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OpenSolaris 2009.06 - man page for fstat (opensolaris section 2)

stat(2) 				   System Calls 				  stat(2)

NAME
       stat, lstat, fstat, fstatat - get file status

SYNOPSIS
       #include <fcntl.h>
       #include <sys/types.h>
       #include <sys/stat.h>

       int stat(const char *restrict path, struct stat *restrict buf);

       int lstat(const char *restrict path, struct stat *restrict buf);

       int fstat(int fildes, struct stat *buf);

       int fstatat(int fildes, const char *path, struct stat *buf,
	    int flag);

DESCRIPTION
       The stat() function obtains information about the file pointed to by 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 searchable.

       The lstat() function obtains file attributes similar to stat(), except when the named file
       is a symbolic link; in that case lstat() returns information about the link, while  stat()
       returns information about the file the link references.

       The  fstat()  function obtains information about an open file known by the file descriptor
       fildes, obtained from a successful open(2), creat(2), dup(2), fcntl(2), or  pipe(2)  func-
       tion.  If  fildes references a shared memory object, the system updates in the stat struc-
       ture 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 system can update other fields and flags. The fstat() function  updates
       any pending time-related fields before writing to the stat structure.

       The fstatat() function obtains file attributes similar to the stat(), lstat(), and fstat()
       functions.  If the path argument is a relative path, it is resolved relative to the fildes
       argument rather than the current working directory.  If path is absolute, the fildes argu-
       ment is unused.	If the fildes argument has the special value AT_FDCWD, relative paths are
       resolved  from  the  current  working directory. If AT_SYMLINK_NOFOLLOW is set in the flag
       argument, the function behaves like lstat() and does  not  automatically  follow  symbolic
       links.  See  fsattr(5).	If  _ATTR_TRIGGER is set in the  flag argument and the vnode is a
       trigger mount point, the mount is performed and the function returns the attributes of the
       root of the mounted filesystem.

       The  buf  argument  is a pointer to a stat structure into which information is placed con-
       cerning the file. A stat structure includes the following members:

	 mode_t   st_mode;	    /* File mode (see mknod(2)) */
	 ino_t	  st_ino;	    /* Inode number */
	 dev_t	  st_dev;	    /* ID of device containing */
				    /* a directory entry for this file */
	 dev_t	  st_rdev;	    /* ID of device */
				    /* This entry is defined only for */
				    /* char special or block special files */
	 nlink_t  st_nlink;	    /* Number of links */
	 uid_t	  st_uid;	    /* User ID of the file's owner */
	 gid_t	  st_gid;	    /* Group ID of the file's group */
	 off_t	  st_size;	    /* File size in bytes */
	 time_t   st_atime;	    /* Time of last access */
	 time_t   st_mtime;	    /* Time of last data modification */
	 time_t   st_ctime;	    /* Time of last file status change */
				    /* Times measured in seconds since */
				    /* 00:00:00 UTC, Jan. 1, 1970 */
	 long	  st_blksize;	    /* Preferred I/O block size */
	 blkcnt_t st_blocks;	    /* Number of 512 byte blocks allocated*/
	 char	  st_fstype[_ST_FSTYPSZ];
				    /* Null-terminated type of filesystem */

       Descriptions of structure members are as follows:

       st_mode	     The mode of the file as described for the mknod() function. In  addition  to
		     the modes described on the mknod(2) manual page, the mode of a file can also
		     be S_IFSOCK if the file is a  socket,  S_IFDOOR  if  the  file  is  a  door,
		     S_IFPORT  if the file is an event port, or S_IFLNK if the file is a symbolic
		     link. S_IFLNK can be returned either by  lstat()  or  by  fstat()	when  the
		     AT_SYMLINK_NOFOLLOW flag is set.

       st_ino	     This  field  uniquely  identifies	the file in a given file system. The pair
		     st_ino and  st_dev uniquely identifies regular files.

       st_dev	     This field uniquely identifies the file system that contains the  file.  Its
		     value  may be used as input to the ustat() function to determine more infor-
		     mation about this file system. No other  meaning  is  associated  with  this
		     value.

       st_rdev	     This  field should be used only by administrative commands. It is valid only
		     for block special or character special files and only  has  meaning  on  the
		     system where the file was configured.

       st_nlink      This field should be used only by administrative commands.

       st_uid	     The user ID of the file's owner.

       st_gid	     The group ID of the file's group.

       st_size	     For  regular  files,  this  is the address of the end of the file. For block
		     special or character special, this is not defined. See also pipe(2).

       st_atime      Time when file data was last accessed. Some of  the  functions  that  change
		     this member are: creat(), mknod(), pipe(), utime(2), and read(2).

       st_mtime      Time  when  data  was  last modified. Some of the functions that change this
		     member are: creat(), mknod(), pipe(), utime(), and write(2).

       st_ctime      Time when file status was last changed. Some of the  functions  that  change
		     this  member  are: chmod(2), chown(2), creat(2), link(2), mknod(2), pipe(2),
		     rename(2), unlink(2), utime(2), and write(2).

       st_blksize    A hint as to the "best" unit size for I/O	operations.  This  field  is  not
		     defined for block special or character special files.

       st_blocks     The  total number of physical blocks of size 512 bytes actually allocated on
		     disk. This field is not defined  for  block  special  or  character  special
		     files.

       st_fstype     A	null-teminated string that uniquely identifies the type of the filesystem
		     that contains the file.

RETURN VALUES
       Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is  set  to
       indicate the error.

ERRORS
       The stat(), fstat(), lstat(), and fstatat() functions will fail if:

       EIO	    An 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 stat(), lstat(), and fstatat() functions will fail if:

       EACCES	       Search permission is denied for a component of the path prefix.

       EFAULT	       The  buf or path argument points to an illegal address.

       EINTR	       A  signal  was caught during the execution of the  stat() or lstat() func-
		       tion.

       ELOOP	       A loop exists in symbolic links encountered during the resolution  of  the
		       path argument.

       ENAMETOOLONG    The  length  of	the  path argument exceeds {PATH_MAX}, or the length of a
		       path component exceeds {NAME_MAX} while _POSIX_NO_TRUNC is in effect.

       ENOENT	       A component of path does not name an existing file or  path  is	an  empty
		       string.

       ENOLINK	       The  path argument points to a remote machine and the link to that machine
		       is no longer active.

       ENOTDIR	       A component of the path prefix is not a directory, or the fildes  argument
		       does not refer to a valid directory when given a non-null relative path.

       The fstat() and fstatat() functions will fail if:

       EBADF	  The fildes argument is not a valid open file descriptor. The fildes argument to
		  fstatat() can also have the valid value of AT_FDCWD.

       EFAULT	  The buf argument points to an illegal address.

       EINTR	  A signal was caught during the execution of the fstat() function.

       ENOLINK	  The fildes argument points to a remote machine and the link to that machine  is
		  no longer active.

       The stat(), fstat(), and lstat() functions may fail if:

       EOVERFLOW    One  of the members is too large to store in the stat structure pointed to by
		    buf.

       The stat() and lstat() functions may fail if:

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

       ENAMETOOLONG    As a result of encountering a symbolic link in resolution of thepath argu-
		       ment, the length of the substituted pathname strings exceeds {PATH_MAX}.

       The stat() and fstatat() functions may fail if:

       ENXIO	The path argument names a character or block device special file and  the  corre-
		sponding I/O device has been retired by the fault management framework.

EXAMPLES
       Example 1 Use stat() to obtain 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);

       Example 2 Use stat() to get 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 owners 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's 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);
	  }

       Example 3 Use fstat() to obtain 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);

       Example 4 Use lstat() to obtain 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 filename  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);

USAGE
       If chmod() or fchmod() is used to change the file group owner permissions on a  file  with
       non-trivial  ACL  entries,  only  the ACL mask is set to the new permissions and the group
       owner permission bits in the file's mode field (defined in  mknod(2))  are  unchanged.	A
       non-trivial  ACL entry is one whose meaning cannot be represented in the file's mode field
       alone. The new ACL mask permissions  might change the effective permissions for additional
       users and groups that have ACL entries on the file.

       The  stat(),  fstat(),  and lstat() functions have transitional interfaces for 64-bit file
       offsets.  See lf64(5).

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+
       |Standard		     |See below.		   |
       +-----------------------------+-----------------------------+

       For stat(), fstat(), and lstat(), see standards(5).

SEE ALSO
       access(2), chmod(2), chown(2), creat(2), link(2),  mknod(2),  pipe(2),  read(2),  time(2),
       unlink(2),  utime(2),  write(2),  fattach(3C),  stat.h(3HEAD),  attributes(5),  fsattr(5),
       lf64(5), standards(5)

SunOS 5.11				   10 Oct 2007					  stat(2)


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