记录器在尝试打开 ofstream 时收到分段错误

Question

当我尝试为 Logger class 打开文件时抛出的一些 SIGSEGV 遇到了一些麻烦。我已经使用这个 class 一段时间了，但这是我第一次得到这个。从像以前这样的简单行开始：

 LOG(logDEBUG) << "Node " << nodeId << " in link layer state waitAck.";

我从 strace 得到这个：

open("simulation.log", O_WRONLY|O_CREAT|O_APPEND, 0666) = 3
lseek(3, 0, SEEK_END)                   = 16380108
--- SIGSEGV {si_signo=SIGSEGV, si_code=SI_KERNEL, si_addr=NULL} ---
+++ killed by SIGSEGV (core dumped) +++

得到这个 gdb：

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7210289 in malloc_consolidate () from /usr/lib/libc.so.6
(gdb) backtrace
#0  0x00007ffff7210289 in malloc_consolidate () from /usr/lib/libc.so.6
#1  0x00007ffff7211d2a in _int_malloc () from /usr/lib/libc.so.6
#2  0x00007ffff7213d44 in malloc () from /usr/lib/libc.so.6
#3  0x00007ffff7ae1a48 in operator new (sz=8192)
    at /build/gcc/src/gcc/libstdc++-v3/libsupc++/new_op.cc:50
#4  0x00007ffff7ae1af5 in operator new[] (sz=<optimized out>)
    at /build/gcc/src/gcc/libstdc++-v3/libsupc++/new_opv.cc:32
#5  0x00007ffff7b41698 in std::basic_filebuf<char, std::char_traits<char> >::_M_allocate_internal_buffer
    (this=0x7fffffffdc68)
    at /build/gcc/src/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/fstream.tcc:55
#6  0x00007ffff7b45932 in std::basic_filebuf<char, std::char_traits<char> >::open (this=0x7fffffffdc68,
    __s=0x690550 <Log::fileName[abi:cxx11]+16> "simulation.log", __mode=17)
    at /build/gcc/src/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/fstream.tcc:187
#7  0x00007ffff7b45a53 in std::basic_filebuf<char, std::char_traits<char> >::open (
    __mode=<optimized out>, __s=..., this=0x7fffffffdc68)
    at /build/gcc/src/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/fstream:308
#8  std::basic_ofstream<char, std::char_traits<char> >::open (this=0x7fffffffdc60, __s=...,
    __mode=<optimized out>)
    at /build/gcc/src/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/fstream:823
#9  0x0000000000421c33 in Log::Log (this=0x7fffffffdc60) at src/log.cpp:21
#10 0x0000000000446198 in LinkCsma::iterate2Receive (this=0x6a9440, t=@0x7fffffffe1fc: 9387)
    at src/link_csma.cpp:329
#11 0x00000000004232a4 in Node::iterate2Receive (this=0x6a52f0, t=@0x7fffffffe1fc: 9387)
    at src/node.cpp:550
#12 0x000000000042f2bc in DirectionalNodes::iterate (this=0x6a6eb0, t=@0x7fffffffe1fc: 9387)
    at src/directional_nodes.cpp:250
#13 0x0000000000460ce5 in Simulation::run (this=0x6a6f00) at src/simulation.cpp:184
#14 0x0000000000429e8c in main (argc=1, argv=0x7fffffffe878) at src/main.cpp:65

日志中的代码 class 是：

#ifndef LOG_H__
#define LOG_H__

#include <fstream>
#include <sstream>
#include <string>
#include <cstdio>
#include <ctime>

#ifdef DEBUG
    #define LOG(level) \
    Log().write(level)
#else
    #define LOG(level) \
    if(level >= logDEBUG) ; \
    else Log().write(level)
#endif

enum LogLevel {
    logERROR,
    logWARNING,
    logINFO,
    logDEBUG
};

class Log
{
    public:
        Log();
        ~Log();
        static void setFile(const std::string& s);
        std::ofstream& write(LogLevel level = logINFO);
    protected:
        std::ofstream fileStream;
    private:
        Log(const Log&);
        Log& operator =(const Log&);
        std::string level2String(LogLevel level);
        std::string timeString();

        static std::string fileName;
        static const std::string DEFAULT_LOG_FILE;
};

#endif //LOG_H__

并且：

#include "../include/log.h"

using namespace std;

string Log::fileName;
const string Log::DEFAULT_LOG_FILE = "logfile.log";

Log::Log()
{
    fileStream.open(fileName, ios::out | ios::app);
}

Log::~Log()
{
    fileStream << endl;
    flush(fileStream);
    fileStream.close();
}

std::string Log::level2String(LogLevel level)
{
    static const char* const buffer[] = { "ERROR", "WARNING", "INFO", "DEBUG" };
    return buffer[level];
}

void Log::setFile(const std::string& s)
{
    fileName = s;
}

std::string Log::timeString()
{
    time_t t = time(0);
    struct tm * now = localtime(&t);
    stringstream ss;

    ss << now->tm_hour << ":" << now->tm_min << " "
        << now->tm_mday << "/" << (now->tm_mon+1) << "/" <<     (now->tm_year+1900);

    return ss.str();
}

std::ofstream& Log::write(LogLevel level)
{
    fileStream << timeString();
    fileStream << " " << level2String(level) << ":\t";
    return fileStream;
}

Answer 1

似乎我通过将输出从 ofstream 更改为 FILE* 并在使用 fprintf 写入 FILE* 之前使用 ostringstream 作为缓冲区来解决它。如图http://www.drdobbs.com/cpp/logging-in-c/201804215.

记录器在尝试打开 ofstream 时收到分段错误

Logger receiving segmentation fault when trying to open ofstream

c++

ofstream

segmentation-fault