse(p));}#define check_free_chunk(P) do_check_free_chunk(P)
#define check_inuse_chunk(P) do_check_inuse_chunk(P)
#define check_chunk(P) do_check_chunk(P)
#define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
#else
#define check_free_chunk(P)
#define check_inuse_chunk(P)
#define check_chunk(P)
#define check_malloced_chunk(P,N)
#endif/*Macro-based internal utilities
*//*Linking chunks in bin lists.Call these only with variables, not arbitrary expressions, as arguments.
*//*Place chunk p of size s in its bin, in size order,putting it ahead of others of same size.
*/#define frontlink(P, S, IDX, BK, FD) \
{ \if (S < MAX_SMALLBIN_SIZE) \{ \IDX = smallbin_index(S); \mark_binblock(IDX); \BK = bin_at(IDX); \FD = BK->fd; \P->bk = BK; \P->fd = FD; \FD->bk = BK->fd = P; \} \else \{ \IDX = bin_index(S); \BK = bin_at(IDX); \FD = BK->fd; \if (FD == BK) mark_binblock(IDX); \else \{ \while (FD != BK && S < chunksize(FD)) FD = FD->fd; \BK = FD->bk; \} \P->bk = BK; \P->fd = FD; \FD->bk = BK->fd = P; \} \
}/* take a chunk off a list */#define unlink(P, BK, FD) \
{ \BK = P->bk; \FD = P->fd; \FD->bk = BK; \BK->fd = FD; \
} \/* Place p as the last remainder */#define link_last_remainder(P) \
{ \last_remainder->fd = last_remainder->bk = P; \P->fd = P->bk = last_remainder; \
}/* Clear the last_remainder bin */#define clear_last_remainder \(last_remainder->fd = last_remainder->bk = last_remainder)/* Routines dealing with mmap(). */#if HAVE_MMAP#if __STD_C
static mchunkptr mmap_chunk(size_t size)
#else
static mchunkptr mmap_chunk(size) size_t size;
#endif
{size_t page_mask = malloc_getpagesize - 1;mchunkptr p;#ifndef MAP_ANONYMOUSstatic int fd = -1;
#endifif(n_mmaps >= n_mmaps_max) return 0; /* too many regions *//* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because* there is no following chunk whose prev_size field could be used.*/size = (size + SIZE_SZ + page_mask) & ~page_mask;#ifdef MAP_ANONYMOUSp = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
#else /* !MAP_ANONYMOUS */if (fd < 0){fd = open("/dev/zero", O_RDWR);if(fd < 0) return 0;}p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
#endifif(p == (mchunkptr)-1) return 0;n_mmaps++;if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;/* We demand that eight bytes into a page must be 8-byte aligned. */assert(aligned_OK(chunk2mem(p)));/* The offset to the start of the mmapped region is stored* in the prev_size field of the chunk; normally it is zero,* but that can be changed in memalign().*/p->prev_size = 0;set_head(p, size|IS_MMAPPED);mmapped_mem += size;if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)max_mmapped_mem = mmapped_mem;if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)max_total_mem = mmapped_mem + sbrked_mem;return p;
}#if __STD_C
static void munmap_chunk(mchunkptr p)
#else
static void munmap_chunk(p) mchunkptr p;
#endif
{INTERNAL_SIZE_T size = chunksize(p);int ret;assert (chunk_is_mmapped(p));assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));assert((n_mmaps > 0));assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);n_mmaps--;mmapped_mem -= (size + p->prev_size);ret = munmap((char *)p - p->prev_size, size + p->prev_size);/* munmap returns non-zero on failure */assert(ret == 0);
}#if HAVE_MREMAP#if __STD_C
static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
#else
static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
#endif
{size_t page_mask = malloc_getpagesize - 1;INTERNAL_SIZE_T offset = p->prev_size;INTERNAL_SIZE_T size = chunksize(p);char *cp;assert (chunk_is_mmapped(p));assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));assert((n_mmaps > 0));assert(((size + offset) & (malloc_getpagesize-1)) == 0);/* Note the extra SIZE_SZ overhead as in mmap_chunk(). */new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);if (cp == (char *)-1) return 0;p = (mchunkptr)(cp + offset);assert(aligned_OK(chunk2mem(p)));assert((p->prev_size == offset));set_head(p, (new_size - offset)|IS_MMAPPED);mmapped_mem -= size + offset;mmapped_mem += new_size;if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)max_mmapped_mem = mmapped_mem;if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)max_total_mem = mmapped_mem + sbrked_mem;return p;
}#endif /* HAVE_MREMAP */#endif /* HAVE_MMAP *//*Extend the top-most chunk by obtaining memory from system.Main interface to sbrk (but see also malloc_trim).
*/#if __STD_C
static void malloc_extend_top(INTERNAL_SIZE_T nb)
#else
static void malloc_extend_top(nb) INTERNAL_SIZE_T nb;
#endif
{char* brk; /* return value from sbrk */INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */char* new_brk; /* return of 2nd sbrk call */INTERNAL_SIZE_T top_size; /* new size of top chunk */mchunkptr old_top = top; /* Record state of old top */INTERNAL_SIZE_T old_top_size = chunksize(old_top);char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));/* Pad request with top_pad plus minimal overhead */INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;unsigned long pagesz = malloc_getpagesize;/* If not the first time through, round to preserve page boundary *//* Otherwise, we need to correct to a page size below anyway. *//* (We also correct below if an intervening foreign sbrk call.) */if (sbrk_base != (char*)(-1))sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);brk = (char*)(MORECORE (sbrk_size));/* Fail if sbrk failed or if a foreign sbrk call killed our space */if (brk == (char*)(MORECORE_FAILURE) ||(brk < old_end && old_top != initial_top))return;sbrked_mem += sbrk_size;if (brk == old_end) /* can just add bytes to current top */{top_size = sbrk_size + old_top_size;set_head(top, top_size | PREV_INUSE);}else{if (sbrk_base == (char*)(-1)) /* First time through. Record base */sbrk_base = brk;else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */sbrked_mem += brk - (char*)old_end;/* Guarantee alignment of first new chunk made from this space */front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;if (front_misalign > 0){correction = (MALLOC_ALIGNMENT) - front_misalign;brk += correction;}elsecorrection = 0;/* Guarantee the next brk will be at a page boundary */correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) &~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size));/* Allocate correction */new_brk = (char*)(MORECORE (correction));if (new_brk == (char*)(MORECORE_FAILURE)) return;sbrked_mem += correction;top = (mchunkptr)brk;top_size = new_brk - brk + correction;set_head(top, top_size | PREV_INUSE);if (old_top != initial_top){/* There must have been an intervening foreign sbrk call. *//* A double fencepost is necessary to prevent consolidation *//* If not enough space to do this, then user did something very wrong */if (old_top_size < MINSIZE){set_head(top, PREV_INUSE); /* will force null return from malloc */return;}/* Also keep size a multiple of MALLOC_ALIGNMENT */old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;set_head_size(old_top, old_top_size);chunk_at_offset(old_top, old_top_size )->size =SIZE_SZ|PREV_INUSE;chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =SIZE_SZ|PREV_INUSE;/* If possible, release the rest. */if (old_top_size >= MINSIZE)fREe(chunk2mem(old_top));}}if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)max_sbrked_mem = sbrked_mem;if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)max_total_mem = mmapped_mem + sbrked_mem;/* We always land on a page boundary */assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0);
}/* Main public routines *//*Malloc Algorthim:The requested size is first converted into a usable form, `nb'.This currently means to add 4 bytes overhead plus possibly more toobtain 8-byte alignment and/or to obtain a size of at leastMINSIZE (currently 16 bytes), the smallest allocatable size.(All fits are considered `exact' if they are within MINSIZE bytes.)From there, the first successful of the following steps is taken:1. The bin corresponding to the request size is scanned, and ifa chunk of exactly the right size is found, it is taken.2. The most recently remaindered chunk is used if it is bigenough. This is a form of (roving) first fit, used only inthe absence of exact fits. Runs of consecutive requests usethe remainder of the chunk used for the previous such requestwhenever possible. This limited use of a first-fit styleallocation strategy tends to give contiguous chunkscoextensive lifetimes, which improves locality and can reducefragmentation in the long run.3. Other bins are scanned in increasing size order, using achunk big enough to fulfill the request, and splitting offany remainder. This search is strictly by best-fit; i.e.,the smallest (with ties going to approximately the leastrecently used) chunk that fits is selected.4. If large enough, the chunk bordering the end of memory(`top') is split off. (This use of `top' is in accord withthe best-fit search rule. In effect, `top' is treated aslarger (and thus less well fitting) than any other availablechunk since it can be extended to be as large as necessary(up to system limitations).5. If the request size meets the mmap threshold and thesystem supports mmap, and there are few enough currentlyallocated mmapped regions, and a call to mmap succeeds,the request is allocated via direct memory mapping.6. Otherwise, the top of memory is extended byobtaining more space from the system (normally using sbrk,but definable to anything else via the MORECORE macro).Memory is gathered from the system (in system page-sizedunits) in a way that allows chunks obtained across differentsbrk calls to be consolidated, but does not requirecontiguous memory. Thus, it should be safe to interspersemallocs with other sbrk calls.All allocations are made from the the `lowest' part of any foundchunk. (The implementation invariant is that prev_inuse isalways true of any allocated chunk; i.e., that each allocatedchunk borders either a previously allocated and still in-use chunk,or the base of its memory arena.)*/#if __STD_C
Void_t* mALLOc(size_t bytes)
#else
Void_t* mALLOc(bytes) size_t bytes;
#endif
{mchunkptr victim; /* inspected/selected chunk */INTERNAL_SIZE_T victim_size; /* its size */int idx; /* index for bin traversal */mbinptr bin; /* associated bin */mchunkptr remainder; /* remainder from a split */long remainder_size; /* its size */int remainder_index; /* its bin index */unsigned long block; /* block traverser bit */int startidx; /* first bin of a traversed block */mchunkptr fwd; /* misc temp for linking */mchunkptr bck; /* misc temp for linking */mbinptr q; /* misc temp */INTERNAL_SIZE_T nb;/* check if mem_malloc_init() was run */if ((mem_malloc_start == 0) && (mem_malloc_end == 0)) {/* not initialized yet */return 0;}if ((long)bytes < 0) return 0;nb = request2size(bytes); /* padded request size; *//* Check for exact match in a bin */if (is_small_request(nb)) /* Faster version for small requests */{idx = smallbin_index(nb);/* No traversal or size check necessary for small bins. */q = bin_at(idx);victim = last(q);/* Also scan the next one, since it would have a remainder < MINSIZE */if (victim == q){q = next_bin(q);victim = last(q);}if (victim != q){victim_size = chunksize(victim);unlink(victim, bck, fwd);set_inuse_bit_at_offset(victim, victim_size);check_malloced_chunk(victim, nb);return chunk2mem(victim);}idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */}else{idx = bin_index(nb);bin = bin_at(idx);for (victim = last(bin); victim != bin; victim = victim->bk){victim_size = chunksize(victim);remainder_size = victim_size - nb;if (remainder_size >= (long)MINSIZE) /* too big */{--idx; /* adjust to rescan below after checking last remainder */break;}else if (remainder_size >= 0) /* exact fit */{unlink(victim, bck, fwd);set_inuse_bit_at_offset(victim, victim_size);check_malloced_chunk(victim, nb);return chunk2mem(victim);}}++idx;}/* Try to use the last split-off remainder */if ( (victim = last_remainder->fd) != last_remainder){victim_size = chunksize(victim);remainder_size = victim_size - nb;if (remainder_size >= (long)MINSIZE) /* re-split */{remainder = chunk_at_offset(victim, nb);set_head(victim, nb | PREV_INUSE);link_last_remainder(remainder);set_head(remainder, remainder_size | PREV_INUSE);set_foot(remainder, remainder_size);check_malloced_chunk(victim, nb);return chunk2mem(victim);}clear_last_remainder;if (remainder_size >= 0) /* exhaust */{set_inuse_bit_at_offset(victim, victim_size);check_malloced_chunk(victim, nb);return chunk2mem(victim);}/* Else place in bin */frontlink(victim, victim_size, remainder_index, bck, fwd);}/*If there are any possibly nonempty big-enough blocks,search for best fitting chunk by scanning bins in blockwidth units.*/if ( (block = idx2binblock(idx)) <= binblocks_r){/* Get to the first marked block */if ( (block & binblocks_r) == 0){/* force to an even block boundary */idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;block <<= 1;while ((block & binblocks_r) == 0){idx += BINBLOCKWIDTH;block <<= 1;}}/* For each possibly nonempty block ... */for (;;){startidx = idx; /* (track incomplete blocks) */q = bin = bin_at(idx);/* For each bin in this block ... */do{/* Find and use first big enough chunk ... */for (victim = last(bin); victim != bin; victim = victim->bk){victim_size = chunksize(victim);remainder_size = victim_size - nb;if (remainder_size >= (long)MINSIZE) /* split */{remainder = chunk_at_offset(victim, nb);set_head(victim, nb | PREV_INUSE);unlink(victim, bck, fwd);link_last_remainder(remainder);set_head(remainder, remainder_size | PREV_INUSE);set_foot(remainder, remainder_size);check_malloced_chunk(victim, nb);return chunk2mem(victim);}else if (remainder_size >= 0) /* take */{set_inuse_bit_at_offset(victim, victim_size);unlink(victim, bck, fwd);check_malloced_chunk(victim, nb);return chunk2mem(victim);}}bin = next_bin(bin);} while ((++idx & (BINBLOCKWIDTH - 1)) != 0);/* Clear out the block bit. */do /* Possibly backtrack to try to clear a partial block */{if ((startidx & (BINBLOCKWIDTH - 1)) == 0){av_[1] = (mbinptr)(binblocks_r & ~block);break;}--startidx;q = prev_bin(q);} while (first(q) == q);/* Get to the next possibly nonempty block */if ( (block <<= 1) <= binblocks_r && (block != 0) ){while ((block & binblocks_r) == 0){idx += BINBLOCKWIDTH;block <<= 1;}}elsebreak;}}/* Try to use top chunk *//* Require that there be a remainder, ensuring top always exists */if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE){#if HAVE_MMAP/* If big and would otherwise need to extend, try to use mmap instead */if ((unsigned long)nb >= (unsigned long)mmap_threshold &&(victim = mmap_chunk(nb)) != 0)return chunk2mem(victim);
#endif/* Try to extend */malloc_extend_top(nb);if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)return 0; /* propagate failure */}victim = top;set_head(victim, nb | PREV_INUSE);top = chunk_at_offset(victim, nb);set_head(top, remainder_size | PREV_INUSE);check_malloced_chunk(victim, nb);return chunk2mem(victim);}/*free() algorithm :cases:1. free(0) has no effect.2. If the chunk was allocated via mmap, it is release via munmap().3. If a returned chunk borders the current high end of memory,it is consolidated into the top, and if the total unusedtopmost memory exceeds the trim threshold, malloc_trim iscalled.4. Other chunks are consolidated as they arrive, andplaced in corresponding bins. (This includes the case ofconsolidating with the current `last_remainder').*/#if __STD_C
void fREe(Void_t* mem)
#else
void fREe(mem) Void_t* mem;
#endif
{mchunkptr p; /* chunk corresponding to mem */INTERNAL_SIZE_T hd; /* its head field */INTERNAL_SIZE_T sz; /* its size */int idx; /* its bin index */mchunkptr next; /* next contiguous chunk */INTERNAL_SIZE_T nextsz; /* its size */INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */mchunkptr bck; /* misc temp for linking */mchunkptr fwd; /* misc temp for linking */int islr; /* track whether merging with last_remainder */if (mem == 0) /* free(0) has no effect */return;p = mem2chunk(mem);hd = p->size;#if HAVE_MMAPif (hd & IS_MMAPPED) /* release mmapped memory. */{munmap_chunk(p);return;}
#endifcheck_inuse_chunk(p);sz = hd & ~PREV_INUSE;next = chunk_at_offset(p, sz);nextsz = chunksize(next);if (next == top) /* merge with top */{sz += nextsz;if (!(hd & PREV_INUSE)) /* consolidate backward */{prevsz = p->prev_size;p = chunk_at_offset(p, -((long) prevsz));sz += prevsz;unlink(p, bck, fwd);}set_head(p, sz | PREV_INUSE);top = p;if ((unsigned long)(sz) >= (unsigned long)trim_threshold)malloc_trim(top_pad);return;}set_head(next, nextsz); /* clear inuse bit */islr = 0;if (!(hd & PREV_INUSE)) /* consolidate backward */{prevsz = p->prev_size;p = chunk_at_offset(p, -((long) prevsz));sz += prevsz;if (p->fd == last_remainder) /* keep as last_remainder */islr = 1;elseunlink(p, bck, fwd);}if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */{sz += nextsz;if (!islr && next->fd == last_remainder) /* re-insert last_remainder */{islr = 1;link_last_remainder(p);}elseunlink(next, bck, fwd);}set_head(p, sz | PREV_INUSE);set_foot(p, sz);if (!islr)frontlink(p, sz, idx, bck, fwd);
}/*Realloc algorithm:Chunks that were obtained via mmap cannot be extended or shrunkunless HAVE_MREMAP is defined, in which case mremap is used.Otherwise, if their reallocation is for additional space, they arecopied. If for less, they are just left alone.Otherwise, if the reallocation is for additional space, and thechunk can be extended, it is, else a malloc-copy-free sequence istaken. There are several different ways that a chunk could beextended. All are tried:* Extending forward into following adjacent free chunk.* Shifting backwards, joining preceding adjacent space* Both shifting backwards and extending forward.* Extending into newly sbrked spaceUnless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with asize argument of zero (re)allocates a minimum-sized chunk.If the reallocation is for less space, and the new request is fora `small' (<512 bytes) size, then the newly unused space is loppedoff and freed.The old unix realloc convention of allowing the last-free'd chunkto be used as an argument to realloc is no longer supported.I don't know of any programs still relying on this feature,and allowing it would also allow too many other incorrectusages of realloc to be sensible.*/#if __STD_C
Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
#else
Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
#endif
{INTERNAL_SIZE_T nb; /* padded request size */mchunkptr oldp; /* chunk corresponding to oldmem */INTERNAL_SIZE_T oldsize; /* its size */mchunkptr newp; /* chunk to return */INTERNAL_SIZE_T newsize; /* its size */Void_t* newmem; /* corresponding user mem */mchunkptr next; /* next contiguous chunk after oldp */INTERNAL_SIZE_T nextsize; /* its size */mchunkptr prev; /* previous contiguous chunk before oldp */INTERNAL_SIZE_T prevsize; /* its size */mchunkptr remainder; /* holds split off extra space from newp */INTERNAL_SIZE_T remainder_size; /* its size */mchunkptr bck; /* misc temp for linking */mchunkptr fwd; /* misc temp for linking */#ifdef REALLOC_ZERO_BYTES_FREESif (bytes == 0) { fREe(oldmem); return 0; }
#endifif ((long)bytes < 0) return 0;/* realloc of null is supposed to be same as malloc */if (oldmem == 0) return mALLOc(bytes);newp = oldp = mem2chunk(oldmem);newsize = oldsize = chunksize(oldp);nb = request2size(bytes);#if HAVE_MMAPif (chunk_is_mmapped(oldp)){
#if HAVE_MREMAPnewp = mremap_chunk(oldp, nb);if(newp) return chunk2mem(newp);
#endif/* Note the extra SIZE_SZ overhead. */if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing *//* Must alloc, copy, free. */newmem = mALLOc(bytes);if (newmem == 0) return 0; /* propagate failure */MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);munmap_chunk(oldp);return newmem;}
#endifcheck_inuse_chunk(oldp);if ((long)(oldsize) < (long)(nb)){/* Try expanding forward */next = chunk_at_offset(oldp, oldsize);if (next == top || !inuse(next)){nextsize = chunksize(next);/* Forward into top only if a remainder */if (next == top){if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE)){newsize += nextsize;top = chunk_at_offset(oldp, nb);set_head(top, (newsize - nb) | PREV_INUSE);set_head_size(oldp, nb);return chunk2mem(oldp);}}/* Forward into next chunk */else if (((long)(nextsize + newsize) >= (long)(nb))){unlink(next, bck, fwd);newsize += nextsize;goto split;}}else{next = 0;nextsize = 0;}/* Try shifting backwards. */if (!prev_inuse(oldp)){prev = prev_chunk(oldp);prevsize = chunksize(prev);/* try forward + backward first to save a later consolidation */if (next != 0){/* into top */if (next == top){if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE)){unlink(prev, bck, fwd);newp = prev;newsize += prevsize + nextsize;newmem = chunk2mem(newp);MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);top = chunk_at_offset(newp, nb);set_head(top, (newsize - nb) | PREV_INUSE);set_head_size(newp, nb);return newmem;}}/* into next chunk */else if (((long)(nextsize + prevsize + newsize) >= (long)(nb))){unlink(next, bck, fwd);unlink(prev, bck, fwd);newp = prev;newsize += nextsize + prevsize;newmem = chunk2mem(newp);MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);goto split;}}/* backward only */if (prev != 0 && (long)(prevsize + newsize) >= (long)nb){unlink(prev, bck, fwd);newp = prev;newsize += prevsize;newmem = chunk2mem(newp);MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);goto split;}}/* Must allocate */newmem = mALLOc (bytes);if (newmem == 0) /* propagate failure */return 0;/* Avoid copy if newp is next chunk after oldp. *//* (This can only happen when new chunk is sbrk'ed.) */if ( (newp = mem2chunk(newmem)) == next_chunk(oldp)){newsize += chunksize(newp);newp = oldp;goto split;}/* Otherwise copy, free, and exit */MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);fREe(oldmem);return newmem;}split: /* split off extra room in old or expanded chunk */if (newsize - nb >= MINSIZE) /* split off remainder */{remainder = chunk_at_offset(newp, nb);remainder_size = newsize - nb;set_head_size(newp, nb);set_head(remainder, remainder_size | PREV_INUSE);set_inuse_bit_at_offset(remainder, remainder_size);fREe(chunk2mem(remainder)); /* let free() deal with it */}else{set_head_size(newp, newsize);set_inuse_bit_at_offset(newp, newsize);}check_inuse_chunk(newp);return chunk2mem(newp);
}/*memalign algorithm:memalign requests more than enough space from malloc, finds a spotwithin that chunk that meets the alignment request, and thenpossibly frees the leading and trailing space.The alignment argument must be a power of two. This property is notchecked by memalign, so misuse may result in random runtime errors.8-byte alignment is guaranteed by normal malloc calls, so don'tbother calling memalign with an argument of 8 or less.Overreliance on memalign is a sure way to fragment space.*/#if __STD_C
Void_t* mEMALIGn(size_t alignment, size_t bytes)
#else
Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
#endif
{INTERNAL_SIZE_T nb; /* padded request size */char* m; /* memory returned by malloc call */mchunkptr p; /* corresponding chunk */char* brk; /* alignment point within p */mchunkptr newp; /* chunk to return */INTERNAL_SIZE_T newsize; /* its size */INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */mchunkptr remainder; /* spare room at end to split off */long remainder_size; /* its size */if ((long)bytes < 0) return 0;/* If need less alignment than we give anyway, just relay to malloc */if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);/* Otherwise, ensure that it is at least a minimum chunk size */if (alignment < MINSIZE) alignment = MINSIZE;/* Call malloc with worst case padding to hit alignment. */nb = request2size(bytes);m = (char*)(mALLOc(nb + alignment + MINSIZE));if (m == 0) return 0; /* propagate failure */p = mem2chunk(m);if ((((unsigned long)(m)) % alignment) == 0) /* aligned */{
#if HAVE_MMAPif(chunk_is_mmapped(p))return chunk2mem(p); /* nothing more to do */
#endif}else /* misaligned */{/*Find an aligned spot inside chunk.Since we need to give back leading space in a chunk of atleast MINSIZE, if the first calculation places us ata spot with less than MINSIZE leader, we can move to thenext aligned spot -- we've allocated enough total room so thatthis is always possible.*/brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment));if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment;newp = (mchunkptr)brk;leadsize = brk - (char*)(p);newsize = chunksize(p) - leadsize;#if HAVE_MMAPif(chunk_is_mmapped(p)){newp->prev_size = p->prev_size + leadsize;set_head(newp, newsize|IS_MMAPPED);return chunk2mem(newp);}
#endif/* give back leader, use the rest */set_head(newp, newsize | PREV_INUSE);set_inuse_bit_at_offset(newp, newsize);set_head_size(p, leadsize);fREe(chunk2mem(p));p = newp;assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);}/* Also give back spare room at the end */remainder_size = chunksize(p) - nb;if (remainder_size >= (long)MINSIZE){remainder = chunk_at_offset(p, nb);set_head(remainder, remainder_size | PREV_INUSE);set_head_size(p, nb);fREe(chunk2mem(remainder));}check_inuse_chunk(p);return chunk2mem(p);}/*valloc just invokes memalign with alignment argument equalto the page size of the system (or as near to this as canbe figured out from all the includes/defines above.)
*/#if __STD_C
Void_t* vALLOc(size_t bytes)
#else
Void_t* vALLOc(bytes) size_t bytes;
#endif
{return mEMALIGn (malloc_getpagesize, bytes);
}/*pvalloc just invokes valloc for the nearest pagesizethat will accommodate request
*/#if __STD_C
Void_t* pvALLOc(size_t bytes)
#else
Void_t* pvALLOc(bytes) size_t bytes;
#endif
{size_t pagesize = malloc_getpagesize;return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
}/*calloc calls malloc, then zeroes out the allocated chunk.*/#if __STD_C
Void_t* cALLOc(size_t n, size_t elem_size)
#else
Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
#endif
{mchunkptr p;INTERNAL_SIZE_T csz;INTERNAL_SIZE_T sz = n * elem_size;/* check if expand_top called, in which case don't need to clear */
#if MORECORE_CLEARSmchunkptr oldtop = top;INTERNAL_SIZE_T oldtopsize = chunksize(top);
#endifVoid_t* mem = mALLOc (sz);if ((long)n < 0) return 0;if (mem == 0)return 0;else{p = mem2chunk(mem);/* Two optional cases in which clearing not necessary */#if HAVE_MMAPif (chunk_is_mmapped(p)) return mem;
#endifcsz = chunksize(p);#if MORECORE_CLEARSif (p == oldtop && csz > oldtopsize){/* clear only the bytes from non-freshly-sbrked memory */csz = oldtopsize;}
#endifMALLOC_ZERO(mem, csz - SIZE_SZ);return mem;}
}/*cfree just calls free. It is needed/defined on some systemsthat pair it with calloc, presumably for odd historical reasons.*/#if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__)
#if __STD_C
void cfree(Void_t *mem)
#else
void cfree(mem) Void_t *mem;
#endif
{fREe(mem);
}
#endif/*Malloc_trim gives memory back to the system (via negativearguments to sbrk) if there is unused memory at the `high' end ofthe malloc pool. You can call this after freeing large blocks ofmemory to potentially reduce the system-level memory requirementsof a program. However, it cannot guarantee to reduce memory. Undersome allocation patterns, some large free blocks of memory will belocked between two used chunks, so they cannot be given back tothe system.The `pad' argument to malloc_trim represents the amount of freetrailing space to leave untrimmed. If this argument is zero,only the minimum amount of memory to maintain internal datastructures will be left (one page or less). Non-zero argumentscan be supplied to maintain enough trailing space to servicefuture expected allocations without having to re-obtain memoryfrom the system.Malloc_trim returns 1 if it actually released any memory, else 0.*/#if __STD_C
int malloc_trim(size_t pad)
#else
int malloc_trim(pad) size_t pad;
#endif
{long top_size; /* Amount of top-most memory */long extra; /* Amount to release */char* current_brk; /* address returned by pre-check sbrk call */char* new_brk; /* address returned by negative sbrk call */unsigned long pagesz = malloc_getpagesize;top_size = chunksize(top);extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;if (extra < (long)pagesz) /* Not enough memory to release */return 0;else{/* Test to make sure no one else called sbrk */current_brk = (char*)(MORECORE (0));if (current_brk != (char*)(top) + top_size)return 0; /* Apparently we don't own memory; must fail */else{new_brk = (char*)(MORECORE (-extra));if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */{/* Try to figure out what we have */current_brk = (char*)(MORECORE (0));top_size = current_brk - (char*)top;if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */{sbrked_mem = current_brk - sbrk_base;set_head(top, top_size | PREV_INUSE);}check_chunk(top);return 0;}else{/* Success. Adjust top accordingly. */set_head(top, (top_size - extra) | PREV_INUSE);sbrked_mem -= extra;check_chunk(top);return 1;}}}
}/*malloc_usable_size:This routine tells you how many bytes you can actually use in anallocated chunk, which may be more than you requested (althoughoften not). You can use this many bytes without worrying aboutoverwriting other allocated objects. Not a particularly greatprogramming practice, but still sometimes useful.*/#if __STD_C
size_t malloc_usable_size(Void_t* mem)
#else
size_t malloc_usable_size(mem) Void_t* mem;
#endif
{mchunkptr p;if (mem == 0)return 0;else{p = mem2chunk(mem);if(!chunk_is_mmapped(p)){if (!inuse(p)) return 0;check_inuse_chunk(p);return chunksize(p) - SIZE_SZ;}return chunksize(p) - 2*SIZE_SZ;}
}/* Utility to update current_mallinfo for malloc_stats and mallinfo() */#ifdef DEBUG
static void malloc_update_mallinfo()
{int i;mbinptr b;mchunkptr p;
#ifdef DEBUGmchunkptr q;
#endifINTERNAL_SIZE_T avail = chunksize(top);int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;for (i = 1; i < NAV; ++i){b = bin_at(i);for (p = last(b); p != b; p = p->bk){
#ifdef DEBUGcheck_free_chunk(p);for (q = next_chunk(p);q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE;q = next_chunk(q))check_inuse_chunk(q);
#endifavail += chunksize(p);navail++;}}current_mallinfo.ordblks = navail;current_mallinfo.uordblks = sbrked_mem - avail;current_mallinfo.fordblks = avail;current_mallinfo.hblks = n_mmaps;current_mallinfo.hblkhd = mmapped_mem;current_mallinfo.keepcost = chunksize(top);}
#endif /* DEBUG *//*malloc_stats:Prints on the amount of space obtain from the system (bothvia sbrk and mmap), the maximum amount (which may be more thancurrent if malloc_trim and/or munmap got called), the maximumnumber of simultaneous mmap regions used, and the current numberof bytes allocated via malloc (or realloc, etc) but not yetfreed. (Note that this is the number of bytes allocated, not thenumber requested. It will be larger than the number requestedbecause of alignment and bookkeeping overhead.)*/#ifdef DEBUG
void malloc_stats()
{malloc_update_mallinfo();printf("max system bytes = %10u\n",(unsigned int)(max_total_mem));printf("system bytes = %10u\n",(unsigned int)(sbrked_mem + mmapped_mem));printf("in use bytes = %10u\n",(unsigned int)(current_mallinfo.uordblks + mmapped_mem));
#if HAVE_MMAPprintf("max mmap regions = %10u\n",(unsigned int)max_n_mmaps);
#endif
}
#endif /* DEBUG *//*mallinfo returns a copy of updated current mallinfo.
*/#ifdef DEBUG
struct mallinfo mALLINFo()
{malloc_update_mallinfo();return current_mallinfo;
}
#endif /* DEBUG *//*mallopt:mallopt is the general SVID/XPG interface to tunable parameters.The format is to provide a (parameter-number, parameter-value) pair.mallopt then sets the corresponding parameter to the argumentvalue if it can (i.e., so long as the value is meaningful),and returns 1 if successful else 0.See descriptions of tunable parameters above.*/#if __STD_C
int mALLOPt(int param_number, int value)
#else
int mALLOPt(param_number, value) int param_number; int value;
#endif
{switch(param_number){case M_TRIM_THRESHOLD:trim_threshold = value; return 1;case M_TOP_PAD:top_pad = value; return 1;case M_MMAP_THRESHOLD:mmap_threshold = value; return 1;case M_MMAP_MAX:
#if HAVE_MMAPn_mmaps_max = value; return 1;
#elseif (value != 0) return 0; else n_mmaps_max = value; return 1;
#endifdefault:return 0;}
}int raise(int signum)
{return 0;
}/*History:V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee)* return null for negative arguments* Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com>* Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'(e.g. WIN32 platforms)* Cleanup up header file inclusion for WIN32 platforms* Cleanup code to avoid Microsoft Visual C++ compiler complaints* Add 'USE_DL_PREFIX' to quickly allow co-existence with existingmemory allocation routines* Set 'malloc_getpagesize' for WIN32 platforms (needs more work)* Use 'assert' rather than 'ASSERT' in WIN32 code to conform tousage of 'assert' in non-WIN32 code* Improve WIN32 'sbrk()' emulation's 'findRegion()' routine toavoid infinite loop* Always call 'fREe()' rather than 'free()'V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)* Fixed ordering problem with boundary-stampingV2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)* Added pvalloc, as recommended by H.J. Liu* Added 64bit pointer support mainly from Wolfram Gloger* Added anonymously donated WIN32 sbrk emulation* Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen* malloc_extend_top: fix mask error that caused wastage afterforeign sbrks* Add linux mremap support code from HJ LiuV2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)* Integrated most documentation with the code.* Add support for mmap, with help fromWolfram Gloger (Gloger@lrz.uni-muenchen.de).* Use last_remainder in more cases.* Pack bins using idea from colin@nyx10.cs.du.edu* Use ordered bins instead of best-fit threshhold* Eliminate block-local decls to simplify tracing and debugging.* Support another case of realloc via move into top* Fix error occuring when initial sbrk_base not word-aligned.* Rely on page size for units instead of SBRK_UNIT toavoid surprises about sbrk alignment conventions.* Add mallinfo, mallopt. Thanks to Raymond Nijssen(raymond@es.ele.tue.nl) for the suggestion.* Add `pad' argument to malloc_trim and top_pad mallopt parameter.* More precautions for cases where other routines call sbrk,courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).* Added macros etc., allowing use in linux libc fromH.J. Lu (hjl@gnu.ai.mit.edu)* Inverted this history listV2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)* Re-tuned and fixed to behave more nicely with V2.6.0 changes.* Removed all preallocation code since under current schemethe work required to undo bad preallocations exceedsthe work saved in good cases for most test programs.* No longer use return list or unconsolidated bins sinceno scheme using them consistently outperforms those that don'tgiven above changes.* Use best fit for very large chunks to prevent some worst-cases.* Added some support for debuggingV2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)* Removed footers when chunks are in use. Thanks toPaul Wilson (wilson@cs.texas.edu) for the suggestion.V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)* Added malloc_trim, with help from Wolfram Gloger(wmglo@Dent.MED.Uni-Muenchen.DE).V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)* realloc: try to expand in both directions* malloc: swap order of clean-bin strategy;* realloc: only conditionally expand backwards* Try not to scavenge used bins* Use bin counts as a guide to preallocation* Occasionally bin return list chunks in first scan* Add a few optimizations from colin@nyx10.cs.du.eduV2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)* faster bin computation & slightly different binning* merged all consolidations to one part of malloc proper(eliminating old malloc_find_space & malloc_clean_bin)* Scan 2 returns chunks (not just 1)* Propagate failure in realloc if malloc returns 0* Add stuff to allow compilation on non-ANSI compilersfrom kpv@research.att.comV2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)* removed potential for odd address access in prev_chunk* removed dependency on getpagesize.h* misc cosmetics and a bit more internal documentation* anticosmetics: mangled names in macros to evade debugger strangeness* tested on sparc, hp-700, dec-mips, rs6000with gcc & native cc (hp, dec only) allowingDetlefs & Zorn comparison study (in SIGPLAN Notices.)Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)* Based loosely on libg++-1.2X malloc. (It retains some of the overallstructure of old version, but most details differ.)*/
===============================================================================================
//malloc.h
/*A version of malloc/free/realloc written by Doug Lea and released to thepublic domain. Send questions/comments/complaints/performance datato dl@cs.oswego.edu* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)Note: There may be an updated version of this malloc obtainable atftp://g.oswego.edu/pub/misc/malloc.cCheck before installing!* Why use this malloc?This is not the fastest, most space-conserving, most portable, ormost tunable malloc ever written. However it is among the fastestwhile also being among the most space-conserving, portable and tunable.Consistent balance across these factors results in a good general-purposeallocator. For a high-level description, seehttp://g.oswego.edu/dl/html/malloc.html* Synopsis of public routines(Much fuller descriptions are contained in the program documentation below.)malloc(size_t n);Return a pointer to a newly allocated chunk of at least n bytes, or nullif no space is available.free(Void_t* p);Release the chunk of memory pointed to by p, or no effect if p is null.realloc(Void_t* p, size_t n);Return a pointer to a chunk of size n that contains the same dataas does chunk p up to the minimum of (n, p's size) bytes, or nullif no space is available. The returned pointer may or may not bethe same as p. If p is null, equivalent to malloc. Unless the#define REALLOC_ZERO_BYTES_FREES below is set, realloc with asize argument of zero (re)allocates a minimum-sized chunk.memalign(size_t alignment, size_t n);Return a pointer to a newly allocated chunk of n bytes, alignedin accord with the alignment argument, which must be a power oftwo.valloc(size_t n);Equivalent to memalign(pagesize, n), where pagesize is the pagesize of the system (or as near to this as can be figured out fromall the includes/defines below.)pvalloc(size_t n);Equivalent to valloc(minimum-page-that-holds(n)), that is,round up n to nearest pagesize.calloc(size_t unit, size_t quantity);Returns a pointer to quantity * unit bytes, with all locationsset to zero.cfree(Void_t* p);Equivalent to free(p).malloc_trim(size_t pad);Release all but pad bytes of freed top-most memory backto the system. Return 1 if successful, else 0.malloc_usable_size(Void_t* p);Report the number usable allocated bytes associated with allocatedchunk p. This may or may not report more bytes than were requested,due to alignment and minimum size constraints.malloc_stats();Prints brief summary statistics on stderr.mallinfo()Returns (by copy) a struct containing various summary statistics.mallopt(int parameter_number, int parameter_value)Changes one of the tunable parameters described below. Returns1 if successful in changing the parameter, else 0.* Vital statistics:Alignment: 8-byte8 byte alignment is currently hardwired into the design. Thisseems to suffice for all current machines and C compilers.Assumed pointer representation: 4 or 8 bytesCode for 8-byte pointers is untested by me but has workedreliably by Wolfram Gloger, who contributed most of thechanges supporting this.Assumed size_t representation: 4 or 8 bytesNote that size_t is allowed to be 4 bytes even if pointers are 8.Minimum overhead per allocated chunk: 4 or 8 bytesEach malloced chunk has a hidden overhead of 4 bytes holding sizeand status information.Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)8-byte ptrs: 24/32 bytes (including, 4/8 overhead)When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byteptrs but 4 byte size) or 24 (for 8/8) additional bytes areneeded; 4 (8) for a trailing size fieldand 8 (16) bytes for free list pointers. Thus, the minimumallocatable size is 16/24/32 bytes.Even a request for zero bytes (i.e., malloc(0)) returns apointer to something of the minimum allocatable size.Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes8-byte size_t: 2^63 - 16 bytesIt is assumed that (possibly signed) size_t bit values suffice torepresent chunk sizes. `Possibly signed' is due to the factthat `size_t' may be defined on a system as either a signed oran unsigned type. To be conservative, values that would appearas negative numbers are avoided.Requests for sizes with a negative sign bit when the requestsize is treaded as a long will return null.Maximum overhead wastage per allocated chunk: normally 15 bytesAlignnment demands, plus the minimum allocatable size restrictionmake the normal worst-case wastage 15 bytes (i.e., up to 15more bytes will be allocated than were requested in malloc), withtwo exceptions:1. Because requests for zero bytes allocate non-zero space,the worst case wastage for a request of zero bytes is 24 bytes.2. For requests >= mmap_threshold that are serviced viammap(), the worst case wastage is 8 bytes plus the remainderfrom a system page (the minimal mmap unit); typically 4096 bytes.* LimitationsHere are some features that are NOT currently supported* No user-definable hooks for callbacks and the like.* No automated mechanism for fully checking that all accessesto malloced memory stay within their bounds.* No support for compaction.* Synopsis of compile-time options:People have reported using previous versions of this malloc on allversions of Unix, sometimes by tweaking some of the definesbelow. It has been tested most extensively on Solaris andLinux. It is also reported to work on WIN32 platforms.People have also reported adapting this malloc for use instand-alone embedded systems.The implementation is in straight, hand-tuned ANSI C. Among otherconsequences, it uses a lot of macros. Because of this, to be atall usable, this code should be compiled using an optimizing compiler(for example gcc -O2) that can simplify expressions and controlpaths.__STD_C (default: derived from C compiler defines)Nonzero if using ANSI-standard C compiler, a C++ compiler, ora C compiler sufficiently close to ANSI to get away with it.DEBUG (default: NOT defined)Define to enable debugging. Adds fairly extensive assertion-basedchecking to help track down memory errors, but noticeably slows downexecution.REALLOC_ZERO_BYTES_FREES (default: NOT defined)Define this if you think that realloc(p, 0) should be equivalentto free(p). Otherwise, since malloc returns a unique pointer formalloc(0), so does realloc(p, 0).HAVE_MEMCPY (default: defined)Define if you are not otherwise using ANSI STD C, but stillhave memcpy and memset in your C library and want to use them.Otherwise, simple internal versions are supplied.USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)Define as 1 if you want the C library versions of memset andmemcpy called in realloc and calloc (otherwise macro versions are used).At least on some platforms, the simple macro versions usuallyoutperform libc versions.HAVE_MMAP (default: defined as 1)Define to non-zero to optionally make malloc() use mmap() toallocate very large blocks.HAVE_MREMAP (default: defined as 0 unless Linux libc set)Define to non-zero to optionally make realloc() use mremap() toreallocate very large blocks.malloc_getpagesize (default: derived from system #includes)Either a constant or routine call returning the system page size.HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)Optionally define if you are on a system with a /usr/include/malloc.hthat declares struct mallinfo. It is not at all necessary todefine this even if you do, but will ensure consistency.INTERNAL_SIZE_T (default: size_t)Define to a 32-bit type (probably `unsigned int') if you are on a64-bit machine, yet do not want or need to allow malloc requests ofgreater than 2^31 to be handled. This saves space, especially forvery small chunks.INTERNAL_LINUX_C_LIB (default: NOT defined)Defined only when compiled as part of Linux libc.Also note that there is some odd internal name-mangling via defines(for example, internally, `malloc' is named `mALLOc') neededwhen compiling in this case. These look funny but don't otherwiseaffect anything.WIN32 (default: undefined)Define this on MS win (95, nt) platforms to compile in sbrk emulation.LACKS_UNISTD_H (default: undefined if not WIN32)Define this if your system does not have a <unistd.h>.LACKS_SYS_PARAM_H (default: undefined if not WIN32)Define this if your system does not have a <sys/param.h>.MORECORE (default: sbrk)The name of the routine to call to obtain more memory from the system.MORECORE_FAILURE (default: -1)The value returned upon failure of MORECORE.MORECORE_CLEARS (default 1)true (1) if the routine mapped to MORECORE zeroes out memory (whichholds for sbrk).DEFAULT_TRIM_THRESHOLDDEFAULT_TOP_PADDEFAULT_MMAP_THRESHOLDDEFAULT_MMAP_MAXDefault values of tunable parameters (described in detail below)controlling interaction with host system routines (sbrk, mmap, etc).These values may also be changed dynamically via mallopt(). Thepreset defaults are those that give best performance for typicalprograms/systems.USE_DL_PREFIX (default: undefined)Prefix all public routines with the string 'dl'. Useful toquickly avoid procedure declaration conflicts and linker symbolconflicts with existing memory allocation routines.*/#ifndef __MALLOC_H__
#define __MALLOC_H__/* Preliminaries */#ifndef __STD_C
#ifdef __STDC__
#define __STD_C 1
#else
#if __cplusplus
#define __STD_C 1
#else
#define __STD_C 0
#endif /*__cplusplus*/
#endif /*__STDC__*/
#endif /*__STD_C*/#ifndef Void_t
#if (__STD_C || defined(WIN32))
#define Void_t void
#else
#define Void_t char
#endif
#endif /*Void_t*/#if __STD_C
//#include <linux/stddef.h> /* for size_t */
typedef unsigned int size_t;
#else
#include <sys/types.h>
#endif /* __STD_C */#ifdef __cplusplus
extern "C" {
#endif#if 0 /* not for U-Boot */
#include <stdio.h> /* needed for malloc_stats */
#endif/*Compile-time options
*//*Debugging:Because freed chunks may be overwritten with link fields, thismalloc will often die when freed memory is overwritten by userprograms. This can be very effective (albeit in an annoying way)in helping track down dangling pointers.If you compile with -DDEBUG, a number of assertion checks areenabled that will catch more memory errors. You probably won't beable to make much sense of the actual assertion errors, but theyshould help you locate incorrectly overwritten memory. Thechecking is fairly extensive, and will slow down executionnoticeably. Calling malloc_stats or mallinfo with DEBUG set willattempt to check every non-mmapped allocated and free chunk in thecourse of computing the summmaries. (By nature, mmapped regionscannot be checked very much automatically.)Setting DEBUG may also be helpful if you are trying to modifythis code. The assertions in the check routines spell out in moredetail the assumptions and invariants underlying the algorithms.*/#if DEBUG
#include <assert.h>
#else
#define assert(x) ((void)0)
#endif/*INTERNAL_SIZE_T is the word-size used for internal bookkeepingof chunk sizes. On a 64-bit machine, you can reduce mallocoverhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'at the expense of not being able to handle requests greater than2^31. This limitation is hardly ever a concern; you are encouragedto set this. However, the default version is the same as size_t.
*/#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif/*REALLOC_ZERO_BYTES_FREES should be set if a call torealloc with zero bytes should be the same as a call to free.Some people think it should. Otherwise, since this mallocreturns a unique pointer for malloc(0), so does realloc(p, 0).
*//* #define REALLOC_ZERO_BYTES_FREES *//*WIN32 causes an emulation of sbrk to be compiled inmmap-based options are not currently supported in WIN32.
*//* #define WIN32 */
#ifdef WIN32
#define MORECORE wsbrk
#define HAVE_MMAP 0#define LACKS_UNISTD_H
#define LACKS_SYS_PARAM_H/*Include 'windows.h' to get the necessary declarations for theMicrosoft Visual C++ data structures and routines used in the 'sbrk'emulation.Define WIN32_LEAN_AND_MEAN so that only the essential MicrosoftVisual C++ header files are included.
*/
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif/*HAVE_MEMCPY should be defined if you are not otherwise usingANSI STD C, but still have memcpy and memset in your C libraryand want to use them in calloc and realloc. Otherwise simplemacro versions are defined here.USE_MEMCPY should be defined as 1 if you actually want tohave memset and memcpy called. People report that the macroversions are often enough faster than libc versions on manysystems that it is better to use them.*/#define HAVE_MEMCPY#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif#if (__STD_C || defined(HAVE_MEMCPY))#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
#else
#ifdef WIN32
/* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
/* 'windows.h' */
#else
Void_t* memset();
Void_t* memcpy();
#endif
#endif
#endif#if USE_MEMCPY/* The following macros are only invoked with (2n+1)-multiples ofINTERNAL_SIZE_T units, with a positive integer n. This is exploitedfor fast inline execution when n is small. */#define MALLOC_ZERO(charp, nbytes) \
do { \INTERNAL_SIZE_T mzsz = (nbytes); \if(mzsz <= 9*sizeof(mzsz)) { \INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \*mz++ = 0; \if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \*mz++ = 0; \if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \*mz++ = 0; }}} \*mz++ = 0; \*mz++ = 0; \*mz = 0; \} else memset((charp), 0, mzsz); \
} while(0)#define MALLOC_COPY(dest,src,nbytes) \
do { \INTERNAL_SIZE_T mcsz = (nbytes); \if(mcsz <= 9*sizeof(mcsz)) { \INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; \if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; \if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; }}} \*mcdst++ = *mcsrc++; \*mcdst++ = *mcsrc++; \*mcdst = *mcsrc ; \} else memcpy(dest, src, mcsz); \
} while(0)#else /* !USE_MEMCPY *//* Use Duff's device for good zeroing/copying performance. */#define MALLOC_ZERO(charp, nbytes) \
do { \INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \switch (mctmp) { \case 0: for(;;) { *mzp++ = 0; \case 7: *mzp++ = 0; \case 6: *mzp++ = 0; \case 5: *mzp++ = 0; \case 4: *mzp++ = 0; \case 3: *mzp++ = 0; \case 2: *mzp++ = 0; \case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \} \
} while(0)#define MALLOC_COPY(dest,src,nbytes) \
do { \INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \switch (mctmp) { \case 0: for(;;) { *mcdst++ = *mcsrc++; \case 7: *mcdst++ = *mcsrc++; \case 6: *mcdst++ = *mcsrc++; \case 5: *mcdst++ = *mcsrc++; \case 4: *mcdst++ = *mcsrc++; \case 3: *mcdst++ = *mcsrc++; \case 2: *mcdst++ = *mcsrc++; \case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \} \
} while(0)#endif/*Define HAVE_MMAP to optionally make malloc() use mmap() toallocate very large blocks. These will be returned to theoperating system immediately after a free().
*//***
#ifndef HAVE_MMAP
#define HAVE_MMAP 1
#endif
***/
#undef HAVE_MMAP /* Not available for U-Boot *//*Define HAVE_MREMAP to make realloc() use mremap() to re-allocatelarge blocks. This is currently only possible on Linux withkernel versions newer than 1.3.77.
*//***
#ifndef HAVE_MREMAP
#ifdef INTERNAL_LINUX_C_LIB
#define HAVE_MREMAP 1
#else
#define HAVE_MREMAP 0
#endif
#endif
***/
#undef HAVE_MREMAP /* Not available for U-Boot */#ifdef HAVE_MMAP#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif#endif /* HAVE_MMAP *//*Access to system page size. To the extent possible, this mallocmanages memory from the system in page-size units.The following mechanics for getpagesize were adapted frombsd/gnu getpagesize.h
*/#define LACKS_UNISTD_H /* Shortcut for U-Boot */
#define malloc_getpagesize 4096#ifndef LACKS_UNISTD_H
# include <unistd.h>
#endif#ifndef malloc_getpagesize
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
# ifndef _SC_PAGE_SIZE
# define _SC_PAGE_SIZE _SC_PAGESIZE
# endif
# endif
# ifdef _SC_PAGE_SIZE
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
# else
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)extern size_t getpagesize();
# define malloc_getpagesize getpagesize()
# else
# ifdef WIN32
# define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
# else
# ifndef LACKS_SYS_PARAM_H
# include <sys/param.h>
# endif
# ifdef EXEC_PAGESIZE
# define malloc_getpagesize EXEC_PAGESIZE
# else
# ifdef NBPG
# ifndef CLSIZE
# define malloc_getpagesize NBPG
# else
# define malloc_getpagesize (NBPG * CLSIZE)
# endif
# else
# ifdef NBPC
# define malloc_getpagesize NBPC
# else
# ifdef PAGESIZE
# define malloc_getpagesize PAGESIZE
# else
# define malloc_getpagesize (4096) /* just guess */
# endif
# endif
# endif
# endif
# endif
# endif
# endif
#endif/*This version of malloc supports the standard SVID/XPG mallinforoutine that returns a struct containing the same kind ofinformation you can get from malloc_stats. It should work onany SVID/XPG compliant system that has a /usr/include/malloc.hdefining struct mallinfo. (If you'd like to install such a thingyourself, cut out the preliminary declarations as described aboveand below and save them in a malloc.h file. But there's nocompelling reason to bother to do this.)The main declaration needed is the mallinfo struct that is returned(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains abunch of fields, most of which are not even meaningful in thisversion of malloc. Some of these fields are are instead filled bymallinfo() with other numbers that might possibly be of interest.HAVE_USR_INCLUDE_MALLOC_H should be set if you have a/usr/include/malloc.h file that includes a declaration of structmallinfo. If so, it is included; else an SVID2/XPG2 compliantversion is declared below. These must be precisely the same formallinfo() to work.*//* #define HAVE_USR_INCLUDE_MALLOC_H */#ifdef HAVE_USR_INCLUDE_MALLOC_H
#include "/usr/include/malloc.h"
#else/* SVID2/XPG mallinfo structure */struct mallinfo {int arena; /* total space allocated from system */int ordblks; /* number of non-inuse chunks */int smblks; /* unused -- always zero */int hblks; /* number of mmapped regions */int hblkhd; /* total space in mmapped regions */int usmblks; /* unused -- always zero */int fsmblks; /* unused -- always zero */int uordblks; /* total allocated space */int fordblks; /* total non-inuse space */int keepcost; /* top-most, releasable (via malloc_trim) space */
};/* SVID2/XPG mallopt options */#define M_MXFAST 1 /* UNUSED in this malloc */
#define M_NLBLKS 2 /* UNUSED in this malloc */
#define M_GRAIN 3 /* UNUSED in this malloc */
#define M_KEEP 4 /* UNUSED in this malloc */#endif/* mallopt options that actually do something */#define M_TRIM_THRESHOLD -1
#define M_TOP_PAD -2
#define M_MMAP_THRESHOLD -3
#define M_MMAP_MAX -4#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif/*M_TRIM_THRESHOLD is the maximum amount of unused top-most memoryto keep before releasing via malloc_trim in free().Automatic trimming is mainly useful in long-lived programs.Because trimming via sbrk can be slow on some systems, and cansometimes be wasteful (in cases where programs immediatelyafterward allocate more large chunks) the value should be highenough so that your overall system performance would improve byreleasing.The trim threshold and the mmap control parameters (see below)can be traded off with one another. Trimming and mmapping aretwo different ways of releasing unused memory back to thesystem. Between these two, it is often possible to keepsystem-level demands of a long-lived program down to a bareminimum. For example, in one test suite of sessions measuringthe XF86 X server on Linux, using a trim threshold of 128K and ammap threshold of 192K led to near-minimal long term resourceconsumption.If you are using this malloc in a long-lived program, it shouldpay to experiment with these values. As a rough guide, youmight set to a value close to the average size of a process(program) running on your system. Releasing this much memorywould allow such a process to run in memory. Generally, it'sworth it to tune for trimming rather tham memory mapping when aprogram undergoes phases where several large chunks areallocated and released in ways that can reuse each other'sstorage, perhaps mixed with phases where there are no suchchunks at all. And in well-behaved long-lived programs,controlling release of large blocks via trimming versus mappingis usually faster.However, in most programs, these parameters serve mainly asprotection against the system-level effects of carrying aroundmassive amounts of unneeded memory. Since frequent calls tosbrk, mmap, and munmap otherwise degrade performance, the defaultparameters are set to relatively high values that serve only assafeguards.The default trim value is high enough to cause trimming only infairly extreme (by current memory consumption standards) cases.It must be greater than page size to have any useful effect. Todisable trimming completely, you can set to (unsigned long)(-1);*/#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif/*M_TOP_PAD is the amount of extra `padding' space to allocate orretain whenever sbrk is called. It is used in two ways internally:* When sbrk is called to extend the top of the arena to satisfya new malloc request, this much padding is added to the sbrkrequest.* When malloc_trim is called automatically from free(),it is used as the `pad' argument.In both cases, the actual amount of padding is roundedso that the end of the arena is always a system page boundary.The main reason for using padding is to avoid calling sbrk sooften. Having even a small pad greatly reduces the likelihoodthat nearly every malloc request during program start-up (orafter trimming) will invoke sbrk, which needlessly wastestime.Automatic rounding-up to page-size units is normally sufficientto avoid measurable overhead, so the default is 0. However, insystems where sbrk is relatively slow, it can pay to increasethis value, at the expense of carrying around more memory thanthe program needs.*/#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
#endif/*M_MMAP_THRESHOLD is the request size threshold for using mmap()to service a request. Requests of at least this size that cannotbe allocated using already-existing space will be serviced via mmap.(If enough normal freed space already exists it is used instead.)Using mmap segregates relatively large chunks of memory so thatthey can be individually obtained and released from the hostsystem. A request serviced through mmap is never reused by anyother request (at least not directly; the system may just sohappen to remap successive requests to the same locations).Segregating space in this way has the benefit that mmapped spacecan ALWAYS be individually released back to the system, whichhelps keep the system level memory demands of a long-livedprogram low. Mapped memory can never become `locked' betweenother chunks, as can happen with normally allocated chunks, whichmenas that even trimming via malloc_trim would not release them.However, it has the disadvantages that:1. The space cannot be reclaimed, consolidated, and thenused to service later requests, as happens with normal chunks.2. It can lead to more wastage because of mmap page alignmentrequirements3. It causes malloc performance to be more dependent on hostsystem memory management support routines which may vary inimplementation quality and may impose arbitrarylimitations. Generally, servicing a request via normalmalloc steps is faster than going through a system's mmap.All together, these considerations should lead you to use mmaponly for relatively large requests.*/#ifndef DEFAULT_MMAP_MAX
#ifdef HAVE_MMAP
#define DEFAULT_MMAP_MAX (64)
#else
#define DEFAULT_MMAP_MAX (0)
#endif
#endif/*M_MMAP_MAX is the maximum number of requests to simultaneouslyservice using mmap. This parameter exists because:1. Some systems have a limited number of internal tables foruse by mmap.2. In most systems, overreliance on mmap can degrade overallperformance.3. If a program allocates many large regions, it is probablybetter off using normal sbrk-based allocation routines thatcan reclaim and reallocate normal heap memory. Using asmall value allows transition into this mode after thefirst few allocations.Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,the default value is 0, and attempts to set it to non-zero valuesin mallopt will fail.
*//*USE_DL_PREFIX will prefix all public routines with the string 'dl'.Useful to quickly avoid procedure declaration conflicts and linkersymbol conflicts with existing memory allocation routines.*//* #define USE_DL_PREFIX *//*Special defines for linux libcExcept when compiled using these special defines for Linux libcusing weak aliases, this malloc is NOT designed to work inmultithreaded applications. No semaphores or other concurrencycontrol are provided to ensure that multiple malloc or free callsdon't run at the same time, which could be disasterous. A singlesemaphore could be used across malloc, realloc, and free (which isessentially the effect of the linux weak alias approach). It wouldbe hard to obtain finer granularity.*/#ifdef INTERNAL_LINUX_C_LIB#if __STD_CVoid_t * __default_morecore_init (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;#elseVoid_t * __default_morecore_init ();
Void_t *(*__morecore)() = __default_morecore_init;#endif#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
#define MORECORE_CLEARS 1#else /* INTERNAL_LINUX_C_LIB */#if __STD_C
extern Void_t* sbrk(int);
#else
extern Void_t* sbrk();
#endif#ifndef MORECORE
#define MORECORE sbrk
#endif#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE -1
#endif#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif#endif /* INTERNAL_LINUX_C_LIB */#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)#define cALLOc __libc_calloc
#define fREe __libc_free
#define mALLOc __libc_malloc
#define mEMALIGn __libc_memalign
#define rEALLOc __libc_realloc
#define vALLOc __libc_valloc
#define pvALLOc __libc_pvalloc
#define mALLINFo __libc_mallinfo
#define mALLOPt __libc_mallopt#pragma weak calloc = __libc_calloc
#pragma weak free = __libc_free
#pragma weak cfree = __libc_free
#pragma weak malloc = __libc_malloc
#pragma weak memalign = __libc_memalign
#pragma weak realloc = __libc_realloc
#pragma weak valloc = __libc_valloc
#pragma weak pvalloc = __libc_pvalloc
#pragma weak mallinfo = __libc_mallinfo
#pragma weak mallopt = __libc_mallopt#else#ifdef USE_DL_PREFIX
#define cALLOc dlcalloc
#define fREe dlfree
#define mALLOc dlmalloc
#define mEMALIGn dlmemalign
#define rEALLOc dlrealloc
#define vALLOc dlvalloc
#define pvALLOc dlpvalloc
#define mALLINFo dlmallinfo
#define mALLOPt dlmallopt
#else /* USE_DL_PREFIX */
#define cALLOc calloc
#define fREe free
#define mALLOc malloc
#define mEMALIGn memalign
#define rEALLOc realloc
#define vALLOc valloc
#define pvALLOc pvalloc
#define mALLINFo mallinfo
#define mALLOPt mallopt
#endif /* USE_DL_PREFIX */#endif/* Public routines */#if __STD_CVoid_t* mALLOc(size_t);
void fREe(Void_t*);
Void_t* rEALLOc(Void_t*, size_t);
Void_t* mEMALIGn(size_t, size_t);
Void_t* vALLOc(size_t);
Void_t* pvALLOc(size_t);
Void_t* cALLOc(size_t, size_t);
void cfree(Void_t*);
int malloc_trim(size_t);
size_t malloc_usable_size(Void_t*);
void malloc_stats(void);
int mALLOPt(int, int);
struct mallinfo mALLINFo(void);
#else
Void_t* mALLOc();
void fREe();
Void_t* rEALLOc();
Void_t* mEMALIGn();
Void_t* vALLOc();
Void_t* pvALLOc();
Void_t* cALLOc();
void cfree();
int malloc_trim();
size_t malloc_usable_size();
void malloc_stats();
int mALLOPt();
struct mallinfo mALLINFo();
#endif/** Begin and End of memory area for malloc(), and current "brk"*/
extern unsigned long mem_malloc_start;
extern unsigned long mem_malloc_end;
extern unsigned long mem_malloc_brk;void mem_malloc_init(unsigned long start, unsigned long size);#ifdef __cplusplus
}; /* end of extern "C" */
#endif#endif /* __MALLOC_H__ */
===============================================================================================
PC环境上模拟验证：
//test.c:
#include <stdio.h>
#include "malloc.h"
void main(void)
{
char testbuf[0x10000];
unsigned long base = (unsigned long)&testbuf[0];
printf("%lx\n",base);
mem_malloc_init(base,0x8000);
char *buf=malloc(100);
sprintf(buf,"hello\n");
printf("%s",buf);
}
===============================================================================================
编译及结果如下：
ubuntu@ubuntu:~/uboot/compo/malloc实现$ gcc -c dlmalloc.c -o dlmalloc.o
ubuntu@ubuntu:~/uboot/compo/malloc实现$ gcc -c test.c -o test.o
ubuntu@ubuntu:~/uboot/compo/malloc实现$ gcc dlmalloc.o test.o -o test
ubuntu@ubuntu:~/uboot/compo/malloc实现$ ./test
bfc5996c
hello
ubuntu@ubuntu:~/uboot/compo/malloc实现$
注：以上dlmalloc.c、malloc.h、test.c放在同一个目录下。
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