Index: busybox-1.8.1/include/applets.h =================================================================== --- busybox-1.8.1.orig/include/applets.h 2007-11-10 16:54:28.318054115 +0100 +++ busybox-1.8.1/include/applets.h 2007-11-10 17:39:21.487529096 +0100 @@ -218,6 +218,7 @@ USE_LOAD_POLICY(APPLET(load_policy, _BB_DIR_USR_SBIN, _BB_SUID_NEVER)) USE_LOADFONT(APPLET(loadfont, _BB_DIR_USR_BIN, _BB_SUID_NEVER)) USE_LOADKMAP(APPLET(loadkmap, _BB_DIR_SBIN, _BB_SUID_NEVER)) +USE_LOCK(APPLET_NOUSAGE(lock, lock, _BB_DIR_BIN, _BB_SUID_NEVER)) USE_LOGGER(APPLET(logger, _BB_DIR_USR_BIN, _BB_SUID_NEVER)) USE_LOGIN(APPLET(login, _BB_DIR_BIN, _BB_SUID_ALWAYS)) USE_LOGNAME(APPLET_NOFORK(logname, logname, _BB_DIR_USR_BIN, _BB_SUID_NEVER, logname)) Index: busybox-1.8.1/miscutils/Config.in =================================================================== --- busybox-1.8.1.orig/miscutils/Config.in 2007-11-10 16:54:16.477379354 +0100 +++ busybox-1.8.1/miscutils/Config.in 2007-11-10 16:54:28.366056851 +0100 @@ -244,6 +244,12 @@ Enables the 'hdparm -d' option to get/set using_dma flag. This is dangerous stuff, so you should probably say N. +config LOCK + bool "lock" + default y + help + Small utility for using locks in scripts + config MAKEDEVS bool "makedevs" default n Index: busybox-1.8.1/miscutils/Kbuild =================================================================== --- busybox-1.8.1.orig/miscutils/Kbuild 2007-11-10 16:54:16.481379580 +0100 +++ busybox-1.8.1/miscutils/Kbuild 2007-11-10 16:54:28.370057076 +0100 @@ -16,6 +16,7 @@ lib-$(CONFIG_HDPARM) += hdparm.o lib-$(CONFIG_LAST) += last.o lib-$(CONFIG_LESS) += less.o +lib-$(CONFIG_LOCK) += lock.o lib-$(CONFIG_MAKEDEVS) += makedevs.o lib-$(CONFIG_MICROCOM) += microcom.o lib-$(CONFIG_MOUNTPOINT) += mountpoint.o Index: busybox-1.8.1/miscutils/lock.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ busybox-1.8.1/miscutils/lock.c 2007-11-10 17:40:37.203843924 +0100 @@ -0,0 +1,132 @@ +/* + * Copyright (C) 2006 Felix Fietkau + * + * This is free software, licensed under the GNU General Public License v2. + */ +#include +#include +#include +#include +#include +#include +#include +#include "busybox.h" + +static int unlock = 0; +static int shared = 0; +static int waitonly = 0; +static int fd; +static char *file; + +static void usage(char *name) +{ + fprintf(stderr, "Usage: %s [-suw] \n" + " -s Use shared locking\n" + " -u Unlock\n" + " -w Wait for the lock to become free, don't acquire lock\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; + 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; + } + } + + if (flock(fd, (shared ? LOCK_SH : LOCK_EX)) < 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; + } + } + c--; + args++; + } + + if (c != 1) + usage(argv[0]); + + file = *args; + if (unlock) + return do_unlock(); + else + return do_lock(); +}