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DIRECTORY(3)		 BSD Library Functions Manual		  DIRECTORY(3)

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

     Standard C	Library	(libc, -lc)

     #include <sys/types.h>
     #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);

     dirfd(DIR *dirp);

     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.  It
     returns NULL upon reaching	the end	of the directory or detecting an in-
     valid seekdir() operation.

     The readdir_r() function provides the same	functionality as readdir(),
     but the caller must provide a directory entry buffer to store the results
     in.  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 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.

     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 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:

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

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

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

BSD				April 16, 2008				   BSD


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