STAT(P) POSIX Programmer's Manual STAT(P)NAMEstat - get file status
SYNOPSIS
#include <sys/stat.h>
int stat(const char *restrict path, struct stat *restrict buf);
DESCRIPTION
The stat() function shall obtain information about the named file and
write it to the area pointed to by the buf argument. The path argument
points to a pathname naming a file. Read, write, or execute permission
of the named file is not required. An implementation that provides
additional or alternate file access control mechanisms may, under
implementation-defined conditions, cause stat() to fail. In particular,
the system may deny the existence of the file specified by path.
If the named file is a symbolic link, the stat() function shall con‐
tinue pathname resolution using the contents of the symbolic link, and
shall return information pertaining to the resulting file if the file
exists.
The buf argument is a pointer to a stat structure, as defined in the
<sys/stat.h> header, into which information is placed concerning the
file.
The stat() 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.
Unless otherwise specified, 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 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.
RETURN VALUE
Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
returned and errno set to indicate the error.
ERRORS
The stat() function shall fail if:
EACCES Search permission is denied for a component of the path prefix.
EIO An error occurred while reading from the file system.
ELOOP A loop exists in symbolic links encountered during resolution of
the path argument.
ENAMETOOLONG
The length of the path argument exceeds {PATH_MAX} or a pathname
component is longer than {NAME_MAX}.
ENOENT A component of path does not name an existing file or path is an
empty string.
ENOTDIR
A component of the path prefix is not a directory.
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 stat() function may fail if:
ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
resolution of the path argument.
ENAMETOOLONG
As a result of encountering a symbolic link in resolution of the
path argument, the length of the substituted pathname string
exceeded {PATH_MAX}.
EOVERFLOW
A value to be stored would overflow one of the members of the
stat structure.
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.
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
struct stat buffer;
int status;
...
status = stat("/home/cnd/mod1", &buffer);
Getting Directory Information
The following example fragment gets status information for each entry
in a directory. The call to the stat() function stores file information
in the stat structure pointed to by statbuf. The lines that follow the
stat() call format the fields in the stat structure for presentation to
the user of the program.
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <locale.h>
#include <langinfo.h>
#include <stdio.h>
#include <stdint.h>
struct dirent *dp;
struct stat statbuf;
struct passwd *pwd;
struct group *grp;
struct tm *tm;
char datestring[256];
...
/* Loop through directory entries. */
while ((dp = readdir(dir)) != NULL) {
/* Get entry's information. */
if (stat(dp->d_name, &statbuf) == -1)
continue;
/* Print out type, permissions, and number of links. */
printf("%10.10s", sperm (statbuf.st_mode));
printf("%4d", statbuf.st_nlink);
/* Print out owner's name if it is found using getpwuid(). */
if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
printf(" %-8.8s", pwd->pw_name);
else
printf(" %-8d", statbuf.st_uid);
/* Print out group name if it is found using getgrgid(). */
if ((grp = getgrgid(statbuf.st_gid)) != NULL)
printf(" %-8.8s", grp->gr_name);
else
printf(" %-8d", statbuf.st_gid);
/* Print size of file. */
printf(" %9jd", (intmax_t)statbuf.st_size);
tm = localtime(&statbuf.st_mtime);
/* Get localized date string. */
strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);
printf(" %s %s\n", datestring, dp->d_name);
}
APPLICATION USAGE
None.
RATIONALE
The intent of the paragraph describing "additional or alternate file
access control mechanisms" is to allow a secure implementation where a
process with a label that does not dominate the file's label cannot
perform a stat() function. This is not related to read permission; a
process with a label that dominates the file's label does not need read
permission. An implementation that supports write-up operations could
fail fstat() function calls even though it has a valid file descriptor
open for writing.
FUTURE DIRECTIONS
None.
SEE ALSOfstat() , lstat() , readlink() , symlink() , the Base Definitions vol‐
ume 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 .
IEEE/The Open Group 2003 STAT(P)
