aboutsummaryrefslogtreecommitdiffstats
path: root/package/utils/busybox/patches/220-add_lock_util.patch
blob: c60f5db39286f8d3d291aa00bc6c7e0a6095fd73 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
--- a/include/applets.src.h
+++ b/include/applets.src.h
@@ -196,6 +196,7 @@ IF_LN(APPLET_NOEXEC(ln, ln, BB_DIR_BIN,
 IF_LOAD_POLICY(APPLET(load_policy, BB_DIR_USR_SBIN, BB_SUID_DROP))
 IF_LOADFONT(APPLET(loadfont, BB_DIR_USR_SBIN, BB_SUID_DROP))
 IF_LOADKMAP(APPLET(loadkmap, BB_DIR_SBIN, BB_SUID_DROP))
+IF_LOCK(APPLET(lock, BB_DIR_BIN, BB_SUID_DROP))
 IF_LOGNAME(APPLET_NOFORK(logname, logname, BB_DIR_USR_BIN, BB_SUID_DROP, logname))
 IF_LOSETUP(APPLET(losetup, BB_DIR_SBIN, BB_SUID_DROP))
 IF_LS(APPLET_NOEXEC(ls, ls, BB_DIR_BIN, BB_SUID_DROP, ls))
--- a/miscutils/Config.src
+++ b/miscutils/Config.src
@@ -375,6 +375,12 @@ config FEATURE_HDPARM_HDIO_GETSET_DMA
 	help
 	  Enables the 'hdparm -d' option to get/set using_dma flag.
 
+config LOCK
+	bool "lock"
+	default n
+	help
+	  Small utility for using locks in scripts
+
 config MAKEDEVS
 	bool "makedevs"
 	default y
--- a/miscutils/Kbuild.src
+++ b/miscutils/Kbuild.src
@@ -33,6 +33,7 @@ lib-$(CONFIG_LAST)        += last.o
 endif
 
 lib-$(CONFIG_LESS)        += less.o
+lib-$(CONFIG_LOCK)        += lock.o
 lib-$(CONFIG_MAKEDEVS)    += makedevs.o
 lib-$(CONFIG_MAN)         += man.o
 lib-$(CONFIG_MICROCOM)    += microcom.o
--- /dev/null
+++ b/miscutils/lock.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2006 Felix Fietkau <nbd@nbd.name>
+ *
+ * This is free software, licensed under the GNU General Public License v2.
+ */
+#include <sys/types.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include "busybox.h"
+
+//usage:#define lock_trivial_usage NOUSAGE_STR
+//usage:#define lock_full_usage ""
+
+static int unlock = 0;
+static int shared = 0;
+static int waitonly = 0;
+static int try_lock = 0;
+static int fd;
+static char *file;
+
+static void usage(char *name)
+{
+	fprintf(stderr, "Usage: %s [-suw] <filename>\n"
+	                "	-s	Use shared locking\n"
+	                "	-u	Unlock\n"
+	                "	-w	Wait for the lock to become free, don't acquire lock\n"
+			"	-n	Don't wait for the lock to become free. Fail with exit code\n"
+					"\n", name);
+	exit(1);
+}
+
+static void exit_unlock(int sig)
+{
+	flock(fd, LOCK_UN);
+	exit(0);
+}
+
+static int do_unlock(void)
+{
+	FILE *f;
+	int i;
+
+	if ((f = fopen(file, "r")) == NULL)
+		return 0;
+
+	fscanf(f, "%d", &i);
+	if (i > 0)
+		kill(i, SIGTERM);
+
+	fclose(f);
+
+	return 0;
+}
+
+static int do_lock(void)
+{
+	int pid;
+	int flags;
+	char pidstr[8];
+
+	if ((fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0700)) < 0) {
+		if ((fd = open(file, O_RDWR)) < 0) {
+			fprintf(stderr, "Can't open %s\n", file);
+			return 1;
+		}
+	}
+
+	flags = shared ? LOCK_SH : LOCK_EX;
+	flags |= try_lock ? LOCK_NB : 0;
+
+	if (flock(fd, flags) < 0) {
+		fprintf(stderr, "Can't lock %s\n", file);
+		return 1;
+	}
+
+	pid = fork();
+
+	if (pid < 0)
+		return -1;
+
+	if (pid == 0) {
+		signal(SIGKILL, exit_unlock);
+		signal(SIGTERM, exit_unlock);
+		signal(SIGINT, exit_unlock);
+		if (waitonly)
+			exit_unlock(0);
+		else
+			while (1)
+				sleep(1);
+	} else {
+		if (!waitonly) {
+			lseek(fd, 0, SEEK_SET);
+			ftruncate(fd, 0);
+			sprintf(pidstr, "%d\n", pid);
+			write(fd, pidstr, strlen(pidstr));
+			close(fd);
+		}
+
+		return 0;
+	}
+	return 0;
+}
+
+int lock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int lock_main(int argc, char **argv)
+{
+	char **args = &argv[1];
+	int c = argc - 1;
+
+	while ((*args != NULL) && (*args)[0] == '-') {
+		char *ch = *args;
+		while (*(++ch) > 0) {
+			switch(*ch) {
+				case 'w':
+					waitonly = 1;
+					break;
+				case 's':
+					shared = 1;
+					break;
+				case 'u':
+					unlock = 1;
+					break;
+				case 'n':
+					try_lock = 1;
+					break;
+			}
+		}
+		c--;
+		args++;
+	}
+
+	if (c != 1)
+		usage(argv[0]);
+
+	file = *args;
+	if (unlock)
+		return do_unlock();
+	else
+		return do_lock();
+}