mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 21:10:07 +00:00
86 lines
2.4 KiB
C
86 lines
2.4 KiB
C
/* Copyright (C) 1994-2012 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* We need to avoid the header declaration of lockf64, because
|
|
the types don't match lockf and then the compiler will
|
|
complain about the mismatch when we do the alias below. */
|
|
#define lockf64 __renamed_lockf64
|
|
|
|
#include <fcntl.h>
|
|
|
|
#undef lockf64
|
|
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
|
|
/* lockf is a simplified interface to fcntl's locking facilities. */
|
|
|
|
int
|
|
lockf (int fd, int cmd, off_t len)
|
|
{
|
|
struct flock fl;
|
|
|
|
memset ((char *) &fl, '\0', sizeof (fl));
|
|
|
|
/* lockf is always relative to the current file position. */
|
|
fl.l_whence = SEEK_CUR;
|
|
fl.l_start = 0;
|
|
fl.l_len = len;
|
|
|
|
switch (cmd)
|
|
{
|
|
case F_TEST:
|
|
/* Test the lock: return 0 if FD is unlocked or locked by this process;
|
|
return -1, set errno to EACCES, if another process holds the lock. */
|
|
fl.l_type = F_RDLCK;
|
|
if (__fcntl (fd, F_GETLK, &fl) < 0)
|
|
return -1;
|
|
if (fl.l_type == F_UNLCK || fl.l_pid == __getpid ())
|
|
return 0;
|
|
__set_errno (EACCES);
|
|
return -1;
|
|
|
|
case F_ULOCK:
|
|
fl.l_type = F_UNLCK;
|
|
cmd = F_SETLK;
|
|
break;
|
|
case F_LOCK:
|
|
fl.l_type = F_WRLCK;
|
|
cmd = F_SETLKW;
|
|
break;
|
|
case F_TLOCK:
|
|
fl.l_type = F_WRLCK;
|
|
cmd = F_SETLK;
|
|
break;
|
|
|
|
default:
|
|
__set_errno (EINVAL);
|
|
return -1;
|
|
}
|
|
|
|
/* lockf() is a cancellation point but so is fcntl() if F_SETLKW is
|
|
used. Therefore we don't have to care about cancellation here,
|
|
the fcntl() function will take care of it. */
|
|
return __fcntl (fd, cmd, &fl);
|
|
}
|
|
|
|
#ifdef __OFF_T_MATCHES_OFF64_T
|
|
weak_alias (lockf, lockf64)
|
|
#endif
|