2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
278 lines
6.6 KiB
Groff
278 lines
6.6 KiB
Groff
.\" $NetBSD: fopen.3,v 1.24 2010/04/05 21:34:47 joerg Exp $
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.\"
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.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Chris Torek and the American National Standards Committee X3,
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.\" on Information Processing Systems.
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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 University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)fopen.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 4, 1993
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.Dt FOPEN 3
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.Os
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.Sh NAME
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.Nm fopen ,
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.Nm fdopen ,
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.Nm freopen
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.Nd stream open functions
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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 fopen "const char * restrict path" "const char * restrict mode"
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.Ft FILE *
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.Fn fdopen "int fildes" "const char *mode"
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.Ft FILE *
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.Fn freopen "const char * restrict path" "const char * restrict mode" "FILE * restrict stream"
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.Sh DESCRIPTION
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The
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.Fn fopen
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function
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opens the file whose name is the string pointed to by
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.Fa path
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and associates a stream with it.
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.Pp
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The argument
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.Fa mode
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points to a string beginning with one of the following
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sequences (Additional characters may follow these sequences.):
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.Bl -tag -width indent
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.It Dq Li r
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Open for reading.
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.It Dq Li r+
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Open for reading and writing.
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.It Dq Li w
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Open for writing.
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Truncate file to zero length or create file.
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.It Dq Li w+
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Open for reading and writing.
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Truncate file to zero length or create file.
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.It Dq Li a
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Append; open for writing.
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The file is created if it does not exist.
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.It Dq Li a+
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Append; open for reading and writing.
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The file is created if it does not exist.
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.El
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.Pp
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The
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.Fa mode
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string can also include the letter ``b'' either as a last character or
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as a character between the characters in any of the two-character strings
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described above.
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This is strictly for compatibility with
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.St -ansiC
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and has no effect; the ``b'' is ignored.
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.Pp
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The letter ``f'' in the mode string restricts fopen to regular
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files; if the file opened is not a regular file,
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.Fn fopen
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will fail.
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This is a non
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.St -ansiC
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extension.
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.Pp
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Any created files will have mode
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.Pf \*q Dv S_IRUSR
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\&|
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.Dv S_IWUSR
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\&|
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.Dv S_IRGRP
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\&|
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.Dv S_IWGRP
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\&|
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.Dv S_IROTH
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\&|
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.Dv S_IWOTH Ns \*q
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.Pq Li 0666 ,
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as modified by the process'
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umask value (see
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.Xr umask 2 ) .
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.Pp
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Opening a file with append mode causes all subsequent writes to it
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to be forced to the then current end of file, regardless of intervening
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repositioning of the stream.
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.Pp
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The
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.Fn fopen
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and
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.Fn freopen
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functions initially position the stream at the start of the file
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unless the file is opened with append mode,
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in which case the stream is initially positioned at the end of the file.
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.\" PR 6072 claims this paragraph is not correct.
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.\" .Pp
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.\" Reads and writes may be intermixed on read/write streams in any order,
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.\" and do not require an intermediate seek as in previous versions of
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.\" .Em stdio .
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.\" This is not portable to other systems, however;
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.\" .Tn ANSI C
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.\" requires that
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.\" a file positioning function intervene between output and input, unless
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.\" an input operation encounters end-of-file.
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.Pp
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The
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.Fn fdopen
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function associates a stream with the existing file descriptor,
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.Fa fildes .
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The
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.Fa mode
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of the stream must be compatible with the mode of the file descriptor.
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The stream is positioned at the file offset of the file descriptor.
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.Pp
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The
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.Fn freopen
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function
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opens the file whose name is the string pointed to by
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.Fa path
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and associates the stream pointed to by
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.Fa stream
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with it.
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The original stream (if it exists) is closed.
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The
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.Fa mode
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argument is used just as in the
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.Fn fopen
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function.
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The primary use of the
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.Fn freopen
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function
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is to change the file associated with a
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standard text stream
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.Pf ( Em stderr ,
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.Em stdin ,
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or
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.Em stdout ) .
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.Sh RETURN VALUES
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Upon successful completion
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.Fn fopen ,
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.Fn fdopen
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and
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.Fn freopen
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return a
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.Tn 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 mode
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provided to
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.Fn fopen ,
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.Fn fdopen ,
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or
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.Fn freopen
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was invalid.
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.It Bq Er EFTYPE
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The file is not a regular file and the character ``f'' is specified
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in the mode.
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.El
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.Pp
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The
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.Fn fopen ,
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.Fn fdopen
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and
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.Fn freopen
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functions
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may also fail and set
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.Va errno
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for any of the errors specified for the routine
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.Xr malloc 3 .
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.Pp
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The
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.Fn fopen
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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 specified for the routine
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.Xr open 2 .
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.Pp
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The
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.Fn fdopen
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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 specified for the routine
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.Xr fcntl 2 .
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.Pp
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The
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.Fn freopen
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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 specified for the routines
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.Xr open 2 ,
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.Xr fclose 3
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and
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.Xr fflush 3 .
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.Sh SEE ALSO
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.Xr open 2 ,
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.Xr fclose 3 ,
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.Xr fileno 3 ,
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.Xr fseek 3 ,
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.Xr funopen 3
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.Sh STANDARDS
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The
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.Fn fopen
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and
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.Fn freopen
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functions
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conform to
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.St -ansiC .
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The
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.Fn fdopen
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function conforms to
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.St -p1003.1-90 .
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.Sh CAVEATS
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Proper code using
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.Fn fdopen
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with error checking should
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.Xr close 2
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.Fa fildes
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in case of failure, and
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.Xr fclose 3
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the resulting FILE * in case of success.
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.Bd -literal
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FILE *file;
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int fd;
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if ((file = fdopen(fd, "r")) != NULL) {
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/* perform operations on the FILE * */
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fclose(file);
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} else {
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/* failure, report the error */
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close(fd);
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}
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.Ed
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