判断文件或者目录，打印其详细信息 lstat

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>
#include <grp.h>
#include <pwd.h>
#include <dirent.h>
//判断文件或者目录，打印其详细信息

//lstat传入一个文件，显示文件详细信息
//-rwxrwxrwx 1 root root      1723 Nov 30 09:49 27_lstat.c
//权限    链接数 所有者 用户组 文件容量 修改日期 文件名
//文件所有者权限 文件所属用户组的权限 其他人对此文件的权限

#if 0
struct stat {
dev_t     st_dev;     /* ID of device containing file */
ino_t     st_ino;     /* inode number */
mode_t    st_mode;    /* protection 权限*/
nlink_t   st_nlink;   /* number of hard links 链接数*/
uid_t     st_uid;     /* user ID of owner 所有者ID*/
gid_t     st_gid;     /* group ID of owner 用户组ID*/
dev_t     st_rdev;    /* device ID (if special file) */
off_t     st_size;    /* total size, in bytes 文件容量*/
blksize_t st_blksize; /* blocksize for file system I/O */
blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
time_t    st_atime;   /* time of last access */
time_t    st_mtime;   /* time of last modification */
time_t    st_ctime;   /* time of last status change 修改日期*/
};
#endif

#if 0
struct group *getgrgid(gid_t gid);
struct group {
char   *gr_name;       /* group name */
char   *gr_passwd;     /* group password */
gid_t   gr_gid;        /* group ID */
char  **gr_mem;        /* group members */
};
#endif

#if 0
struct dirent {
ino_t          d_ino;       /* inode number */
off_t          d_off;       /* offset to the next dirent */
unsigned short d_reclen;    /* length of this record */
unsigned char  d_type;      /* type of file; not supported
by all file system types */
char           d_name[256]; /* filename 需要*/
};
#endif

void fun_lstat(char *filename);

int main(int argc,char *argv[])
{
DIR *dp;
struct stat st;//文件结构体
char buf[BUFSIZ];

if(lstat(argv[1],&st) < 0)//lstat获取文件或者目录信息
{
perror("main lstat failed");//需要加""
exit(1);
}
//判断确定是文件
if(S_ISREG(st.st_mode))
fun_lstat(argv[1]);

//判断确定是目录
else if(S_ISDIR(st.st_mode))// 不是buf.st_mode
{
dp = opendir(argv[1]);
if(dp == NULL)
{
perror("opendir failed");
exit(1);
}

struct dirent *dir;
dir = readdir(dp);
while(dir == NULL)
{
printf("%s\n",dir->d_name);
}

}
return 0;
}

void fun_lstat(char *filename)
{
struct stat buf;
if(lstat(filename,&buf) < 0)//lstat获取文件信息
{
perror("lstat failed");//需要加""
exit(1);
}
//打印文件类型
if(S_ISREG(buf.st_mode))
printf("-");
if(S_ISDIR(buf.st_mode))
printf("d");
if(S_ISCHR(buf.st_mode))
printf("c");
if(S_ISBLK(buf.st_mode))
printf("b");
if(S_ISFIFO(buf.st_mode))
printf("p");
if(S_ISLNK(buf.st_mode))
printf("l");
if(S_ISSOCK(buf.st_mode))
printf("s");

//打印文件权限    -rwxrwxrwx 421421421
char str[] = "xwr-";
int i;
for(i=8;i>0;i--)
{
if(buf.st_mode & 1 << i)//左移
printf("%c",str[i%3]);
else
printf("%c",str[3]);
}

//打印文件链接数
printf(" %d ",buf.st_nlink);

//打印文件所有者
printf("%s ",getpwuid(buf.st_uid)->pw_name);//

//打印文件用户组
printf("%s ",getgrgid(buf.st_gid)->gr_name);

//打印文件容量
printf("%ld ",buf.st_size);

//打印修改日期
struct tm *tp;
tp = localtime(&buf.st_ctime);//
printf("%d-%d-%d %d:%d:%d\n",tp->tm_year+1900, tp->tm_mon+1, \
tp->tm_mday, tp->tm_hour, tp->tm_min, tp->tm_sec);

//打印文件名
printf("%s\n",filename);

}