diff options
Diffstat (limited to 'REORG.TODO/io/lockf.c')
-rw-r--r-- | REORG.TODO/io/lockf.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/REORG.TODO/io/lockf.c b/REORG.TODO/io/lockf.c new file mode 100644 index 0000000000..4ab7e9357f --- /dev/null +++ b/REORG.TODO/io/lockf.c @@ -0,0 +1,85 @@ +/* Copyright (C) 1994-2017 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 |