package/busybox/patches/340-lock_util.patch

   1 --- a/include/applets.src.h
   2 +++ b/include/applets.src.h
   3 @@ -229,6 +229,7 @@ IF_LN(APPLET_NOEXEC(ln, ln, _BB_DIR_BIN,
   4  IF_LOAD_POLICY(APPLET(load_policy, _BB_DIR_USR_SBIN, _BB_SUID_DROP))
   5  IF_LOADFONT(APPLET(loadfont, _BB_DIR_USR_SBIN, _BB_SUID_DROP))
   6  IF_LOADKMAP(APPLET(loadkmap, _BB_DIR_SBIN, _BB_SUID_DROP))
   7 +IF_LOCK(APPLET(lock, _BB_DIR_BIN, _BB_SUID_DROP))
   8  IF_LOGGER(APPLET(logger, _BB_DIR_USR_BIN, _BB_SUID_DROP))
   9  IF_LOGIN(APPLET(login, _BB_DIR_BIN, _BB_SUID_REQUIRE))
  10  IF_LOGNAME(APPLET_NOFORK(logname, logname, _BB_DIR_USR_BIN, _BB_SUID_DROP, logname))
  11 --- a/include/usage.src.h
  12 +++ b/include/usage.src.h
  13 @@ -2320,6 +2320,9 @@ INSERT
  14  #define loadkmap_example_usage \
  15         "$ loadkmap < /etc/i18n/lang-keymap\n"
  16
  17 +#define lock_trivial_usage NOUSAGE_STR
  18 +#define lock_full_usage ""
  19 +
  20  #define logger_trivial_usage \
  21         "[OPTIONS] [MESSAGE]"
  22  #define logger_full_usage "\n\n" \
  23 --- a/miscutils/Config.src
  24 +++ b/miscutils/Config.src
  25 @@ -465,6 +465,11 @@ config FEATURE_HDPARM_HDIO_GETSET_DMA
  26         help
  27           Enables the 'hdparm -d' option to get/set using_dma flag.
  28
  29 +config LOCK
  30 +       bool "lock"
  31 +       help
  32 +         Small utility for using locks in scripts
  33 +
  34  config MAKEDEVS
  35         bool "makedevs"
  36         default y
  37 --- a/miscutils/Kbuild.src
  38 +++ b/miscutils/Kbuild.src
  39 @@ -29,6 +29,7 @@ lib-$(CONFIG_INOTIFYD)    += inotifyd.o
  40  lib-$(CONFIG_FEATURE_LAST_SMALL)+= last.o
  41  lib-$(CONFIG_FEATURE_LAST_FANCY)+= last_fancy.o
  42  lib-$(CONFIG_LESS)        += less.o
  43 +lib-$(CONFIG_LOCK)        += lock.o
  44  lib-$(CONFIG_MAKEDEVS)    += makedevs.o
  45  lib-$(CONFIG_MAN)         += man.o
  46  lib-$(CONFIG_MICROCOM)    += microcom.o
  47 --- /dev/null
  48 +++ b/miscutils/lock.c
  49 @@ -0,0 +1,132 @@
  50 +/*
  51 + * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
  52 + *
  53 + * This is free software, licensed under the GNU General Public License v2.
  54 + */
  55 +#include <sys/types.h>
  56 +#include <sys/file.h>
  57 +#include <sys/stat.h>
  58 +#include <signal.h>
  59 +#include <fcntl.h>
  60 +#include <unistd.h>
  61 +#include <stdio.h>
  62 +#include "busybox.h"
  63 +
  64 +static int unlock = 0;
  65 +static int shared = 0;
  66 +static int waitonly = 0;
  67 +static int fd;
  68 +static char *file;
  69 +
  70 +static void usage(char *name)
  71 +{
  72 +       fprintf(stderr, "Usage: %s [-suw] <filename>\n"
  73 +                       "       -s      Use shared locking\n"
  74 +                       "       -u      Unlock\n"
  75 +                       "       -w      Wait for the lock to become free, don't acquire lock\n"
  76 +                                       "\n", name);
  77 +       exit(1);
  78 +}
  79 +
  80 +static void exit_unlock(int sig)
  81 +{
  82 +       flock(fd, LOCK_UN);
  83 +       exit(0);
  84 +}
  85 +
  86 +static int do_unlock(void)
  87 +{
  88 +       FILE *f;
  89 +       int i;
  90 +
  91 +       if ((f = fopen(file, "r")) == NULL)
  92 +               return 0;
  93 +
  94 +       fscanf(f, "%d", &i);
  95 +       if (i > 0)
  96 +               kill(i, SIGTERM);
  97 +
  98 +       fclose(f);
  99 +
 100 +       return 0;
 101 +}
 102 +
 103 +static int do_lock(void)
 104 +{
 105 +       int pid;
 106 +       char pidstr[8];
 107 +
 108 +       if ((fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0700)) < 0) {
 109 +               if ((fd = open(file, O_RDWR)) < 0) {
 110 +                       fprintf(stderr, "Can't open %s\n", file);
 111 +                       return 1;
 112 +               }
 113 +       }
 114 +
 115 +       if (flock(fd, (shared ? LOCK_SH : LOCK_EX)) < 0) {
 116 +               fprintf(stderr, "Can't lock %s\n", file);
 117 +               return 1;
 118 +       }
 119 +
 120 +       pid = fork();
 121 +
 122 +       if (pid < 0)
 123 +               return -1;
 124 +
 125 +       if (pid == 0) {
 126 +               signal(SIGKILL, exit_unlock);
 127 +               signal(SIGTERM, exit_unlock);
 128 +               signal(SIGINT, exit_unlock);
 129 +               if (waitonly)
 130 +                       exit_unlock(0);
 131 +               else
 132 +                       while (1)
 133 +                               sleep(1);
 134 +       } else {
 135 +               if (!waitonly) {
 136 +                       lseek(fd, 0, SEEK_SET);
 137 +                       ftruncate(fd, 0);
 138 +                       sprintf(pidstr, "%d\n", pid);
 139 +                       write(fd, pidstr, strlen(pidstr));
 140 +                       close(fd);
 141 +               }
 142 +
 143 +               return 0;
 144 +       }
 145 +       return 0;
 146 +}
 147 +
 148 +int lock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 149 +int lock_main(int argc, char **argv)
 150 +{
 151 +       char **args = &argv[1];
 152 +       int c = argc - 1;
 153 +
 154 +       while ((*args != NULL) && (*args)[0] == '-') {
 155 +               char *ch = *args;
 156 +               while (*(++ch) > 0) {
 157 +                       switch(*ch) {
 158 +                               case 'w':
 159 +                                       waitonly = 1;
 160 +                                       break;
 161 +                               case 's':
 162 +                                       shared = 1;
 163 +                                       break;
 164 +                               case 'u':
 165 +                                       unlock = 1;
 166 +                                       break;
 167 +                       }
 168 +               }
 169 +               c--;
 170 +               args++;
 171 +       }
 172 +
 173 +       if (c != 1)
 174 +               usage(argv[0]);
 175 +
 176 +       file = *args;
 177 +       if (unlock)
 178 +               return do_unlock();
 179 +       else
 180 +               return do_lock();
 181 +}