파일의 속성을 check 하는 코드 - fstatat, fstat, stat, lstat

아래는 dirfd 아래에 asecName 이라는 파일이 regular file인지 check 하는 코드

ex) dirfd = "/mnt/secure/asec/"

     asecName = "1234"

이면 /mnt/secure/asec/1234 라는 regular file 이 있는지 check 해 준다.

    struct stat sb;

    bool ret = (fstatat(dirfd, asecName, &sb, AT_SYMLINK_NOFOLLOW) == 0)

        && S_ISREG(sb.st_mode);

http://www.tutorialspoint.com/unix_system_calls/stat.htm

The following POSIX macros are defined to check the file type using the st_mode field:

Tag	Description
S_ISREG(m)	is it a regular file?
S_ISDIR(m)	directory?
S_ISCHR(m)	character device?
S_ISBLK(m)	block device?
S_ISFIFO(m)	FIFO (named pipe)?
S_ISLNK(m)	symbolic link? (Not in POSIX.1-1996.)
S_ISSOCK(m)	socket? (Not in POSIX.1-1996.)

The following flags are defined for the st_mode field:

S_IFMT	0170000	bitmask for the file type bitfields
S_IFSOCK	0140000	socket
S_IFLNK	0120000	symbolic link
S_IFREG	0100000	regular file
S_IFBLK	0060000	block device
S_IFDIR	0040000	directory
S_IFCHR	0020000	character device
S_IFIFO	0010000	FIFO
S_ISUID	0004000	set UID bit
S_ISGID	0002000	set-group-ID bit (see below)
S_ISVTX	0001000	sticky bit (see below)
S_IRWXU	00700	mask for file owner permissions
S_IRUSR	00400	owner has read permission
S_IWUSR	00200	owner has write permission
S_IXUSR	00100	owner has execute permission
S_IRWXG	00070	mask for group permissions
S_IRGRP	00040	group has read permission
S_IWGRP	00020	group has write permission
S_IXGRP	00010	group has execute permission
S_IRWXO	00007	mask for permissions for others (not in group)
S_IROTH	00004	others have read permission
S_IWOTH	00002	others have write permission
S_IXOTH	00001	others have execute permission