1 /* Copyright (C) 1994, 1996, 1997, 1998, 2000 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
8
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 Library General Public License for more details.
13
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 see <http://www.gnu.org/licenses/>. */
17
18 #include <_lfs_64.h>
19
20 #include <sys/types.h>
21 #include <unistd.h>
22 #include <fcntl.h>
23 #include <errno.h>
24 #include <string.h>
25 #include <sys/syscall.h>
26
27 #ifdef __NR_fcntl64
28 #define flock flock64
29 #define fcntl fcntl64
30 #undef F_GETLK
31 #define F_GETLK F_GETLK64
32 #undef F_SETLK
33 #define F_SETLK F_SETLK64
34 #else
35 #endif
36
37
38 /* lockf is a simplified interface to fcntl's locking facilities. */
39
lockf64(int fd,int cmd,off64_t len64)40 int lockf64 (int fd, int cmd, off64_t len64)
41 {
42 struct flock fl;
43 off_t len = (off_t) len64;
44
45 if (len64 != (off64_t) len)
46 {
47 /* We can't represent the length. */
48 __set_errno(EOVERFLOW);
49 return -1;
50 }
51
52 memset((char *) &fl, '\0', sizeof (fl));
53
54 /* lockf is always relative to the current file position. */
55 fl.l_whence = SEEK_CUR;
56 fl.l_start = 0;
57 fl.l_len = len;
58
59 switch (cmd)
60 {
61 case F_TEST:
62 /* Test the lock: return 0 if FD is unlocked or locked by this process;
63 return -1, set errno to EACCES, if another process holds the lock. */
64 fl.l_type = F_RDLCK;
65 if (fcntl (fd, F_GETLK, &fl) < 0)
66 return -1;
67 if (fl.l_type == F_UNLCK || fl.l_pid == getpid ())
68 return 0;
69 __set_errno(EACCES);
70 return -1;
71
72 case F_ULOCK:
73 fl.l_type = F_UNLCK;
74 cmd = F_SETLK;
75 break;
76 case F_LOCK:
77 fl.l_type = F_WRLCK;
78 cmd = F_SETLKW;
79 break;
80 case F_TLOCK:
81 fl.l_type = F_WRLCK;
82 cmd = F_SETLK;
83 break;
84
85 default:
86 __set_errno(EINVAL);
87 return -1;
88 }
89
90 return fcntl(fd, cmd, &fl);
91 }
92