directory(3C)

NAME

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

SYNOPSIS (AT&T System V)

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

DIR ∗opendir(filename)
char ∗filename;

struct dirent ∗readdir(dirp)
DIR ∗dirp;

long telldir(dirp)
DIR ∗dirp;

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

void rewinddir(dirp)
DIR ∗dirp;

closedir(dirp)
DIR ∗dirp;

SYNOPSIS (4 BSD)

#include <sys/dir.h>

DIR ∗opendir(filename)
char ∗filename;

struct direct ∗readdir(dirp)
DIR ∗dirp;

long telldir(dirp)
DIR ∗dirp;

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

void rewinddir(dirp)
DIR ∗dirp;

void 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(3C) enough memory to hold a DIR structure or a buffer for the directory entries.

Readdir returns a pointer to the next directory entry. No inactive entries are returned. 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 from which loc was obtained 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.

The following errors can occur as a result of these operations.

opendir:

[EACCES] A component of filename denies search permission.

[EFAULT] Filename points outside the allocated address space.

[EMFILE] The maximum number of file descriptors for the process are currently open.

[ENAMETOOLONG]
The length of the filename argument exceeds {PATH_MAX}, or a pathname component is longer that {NAME_MAX} (see pathconf(2)).

[ENFILE] The maximum number of file descriptors in the system are currently open.

[ENOENT] The named directory does not exist or filename points to an empty string.

[ENOTDIR] A component of filename is not a directory.

readdir:

[EBADF] The file descriptor determined by the DIR stream is no longer valid. This results if the DIR stream has been closed.

[ENOENT] The current file pointer for the directory is not located at a valid entry.

telldir, seekdir, and closedir:

[EBADF] The file descriptor determined by the DIR stream is no longer valid. This results if the DIR stream has been closed.

EXAMPLE

Sample code which searches a directory for entry name:

dirp = opendir( "." );
while ( (dp = readdir( dirp )) != NULL )
if ( strcmp( dp->d_name, name ) == 0 )
{
closedir( dirp );
return FOUND;
}
closedir( dirp );
return NOT_FOUND;

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