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FreeBSD 11.0 - man page for readdir (freebsd section 3)

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

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <dirent.h>

     DIR *
     opendir(const char *filename);

     DIR *
     fdopendir(int fd);

     struct dirent *
     readdir(DIR *dirp);

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

     long
     telldir(DIR *dirp);

     void
     seekdir(DIR *dirp, long loc);

     void
     rewinddir(DIR *dirp);

     int
     closedir(DIR *dirp);

     int
     fdclosedir(DIR *dirp);

     int
     dirfd(DIR *dirp);

DESCRIPTION
     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 returned 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 descriptor, or to modify the state of
     the associated description other than by means of closedir(), readdir(), readdir_r(), or
     rewinddir(), the behavior is undefined.  Upon calling closedir() the file descriptor is
     closed.  The FD_CLOEXEC flag is set on the file descriptor by a successful 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 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.	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 it.

     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) {
			   (void)closedir(dirp);
			   return (FOUND);
		   }
	   }
	   (void)closedir(dirp);
	   return (NOT_FOUND);

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

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

BUGS
     The invalidation of telldir() tokens when calling seekdir() is non-standard.

BSD					  July 28, 2014 				      BSD
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