DIRECTORY(3X)

NAME
opendir, readdir, telldir, seekdir, rewinddir, closedir - flexible length directory operations

SYNOPSIS
#include <dir.h>

DIR *opendir(filename)
char *filename;

struct direct *readdir(dirp)
DIR *dirp;

long telldir(dirp)
DIR *dirp;

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

rewinddir(dirp)
DIR *dirp;

closedir(dirp)
DIR *dirp;

cc ... -lndir

DESCRIPTION
The purpose of this library is to simulate the new flexible length directory names of 4.2bsd Unix on top of the old directory structure of 4.1bsd. It allows programs to be converted immediately to the new directory access interface, so that they need only be relinked when 4.2bsd becomes available.

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.

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 causes the named directory stream to be closed, and the structure associated with the DIR pointer to be freed.

See /usr/include/dir.h for a description of the fields available in a directory entry. The preferred way to search the current directory for entry "name" is:

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

LINKING
This library is accessed by specifying "-lndir" as the last argument to the compile line, e.g.:

    cc -o prog prog.c -lndir

SEE ALSO
/usr/include/dir.h, open(2), close(2), read(2), lseek(2)

AUTHOR
Kirk McKusick. Report problems to mckusick@berkeley or ucbvax!mckusick.