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59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
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/* Copyright (C) 1992, 1995 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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/* This file implements the `flock' function in terms of the POSIX.1 `fcntl'
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locking mechanism. In 4BSD, these are two incompatible locking mechanisms,
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perhaps with different semantics? */
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#include <ansidecl.h>
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/file.h>
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/* Apply or remove an advisory lock, according to OPERATION,
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on the file FD refers to. */
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int
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DEFUN(__flock, (fd, operation), int fd AND int operation)
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{
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struct flock lbuf;
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switch (operation & ~LOCK_NB)
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{
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case LOCK_SH:
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lbuf.l_type = F_RDLCK;
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break;
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case LOCK_EX:
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lbuf.l_type = F_WRLCK;
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break;
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case LOCK_UN:
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lbuf.l_type = F_UNLCK;
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break;
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default:
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errno = EINVAL;
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return -1;
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}
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lbuf.l_whence = SEEK_SET;
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lbuf.l_start = lbuf.l_len = 0L; /* Lock the whole file. */
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return __fcntl (fd, (operation & LOCK_NB) ? F_SETLK : F_SETLKW, &lbuf);
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}
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weak_alias (__flock, flock)
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