opendir

DIRECTORY(3)              OpenBSD Programmer's Manual             DIRECTORY(3)

NAME

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

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(const DIR *dirp);

     void
     seekdir(DIR *dirp, long loc);

     void
     rewinddir(DIR *dirp);

     int
     closedir(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.  On failure, NULL is
     returned and errno is set to indicate the error.

     The fdopendir() function is equivalent to opendir() except that the
     directory is specified by file descriptor rather than by 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 directory, other than
     by means of closedir(), readdir(), readdir_r(), or rewinddir(), the
     behavior is undefined.  Upon calling closedir() the file descriptor shall
     be closed.

     The readdir() function returns a pointer to the next directory entry in
     the named directory stream dirp.  It returns NULL upon reaching the end
     of the directory or detecting an invalid seekdir() operation.

     The readdir_r() function (much like readdir()) initializes the dirent
     structure referenced by entry to represent the next directory entry in
     the named directory stream dirp, and stores a pointer to this structure
     at the location referenced by result.  The storage pointed to by entry
     must be large enough for a dirent with a d_name array member containing
     at least NAME_MAX plus one elements.  On successful return, the pointer
     returned at *result will have the same value as the argument entry.  Upon
     reaching the end of the directory stream, this pointer shall have the
     value NULL.

     The telldir() function returns the current location associated with the
     named directory stream dirp.  On failure, -1 is returned and errno is set
     to indicate the error.

     The seekdir() function sets the position of the next readdir() operation
     on the named directory stream dirp.  The new position reverts to the one
     associated with the directory stream when the telldir() operation was
     performed.  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, the telldir() value may be invalidated due
     to undetected directory compaction.

     The rewinddir() function resets the position of the named directory
     stream dirp 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 dirp (see open(2)).

EXAMPLES

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

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

ERRORS

     The opendir() function will fail if:

     [ENOTDIR]          The supplied filename is not a directory.

     The opendir() function may also fail and set errno for any of the errors
     specified for the routines fcntl(2), fstat(2), open(2), and malloc(3).

     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 getdirentries(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).

SEE ALSO

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

STANDARDS

     The opendir(), fdopendir(), readdir(), readdir_r(), telldir(), seekdir(),
     rewinddir(), closedir(), and dirfd() functions conform to IEEE Std
     1003.1-2008 (``POSIX.1'').

HISTORY

     The opendir(), readdir(), telldir(), seekdir(), rewinddir(), closedir(),
     and dirfd() functions appeared in 4.2BSD.  The fdopendir() function
     appeared in OpenBSD 5.0.

OpenBSD 5.1                      July 18, 2011                     OpenBSD 5.1