opendir(3) - NetBSD Manual Pages

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


NAME

     opendir, readdir, telldir, seekdir, rewinddir, closedir, dirfd - directo-
     ry operations


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

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

     DIR *
     opendir(const char *filename);

     struct dirent *
     readdir(DIR *dirp);

     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.  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 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 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 may be invalidated due to unde-
     tected directory compaction.  It is safe to use a previous telldir() val-
     ue immediately after a call to opendir() and before any calls to
     readdir().

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


SEE ALSO

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


STANDARDS

     The opendir(), readdir(), rewinddir() and closedir() functions conform to
     IEEE Std 1003.1-1990 (``POSIX'').


HISTORY

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

NetBSD 1.5.2                     June 4, 1993                                2