package/utils/busybox/patches/220-add_lock_util.patch

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