DIRECTORY(3) — C LIBRARY FUNCTIONS

NAME

directory, opendir, readdir, telldir, seekdir, rewinddir, closedir − directory operations

SYNOPSIS

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

DIR ∗opendir(filename)
char ∗filename;

struct dirent
∗readdir(dirp)
DIR ∗dirp;

long
telldir(dirp)
DIR ∗dirp;

seekdir(dirp, loc)
DIR ∗dirp;
long loc;

rewinddir(dirp)
DIR ∗dirp;

closedir(dirp)
DIR ∗dirp;

DESCRIPTION

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 is not a directory, 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.

EXAMPLES

Sample code which searchs a directory for entry “name” is:

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

NOTES

The directory() library routines now use a new include file, <dirent.h>. This replaces the file, <sys/dir.h>, used in previous releases. Furthermore, with the use of this new file, the readdir() routine returns directory entries whose structure is named struct dirent rather than struct direct as before. The file, <sys/dir.h>, is retained in the current SunOS release for purposes of backwards source code compatibility; programs which use the directory() library and the file, <sys/dir.h>, will continue to compile and run without source code modifications. However, existing programs should convert to the use of the new include file, <dirent.h>, as <sys/dir.h> will be removed in a future major release.

Museum