apue 01 文件和目录的操作 文件系统

/* get and set file flags */
void Set_flags(int fd, int flags)
{
int val ;
val = fcntl(0, F_GETFL, 0);
if(-1 == val)
ERR_EXIT("fcntl get flags error");
val |= flags;

if( (fcntl(0, F_SETFL, val)) < 0 )
ERR_EXIT("fcntl set flags error");
}

/* clear file flags*/
void Clear_flags(int fd, int flags)
{
int val ;
val = fcntl(0, F_GETFL, 0);
if(-1 == val)
ERR_EXIT("fcntl get flags error");
val &= ~flags;

if( (fcntl(0, F_SETFL, val)) < 0 )
ERR_EXIT("fcntl set flags error");
}
Set_flags(0, O_NONBLOCK);
Clear_flags(0,O_NONBLOCK);

struct flock flck;
memset(&flck, 0, sizeof(flck));
flck.l_type = F_WRLCK;/*lock type*/
flck.l_whence = SEEK_SET;
flck.l_start = 0;
flck.l_len = 0;

if( 0 == fcntl(fd, F_SETLKW, &flck) )
ERR_EXIT("lock ok");
else
ERR_EXIT("lock fail");

DIR *dir = opendir(".");
struct dirent *dirent_;
while( (dirent_ = readdir(dir)) != NULL)
{
if( 0 == strncmp(dirent_->d_name, ".", 1) ) /*remove .file */
continue;
printf("%s\n", dirent_->d_name);
}
closedir(dir);

int file_type(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 file_perm(struct stat* sbuf, char *perm)
{
strcpy(perm, "----------");
perm[0] = '?';
mode_t mode;
mode = sbuf->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';
}

#define MAJOR(a) (int)((unsigned short)a >> 8)
#define MINOR(a) (int)((unsigned short)a & 0xFF)

struct stat sbuf;

if (lstat(argv[1], &sbuf) == -1)
ERR_EXIT("stat error");

/* 1.get file major and minor */
printf("File number:major %d,minor %d inode %d\n", MAJOR(sbuf.st_dev), MINOR(sbuf.st_dev), (int)sbuf.st_ino);
if (file_type(&sbuf))
{
printf("Device number:major %d,minor %d\n", MAJOR(sbuf.st_rdev), MINOR(sbuf.st_rdev));
}
/* 2. get file perm */
char perm[11] = {0};
file_perm(&sbuf, perm);
printf("File permission bits=%o %s\n", sbuf.st_mode & 07777, perm);