STAT(2) MidnightBSD System Calls Manual STAT(2)

NAME

stat, lstat, fstat — get file status

LIBRARY

Standard C Library (libc, −lc)

SYNOPSIS

#include <sys/types.h>
#include <sys/stat.h>

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() system call 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.

The lstat() system call is like stat() except in the case where the named file is a symbolic link, in which case lstat() returns information about the link, while stat() returns information about the file the link references.

The fstat() system call 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 <sys/stat.h> and into which information is placed concerning the file.

The fields of struct stat related to the file system are as follows:

st_dev

The numeric ID of the device containing the file.

st_ino

The file’s inode number.

st_nlink

The number of hard links to the file.

The st_dev and st_ino fields together identify the file uniquely within the system.

The time-related fields of struct stat are as follows:

st_atime

Time when file data last accessed. Changed by the mknod(2), utimes(2), read(2) and readv(2) system calls.

st_mtime

Time when file data last modified. Changed by the mkdir(2), mkfifo(2), mknod(2), utimes(2), write(2) and writev(2) system calls.

st_ctime

Time when file status was last changed (inode data modification). Changed by the chflags(2), chmod(2), chown(2), creat(2), link(2), mkdir(2), mkfifo(2), mknod(2), rename(2), rmdir(2), symlink(2), truncate(2), unlink(2), utimes(2), write(2) and writev(2) system calls.

st_birthtime

Time when the inode was created.

If _POSIX_SOURCE is not defined, the time-related fields are defined as:

#ifndef _POSIX_SOURCE
#define st_atime st_atimespec.tv_sec
#define st_mtime st_mtimespec.tv_sec
#define st_ctime st_ctimespec.tv_sec
#endif

The size-related fields of the struct stat are as follows:

st_size

The file size in bytes.

st_blksize

The optimal I/O block size for the file.

st_blocks

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 access-related fields of struct stat are as follows:

st_uid

The user ID of the file’s owner.

st_gid

The group ID of the file.

st_mode

Status of the file (see below).

The status information word st_mode has the following bits:

#define S_IFMT 0170000 /* type of file mask */
#define S_IFIFO 0010000 /* named pipe (fifo) */
#define S_IFCHR 0020000 /* character special */
#define S_IFDIR 0040000 /* directory */
#define S_IFBLK 0060000 /* block special */
#define S_IFREG 0100000 /* regular */
#define S_IFLNK 0120000 /* symbolic link */
#define S_IFSOCK 0140000 /* socket */
#define S_IFWHT 0160000 /* whiteout */
#define S_ISUID 0004000 /* set user id on execution */
#define S_ISGID 0002000 /* set group id on execution */
#define S_ISVTX 0001000 /* save swapped text even after use */
#define S_IRWXU 0000700 /* RWX mask for owner */
#define S_IRUSR 0000400 /* read permission, owner */
#define S_IWUSR 0000200 /* write permission, owner */
#define S_IXUSR 0000100 /* execute/search permission, owner */
#define S_IRWXG 0000070 /* RWX mask for group */
#define S_IRGRP 0000040 /* read permission, group */
#define S_IWGRP 0000020 /* write permission, group */
#define S_IXGRP 0000010 /* execute/search permission, group */
#define S_IRWXO 0000007 /* RWX mask for other */
#define S_IROTH 0000004 /* read permission, other */
#define S_IWOTH 0000002 /* write permission, other */
#define S_IXOTH 0000001 /* execute/search permission, other */

For a list of access modes, see <sys/stat.h>, access(2) and chmod(2). The following macros are available to test whether a st_mode value passed in the m argument corresponds to a file of the specified type:

S_ISBLK(m)

Test for a block special file.

S_ISCHR(m)

Test for a character special file.

S_ISDIR(m)

Test for a directory.

S_ISFIFO(m)

Test for a pipe or FIFO special file.

S_ISLNK(m)

Test for a symbolic link.

S_ISREG(m)

Test for a regular file.

S_ISSOCK(m)

Test for a socket.

S_ISWHT(m)

Test for a whiteout.

The macros evaluate to a non-zero value if the test is true or to the value 0 if the test is false.

RETURN VALUES

Upon successful completion, the value 0 is returned; otherwise the value −1 is returned and the global variable errno is set to indicate the error.

COMPATIBILITY

Previous versions of the system used different types for the st_dev, st_uid, st_gid, st_rdev, st_size, st_blksize and st_blocks fields.

ERRORS

The stat() and lstat() system calls will fail if:

[EACCES]

Search permission is denied for a component of the path prefix.

[EFAULT]

The sb or path argument points to an invalid address.

[EIO]

An I/O error occurred while reading from or writing to the file system.

[ELOOP]

Too many symbolic links were encountered in translating the pathname.

[ENAMETOOLONG]

A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

[ENOENT]

The named file does not exist.

[ENOTDIR]

A component of the path prefix is not a directory.

[EOVERFLOW]

The file size in bytes cannot be represented correctly in the structure pointed to by sb.

The fstat() system call will fail if:

[EBADF]

The fd argument is not a valid open file descriptor.

[EFAULT]

The sb argument points to an invalid address.

[EIO]

An I/O error occurred while reading from or writing to the file system.

[EOVERFLOW]

The file size in bytes cannot be represented correctly in the structure pointed to by sb.

SEE ALSO

access(2), chmod(2), chown(2), fhstat(2), statfs(2), utimes(2), symlink(7), sticky(8)

STANDARDS

The stat() and fstat() system calls are expected to conform to ISO/IEC 9945-1:1990 (‘‘POSIX.1’’).

HISTORY

The stat() and fstat() system calls appeared in Version 7 AT&T UNIX. The lstat() system call appeared in 4.2BSD.

BUGS

Applying fstat() to a socket (and thus to a pipe) returns a zeroed buffer, except for the blocksize field, and a unique device and inode number.

MidnightBSD 0.3 October 12, 2006 MidnightBSD 0.3