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sourceware.org Git - glibc.git/blob - io/lockf64.c
1 /* Copyright (C) 1994-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
22 /* lockf is a simplified interface to fcntl's locking facilities. */
24 __lockf64 (int fd
, int cmd
, off64_t len64
)
26 /* lockf is always relative to the current file position. */
27 struct flock64 fl64
= {
33 /* lockf() is a cancellation point but so is fcntl() if F_SETLKW is
34 used. Therefore we don't have to care about cancellation here,
35 the fcntl() function will take care of it. */
39 /* Test the lock: return 0 if FD is unlocked or locked by this process;
40 return -1, set errno to EACCES, if another process holds the lock. */
41 fl64
.l_type
= F_RDLCK
;
42 if (__fcntl (fd
, F_GETLK64
, &fl64
) < 0)
44 if (fl64
.l_type
== F_UNLCK
|| fl64
.l_pid
== __getpid ())
49 fl64
.l_type
= F_UNLCK
;
50 return __fcntl64 (fd
, F_SETLK64
, &fl64
);
52 return __fcntl64 (fd
, F_SETLKW64
, &fl64
);
54 return __fcntl64 (fd
, F_SETLK64
, &fl64
);
59 weak_alias (__lockf64
, lockf64
)
60 #ifdef __OFF_T_MATCHES_OFF64_T
61 weak_alias (lockf64
, lockf
)
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