Copyright (c) 1983 Regents of the University of California.
All rights reserved.

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@(#)directory.3 6.5 (Berkeley) 05/25/90

C 5 opendir, readdir, telldir, seekdir, rewinddir, closedir, dirfd - directory operations

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

DIR *
opendir(const char *filename);

struct direct
*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)

Opendir opens the directory named by filename and associates a directory stream with it. Opendir 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.

Readdir returns a pointer to the next directory entry. It returns NULL upon reaching the end of the directory or detecting an invalid seekdir operation.

Telldir returns the current location associated with the named directory stream.

Seekdir 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 from which they are derived. If the directory is closed and then reopened, the telldir value may be invalidated due to undetected directory compaction. It is safe to use a previous telldir value immediately after a call to opendir and before any calls to readdir.

Rewinddir resets the position of the named directory stream to the beginning of the directory.

Closedir closes the named directory stream and frees the structure associated with the DIR pointer, returning 0 on success. On failure, -1 is returned and errno is set to indicate the error.

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

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