source: freewrt/package/busybox/patches/patch-miscutils_lock_c@ c6b195c

$FreeWRT$
--- busybox-1.1.3.orig/miscutils/lock.c Thu Jan  1 00:00:00 1970
+++ busybox-1.1.3/miscutils/lock.c      Sat Nov 25 19:54:19 2006
@@ -0,0 +1,128 @@
+#include <sys/types.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#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] <filename>\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);
+       unlink(file);
+       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, 0700)) < 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;
+       }
+}
+
+#ifndef CONFIG_LOCK
+int main(int argc, char **argv)
+#else
+int lock_main(int argc, char **argv)
+#endif
+{
+       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();
+}