readdir(3) - NetBSD Manual Pages

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DIRECTORY(3)            NetBSD Library Functions Manual           DIRECTORY(3)


NAME

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


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <dirent.h>

     DIR *
     opendir(const char *filename);

     struct dirent *
     readdir(DIR *dirp);

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

     long
     telldir(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.  The pointer NULL is
     returned if filename cannot be accessed, or if it cannot malloc(3) enough
     memory to hold the whole thing.

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

     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.
     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 cannot be re-used.

     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).


EXAMPLES

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

           len = strlen(name);
           dirp = opendir(".");
           if (dirp != NULL) {
                   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);


SEE ALSO

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


STANDARDS

     The opendir(), readdir(), rewinddir() and closedir() functions conform to
     ISO/IEC 9945-1:1990 (``POSIX.1'').


HISTORY

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

NetBSD 5.1                       May 18, 2006                       NetBSD 5.1