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+/* Copyright (C) 1994, 1996, 1997, 1998, 2000 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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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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+
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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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+
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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 not,
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+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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+ Boston, MA 02111-1307, USA. */
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+
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+#include <sys/types.h>
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+#include <unistd.h>
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+#include <fcntl.h>
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+#include <errno.h>
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+#include <string.h>
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+
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+#ifdef __NR_fcntl64
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+#define flock flock64
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+#define fcntl fcntl64
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+#define F_GETLK F_GETLK64
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+#define F_SETLK F_SETLK64
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+#endif
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+
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+/* lockf is a simplified interface to fcntl's locking facilities. */
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+
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+int lockf64 (int fd, int cmd, off64_t len64)
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+{
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+ struct flock fl;
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+ off_t len = (off_t) len64;
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+
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+ if (len64 != (off64_t) len)
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+ {
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+ /* We can't represent the length. */
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+ __set_errno(EOVERFLOW);
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+ return -1;
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+ }
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+
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+ memset((char *) &fl, '\0', sizeof (fl));
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+
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+ /* lockf is always relative to the current file position. */
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+ fl.l_whence = SEEK_CUR;
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+ fl.l_start = 0;
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+ fl.l_len = len;
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+
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+ switch (cmd)
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+ {
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+ case F_TEST:
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+ /* Test the lock: return 0 if FD is unlocked or locked by this process;
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+ return -1, set errno to EACCES, if another process holds the lock. */
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+ fl.l_type = F_RDLCK;
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+ if (fcntl (fd, F_GETLK, &fl) < 0)
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+ return -1;
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+ if (fl.l_type == F_UNLCK || fl.l_pid == getpid ())
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+ return 0;
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+ __set_errno(EACCES);
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+ return -1;
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+
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+ case F_ULOCK:
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+ fl.l_type = F_UNLCK;
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+ cmd = F_SETLK;
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+ break;
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+ case F_LOCK:
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+ fl.l_type = F_WRLCK;
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+ cmd = F_SETLKW;
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+ break;
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+ case F_TLOCK:
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+ fl.l_type = F_WRLCK;
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+ cmd = F_SETLK;
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+ break;
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+
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+ default:
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+ __set_errno(EINVAL);
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+ return -1;
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+ }
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+
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+ return fcntl(fd, cmd, &fl);
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+}
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