STAT(2-BSD) RISC/os Reference Manual STAT(2-BSD)
NAME
stat, lstat, fstat - get file status
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
stat(path, buf)
char *path;
struct stat *buf;
lstat(path, buf)
char *path;
struct stat *buf;
fstat(fd, buf)
int fd;
struct stat *buf;
DESCRIPTION
stat obtains information about the file 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 reachable.
lstat 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.
fstat obtains the same information about an open file refer-
enced by the argument descriptor, such as would be obtained
by an open call.
buf is a pointer to a stat structure into which information
is placed concerning the file. The contents of the struc-
ture pointed to by buf
struct stat {
dev_t st_dev; /* device inode resides on */
ino_t st_ino; /* this inode's number */
u_short st_mode;/* protection */
short st_nlink;/* number or hard links to the file */
short st_uid; /* user-id of owner */
short st_gid; /* group-id of owner */
dev_t st_rdev;/* the device type, for inode that is device */
off_t st_size;/* total size of file */
time_t st_atime;/* file last access time */
int st_spare1;
time_t st_mtime;/* file last modify time */
int st_spare2;
time_t st_ctime;/* file last status change time */
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int st_spare3;
long st_blksize;/* optimal blocksize for file system i/o ops */
long st_blocks;/* actual number of blocks allocated */
long st_spare4[2];
};
st_atime Time when file data was last read or
modified. Changed by the following sys-
tem calls: mknod(2), utimes(2),
read(2), and write(2). For reasons of
efficiency, st_atime is not set when a
directory is searched, although this
would be more logical.
st_mtime Time when data was last modified. It is
not set by changes of owner, group, link
count, or mode. Changed by the follow-
ing system calls: mknod(2), utimes(2),
write(2).
st_ctime Time when file status was last changed.
It is set both both by writing and
changing the i-node. Changed by the
following system calls: chmod(2)
chown(2), link(2), mknod(2), rename(2),
unlink(2), utimes(2), write(2).
The status information word st_mode has bits:
#define S_IFMT 0170000 /* type of file */
#define S_IFDIR 0040000/* directory */
#define S_IFCHR 0020000/* character special */
#define S_IFBLK 0060000/* block special */
#define S_IFREG 0100000/* regular */
#define S_IFLNK 0200000/* symbolic link */
#define S_IFSOCK 0140000/* socket */
#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_IREAD 0000400 /* read permission, owner */
#define S_IWRITE 0000200/* write permission, owner */
#define S_IEXEC 0000100 /* execute/search permission, owner */
The mode bits 0000070 and 0000007 encode group and others
permissions (see chmod(2)).
RETURN VALUE
Upon successful completion a value of 0 is returned. Other-
wise, a value of -1 is returned and errno is set to indicate
the error.
ERRORS
stat and lstat will fail if one or more of the following are
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true:
[ENOTDIR] A component of the path prefix is not a
directory.
[EINVAL] The pathname contains a character with
the high-order bit set.
[ENAMETOOLONG] A component of a pathname exceeded 255
characters, or an entire path name
exceeded 1023 characters.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a com-
ponent of the path prefix.
[ELOOP] Too many symbolic links were encountered
in translating the pathname.
[EFAULT] buf 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 one or both of the following are true:
[EBADF] fildes is not a valid open file descrip-
tor.
[EFAULT] buf points to an invalid address.
[EIO] An I/O error occurred while reading from
or writing to the file system.
CAVEAT
The fields in the stat structure currently marked st_spare1,
st_spare2, and st_spare3 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)
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.
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