为什么使用信号处理程序在此代码中会出现分段错误？答案

【问题标题】：Why do I get a segmentation fault in this code with a signal handler?为什么使用信号处理程序在此代码中会出现分段错误？
【发布时间】：2020-05-03 20:55:19
【问题描述】：

我在我的程序中编写了一个信号处理程序，但是在这个文件结构中我遇到了分段错误。但如果一切都在一个文件中，那么一切正常。据我了解，它无法访问返回地址。我该如何解决？

“测试.h”

#ifndef TEST_H
#define TEST_H
#include <string.h>
#include <setjmp.h>
#include <signal.h>
static jmp_buf g_env;
void sig_handler(int sig);
endif TEST_H

“test.c”

#include "test.h"
void sig_handler(int sig) {
  psignal(sig, "Signal");
  siglongjmp(g_env, 1);
}

“main.c”

#include "test.h"
int main(void) {
  struct sigaction act;
  memset(&act, 0, sizeof(act));
  act.sa_handler = sig_handler;
  sigemptyset(&act.sa_mask);
  sigaddset(&act.sa_mask, SIGSEGV);
  sigaction(SIGSEGV, &act, 0);

  if (!sigsetjmp(g_env, 1)) {
    raise(SIGSEGV);
  }
  return (1);
}

“结果：”

Signal: Segmentation fault
Segmentation fault (core dumped)

“瓦尔格林：”

==44698== Command: ./a.out
==44698==
Signal: Segmentation fault
==44698== Warning: client switching stacks?  SP change: 0x1ffeffee08 --> 0xf7c1f413060a2966
==44698==          to suppress, use: --max-stackframe=593925450715481250 or greater
==44698== Jump to the invalid address stated on the next line
==44698==    at 0xF7C1F413060A2966: ???
==44698==  Address 0xf7c1f413060a2966 is not stack'd, malloc'd or (recently) free'd
==44698==
==44698==
==44698== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==44698==  Bad permissions for mapped region at address 0xF7C1F413060A2966
==44698==    at 0xF7C1F413060A2966: ???
==44698== Invalid write of size 8
==44698==    at 0x482F120: _vgnU_freeres (vg_preloaded.c:59)
==44698==  Address 0xf7c1f413060a295e is not stack'd, malloc'd or (recently) free'd
==44698==
==44698==
==44698== Process terminating with default action of signal 11 (SIGSEGV)
==44698==  General Protection Fault
==44698==    at 0x482F120: _vgnU_freeres (vg_preloaded.c:59)

【问题讨论】：

标签： c segmentation-fault signals setjmp

【解决方案1】：

这是因为您有不同的 g_env 实例 - 每个翻译单元都有不同的 g_env。因此，sigsetjmp 中使用的 g_env 缓冲区与 siglongjmp 中使用的缓冲区不同。

只需将static 从以下位置删除：

static jmp_buf g_env;

现在，g_env 将只有一个全局实例。

【讨论】：