getdirentries(2)

NAME

getdirentries, getdents - get directory entries in a file

system independent format

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/types.h>
#include <dirent.h>
int
getdirentries(int fd, char *buf, int nbytes, long *basep);
int
getdents(int fd, char *buf, int nbytes);

DESCRIPTION

The getdirentries() and getdents() system calls read direc

tory entries
from the directory referenced by the file descriptor fd into

the buffer
pointed to by buf, in a file system independent format. Up

to nbytes of
data will be transferred. The nbytes argument must be

greater than or
equal to the block size associated with the file, see

stat(2). Some file
systems may not support these system calls with buffers

smaller than this
size.

The data in the buffer is a series of dirent structures each

containing
the following entries:

u_int32_t d_fileno;
u_int16_t d_reclen;
u_int8_t d_type;
u_int8_t d_namlen;
char d_name[MAXNAMELEN + 1]; /* see below */

The d_fileno entry is a number which is unique for each dis

tinct file in
the file system. Files that are linked by hard links (see

link(2)) have
the same d_fileno. The d_reclen entry is the length, in

bytes, of the
directory record. The d_type entry is the type of the file

pointed to by
the directory record. The file type values are defined in
<sys/dirent.h>. The d_name entry contains a null terminated

file name.
The d_namlen entry specifies the length of the file name ex

cluding the
null byte. Thus the actual size of d_name may vary from 1

to MAXNAMELEN
+ 1.

Entries may be separated by extra space. The d_reclen entry

may be used
as an offset from the start of a dirent structure to the

next structure,
if any.

The actual number of bytes transferred is returned. The

current position
pointer associated with fd is set to point to the next block

of entries.
The pointer may not advance by the number of bytes returned

by
getdirentries() or getdents(). A value of zero is returned

when the end
of the directory has been reached.

The getdirentries() system call writes the position of the

block read
into the location pointed to by basep. Alternatively, the

current position pointer may be set and retrieved by lseek(2). The cur

rent position
pointer should only be set to a value returned by lseek(2),

a value
returned in the location pointed to by basep

(getdirentries() only) or
zero.

RETURN VALUES

If successful, the number of bytes actually transferred is

returned.
Otherwise, -1 is returned and the global variable errno is

set to indicate the error.

ERRORS

The getdirentries() system call will fail if:

[EBADF] The fd argument is not a valid file de

scriptor open

for reading.

[EFAULT] Either buf or basep point outside the al

located

address space.

[EINVAL] The file referenced by fd is not a direc

tory, or

nbytes is too small for returning a di

rectory entry or
block of entries, or the current position

pointer is
invalid.

[EIO] An I/O error occurred while reading from

or writing to

the file system.

SEE ALSO

lseek(2), open(2)

HISTORY

The getdirentries() system call first appeared in 4.4BSD.

The getdents()
system call first appeared in FreeBSD 3.0.

BSD May 3, 1995

BSD