package/busybox/patches/340-lock_util.patch

   1 --- a/include/applets.src.h
   2 +++ b/include/applets.src.h
   3 @@ -218,6 +218,7 @@ 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  /* Needs to be run by root or be suid root - needs to change uid and gid: */
  10  IF_LOGIN(APPLET(login, BB_DIR_BIN, BB_SUID_REQUIRE))
  11 --- a/miscutils/Config.src
  12 +++ b/miscutils/Config.src
  13 @@ -419,6 +419,11 @@ config FEATURE_HDPARM_HDIO_GETSET_DMA
  14         help
  15           Enables the 'hdparm -d' option to get/set using_dma flag.
  16
  17 +config LOCK
  18 +       bool "lock"
  19 +       help
  20 +         Small utility for using locks in scripts
  21 +
  22  config MAKEDEVS
  23         bool "makedevs"
  24         default y
  25 --- a/miscutils/Kbuild.src
  26 +++ b/miscutils/Kbuild.src
  27 @@ -29,6 +29,7 @@ lib-$(CONFIG_INOTIFYD)    += inotifyd.o
  28  lib-$(CONFIG_FEATURE_LAST_SMALL)+= last.o
  29  lib-$(CONFIG_FEATURE_LAST_FANCY)+= last_fancy.o
  30  lib-$(CONFIG_LESS)        += less.o
  31 +lib-$(CONFIG_LOCK)        += lock.o
  32  lib-$(CONFIG_MAKEDEVS)    += makedevs.o
  33  lib-$(CONFIG_MAN)         += man.o
  34  lib-$(CONFIG_MICROCOM)    += microcom.o
  35 --- /dev/null
  36 +++ b/miscutils/lock.c
  37 @@ -0,0 +1,135 @@
  38 +/*
  39 + * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
  40 + *
  41 + * This is free software, licensed under the GNU General Public License v2.
  42 + */
  43 +#include <sys/types.h>
  44 +#include <sys/file.h>
  45 +#include <sys/stat.h>
  46 +#include <signal.h>
  47 +#include <fcntl.h>
  48 +#include <unistd.h>
  49 +#include <stdio.h>
  50 +#include "busybox.h"
  51 +
  52 +//usage:#define lock_trivial_usage NOUSAGE_STR
  53 +//usage:#define lock_full_usage ""
  54 +
  55 +static int unlock = 0;
  56 +static int shared = 0;
  57 +static int waitonly = 0;
  58 +static int fd;
  59 +static char *file;
  60 +
  61 +static void usage(char *name)
  62 +{
  63 +       fprintf(stderr, "Usage: %s [-suw] <filename>\n"
  64 +                       "       -s      Use shared locking\n"
  65 +                       "       -u      Unlock\n"
  66 +                       "       -w      Wait for the lock to become free, don't acquire lock\n"
  67 +                                       "\n", name);
  68 +       exit(1);
  69 +}
  70 +
  71 +static void exit_unlock(int sig)
  72 +{
  73 +       flock(fd, LOCK_UN);
  74 +       exit(0);
  75 +}
  76 +
  77 +static int do_unlock(void)
  78 +{
  79 +       FILE *f;
  80 +       int i;
  81 +
  82 +       if ((f = fopen(file, "r")) == NULL)
  83 +               return 0;
  84 +
  85 +       fscanf(f, "%d", &i);
  86 +       if (i > 0)
  87 +               kill(i, SIGTERM);
  88 +
  89 +       fclose(f);
  90 +
  91 +       return 0;
  92 +}
  93 +
  94 +static int do_lock(void)
  95 +{
  96 +       int pid;
  97 +       char pidstr[8];
  98 +
  99 +       if ((fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0700)) < 0) {
 100 +               if ((fd = open(file, O_RDWR)) < 0) {
 101 +                       fprintf(stderr, "Can't open %s\n", file);
 102 +                       return 1;
 103 +               }
 104 +       }
 105 +
 106 +       if (flock(fd, (shared ? LOCK_SH : LOCK_EX)) < 0) {
 107 +               fprintf(stderr, "Can't lock %s\n", file);
 108 +               return 1;
 109 +       }
 110 +
 111 +       pid = fork();
 112 +
 113 +       if (pid < 0)
 114 +               return -1;
 115 +
 116 +       if (pid == 0) {
 117 +               signal(SIGKILL, exit_unlock);
 118 +               signal(SIGTERM, exit_unlock);
 119 +               signal(SIGINT, exit_unlock);
 120 +               if (waitonly)
 121 +                       exit_unlock(0);
 122 +               else
 123 +                       while (1)
 124 +                               sleep(1);
 125 +       } else {
 126 +               if (!waitonly) {
 127 +                       lseek(fd, 0, SEEK_SET);
 128 +                       ftruncate(fd, 0);
 129 +                       sprintf(pidstr, "%d\n", pid);
 130 +                       write(fd, pidstr, strlen(pidstr));
 131 +                       close(fd);
 132 +               }
 133 +
 134 +               return 0;
 135 +       }
 136 +       return 0;
 137 +}
 138 +
 139 +int lock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 140 +int lock_main(int argc, char **argv)
 141 +{
 142 +       char **args = &argv[1];
 143 +       int c = argc - 1;
 144 +
 145 +       while ((*args != NULL) && (*args)[0] == '-') {
 146 +               char *ch = *args;
 147 +               while (*(++ch) > 0) {
 148 +                       switch(*ch) {
 149 +                               case 'w':
 150 +                                       waitonly = 1;
 151 +                                       break;
 152 +                               case 's':
 153 +                                       shared = 1;
 154 +                                       break;
 155 +                               case 'u':
 156 +                                       unlock = 1;
 157 +                                       break;
 158 +                       }
 159 +               }
 160 +               c--;
 161 +               args++;
 162 +       }
 163 +
 164 +       if (c != 1)
 165 +               usage(argv[0]);
 166 +
 167 +       file = *args;
 168 +       if (unlock)
 169 +               return do_unlock();
 170 +       else
 171 +               return do_lock();
 172 +}