模拟实现ls命令

#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <errno.h>
#include <sys/stat.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>

int main(int argc, char* argv[])
{
    if (argc != 2)
    {
        printf("Usage : ls path
");
        return 0;
    }

    char path[256] = {0};
    strcpy(path, argv[1]);

    int l = strlen(path);
    if (path[l - 1] != '/')
        path[l] = '/';

    DIR* d = opendir(path);
    if (!d)
    {
        printf("Failed to open path : %s
", strerror(errno));
        return 0;
    }

    char cp[256];
    while (dirent* ent = readdir(d))
    {
        memset(cp, 0, sizeof(cp));
        strcpy(cp, path);
        strcat(cp, ent->d_name);

        struct stat s;
        stat(cp, &s);

        if (S_ISDIR(s.st_mode))
            printf("d");
        else if (S_ISCHR(s.st_mode))
            printf("c");
        else if (S_ISBLK(s.st_mode))
            printf("b");
        else if (S_ISFIFO(s.st_mode))
            printf("c");
        else if (S_ISLNK(s.st_mode))
            printf("l");
        else if (S_ISSOCK(s.st_mode))
            printf("c");
        else
            printf("-");

        if (s.st_mode & S_IRUSR)
            printf("r");
        else
            printf("-");

        if (s.st_mode & S_IWUSR)
            printf("w");
        else
            printf("-");

        if (s.st_mode & S_IXUSR)
            printf("x");
        else
            printf("-");

        if (s.st_mode & S_IRGRP)
            printf("r");
        else
            printf("-");

        if (s.st_mode & S_IWGRP)
            printf("w");
        else
            printf("-");

        if (s.st_mode & S_IXGRP)
            printf("x");
        else
            printf("-");

        if (s.st_mode & S_IROTH)
            printf("r");
        else
            printf("-");

        if (s.st_mode & S_IWOTH)
            printf("w");
        else
            printf("-");

        if (s.st_mode & S_IXOTH)
            printf("x");
        else
            printf("-");

        struct passwd* pwd = getpwuid(s.st_uid);
        struct group* grp = getgrgid(s.st_gid);
        printf(" %6ld %s %s %10ld %s
", s.st_nlink, pwd->pw_name, grp->gr_name, s.st_size, ent->d_name);
    }
    return 0;
}