在退出时关闭文件描述符是一个好习惯吗 [英] is it a good practice to close file descriptors on exit

问题描述

如果由于某种原因，我在程序中发现了致命的情况，并且我想退出并显示错误代码。
有时，致命错误的上下文不在其他文件描述符的范围内。
是关闭这些文件描述符的一个好习惯。
据我所知，这些文件在进程终止时会自动关闭。

If for some reason, I discover a fatal situation in my program, and I would like to exit with an error code. Sometimes, the context of the fatal error is outside the scope of other file-descriptors. is it a good practice to close these file descriptors. As far as I know, these files are automatically closed when the process dies.

推荐答案

文件会自动关闭，

请参见此示例中的valgrind

See valgrind on this example

david@debian:~$ cat demo.c
#include <stdio.h>

int main(void)
{
    FILE *f;

    f = fopen("demo.c", "r");
    return 0;
}
david@debian:~$ valgrind ./demo
==3959== Memcheck, a memory error detector
==3959== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==3959== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info
==3959== Command: ./demo
==3959== 
==3959== 
==3959== HEAP SUMMARY:
==3959==     in use at exit: 568 bytes in 1 blocks
==3959==   total heap usage: 1 allocs, 0 frees, 568 bytes allocated
==3959== 
==3959== LEAK SUMMARY:
==3959==    definitely lost: 0 bytes in 0 blocks
==3959==    indirectly lost: 0 bytes in 0 blocks
==3959==      possibly lost: 0 bytes in 0 blocks
==3959==    still reachable: 568 bytes in 1 blocks
==3959==         suppressed: 0 bytes in 0 blocks
==3959== Rerun with --leak-check=full to see details of leaked memory
==3959== 
==3959== For counts of detected and suppressed errors, rerun with: -v
==3959== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 4 from 4)

如您所见，它会引发内存泄漏

As you can see, it raises a memory leak

在某些情况下，您可以使用 atexit（）：

On some circumstances you can make use of atexit():

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

static FILE *f;

static void free_all(void)
{
    fclose(f);
}

static int check(void)
{
    return 0;
}

int main(void)
{
    atexit(free_all);
    f = fopen("demo.c", "r");
    if (!check()) exit(EXIT_FAILURE);
    /* more code */
    return 0;
}

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