linux系统编程之文件与I/O（四）：文件的属性

#include<sys/types.h>
#include<sys/stat.h>
#include<unistd.h>
#include<fcntl.h>
#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>

#define ERR_EXIT(m) \
do { \
perror(m); \
exit(EXIT_FAILURE); \
} while(0)

#define MAJOR(a) (int)((unsigned short)a >> 8)  // 高8位，主设备号
#define MINOR(a) (int)((unsigned short)a & 0xFF)

int filetype(struct stat *buf)
{
int flag = 0;
printf("Filetype:");
mode_t mode;
mode = buf->st_mode;
switch (mode & S_IFMT)
{

case S_IFSOCK:
printf("socket\n");
break;
case S_IFLNK:
printf("symbolic link\n");
break;
case S_IFREG:
printf("regular file\n");
break;
case S_IFBLK:
printf("block device\n");
flag = 1;
break;
case S_IFDIR:
printf("directory\n");
break;
case S_IFCHR:
printf("character device\n");
flag = 1;
break;
case S_IFIFO:
printf("FIFO\n");
break;
default:
printf("unknown file type\n");
break;
}

return flag;
}

void fileperm(struct stat *buf, char perm [])
{
strcpy(perm, "----------");
perm[0] = '?';
mode_t mode;
mode = buf->st_mode;
switch (mode & S_IFMT)
{

case S_IFSOCK:
perm[0] = 's';
break;
case S_IFLNK:
perm[0] = 'l';
break;
case S_IFREG:
perm[0] = '-';
break;
case S_IFBLK:
perm[0] = 'b';
break;
case S_IFDIR:
perm[0] = 'd';
break;
case S_IFCHR:
perm[0] = 'c';
break;
case S_IFIFO:
perm[0] = 'p';
break;
}

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';
perm[10] = '\0';
}

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

printf("Filename:%s\n", "test.txt");
struct stat sbuf;
if (lstat("test.txt", &sbuf) == -1)
ERR_EXIT("stat error");

printf("file in Dev number:major %d, minor %d\n",
MAJOR(sbuf.st_dev),
MINOR(sbuf.st_dev));
printf("File inode:%d\n", (int) sbuf.st_ino);

if (filetype(&sbuf))
{
printf("Device number:major %d, minor %d\n",
MAJOR(sbuf.st_rdev),
MINOR(sbuf.st_rdev));
}

char perm[11] = {0};
fileperm(&sbuf, perm);
printf("File permission bits=%o %s\n", sbuf.st_mode & 0777, perm);  // 0777 是八进制数

return 0;
}

/*
Filename:test.txt
file in Dev number:major 253, minor 0
File inode:901535
Filetype:regular file
File permission bits=644 -rw-r--r--

*/