我的realpath为文件返回null

时间:2015-11-05 17:15:09

标签: c unix realpath

我从C开始,我需要使用函数realpath,但我找不到很多例子。我帮助自己:link。 我当前的问题是我的函数适用于文件夹,但是当它是文件时,realpath返回null。

 while ((dir = readdir(rep)) != NULL)
    {
        if ( !strcmp(dir->d_name, ".") || !strcmp(dir->d_name, "..") )
            {
                // do nothing (straight logic)
        } else {
            char buf[_POSIX_PATH_MAX];
            char *path;
            path = realpath(dir->d_name, buf);
            if (!path)
            {
                    perror("realpath");
                    exit(EXIT_FAILURE);
            }
    }

编辑:我的功能的目的是为文件夹目录中的文件和文件夹设置任何绝对的实时路径

1 个答案:

答案 0 :(得分:1)

问题是您无法将当前目录作为realpath的名称的一部分传递。您不能简单地传递dir->d_name(这只是当前目录下的文件或子目录的名称)。您必须将dir->d_name(带strcat等)附加到您在opendir调用中使用的目录名称。例如:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <errno.h>
#include <unistd.h>

#ifndef _POSIX_PATH_MAX
#define _POSIX_PATH_MAX  512
#endif

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

    if (argc < 2) {
        fprintf (stderr, "error: insufficient arguments.  usage: %s dirname\n",
                argv[0]);
        return 1;
    }

    char *p = argv[1];
    size_t len = strlen (p);
    while (*p && p[len-1] == '/')
        p[--len] = 0;

    DIR *rep = opendir (p);
    struct dirent *dir = NULL;

    if (!rep) {
        fprintf (stderr, "error: opendir failed on '%s'\n", p);
        return 0;
    }

    while ((dir = readdir(rep)))
    {
        if ( !strcmp(dir->d_name, ".") || !strcmp(dir->d_name, "..") )
        {
            // do nothing (straight logic)
        }
        else {
            char buf[_POSIX_PATH_MAX] = {0};
            char entry[_POSIX_PATH_MAX] = {0};
            char *path = NULL;
            errno = 0;
            strcat (entry, p);
            strcat (entry, "/");
            strcat (entry, dir->d_name);
            printf ("getting realpath for : '%s'\n", entry);
            path = realpath (entry, buf);
            if (!path || errno)
            {
                perror("realpath");
                exit(EXIT_FAILURE);
            }
            else
                printf (" realpath for '%s' : %s\n", entry, buf);
        }
    }

    return 0;
}

注意具体来说:

    else {
        char buf[_POSIX_PATH_MAX] = {0};
        char entry[_POSIX_PATH_MAX] = {0};
        char *path = NULL;
        errno = 0;
        strcat (entry, p);
        strcat (entry, "/");
        strcat (entry, dir->d_name);
        printf ("getting realpath for : '%s'\n", entry);
        path = realpath (entry, buf);

其中entry是包含当前目录的字符串,分隔符为'/',最后为dir->_dname

示例/输出

$ ./bin/realpathtst debug
getting realpath for : 'debug/ptrrtn.c'
 realpath for 'debug/ptrrtn.c' : /home/david/dev/src-c/tmp/debug/ptrrtn.c
getting realpath for : 'debug/structinit.c'
 realpath for 'debug/structinit.c' : /home/david/dev/src-c/tmp/debug/structinit.c
getting realpath for : 'debug/leetcode.c'
 realpath for 'debug/leetcode.c' : /home/david/dev/src-c/tmp/debug/leetcode.c