NAME
fstat - get file status
SYNOPSIS
#include <sys/stat.h>
int fstat(int fildes, struct stat *buf);
DESCRIPTION
The fstat() function shall obtain information about an open file
associated with the file descriptor fildes, and shall write it to the
area pointed to by buf.
If fildes references a shared memory object, the implementation shall
update in the stat structure pointed to by the buf argument only the
st_uid, st_gid, st_size, and st_mode fields, and only the S_IRUSR,
S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits
need be valid. The implementation may update other fields and flags.
If fildes references a typed memory object, the implementation shall
update in the stat structure pointed to by the buf argument only the
st_uid, st_gid, st_size, and st_mode fields, and only the S_IRUSR,
S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits
need be valid. The implementation may update other fields and flags.
The buf argument is a pointer to a stat structure, as defined in
<sys/stat.h>, into which information is placed concerning the file.
The structure members st_mode, st_ino, st_dev, st_uid, st_gid,
st_atime, st_ctime, and st_mtime shall have meaningful values for all
other file types defined in this volume of IEEE Std 1003.1-2001. The
value of the member st_nlink shall be set to the number of links to the
file.
An implementation that provides additional or alternative file access
control mechanisms may, under implementation-defined conditions, cause
fstat() to fail.
The fstat() function shall update any time-related fields as described
in the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.7,
File Times Update, before writing into the stat structure.
RETURN VALUE
Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
returned and errno set to indicate the error.
ERRORS
The fstat() function shall fail if:
EBADF The fildes argument is not a valid file descriptor.
EIO An I/O error occurred while reading from the file system.
EOVERFLOW
The file size in bytes or the number of blocks allocated to the
file or the file serial number cannot be represented correctly
in the structure pointed to by buf.
The fstat() function may fail if:
EOVERFLOW
One of the values is too large to store into the structure
pointed to by the buf argument.
The following sections are informative.
EXAMPLES
Obtaining File Status Information
The following example shows how to obtain file status information for a
file named /home/cnd/mod1. The structure variable buffer is defined for
the stat structure. The /home/cnd/mod1 file is opened with read/write
privileges and is passed to the open file descriptor fildes.
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
struct stat buffer;
int status;
...
fildes = open("/home/cnd/mod1", O_RDWR);
status = fstat(fildes, &buffer);
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
lstat() , stat() , the Base Definitions volume of IEEE Std 1003.1-2001,
<sys/stat.h>, <sys/types.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .