如何在系统崩溃时从C++中获取函数调用栈信息？

程序在执行过程中 crash 是非常严重的问题，一般都应该在测试阶段排除掉这些问题，但是总会有漏网之鱼被带到 release 阶段。

因此，程序的日志系统需要侦测这种情况，在代码崩溃的时候获取函数调用栈信息，为 debug 提供有效的信息。

这篇文章的理论知识很少，直接分享 2 段代码：在 Linux 和 Windows 这 2 个平台上，如何用C++ 来捕获函数调用栈里的信息。

1. 注册异常信号的处理函数
需要处理哪些异常信号

#include  
#include  
#include  
 
const std::map Signals = { 
    {SIGINT, "SIGINT"},     
    {SIGABRT, "SIGABRT"},  
    {SIGFPE, "SIGFPE"},    
    {SIGILL, "SIGILL"},   
    {SIGSEGV, "SIGSEGV"} 
    // 可以添加其他信号 
}; 

注册信号处理函数

struct sigaction action; 
sigemptyset(&action.sa_mask); 
action.sa_sigaction = &sigHandler; 
action.sa_flags = SA_SIGINFO;  
 
 for (const auto &sigPair : Signals) 
 { 
    if (sigaction(sigPair.first, &action, NULL) < 0) 
        fprintf(stderr, "Error: sigaction failed! /n"); 
 } 

2. 捕获异常，获取函数调用栈信息

void sigHandler(int signum, siginfo_t *info, void *ctx) 
{ 
    const size_t dump_size = 50; 
    void *array[dump_size]; 
    int size = backtrace(array, dump_size); 
    char **symbols = backtrace_symbols(array, size); 
    std::ostringstream oss; 
 
    for (int i = 0; i < size; ++i) 
    { 
        char *mangleName = 0; 
        char *offsetBegin = 0; 
        char *offsetEnd = 0; 
 
        for (char *p = symbols[i]; *p; ++p) 
        { 
            if ('(' == *p) 
            {    
                 mangleName = p; 
            }    
            else if ('+' == *p) 
            { 
                offsetBegin = p; 
            } 
            else if (')' == *p) 
            { 
                offsetEnd = p; 
                break; 
            } 
        } 
 
        if (mangleName && offsetBegin && offsetEnd && mangleName < offsetBegin) 
        { 
            *mangleName++ = '/0'; 
            *offsetBegin++ = '/0'; 
            *offsetEnd++ = '/0'; 
             
            int status; 
            char *realName = abi::__cxa_demangle(mangleName, 0, 0, &status); 
            if (0 == status) 
                oss << "/tstack dump [" << i << "]  " << symbols[i] << " : " << realName << "+"; 
            else 
                oss << "/tstack dump [" << i << "]  " << symbols[i] << mangleName << "+"; 
            oss << offsetBegin << offsetEnd << std::endl; 
            free(realName); 
        } 
        else 
        { 
            oss << "/tstack dump [" << i << "]  " << symbols[i] << std::endl; 
        } 
    } 
    free(symbols); 
    oss << std::endl; 
    std::cout << oss.str(); // 打印函数调用栈信息 
} 

在 Windows 平台下的代码实现，参考了国外某个老兄的代码，如下：

#include  
#include  
 
SetUnhandledExceptionFilter(exceptionHandler); 

void exceptionHandler(LPEXCEPTION_POINTERS info) 
{ 
    CONTEXT *context = info->ContextRecord; 
    std::shared_ptr RaiiSysCleaner(nullptr, [&](void *) { 
      SymCleanup(GetCurrentProcess()); 
    }); 
 
  const size_t dumpSize = 64; 
  std::vector frameVector(dumpSize); 
 
  DWORD machine_type = 0; 
  STACKFRAME64 frame = {}; 
  frame.AddrPC.Mode = AddrModeFlat; 
  frame.AddrFrame.Mode = AddrModeFlat; 
  frame.AddrStack.Mode = AddrModeFlat; 
 
#ifdef _M_IX86 
  frame.AddrPC.Offset = context->Eip; 
  frame.AddrFrame.Offset = context->Ebp; 
  frame.AddrStack.Offset = context->Esp; 
  machine_type = IMAGE_FILE_MACHINE_I386; 
#elif _M_X64 
  frame.AddrPC.Offset = context->Rip; 
  frame.AddrFrame.Offset = context->Rbp; 
  frame.AddrStack.Offset = context->Rsp; 
  machine_type = IMAGE_FILE_MACHINE_AMD64; 
#elif _M_IA64 
  frame.AddrPC.Offset = context->StIIP; 
  frame.AddrFrame.Offset = context->IntSp; 
  frame.AddrStack.Offset = context->IntSp; 
  machine_type = IMAGE_FILE_MACHINE_IA64; 
  frame.AddrBStore.Offset = context.RsBSP; 
  frame.AddrBStore.Mode = AddrModeFlat; 
#else 
  frame.AddrPC.Offset = context->Eip; 
  frame.AddrFrame.Offset = context->Ebp; 
  frame.AddrStack.Offset = context->Esp; 
  machine_type = IMAGE_FILE_MACHINE_I386; 
#endif 
 
  for (size_t index = 0; index < frameVector.size(); ++index) 
  { 
    if (StackWalk64(machine_type, 
           GetCurrentProcess(), 
           GetCurrentThread(), 
           &frame, 
           context, 
           NULL, 
           SymFunctionTableAccess64, 
           SymGetModuleBase64, 
           NULL)) { 
      frameVector[index] = frame.AddrPC.Offset; 
    } else { 
      break; 
    } 
  } 
 
  std::string dump; 
  const size_t kSize = frameVector.size(); 
  for (size_t index = 0; index < kSize && frameVector[index]; ++index) { 
    dump += getSymbolInfo(index, frameVector); 
    dump += "/n"; 
  } 
 
std::cout << dump;  
} 

主要是利用了 StackWalk64 这个函数，从地址转换为函数名称。

利用以上几个神器，基本上可以获取到程序崩溃时的函数调用栈信息，定位问题，有如神助!