DIRECTORY(3) MachTen Programmer’s Manual DIRECTORY(3)

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

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)

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

4.2 Berkeley Distribution June 4, 1993 2