directory(3X)
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directory: opendir, readdir, telldir, seekdir, Subroutine
rewinddir, closedir
directory operations
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SYNTAX
#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;
int closedir(dirp)
DIR *dirp;
Alternate Syntax
#include <sys/dir.h>
struct direct *readdir (dirp)
DIR *dirp;
(All other function interfaces remain the same.)
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 allocate enough memory to hold a DIR
structure or a buffer for the directory entries.
Readdir returns a pointer to the next active directory entry. No
inactive entries are returned. It returns NULL upon reaching the
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directory(3X)
end of the directory or upon detecting an invalid location in the
directory.
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 if the directory has not changed due to compaction or
expansion. This is not a problem with System V, but it can be
with DG/UX and some file system types.
Rewinddir resets the position of the named directory stream to
the beginning of the directory.
Closedir closes the named directory stream and frees the DIR
structure.
The following errors can occur as a result of these operations.
opendir:
[ENOTDIR] A component of filename is not a directory.
[EACCES] A component of filename denies search permission.
[EMFILE] The maximum number of file descriptors are
currently open.
[EFAULT] Filename points outside the allocated address
space.
readdir:
[ENOENT] The current file pointer for the directory is not
located at a valid entry.
[EBADF] The file descriptor determined by the DIR stream
is no longer valid. This results if the DIR
stream has been closed.
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.
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directory(3X)
EXAMPLE
Sample code which searches a directory for entry name:
dirp = opendir( "." );
while ( (dp = readdir( dirp )) != NULL )
if ( strcmp( dp->dname, name ) == 0 )
{
closedir( dirp );
return FOUND;
}
closedir( dirp );
return NOTFOUND;
SEE ALSO
getdents(2), dirent(4).
WARNINGS
Rewinddir is implemented as a macro, so its function address
cannot be taken.
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