f14fb60209
* Updating common/lib * Updating lib/csu * Updating lib/libc * Updating libexec/ld.elf_so * Corrected test on __minix in featuretest to actually follow the meaning of the comment. * Cleaned up _REENTRANT-related defintions. * Disabled -D_REENTRANT for libfetch * Removing some unneeded __NBSD_LIBC defines and tests Change-Id: Ic1394baef74d11b9f86b312f5ff4bbc3cbf72ce2
125 lines
3.7 KiB
Groff
125 lines
3.7 KiB
Groff
.\" $NetBSD: fread.3,v 1.15 2011/09/11 04:55:48 jruoho Exp $
|
|
.\"
|
|
.\" Copyright (c) 1990, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" Chris Torek and the American National Standards Committee X3,
|
|
.\" on Information Processing Systems.
|
|
.\"
|
|
.\" 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.
|
|
.\" 3. 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.
|
|
.\"
|
|
.\" @(#)fread.3 8.2 (Berkeley) 3/8/94
|
|
.\"
|
|
.Dd September 11, 2011
|
|
.Dt FREAD 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm fread ,
|
|
.Nm fwrite
|
|
.Nd binary stream input/output
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In stdio.h
|
|
.Ft size_t
|
|
.Fn fread "void * restrict ptr" "size_t size" "size_t nmemb" "FILE * restrict stream"
|
|
.Ft size_t
|
|
.Fn fwrite "const void * restrict ptr" "size_t size" "size_t nmemb" "FILE * restrict stream"
|
|
.Sh DESCRIPTION
|
|
The function
|
|
.Fn fread
|
|
reads
|
|
.Fa nmemb
|
|
objects, each
|
|
.Fa size
|
|
bytes long, from the stream pointed to by
|
|
.Fa stream ,
|
|
storing them at the location given by
|
|
.Fa ptr .
|
|
.Pp
|
|
The function
|
|
.Fn fwrite
|
|
writes
|
|
.Fa nmemb
|
|
objects, each
|
|
.Fa size
|
|
bytes long, to the stream pointed to by
|
|
.Fa stream ,
|
|
obtaining them from the location given by
|
|
.Fa ptr .
|
|
.Pp
|
|
Mixing
|
|
.Fn fread
|
|
and
|
|
.Fn fwrite
|
|
calls without setting the file position explicitly using
|
|
.Xr fsetpos 3
|
|
between read and write or write and read operations will lead to unexpected
|
|
results because of buffering the file pointer not being set to the
|
|
expected position after each operation completes.
|
|
This behavior is allowed by ANSI C for efficiency and it will not be changed.
|
|
.Sh RETURN VALUES
|
|
The functions
|
|
.Fn fread
|
|
and
|
|
.Fn fwrite
|
|
advance the file position indicator for the stream
|
|
by the number of bytes read or written.
|
|
They return the number of objects read or written.
|
|
If
|
|
.Fa size
|
|
or
|
|
.Fa nmemb
|
|
is 0, the functions return 0 and the state of
|
|
.Fa stream
|
|
remains unchanged.
|
|
If an error occurs, or the end-of-file is reached,
|
|
the return value is a short object count (or zero).
|
|
.Pp
|
|
The function
|
|
.Fn fread
|
|
does not distinguish between end-of-file and error, and callers
|
|
must use
|
|
.Xr feof 3
|
|
and
|
|
.Xr ferror 3
|
|
to determine which occurred.
|
|
The function
|
|
.Fn fwrite
|
|
returns a value less than
|
|
.Fa nmemb
|
|
only if a write error has occurred.
|
|
.Sh SEE ALSO
|
|
.Xr read 2 ,
|
|
.Xr write 2
|
|
.Sh STANDARDS
|
|
The functions
|
|
.Fn fread
|
|
and
|
|
.Fn fwrite
|
|
conform to
|
|
.St -ansiC .
|