Originální popis anglicky:
stat - get file status
Návod, kniha: POSIX Programmer's Manual
#include <sys/stat.h>
int stat(const char *restrict
path, struct stat
*restrict buf);
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 continue
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.
Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned
and
errno set to indicate the error.
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.
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);
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);
}
None.
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.
None.
fstat() ,
lstat() ,
readlink() ,
symlink() , the
Base Definitions volume of IEEE Std 1003.1-2001,
<sys/stat.h>,
<sys/types.h>
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
.
