1/* unlock.c: The opieunlock() library function.
2
3%%% portions-copyright-cmetz-96
4Portions of this software are Copyright 1996-1999 by Craig Metz, All Rights
5Reserved. The Inner Net License Version 2 applies to these portions of
6the software.
7You should have received a copy of the license with this software. If
8you didn't get a copy, you may request one from <license@inner.net>.
9
10Portions of this software are Copyright 1995 by Randall Atkinson and Dan
11McDonald, All Rights Reserved. All Rights under this copyright are assigned
12to the U.S. Naval Research Laboratory (NRL). The NRL Copyright Notice and
13License Agreement applies to this software.
14
15        History:
16
17	Modified by cmetz for OPIE 2.31. Bug fix.
18	Modified by cmetz for OPIE 2.3. Do refcounts whether or not
19            we actually lock. Fixed USER_LOCKING=0 case.
20	Modified by cmetz for OPIE 2.22. Added reference count support.
21	    Changed lock filename/refcount symbol names to better indicate
22	    that they're not user serviceable.
23	Modified by cmetz for OPIE 2.2. Use FUNCTION declaration.
24            Check for read() == -1. ifdef around unistd.h.
25        Created at NRL for OPIE 2.2 from opiesubr2.c
26*/
27#include "opie_cfg.h"
28#include <string.h>
29#if HAVE_UNISTD_H
30#include <unistd.h>
31#endif /* HAVE_UNISTD_H */
32#include <fcntl.h>
33#include "opie.h"
34
35extern int __opie_lockrefcount;
36#if USER_LOCKING
37extern char *__opie_lockfilename;
38#endif /* USER_LOCKING */
39
40/*
41  Just remove the lock, right?
42  Well, not exactly -- we need to make sure it's ours.
43*/
44int opieunlock FUNCTION_NOARGS
45{
46#if USER_LOCKING
47  int fh, rval = -1, pid, t, i;
48  char buffer[128], *c, *c2;
49
50  if (--__opie_lockrefcount > 0)
51    return 0;
52
53  if (!__opie_lockfilename)
54    return -1;
55
56  if (!(fh = open(__opie_lockfilename, O_RDWR, 0600)))
57    goto unlockret;
58
59  if ((i = read(fh, buffer, sizeof(buffer))) < 0)
60    goto unlockret;
61
62  buffer[sizeof(buffer) - 1] = 0;
63  buffer[i - 1] = 0;
64
65  if (!(c = strchr(buffer, '\n')))
66    goto unlockret;
67
68  *(c++) = 0;
69
70  if (!(c2 = strchr(c, '\n')))
71    goto unlockret;
72
73  *(c2++) = 0;
74
75  if (!(pid = atoi(buffer)))
76    goto unlockret;
77
78  if (!(t = atoi(c)))
79    goto unlockret;
80
81  if ((pid != getpid()) && (time(0) <= OPIE_LOCK_TIMEOUT + t) && (!kill(pid, 0))) {
82    rval = 1;
83    goto unlockret1;
84  }
85
86  rval = 0;
87
88unlockret:
89  unlink(__opie_lockfilename);
90
91unlockret1:
92  if (fh)
93    close(fh);
94  free(__opie_lockfilename);
95  __opie_lockfilename = NULL;
96  return rval;
97#else /* USER_LOCKING */
98  if (__opie_lockrefcount-- > 0)
99    return 0;
100
101  return -1;
102#endif /* USER_LOCKING */
103}
104