1 /*
2 Mutex implementation for SnapScan backend
3
4 Copyright (C) 2000, 2004 Henrik Johansson, Oliver Schwartz
5
6 This program is free software; you can redistribute it and/or
7 modify it under the terms of the GNU General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>.
18
19 As a special exception, the authors of SANE give permission for
20 additional uses of the libraries contained in this release of SANE.
21
22 The exception is that, if you link a SANE library with other files
23 to produce an executable, this does not by itself cause the
24 resulting executable to be covered by the GNU General Public
25 License. Your use of that executable is in no way restricted on
26 account of linking the SANE library code into it.
27
28 This exception does not, however, invalidate any other reasons why
29 the executable file might be covered by the GNU General Public
30 License.
31
32 If you submit changes to SANE to the maintainers to be included in
33 a subsequent release, you agree by submitting the changes that
34 those changes may be distributed with this exception intact.
35
36 If you write modifications of your own for SANE, it is your choice
37 whether to permit this exception to apply to your modifications.
38 If you do not wish that, delete this exception notice.*/
39
40 #if defined __BEOS__
41
42 #include <OS.h>
43 #define snapscan_mutex_t sem_id
44
snapscani_mutex_open(snapscan_mutex_t* a_sem, const char* dev __sane_unused__)45 static int snapscani_mutex_open(snapscan_mutex_t* a_sem, const char* dev __sane_unused__)
46 {
47 *a_sem = create_sem(1, "snapscan_mutex");
48 return 1;
49 }
50
snapscani_mutex_close(snapscan_mutex_t* a_sem)51 static void snapscani_mutex_close(snapscan_mutex_t* a_sem)
52 {
53 delete_sem(*a_sem);
54 }
55
snapscani_mutex_lock(snapscan_mutex_t* a_sem)56 static void snapscani_mutex_lock(snapscan_mutex_t* a_sem)
57 {
58 acquire_sem(*a_sem);
59 }
60
snapscani_mutex_unlock(snapscan_mutex_t* a_sem)61 static void snapscani_mutex_unlock(snapscan_mutex_t* a_sem)
62 {
63 release_sem(*a_sem);
64 }
65
66
67
68 #elif defined USE_PTHREAD || defined HAVE_OS2_H
69
70 #include <pthread.h>
71 #define snapscan_mutex_t pthread_mutex_t
72
snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev __sane_unused__)73 static int snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev __sane_unused__)
74 {
75 pthread_mutex_init(sem_id, NULL);
76 return 1;
77 }
78
snapscani_mutex_close(snapscan_mutex_t* sem_id)79 static void snapscani_mutex_close(snapscan_mutex_t* sem_id)
80 {
81 pthread_mutex_destroy(sem_id);
82 }
83
snapscani_mutex_lock(snapscan_mutex_t* sem_id)84 static void snapscani_mutex_lock(snapscan_mutex_t* sem_id)
85 {
86 pthread_mutex_lock(sem_id);
87 }
88
snapscani_mutex_unlock(snapscan_mutex_t* sem_id)89 static void snapscani_mutex_unlock(snapscan_mutex_t* sem_id)
90 {
91 pthread_mutex_unlock(sem_id);
92 }
93
94 #else /* defined USE_PTHREAD || defined HAVE_OS2_H */
95
96 #include <sys/ipc.h>
97 #include <sys/sem.h>
98 #include <sys/types.h>
99 #include <unistd.h>
100
101 #define snapscan_mutex_t int
102
103 /* check for union semun */
104 #if defined(HAVE_UNION_SEMUN)
105 /* union semun is defined by including <sys/sem.h> */
106 #else
107 /* according to X/OPEN we have to define it ourselves */
108 union semun {
109 int val; /* value for SETVAL */
110 struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
111 unsigned short int *array; /* array for GETALL, SETALL */
112 struct seminfo *__buf; /* buffer for IPC_INFO */
113 };
114 #endif /* defined HAVE_UNION_SEMUN */
115
116 static struct sembuf sem_wait = { 0, -1, 0 };
117 static struct sembuf sem_signal = { 0, 1, 0 };
118
snapscani_bernstein(const unsigned char* str)119 static unsigned int snapscani_bernstein(const unsigned char* str)
120 {
121 unsigned int hash = 5381; /* some arbitrary number */
122 int c;
123
124 while (*str)
125 {
126 c = *str++;
127 hash = ((hash << 5) + hash) + c;
128 }
129 return hash;
130 }
131
snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev)132 static int snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev)
133 {
134 static const char *me = "snapscani_mutex_open";
135 key_t ipc_key = -1;
136
137 if (strstr(dev, "libusb:") == dev)
138 {
139 key_t ipc_key = (key_t) snapscani_bernstein((const unsigned char*) dev+7);
140 DBG (DL_INFO, "%s: using IPC key 0x%08x for device %s\n",
141 me, ipc_key, dev);
142 }
143 else
144 {
145 ipc_key = ftok(dev, 0x12);
146
147 if (ipc_key == -1)
148 {
149 DBG (DL_MAJOR_ERROR, "%s: could not obtain IPC key for device %s: %s\n", me, dev, strerror(errno));
150 return 0;
151 }
152 }
153
154 *sem_id = semget( ipc_key, 1, IPC_CREAT | 0660 );
155 if (*sem_id == -1)
156 {
157 DBG (DL_MAJOR_ERROR, "%s: semget failed: %s\n", me, strerror(errno));
158 return 0;
159 }
160
161 semop(*sem_id, &sem_signal, 1);
162 return 1;
163 }
164
snapscani_mutex_close(snapscan_mutex_t* sem_id)165 static void snapscani_mutex_close(snapscan_mutex_t* sem_id)
166 {
167 static union semun dummy_semun_arg;
168 semctl(*sem_id, 0, IPC_RMID, dummy_semun_arg);
169 }
170
snapscani_mutex_lock(snapscan_mutex_t* sem_id)171 static void snapscani_mutex_lock(snapscan_mutex_t* sem_id)
172 {
173 semop(*sem_id, &sem_wait, 1);
174 }
175
snapscani_mutex_unlock(snapscan_mutex_t* sem_id)176 static void snapscani_mutex_unlock(snapscan_mutex_t* sem_id)
177 {
178 semop(*sem_id, &sem_signal, 1);
179 }
180
181 #endif /* defined USE_PTHREAD || defined HAVE_OS2_H */
182