STAT(2) BSD System Calls Manual STAT(2)
NAME
stat, lstat, fstat -- get file status
SYNOPSIS
##include <>
##include <>
int
stat(const char *path, struct stat *sb);
int
lstat(const char *path, struct stat *sb);
int
fstat(int fd, struct stat *sb);
DESCRIPTION
The stat() function obtains information about the file pointed to by
path. Read, write or execute permission of the named file is not
required, but all directories listed in the path name leading to the file
must be searchable.
Lstat() is like stat() except in the case where the named file is a sym-
bolic link, in which case lstat() returns information about the link,
while stat() returns information about the file the link references.
Unlike other filesystem objects, symbolic links do not have an owner,
group, access mode, times, etc. Instead, these attributes are taken from
the directory that contains the link. The only attributes returned from
an lstat() that refer to the symbolic link itself are the file type
(SIFLNK), size, blocks, and link count (always 1).
The fstat() obtains the same information about an open file known by the
file descriptor fd.
The sb argument is a pointer to a stat() structure as defined by
(shown below) and into which information is placed concern-
ing the file.
struct stat {
devt stdev; /* device inode resides on */
inot stino; /* inode's number */
modet stmode; /* inode protection mode */
nlinkt stnlink; /* number or hard links to the file */
uidt stuid; /* user-id of owner */
gidt stgid; /* group-id of owner */
devt strdev; /* device type, for special file inode */
struct timespec statimespec; /* time of last access */
struct timespec stmtimespec; /* time of last data modification */
struct timespec stctimespec; /* time of last file status change */
offt stsize; /* file size, in bytes */
quadt stblocks; /* blocks allocated for file */
ulong stblksize;/* optimal file sys I/O ops blocksize */
ulong stflags; /* user defined flags for file */
ulong stgen; /* file generation number */
};
The time-related fields of struct stat are as follows:
statime Time when file data last accessed. Changed by the mknod(2),
utimes(2) and read(2) system calls.
stmtime Time when file data last modified. Changed by the mknod(2),
utimes(2) and write(2) system calls.
stctime Time when file status was last changed (inode data modifica-
tion). Changed by the chmod(2), chown(2), link(2),
mknod(2), rename(2), unlink(2), utimes(2) and write(2) sys-
tem calls.
The size-related fields of the struct stat are as follows:
stblksize The optimal I/O block size for the file.
stblocks The actual number of blocks allocated for the file in
512-byte units. As short symbolic links are stored in the
inode, this number may be zero.
The status information word stmode has the following bits:
#define SIFMT 0170000 /* type of file */
#define SIFIFO 0010000 /* named pipe (fifo) */
#define SIFCHR 0020000 /* character special */
#define SIFDIR 0040000 /* directory */
#define SIFBLK 0060000 /* block special */
#define SIFREG 0100000 /* regular */
#define SIFLNK 0120000 /* symbolic link */
#define SIFSOCK 0140000 /* socket */
#define SIFWHT 0160000 /* whiteout */
#define SISUID 0004000 /* set user id on execution */
#define SISGID 0002000 /* set group id on execution */
#define SISVTX 0001000 /* save swapped text even after use */
#define SIRUSR 0000400 /* read permission, owner */
#define SIWUSR 0000200 /* write permission, owner */
#define SIXUSR 0000100 /* execute/search permission, owner */
For a list of access modes, see , access(2) and chmod(2).
RETURN VALUES
Upon successful completion a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate the error.
COMPATIBILITY
Previous versions of the system used different types for the stdev,
stuid, stgid, strdev, stsize, stblksize and stblocks fields.
ERORS
Stat() and lstat() will fail if:
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOLONG] A component of a pathname exceeded {NAMEMAX} charac-
ters, or an entire path name exceeded {PATHMAX} char-
acters.
[ENOENT] The named file does not exist.
[EACES] Search permission is denied for a component of the
path prefix.
[ELOP] Too many symbolic links were encountered in translat-
ing the pathname.
[EFAULT] Sb or name points to an invalid address.
[EIO] An I/O error occurred while reading from or writing to
the file system.
Fstat() will fail if:
[EBADF] fd is not a valid open file descriptor.
[EFAULT] Sb points to an invalid address.
[EIO] An I/O error occurred while reading from or writing to
the file system.
CAVEATS
The file generation number, stgen, is only available to the super-user.
The fields in the stat structure currently marked stspare1, stspare2,
and stspare3 are present in preparation for inode time stamps expanding
to 64 bits. This, however, can break certain programs that depend on the
time stamps being contiguous (in calls to utimes(2)).
SEE ALSO
chmod(2), chown(2), utimes(2) symlink(7)
BUGS
Applying fstat to a socket (and thus to a pipe) returns a zero'd buffer,
except for the blocksize field, and a unique device and inode number.
STANDARDS
The stat() and fstat() function calls are expected to conform to IE Std
1003.1-1988 (``POSIX.1'').
HISTORY
An lstat() function call appeared in 4.2BSD.
4th Berkeley Distribution April 19, 1994 4th Berkeley Distribution
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