Add a manual page for flockfile(3) etc.; while here, also add *_unlocked()
to stdio(3) overview documentation. Fixes PR lib/20096 from Jason Thorpe.
This commit is contained in:
kleink
parent
e5cd4ce42c
commit
5b62d84e6e
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@ -1,5 +1,5 @@
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# from: @(#)Makefile.inc 5.7 (Berkeley) 6/27/91
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# $NetBSD: Makefile.inc,v 1.23 2003/01/18 11:29:50 thorpej Exp $
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# $NetBSD: Makefile.inc,v 1.24 2003/01/28 20:26:04 kleink Exp $
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# stdio sources
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.PATH: ${.CURDIR}/stdio
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@ -26,13 +26,14 @@ SRCS+= gets.c sprintf.c vsprintf.c tempnam.c tmpnam.c mktemp.c
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# namespace purity wrappers
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SRCS+= _fseeko.c _ftello.c
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MAN+= fclose.3 ferror.3 fflush.3 fgetln.3 fgets.3 fopen.3 fputs.3 \
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fread.3 fseek.3 funopen.3 getc.3 mktemp.3 perror.3 printf.3 putc.3 \
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remove.3 scanf.3 setbuf.3 stdio.3 tmpnam.3 ungetc.3 putwc.3 getwc.3 \
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ungetwc.3 fwide.3 fparseln.3
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MAN+= fclose.3 ferror.3 fflush.3 fgetln.3 fgets.3 flockfile.3 fopen.3 \
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fputs.3 fread.3 fseek.3 funopen.3 getc.3 mktemp.3 perror.3 printf.3 \
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putc.3 remove.3 scanf.3 setbuf.3 stdio.3 tmpnam.3 ungetc.3 putwc.3 \
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getwc.3 ungetwc.3 fwide.3 fparseln.3
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MLINKS+=ferror.3 clearerr.3 ferror.3 feof.3 ferror.3 fileno.3
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MLINKS+=fflush.3 fpurge.3
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MLINKS+=flockfile.3 ftrylockfile.3 flockfile.3 funlockfile.3
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MLINKS+=fgets.3 gets.3
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MLINKS+=fopen.3 fdopen.3 fopen.3 freopen.3
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MLINKS+=fputs.3 puts.3
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@ -0,0 +1,127 @@
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.\" $NetBSD: flockfile.3,v 1.1 2003/01/28 20:26:04 kleink Exp $
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.\"
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.\" Copyright (c) 2003 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 Klaus Klein.
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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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. 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 January 28, 2003
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.Dt FLOCKFILE 3
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.Os
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.Sh NAME
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.Nm flockfile ,
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.Nm ftrylockfile ,
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.Nm funlockfile
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.Nd stdio stream locking functions
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include \*[Lt]stdio.h\*[Gt]
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.Ft void
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.Fn flockfile "FILE *file"
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.Ft int
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.Fn ftrylockfile "FILE *file"
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.Ft void
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.Fn funlockfile "FILE *file"
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.Sh DESCRIPTION
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The
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.Fn flockfile ,
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.Fn ftrylockfile
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and
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.Fn funlockfile
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functions provide applications with explicit control of locking of
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stdio stream objects.
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They can be used by a thread to execute a sequence of I/O operations
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as a unit, without interference from another thread.
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.Pp
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Locks on stdio streams are recursive, and a lock count is maintained.
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stdio streams are created unlocked, with a lock count of zero.
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After successful acquisition of the lock, its count is incremented
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to one, indicating locked state of the stdio stream.
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Each subsequent relock operation performed by the owner thread
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increments the lock count by one, and each subsequent unlock
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operation performed by the owner thread decrements the lock count by one,
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allowing matching lock and unlock operations to be nested.
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After its lock count is decremented to zero, the stdio stream returns
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to unlocked state, and ownership of the stdio stream is relinquished.
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.Pp
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The
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.Fn flockfile
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function acquires the ownership of
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.Fa file
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for the calling thread.
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If
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.Fa file
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is already owned by another thread, the calling thread is suspended
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until the acquisition is possible (i.e.,
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.Fa file
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is relinquished again and the calling thread is scheduled to acquire it).
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.Pp
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The
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.Fn ftrylockfile
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function acquires the ownership of
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.Fa file
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for the calling thread only if
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.Fa file
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is available.
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.Pp
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The
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.Fn funlockfile
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function relinquishes the ownership of
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.Fa file
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previously granted to the calling thread.
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Only the current owner of
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.Fa file
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may
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.Fn funlockfile
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it.
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.Sh RETURN VALUES
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If successful, the
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.Fn ftrylockfile
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function returns 0.
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Otherwise, it returns non-zero to indicate that the lock cannot be acquired.
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.Sh SEE ALSO
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.Xr getc_unlocked 3 ,
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.Xr getchar_unlocked 3 ,
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.Xr putc_unlocked 3 ,
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.Xr putchar_unlocked 3
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.Sh STANDARDS
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The
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.Fn flockfile ,
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.Fn ftrylockfile
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and
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.Fn funlockfile
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functions conform to
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.St -p1003.1-2001 .
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.Sh BUGS
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The design of these interfaces does not allow for addressing the
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problem of priority inversion.
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@ -1,4 +1,4 @@
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.\" $NetBSD: getc.3,v 1.9 2003/01/18 11:29:55 thorpej Exp $
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.\" $NetBSD: getc.3,v 1.10 2003/01/28 20:26:04 kleink 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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@ -136,8 +136,11 @@ until the condition is cleared with
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.Xr clearerr 3 .
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.Sh SEE ALSO
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.Xr ferror 3 ,
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.Xr flockfile 3 ,
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.Xr fopen 3 ,
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.Xr fread 3 ,
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.Xr ftrylockfile 3 ,
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.Xr funlockfile 3 ,
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.Xr putc 3 ,
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.Xr ungetc 3
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.Sh STANDARDS
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@ -1,4 +1,4 @@
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.\" $NetBSD: stdio.3,v 1.16 2003/01/18 11:29:58 thorpej Exp $
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.\" $NetBSD: stdio.3,v 1.17 2003/01/28 20:26:04 kleink 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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@ -33,7 +33,7 @@
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.\"
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.\" @(#)stdio.3 8.7 (Berkeley) 4/19/94
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.\"
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.Dd April 19, 1994
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.Dd January 28, 2003
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.Dt STDIO 3
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.Os
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.Sh NAME
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@ -168,6 +168,21 @@ sections of the following manual pages indicate which include files
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are to be used, what the compiler declaration for the function
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looks like and which external variables are of interest.
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.Pp
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In multi-threaded applications, operations on streams perform implicit
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locking, except for the
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.Fa getc_unlocked ,
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.Fa getchar_unlocked ,
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.Fa putc_unlocked ,
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and
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.Fa putchar_unlocked
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functions.
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Explicit control of stream locking is available through the
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.Fa flockfile ,
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.Fa ftrylockfile ,
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and
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.Fa funlockfile
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functions .
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.Pp
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The following are defined as macros; these names may not be re-used
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without first removing their current definitions with
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.Dv #undef :
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@ -190,9 +205,13 @@ without first removing their current definitions with
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.Fn freopen ,
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.Fn fwopen ,
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.Fn getc ,
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.Fn getc_unlocked ,
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.Fn getchar ,
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.Fn getchar_unlocked ,
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.Fn putc ,
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.Fn putc_unlocked ,
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.Fn putchar ,
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.Fn putchar_unlocked ,
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.Dv stderr ,
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.Dv stdin ,
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.Dv stdout .
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@ -202,10 +221,14 @@ Function versions of the macro functions
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.Fn clearerr ,
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.Fn fileno ,
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.Fn getc ,
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.Fn getc_unlocked ,
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.Fn getchar ,
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.Fn getchar_unlocked ,
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.Fn putc ,
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.Fn putc_unlocked ,
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.Fn putchar ,
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and
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.Fn putchar
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.Fn putchar_unlocked
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exist and will be used if the macros definitions are explicitly removed.
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.Sh SEE ALSO
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.Xr close 2 ,
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@ -218,7 +241,7 @@ The
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library conforms to
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.St -ansiC .
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.Sh LIST OF FUNCTIONS
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.Bl -column "Description"
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.Bl -column "Functionxxxxxxxx" "Description"
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.Sy Function Description
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clearerr check and reset stream status
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fclose close a stream
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@ -232,6 +255,7 @@ fgetpos reposition a stream
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fgets get a line from a stream
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fgetwc get next wide character from input stream
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fileno check and reset stream status
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flockfile lock a stream
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fopen stream open functions
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fprintf formatted output conversion
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fpurge flush a stream
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@ -245,12 +269,18 @@ fscanf input format conversion
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fseek reposition a stream
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fsetpos reposition a stream
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ftell reposition a stream
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ftrylockfile lock a stream (non-blocking)
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funlockfile unlock a stream
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funopen open a stream
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fwide set/get orientation of a stream
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fwopen open a stream
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fwrite binary stream input/output
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getc get next character or word from input stream
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getc_unlocked get next character or word from input stream
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(no implicit locking)
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getchar get next character or word from input stream
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getchar_unlocked get next character or word from input stream
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(no implicit locking)
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gets get a line from a stream
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getw get next character or word from input stream
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getwc get next wide character from input stream
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@ -260,7 +290,11 @@ mktemp create unique temporary file
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perror system error messages
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printf formatted output conversion
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putc output a character or word to a stream
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putc_unlocked output a character or word to a stream
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(no implicit locking)
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putchar output a character or word to a stream
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putchar_unlocked output a character or word to a stream
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(no implicit locking)
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puts output a line to a stream
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putw output a character or word to a stream
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putwc output a wide character to a stream
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