182 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			182 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
--- a/include/applets.src.h
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+++ b/include/applets.src.h
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@@ -229,6 +229,7 @@ IF_LN(APPLET_NOEXEC(ln, ln, _BB_DIR_BIN,
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 IF_LOAD_POLICY(APPLET(load_policy, _BB_DIR_USR_SBIN, _BB_SUID_DROP))
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 IF_LOADFONT(APPLET(loadfont, _BB_DIR_USR_SBIN, _BB_SUID_DROP))
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 IF_LOADKMAP(APPLET(loadkmap, _BB_DIR_SBIN, _BB_SUID_DROP))
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+IF_LOCK(APPLET(lock, _BB_DIR_BIN, _BB_SUID_DROP))
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 IF_LOGGER(APPLET(logger, _BB_DIR_USR_BIN, _BB_SUID_DROP))
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 IF_LOGIN(APPLET(login, _BB_DIR_BIN, _BB_SUID_REQUIRE))
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 IF_LOGNAME(APPLET_NOFORK(logname, logname, _BB_DIR_USR_BIN, _BB_SUID_DROP, logname))
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--- a/include/usage.src.h
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+++ b/include/usage.src.h
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@@ -2320,6 +2320,9 @@ INSERT
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 #define loadkmap_example_usage \
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        "$ loadkmap < /etc/i18n/lang-keymap\n"
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+#define lock_trivial_usage NOUSAGE_STR
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+#define lock_full_usage ""
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+
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 #define logger_trivial_usage \
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        "[OPTIONS] [MESSAGE]"
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 #define logger_full_usage "\n\n" \
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--- a/miscutils/Config.src
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+++ b/miscutils/Config.src
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@@ -465,6 +465,11 @@ config FEATURE_HDPARM_HDIO_GETSET_DMA
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 	help
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 	  Enables the 'hdparm -d' option to get/set using_dma flag.
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+config LOCK
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+	bool "lock"
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+	help
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+	  Small utility for using locks in scripts
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+
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 config MAKEDEVS
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 	bool "makedevs"
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 	default y
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--- a/miscutils/Kbuild.src
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+++ b/miscutils/Kbuild.src
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@@ -29,6 +29,7 @@ lib-$(CONFIG_INOTIFYD)    += inotifyd.o
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 lib-$(CONFIG_FEATURE_LAST_SMALL)+= last.o
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 lib-$(CONFIG_FEATURE_LAST_FANCY)+= last_fancy.o
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 lib-$(CONFIG_LESS)        += less.o
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+lib-$(CONFIG_LOCK)        += lock.o
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 lib-$(CONFIG_MAKEDEVS)    += makedevs.o
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 lib-$(CONFIG_MAN)         += man.o
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 lib-$(CONFIG_MICROCOM)    += microcom.o
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--- /dev/null
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+++ b/miscutils/lock.c
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@@ -0,0 +1,132 @@
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+/*
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+ * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
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+ *
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+ * This is free software, licensed under the GNU General Public License v2.
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+ */
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+#include <sys/types.h>
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+#include <sys/file.h>
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+#include <sys/stat.h>
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+#include <signal.h>
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+#include <fcntl.h>
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+#include <unistd.h>
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+#include <stdio.h>
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+#include "busybox.h"
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+
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+static int unlock = 0;
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+static int shared = 0;
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+static int waitonly = 0;
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+static int fd;
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+static char *file;
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+
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+static void usage(char *name)
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+{
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+	fprintf(stderr, "Usage: %s [-suw] <filename>\n"
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+	                "	-s	Use shared locking\n"
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+	                "	-u	Unlock\n"
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+	                "	-w	Wait for the lock to become free, don't acquire lock\n"
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+					"\n", name);
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+	exit(1);
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+}
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+
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+static void exit_unlock(int sig)
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+{
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+	flock(fd, LOCK_UN);
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+	exit(0);
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+}
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+
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+static int do_unlock(void)
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+{
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+	FILE *f;
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+	int i;
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+
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+	if ((f = fopen(file, "r")) == NULL)
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+		return 0;
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+
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+	fscanf(f, "%d", &i);
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+	if (i > 0)
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+		kill(i, SIGTERM);
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+
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+	fclose(f);
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+
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+	return 0;
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+}
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+
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+static int do_lock(void)
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+{
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+	int pid;
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+	char pidstr[8];
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+
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+	if ((fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0700)) < 0) {
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+		if ((fd = open(file, O_RDWR)) < 0) {
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+			fprintf(stderr, "Can't open %s\n", file);
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+			return 1;
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+		}
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+	}
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+
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+	if (flock(fd, (shared ? LOCK_SH : LOCK_EX)) < 0) {
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+		fprintf(stderr, "Can't lock %s\n", file);
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+		return 1;
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+	}
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+
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+	pid = fork();
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+
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+	if (pid < 0)
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+		return -1;
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+
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+	if (pid == 0) {
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+		signal(SIGKILL, exit_unlock);
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+		signal(SIGTERM, exit_unlock);
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+		signal(SIGINT, exit_unlock);
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+		if (waitonly)
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+			exit_unlock(0);
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+		else
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+			while (1)
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+				sleep(1);
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+	} else {
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+		if (!waitonly) {
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+			lseek(fd, 0, SEEK_SET);
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+			ftruncate(fd, 0);
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+			sprintf(pidstr, "%d\n", pid);
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+			write(fd, pidstr, strlen(pidstr));
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+			close(fd);
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+		}
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+
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+		return 0;
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+	}
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+	return 0;
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+}
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+
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+int lock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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+int lock_main(int argc, char **argv)
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+{
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+	char **args = &argv[1];
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+	int c = argc - 1;
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+
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+	while ((*args != NULL) && (*args)[0] == '-') {
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+		char *ch = *args;
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+		while (*(++ch) > 0) {
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+			switch(*ch) {
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+				case 'w':
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+					waitonly = 1;
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+					break;
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+				case 's':
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+					shared = 1;
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+					break;
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+				case 'u':
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+					unlock = 1;
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+					break;
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+			}
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+		}
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+		c--;
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+		args++;
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+	}
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+
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+	if (c != 1)
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+		usage(argv[0]);
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+
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+	file = *args;
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+	if (unlock)
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+		return do_unlock();
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+	else
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+		return do_lock();
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+}
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