c - 遍历目录并打印一些信息

Question

我想编写一个 C 程序，它将文件夹的路径作为参数并显示有关它包含的文件的一些信息。

到目前为止我已经写了这个:

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char** argv){
    char* dir_path = argv[1];
    char* dir_path_bar = strcat(dir_path, "/");
    DIR* dir = opendir(dir_path);

    for(struct dirent* entry = readdir(dir); entry != NULL; entry = readdir(dir)){
        printf("Next entry is %s\n", entry->d_name);
        char* entry_path = strcat(dir_path_bar, entry->d_name);
        printf("%s\n", entry_path);
        struct stat buf;
        stat(entry_path, &buf);
        printf("Its inode number is %s\n", entry->d_ino);
        printf("Its inode number is %s\n", buf.st_ino);
        printf("Its uid is %s\n", buf.st_uid);
        printf("Its size is %s bytes\n", buf.st_size);
    };
    closedir(dir);
}

可以编译，但是 stat 调用给我一个 SEGFAULT。这是怎么回事？

Answer 1

正如其他人所提到的，您不能附加到 argv[1]。您不能在循环内继续追加它。而且，您不能使用 %s 来输出数字。

这是您的代码，其中包含注释和修复的错误 [使用 #if 0 显示旧代码]:

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int
main(int argc, char **argv)
{
    char *dir_path = argv[1];

// NOTE/BUG: argv[1] has a fixed size you can't append to it
#if 0
    char *dir_path_bar = strcat(dir_path, "/");
#else
    char dir_path_bar[PATH_MAX];
    strcpy(dir_path_bar,dir_path);
    strcat(dir_path_bar,"/");
#endif

    DIR *dir = opendir(dir_path);
#if 1
    if (dir == NULL) {
        perror(dir_path);
        exit(1);
    }
#endif

    for (struct dirent *entry = readdir(dir); entry != NULL;
        entry = readdir(dir)) {
        printf("Next entry is %s\n", entry->d_name);

// NOTE/BUG: because you don't reset dir_path_bar, this just keeps appending
// to it
#if 0
        char *entry_path = strcat(dir_path_bar, entry->d_name);
#else
        char entry_path[PATH_MAX];
        strcpy(entry_path,dir_path_bar);
        strcat(entry_path,entry->d_name);
#endif

        printf("\n");
        printf("%s\n", entry_path);
        struct stat buf;

        stat(entry_path, &buf);

// NOTE/BUG: these need one or more of: %d/%ld/%lld (vs %s)
#if 0
        printf("Its inode number is %s\n", entry->d_ino);
        printf("Its inode number is %s\n", buf.st_ino);
        printf("Its uid is %s\n", buf.st_uid);
        printf("Its size is %s bytes\n", buf.st_size);
#else
        printf("Its inode number is %ld\n", entry->d_ino);
        printf("Its inode number is %ld\n", buf.st_ino);
        printf("Its uid is %d\n", buf.st_uid);
        printf("Its size is %ld bytes\n", buf.st_size);
#endif
    };

    closedir(dir);

    return 0;
}