c - C 中 mkfifo() 产生的段错误

Question

我已经尝试调试这个问题几个小时了，但我仍然卡住了......

我在这段代码中遇到了“mkfifo”调用的段错误(它只是我整个代码的一部分，因为我认为其余部分与这里无关):

#include "marketfunc.h"
#include "error.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>

#define PIPE_PATH "./pipe.fifo"

struct myStruct
{
    int x;      
    int y;
    int z;  
};


struct myStruct *s;

int main(int argc, char **argv)
{

    s = malloc(sizeof(struct myStruct));

    // 'int marketfunc_init(int x)' is defined in a perfectly working extern library
    if(marketfunc_init(1) == -1) error("failed to initialize marketfunc library", 5);

    printf("test1\n");

    // Segmentation fault
    if(mkfifo(PIPE_PATH, 0666) == -1) error("failed to create pipe", 1);

    printf("test2\n");

    //...

}

这会产生以下输出(executableFile 是我的文件的名称):

test1
bin/executableFile: Segmentation fault (core dumped)

gdb 回溯产生以下结果:

#0  strchrnul () at ../sysdeps/x86_64/strchr.S:32
#1  0x00007ffff7a5ed82 in __find_specmb (format=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>)
    at printf-parse.h:108
#2  _IO_vfprintf_internal (s=0x7fffffffb5a0, format=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>, 
    ap=0x7fffffffdd58) at vfprintf.c:1332
#3  0x00007ffff7a63f31 in buffered_vfprintf (s=s@entry=0x7ffff7dd41c0 <_IO_2_1_stderr_>, 
    format=format@entry=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>, args=args@entry=0x7fffffffdd58)
    at vfprintf.c:2356
#4  0x00007ffff7a5eeae in _IO_vfprintf_internal (s=0x7ffff7dd41c0 <_IO_2_1_stderr_>, 
    format=format@entry=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>, ap=ap@entry=0x7fffffffdd58)
    at vfprintf.c:1313
#5  0x00007ffff7b0c595 in error_tail (status=status@entry=4199947, errnum=errnum@entry=1, 
    message=message@entry=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>, args=args@entry=0x7fffffffdd58)
    at error.c:201
#6  0x00007ffff7b0c6ed in __error (status=4199947, errnum=1, 
    message=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>) at error.c:251
#7  0x0000000000400b78 in main (argc=1, argv=0x7fffffffdf38) at src/executableFile.c:75

虽然创建了“pipe.fifo”文件...预先感谢您的帮助!

编辑:

error 在 error.c 中简单定义，它的签名在 error.h 中:

#include "error.h"
#include <stdlib.h>
#include <stdio.h>

void error(char *msg, int ret)
{
    perror(msg);
    exit(ret);
}

Answer 1

如果您查看堆栈跟踪，您将看到对 error() 的调用显示为:

0x00007ffff7b0c6ed in __error (status=4199947, errnum=1, message=0xffffffffffffff60 <error: Cannot access memory at address 0xffffffffffffff60>) at error.c:251

这不是您定义的error() 函数。相反，它是 error.h 中定义的 error() 函数，具有以下签名:

void error(int status, int errnum, const char *format, ...);

参见error.h .

如您所见，此函数需要 char* 格式 作为最后一个参数，这会从堆栈中获取一些垃圾 0xffffffffffffff60，因为您没有传递在第三个参数中。链接器似乎将对 error() 的调用解析为错误的函数。

作为快速修复，我将重命名如下:

rename your file `error.h` to `error_my.h`

your definition of `error()` to, say, `error_my()`

replace the calls to `error()` with `error_my()`.

您的代码如下所示:

#include "marketfunc.h"
#include "error_my.h" // <=======================
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>

#define PIPE_PATH "./pipe.fifo"

struct myStruct
{
    int x;      
    int y;
    int z;  
};


struct myStruct *s;

int main(int argc, char **argv)
{

    s = malloc(sizeof(struct myStruct));

    // 'int marketfunc_init(int x)' is defined in a perfectly working extern library
    if(marketfunc_init(1) == -1) error_my("failed to initialize marketfunc library", 5); // <=======================

    printf("test1\n");

    // Segmentation fault
    if(mkfifo(PIPE_PATH, 0666) == -1) error_my("failed to create pipe", 1); // <=======================

    printf("test2\n");

    //...

}

当 mkfifo() 无法找出失败的原因时，打印出 errno。