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PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       fstatat, lstat, stat — get file status

SYNOPSIS

       #include <sys/stat.h>

       int fstatat(int fd, const char *restrict path,
           struct stat *restrict buf, int flag);
       int lstat(const char *restrict path, struct stat *restrict buf);
       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  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 POSIX.1‐2008, Section 4.8, File Times Update), before  writing  into
       the stat structure.

       If  the  named file is a shared memory object, the implementation shall update in the stat
       structure pointed to by the buf argument 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 the named file is a typed memory object, the implementation shall update  in  the  stat
       structure  pointed to by the buf argument 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.

       For  all  other  file  types defined in this volume of POSIX.1‐2008, the structure members
       st_mode, st_ino,  st_dev,  st_uid,  st_gid,  st_atim,  st_ctim,  and  st_mtim  shall  have
       meaningful values and the value of the member st_nlink shall be set to the number of links
       to the file.

       The lstat() function shall be equivalent to stat(), except when path refers to a  symbolic
       link.  In  that  case  lstat() shall return information about the link, while stat() shall
       return information about the file the link references.

       For symbolic links, the st_mode member shall contain meaningful information when used with
       the file type macros. The file mode bits in st_mode are unspecified. The structure members
       st_ino, st_dev, st_uid, st_gid, st_atim, st_ctim, and st_mtim shall have meaningful values
       and  the  value  of  the st_nlink member shall be set to the number of (hard) links to the
       symbolic link.  The value of the st_size member shall be set to the length of the pathname
       contained in the symbolic link not including any terminating null byte.

       The fstatat() function shall be equivalent to the stat() or lstat() function, depending on
       the value of flag (see below), except in the case where path specifies a relative path. In
       this  case  the status shall be retrieved from a file relative to the directory associated
       with the file descriptor fd  instead  of  the  current  working  directory.  If  the  file
       descriptor  was  opened  without  O_SEARCH,  the  function  shall  check whether directory
       searches are permitted using the current permissions of the directory underlying the  file
       descriptor.  If  the  file  descriptor  was  opened  with O_SEARCH, the function shall not
       perform the check.

       Values for flag are constructed by a bitwise-inclusive OR  of  flags  from  the  following
       list, defined in <fcntl.h>:

       AT_SYMLINK_NOFOLLOW
             If path names a symbolic link, the status of the symbolic link is returned.

       If fstatat() is passed the special value AT_FDCWD in the fd parameter, the current working
       directory shall be used and the behavior shall be identical to a call to stat() or lstat()
       respectively, depending on whether or not the AT_SYMLINK_NOFOLLOW bit is set in flag.

RETURN VALUE

       Upon  successful  completion,  these functions shall return 0.  Otherwise, these functions
       shall return −1 and set errno to indicate the error.

ERRORS

       These functions 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 a component of a pathname 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 names an existing file that is neither  a  directory
              nor  a  symbolic  link  to  a directory, or the path argument contains at least one
              non-<slash> character and ends with one or more trailing <slash> characters and the
              last  pathname  component  names an existing file that is neither a directory nor a
              symbolic link to 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 fstatat() function shall fail if:

       EACCES fd  was not opened with O_SEARCH and the permissions of the directory underlying fd
              do not permit directory searches.

       EBADF  The path argument does not specify an absolute path and the fd argument is  neither
              AT_FDCWD nor a valid file descriptor open for reading or searching.

       ENOTDIR
              The  path  argument  is not an absolute path and fd is a file descriptor associated
              with a non-directory file.

       These functions may fail if:

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during  resolution  of  the
              path argument.

       ENAMETOOLONG
              The  length  of a pathname exceeds {PATH_MAX}, or pathname resolution of a symbolic
              link produced an intermediate result with a length that exceeds {PATH_MAX}.

       EOVERFLOW
              A value to be stored would overflow one of the members of the stat structure.

       The fstatat() function may fail if:

       EINVAL The value of the flag argument is not valid.

       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);
           }

   Obtaining Symbolic Link Status Information
       The following example shows how to obtain status information for  a  symbolic  link  named
       /modules/pass1.   The  structure variable buffer is defined for the stat structure. If the
       path argument specified the pathname  for  the  file  pointed  to  by  the  symbolic  link
       (/home/cnd/mod1),  the results of calling the function would be the same as those returned
       by a call to the stat() function.

           #include <sys/stat.h>

           struct stat buffer;
           int status;
           ...
           status = lstat("/modules/pass1", &buffer);

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.

       The  lstat()  function is not required to update the time-related fields if the named file
       is not a symbolic link. While the st_uid, st_gid, st_atim, st_mtim, and st_ctim members of
       the  stat  structure  may  apply  to  a symbolic link, they are not required to do so.  No
       functions in POSIX.1‐2008 are required to maintain any of these time fields.

       The purpose of the fstatat() function is to obtain the  status  of  files  in  directories
       other  than the current working directory without exposure to race conditions. Any part of
       the path of a file could be changed  in  parallel  to  a  call  to  stat(),  resulting  in
       unspecified  behavior. By opening a file descriptor for the target directory and using the
       fstatat() function it can be guaranteed that the file for  which  status  is  returned  is
       located relative to the desired directory.

FUTURE DIRECTIONS

       None.

SEE ALSO

       access(), chmod(), fdopendir(), fstat(), mknod(), readlink(), symlink()

       The  Base  Definitions  volume of POSIX.1‐2008, Section 4.8, File Times Update, <fcntl.h>,
       <sys_stat.h>, <sys_types.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .