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
195 lines
4.2 KiB
Groff
195 lines
4.2 KiB
Groff
.\" $NetBSD: fmemopen.3,v 1.7 2012/10/08 18:15:09 njoly Exp $
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.\"
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.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Christos Zoulas.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd October 15, 2011
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.Dt FMEMOPEN 3
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.Os
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.Sh NAME
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.Nm fmemopen
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.Nd open a stream that points to the given buffer
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdio.h
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.Ft FILE *
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.Fn fmemopen "void *restrict buffer" "size_t size" "const char *restrict mode"
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.Sh DESCRIPTION
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The
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.Fn fmemopen
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function
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associates a stream with the given
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.Fa buffer
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and
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.Fa size .
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The
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.Fa buffer
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can be either
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.Dv NULL ,
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or must be of the given
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.Fa size .
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If the
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.Fa buffer
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is
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.Dv NULL ,
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a
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.Fa buffer
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of the given
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.Fa size
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will be dynamically allocated using
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.Xr malloc 3
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and freed when
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.Xr fclose 3
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is called.
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.Pp
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The
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.Fa mode
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argument has the same meaning as in
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.Xr fopen 3 .
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.Pp
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The stream treats the buffer as it would treat a file tracking the current
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position to perform I/O operations.
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For example, in the beginning the stream points to the beginning of the buffer,
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unless
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.Dv a
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was specified in the
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.Fa mode
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argument, and then it points to the first
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.Dv NUL
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byte.
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If a
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.Dv NULL
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.Fa buffer
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was specified, then the stream will always point at the first byte of the
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.Fa buffer .
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.Pp
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The stream also keeps track of the
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.Fa size
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of the
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.Fa buffer .
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The
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.Fa size
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is initialized depending on the mode:
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.Bl -tag -width r/w+
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.It Dv r/r+
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Set to the
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.Fa size
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argument.
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.It Dv w/w+
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Set to
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.Dv 0 .
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.It Dv a/a+
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Set to the first
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.Dv NUL
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byte, or the
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.Fa size
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argument if one is not found.
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.El
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.Pp
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Read or write operations advance the buffer, but not to exceed the given
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.Fa size
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of the
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.Fa buffer .
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Trying to read beyond the
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.Fa size
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of the
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.Fa buffer
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results in
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.Dv EOF
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returned.
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.Dv NUL
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bytes are read normally.
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Trying to write beyond the
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.Fa size
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of the
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.Fa buffer
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has no effect.
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.Pp
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When a stream open for writing is either flushed or closed, a
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.Dv NUL
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byte is written at the current position or at the end of the current
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.Fa size
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as kept internally, if there is room.
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.Sh RETURN VALUES
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Upon successful completion,
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.Fn fmemopen
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returns a
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.Dv FILE
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pointer.
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Otherwise,
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.Dv NULL
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is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa size
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was
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.Dv 0 ;
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or the
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.Fa mode
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argument is invalid;
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or the
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.Fa buffer
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argument is
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.Dv NULL
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and the
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.Fa mode
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argument does not specify a
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.Dv + .
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.El
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.Pp
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The
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.Fn fmemopen
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function
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may also fail and set
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.Va errno
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for any of the errors
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specified for the routine
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.Xr malloc 3 .
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.Sh SEE ALSO
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.Xr fclose 3 ,
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.Xr fflush 3 ,
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.Xr fopen 3 ,
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.Xr malloc 3
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.Sh STANDARDS
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The
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.Fn fmemopen
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function conforms to
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.St -p1003.1-2008 .
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.Sh HISTORY
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The
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.Fn fmemopen
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functions first appeared in
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.Nx 6.0 .
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