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DIRECTORY(3)	       FreeBSD Library Functions Manual		  DIRECTORY(3)

     opendir, fdopendir, readdir, readdir_r, telldir, seekdir, rewinddir,
     closedir, fdclosedir, dirfd -- directory operations

     Standard C	Library	(libc, -lc)

     #include <dirent.h>

     DIR *
     opendir(const char	*filename);

     DIR *
     fdopendir(int fd);

     struct dirent *
     readdir(DIR *dirp);

     readdir_r(DIR *dirp, struct dirent	*entry,	struct dirent **result);

     telldir(DIR *dirp);

     seekdir(DIR *dirp,	long loc);

     rewinddir(DIR *dirp);

     closedir(DIR *dirp);

     fdclosedir(DIR *dirp);

     dirfd(DIR *dirp);

     The readdir_r() interface is deprecated because it	cannot be used cor-
     rectly unless {NAME_MAX} is a fixed value.

     The opendir() function opens the directory	named by filename, associates
     a directory stream	with it	and returns a pointer to be used to identify
     the directory stream in subsequent	operations.  The pointer NULL is re-
     turned if filename	cannot be accessed, or if it cannot malloc(3) enough
     memory to hold the	whole thing.

     The fdopendir() function is equivalent to the opendir() function except
     that the directory	is specified by	a file descriptor fd rather than by a
     name.  The	file offset associated with the	file descriptor	at the time of
     the call determines which entries are returned.

     Upon successful return from fdopendir(), the file descriptor is under the
     control of	the system, and	if any attempt is made to close	the file de-
     scriptor, or to modify the	state of the associated	description other than
     by	means of closedir(), readdir(),	readdir_r(), or	rewinddir(), the be-
     havior is undefined.  Upon	calling	closedir() the file descriptor is
     closed.  The FD_CLOEXEC flag is set on the	file descriptor	by a success-
     ful call to fdopendir().

     The readdir() function returns a pointer to the next directory entry.
     The directory entry remains valid until the next call to readdir()	or
     closedir()	on the same directory stream.  The function returns NULL upon
     reaching the end of the directory or on error.  In	the event of an	error,
     errno may be set to any of	the values documented for the getdirentries(2)
     system call.

     The readdir_r() function provides the same	functionality as readdir(),
     but the caller must provide a directory entry buffer to store the results
     in.  The buffer must be large enough for a	struct dirent with a d_name
     array with	{NAME_MAX} + 1 elements.  If the read succeeds,	result is
     pointed at	the entry; upon	reaching the end of the	directory result is
     set to NULL.  The readdir_r() function returns 0 on success or an error
     number to indicate	failure.

     The telldir() function returns a token representing the current location
     associated	with the named directory stream.  Values returned by telldir()
     are good only for the lifetime of the DIR pointer,	dirp, from which they
     are derived.  If the directory is closed and then reopened, prior values
     returned by telldir() will	no longer be valid.  Values returned by
     telldir() are also	invalidated by a call to rewinddir().

     The seekdir() function sets the position of the next readdir() operation
     on	the directory stream.  The new position	reverts	to the one associated
     with the directory	stream when the	telldir() operation was	performed.

     The rewinddir() function resets the position of the named directory
     stream to the beginning of	the directory.

     The closedir() function closes the	named directory	stream and frees the
     structure associated with the dirp	pointer, returning 0 on	success.  On
     failure, -1 is returned and the global variable errno is set to indicate
     the error.

     The fdclosedir() function is equivalent to	the closedir() function	except
     that this function	returns	directory file descriptor instead of closing

     The dirfd() function returns the integer file descriptor associated with
     the named directory stream, see open(2).

     Sample code which searches	a directory for	entry ``name'' is:

	   dirp	= opendir(".");
	   if (dirp == NULL)
		   return (ERROR);
	   len = strlen(name);
	   while ((dp =	readdir(dirp)) != NULL)	{
		   if (dp->d_namlen == len && strcmp(dp->d_name, name) == 0) {
			   return (FOUND);
	   return (NOT_FOUND);

     The opendir() function will fail if:

     [EACCES]		Search permission is denied for	the component of the
			path prefix of filename	or read	permission is denied
			for filename.

     [ELOOP]		A loop exists in symbolic links	encountered during
			resolution of the filename argument.

     [ENAMETOOLONG]	The length of the filename argument exceeds {PATH_MAX}
			or a pathname component	is longer than {NAME_MAX}.

     [ENOENT]		A component of filename	does not name an existing di-
			rectory	or filename is an empty	string.

     [ENOTDIR]		A component of filename	is not a directory.

     The fdopendir() function will fail	if:

     [EBADF]		The fd argument	is not a valid file descriptor open
			for reading.

     [ENOTDIR]		The descriptor fd is not associated with a directory.

     The readdir() and readdir_r() functions may also fail and set errno for
     any of the	errors specified for the routine getdents(2).

     The telldir() function may	also fail and set errno	for any	of the errors
     specified for the routine realloc(3).

     The closedir() function may also fail and set errno for any of the	errors
     specified for the routine close(2).

     close(2), lseek(2), open(2), read(2), dir(5)

     The closedir(), dirfd(), fdopendir(), opendir(), readdir(), readdir_r(),
     rewinddir(), seekdir() and	telldir() functions are	expected to conform to
     IEEE Std 1003.1-2008 ("POSIX.1").	The fdclosedir() function and the
     d_off, d_reclen and d_type	fields of struct dirent	are non-standard, and
     should not	be used	in portable programs.

     The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(),
     and dirfd() functions appeared in 4.2BSD.	The fdopendir()	function ap-
     peared in FreeBSD 8.0.  fdclosedir() function appeared in FreeBSD 10.0.

     The behaviour of telldir()	and seekdir() is likely	to be wrong if there
     are parallel unlinks happening and	the directory is larger	than one page.
     There is code to ensure that a seekdir() to the location given by a
     telldir() immediately before the last readdir() will always set the cor-
     rect location to return the same value as that last readdir() performed.
     This is enough for	some applications which	want to	"push back the last
     entry read", e.g.,	Samba.	Seeks back to any other	location, other	than
     the beginning of the directory, may result	in unexpected behaviour	if
     deletes are present.  It is hoped that this situation will	be resolved
     with changes to getdirentries() and the VFS.

FreeBSD	13.0			August 1, 2020			  FreeBSD 13.0


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