186 lines
5.0 KiB
Groff
186 lines
5.0 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)getdirentries.2 8.2 (Berkeley) 5/3/95
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd May 3, 1995
|
|
.Dt GETDIRENTRIES 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm getdirentries ,
|
|
.Nm getdents
|
|
.Nd "get directory entries in a file system independent format"
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/types.h
|
|
.In dirent.h
|
|
.Ft int
|
|
.Fn getdirentries "int fd" "char *buf" "int nbytes" "long *basep"
|
|
.Ft int
|
|
.Fn getdents "int fd" "char *buf" "int nbytes"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn getdirentries
|
|
and
|
|
.Fn getdents
|
|
system calls read directory entries from the directory
|
|
referenced by the file descriptor
|
|
.Fa fd
|
|
into the buffer pointed to by
|
|
.Fa buf ,
|
|
in a file system independent format.
|
|
Up to
|
|
.Fa nbytes
|
|
of data will be transferred.
|
|
The
|
|
.Fa nbytes
|
|
argument must be greater than or equal to the
|
|
block size associated with the file,
|
|
see
|
|
.Xr stat 2 .
|
|
Some file systems may not support these system calls
|
|
with buffers smaller than this size.
|
|
.Pp
|
|
The data in the buffer is a series of
|
|
.Vt dirent
|
|
structures each containing the following entries:
|
|
.Bd -literal -offset indent
|
|
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 */
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fa d_fileno
|
|
entry is a number which is unique for each
|
|
distinct file in the file system.
|
|
Files that are linked by hard links (see
|
|
.Xr link 2 )
|
|
have the same
|
|
.Fa d_fileno .
|
|
The
|
|
.Fa d_reclen
|
|
entry is the length, in bytes, of the directory record.
|
|
The
|
|
.Fa d_type
|
|
entry is the type of the file pointed to by the directory record.
|
|
The file type values are defined in
|
|
.Fa <sys/dirent.h> .
|
|
The
|
|
.Fa d_name
|
|
entry contains a null terminated file name.
|
|
The
|
|
.Fa d_namlen
|
|
entry specifies the length of the file name excluding the null byte.
|
|
Thus the actual size of
|
|
.Fa d_name
|
|
may vary from 1 to
|
|
.Dv MAXNAMELEN
|
|
\&+ 1.
|
|
.Pp
|
|
Entries may be separated by extra space.
|
|
The
|
|
.Fa d_reclen
|
|
entry may be used as an offset from the start of a
|
|
.Fa dirent
|
|
structure to the next structure, if any.
|
|
.Pp
|
|
The actual number of bytes transferred is returned.
|
|
The current position pointer associated with
|
|
.Fa fd
|
|
is set to point to the next block of entries.
|
|
The pointer may not advance by the number of bytes returned by
|
|
.Fn getdirentries
|
|
or
|
|
.Fn getdents .
|
|
A value of zero is returned when
|
|
the end of the directory has been reached.
|
|
.Pp
|
|
The
|
|
.Fn getdirentries
|
|
system call writes the position of the block read into the location pointed to by
|
|
.Fa basep .
|
|
Alternatively, the current position pointer may be set and retrieved by
|
|
.Xr lseek 2 .
|
|
The current position pointer should only be set to a value returned by
|
|
.Xr lseek 2 ,
|
|
a value returned in the location pointed to by
|
|
.Fa basep
|
|
.Fn ( getdirentries
|
|
only)
|
|
or zero.
|
|
.Sh RETURN VALUES
|
|
If successful, the number of bytes actually transferred is returned.
|
|
Otherwise, -1 is returned and the global variable
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
The
|
|
.Fn getdirentries
|
|
system call
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa fd
|
|
argument
|
|
is not a valid file descriptor open for reading.
|
|
.It Bq Er EFAULT
|
|
Either
|
|
.Fa buf
|
|
or
|
|
.Fa basep
|
|
point outside the allocated address space.
|
|
.It Bq Er EINVAL
|
|
The file referenced by
|
|
.Fa fd
|
|
is not a directory, or
|
|
.Fa nbytes
|
|
is too small for returning a directory entry or block of entries,
|
|
or the current position pointer is invalid.
|
|
.It Bq Er EIO
|
|
An
|
|
.Tn I/O
|
|
error occurred while reading from or writing to the file system.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr lseek 2 ,
|
|
.Xr open 2
|
|
.Sh HISTORY
|
|
The
|
|
.Fn getdirentries
|
|
system call first appeared in
|
|
.Bx 4.4 .
|
|
The
|
|
.Fn getdents
|
|
system call first appeared in
|
|
.Fx 3.0 .
|