我在使用

gcc编写用C语言编写的信号处理程序时遇到错误,在出现Segmentation fault之后显示转储的寄存器值.当我尝试使用代码访问它时：

void print_registers(FILE *fd, ucontext_t *ctx, bool fpu = false)

{

const char *flags_str[] = {

"CF", 0, "PF", 0, "AF", 0, "ZF", "SF", "TP", "IF", "DF",

"OF", 0, 0, "NT", 0, "RF", "VM", "AC", "VIF", "VIP", "ID"

};

greg_t *regs = ctx->uc_mcontext.gregs;

void *eip[1] = { (void*)regs[REG_EIP] };

char **symbol = backtrace_symbols(eip, 1);

fprintf(fd, "Registers:\neip is at ");

backtrace_symbols_fd(eip, 1, fd->_fileno);

size_type flags = regs[REG_EFL];

fprintf(fd, "eflags: %x [ ", flags);

for (size_type i = 0; i < sizeof(flags_str) / sizeof(flags_str[0]); ++i) {

if (!flags_str[i]) continue;

if (flags & (1 << i)) fprintf(fd, "%s ", flags_str[i]);

}

size_type iopl = (flags & 0x3000) >> 12;

fprintf(fd, "] iopl: %i\n"

"eax: %08x\tebx: %08x\tecx: %08x\tedx: %08x\n"

"esi: %08x\tedi: %08x\tebp: %08x\tesp: %08x\n"

"cs: %04x\tgs: %04x\tfs: %04x\n"

"ds: %04x\tes: %04x\tss: %04x\n",

iopl,

regs[REG_EAX], regs[REG_EBX], regs[REG_ECX], regs[REG_EDX],

regs[REG_ESI], regs[REG_EDI], regs[REG_EBP], regs[REG_ESP],

regs[REG_CS], regs[REG_GS], regs[REG_FS],

regs[REG_DS], regs[REG_ES], regs[REG_SS]);

}

}

我通过添加尝试了代码

#include

以及

#define _GNU_SOURCE

#ifndef REG_EIP

#define REG_EIP 0x23b46F

#endif

但是,出现的错误是：

‘REG_EIP’ undeclared (first use in this function)

(Each undeclared identifier is reported only once for each function it appears in.)

并且所有寄存器都出现错误

我尝试了很多文件……但无法得到解决方案.

任何人都可以共享解决此错误的详细信息.

感谢所有的回复者

在包含< ucontext.h之前尝试定义__USE_GNU：

#define __USE_GNU

#include

您不需要包含< sys / ucontext.h>显式,< ucontext.h>会这样做的.