实现代码

#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <dirent.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <string.h>

#include <time.h>

#include <pwd.h>

#include <grp.h>

#include <libgen.h>

#define ERR_EXIT(m) \

do\

{\

    perror(m);\

    exit(EXIT_FAILURE);\

}while(0)\

void lsdir(char *dirname);

void lsfile(char *filename);

void lsfile(char *filename);

char getFileType(struct stat *fstat);

void getFilePerm(struct stat *st, char *perm);

int main(int argc,char **argv)

{

if(argc != 2){

    fprintf(stderr,"usage:%s [filepath]\n",argv[0]);

    exit(EXIT_FAILURE);

}

struct stat fstat;

if(lstat(argv[1],&fstat) == -1)

    ERR_EXIT("STAT ERROR");

if(S_ISDIR(fstat.st_mode))

{

    lsdir(argv[1]);

}

else{

    lsfile(argv[1]);

}

return 0;

}

void lsdir(char *dirname)

{

DIR *dir;

char filename[100] = {0};

dir =opendir(dirname);

if(dir == NULL)

    ERR_EXIT("opendir error");

struct dirent *dentry;

while((dentry = readdir(dir)) != NULL)

{

    char *fname;

    fname = dentry->d_name;

    if(strncmp(fname,".",1) == 0)

        continue;

    sprintf(filename,"%s/%s",dirname,fname);

    lsfile(filename);

}

closedir(dir);

}

//-rw-r--r--.   1            zxy        zxy        2586        Jul 10 17:00    ls.c

//类型及权限  硬链接数        拥有者    所属组    文件大小    创建时间        文件名

void lsfile(char *filename)

{

struct stat tmpstat;

if(lstat(filename,&tmpstat) == -1)

    ERR_EXIT("STAT ERROR");

char buf[11]= {0};

strcpy(buf,"----------");

char type;

type = getFileType(&tmpstat);

char *bname = basename(filename);

buf[0] = type;

if(type == 'l'){

    char content[1024];

    if(readlink(filename,content,1024) == -1)

        ERR_EXIT("readlink error");

    sprintf(bname,"%s -> %s",bname,content);

}

getFilePerm(&tmpstat,buf);

struct tm *ftime;

ftime = localtime(&tmpstat.st_mtime);

printf("%s %d %s %s %10ld %02d %02d %02d:%02d %s\n",

    buf,tmpstat.st_nlink,

    getpwuid(tmpstat.st_uid)->pw_name,

    getgrgid(tmpstat.st_gid)->gr_name,

    tmpstat.st_size,

    ftime->tm_mon+1,

    ftime->tm_mday,

    ftime->tm_hour,

    ftime->tm_min,

    bname);

}

//获得文件类型

char getFileType(struct stat *st)

{

char type = '-';

switch (st->st_mode  & S_IFMT)

{

    case S_IFSOCK:

    type = 's';

            break;

    case S_IFLNK:

    type = 'l';

            break;

    case S_IFREG:

    type = '-';

            break;

    case S_IFBLK:

    type = 'b';

            break;

    case S_IFDIR:

    type = 'd';

            break;

    case S_IFCHR:

    type = 'c';

            break;

    case S_IFIFO:

    type = 'p';

            break;

}

return type;

}

//获得文件访问权限

void getFilePerm(struct stat *st, char *perm)

{

mode_t mode = st->st_mode;

if (mode & S_IRUSR)

    perm[1] = 'r';

if (mode & S_IWUSR)

    perm[2] = 'w';

if (mode & S_IXUSR)

    perm[3] = 'x';

if (mode & S_IRGRP)

    perm[4] = 'r';

if (mode & S_IWGRP)

    perm[5] = 'w';

if (mode & S_IXGRP)

    perm[6] = 'x';

if (mode & S_IROTH)

    perm[7] = 'r';

if (mode & S_IWOTH)

    perm[8] = 'w';

if (mode & S_IXOTH)

    perm[9] = 'x';

}