--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/thermferm/lock.c Sun May 25 22:06:56 2014 +0200
@@ -0,0 +1,132 @@
+/*****************************************************************************
+ * Copyright (C) 2014
+ *
+ * Michiel Broek <mbroek at mbse dot eu>
+ *
+ * This file is part of the mbsePi-apps
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * mbsePi-apps is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EC-65K; see the file COPYING. If not, write to the Free
+ * Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *****************************************************************************/
+
+#include "thermferm.h"
+
+/*
+ * Put a lock on this program.
+ */
+int lockprog(char *name)
+{
+ char *tempfile, *lockfile;
+ FILE *fp;
+ pid_t oldpid;
+
+ tempfile = calloc(PATH_MAX, sizeof(char));
+ lockfile = calloc(PATH_MAX, sizeof(char));
+
+ snprintf(tempfile, PATH_MAX, "/var/run/%s.tmp", name);
+ snprintf(lockfile, PATH_MAX, "/var/run/%s.pid", name);
+
+ if ((fp = fopen(tempfile, "w")) == NULL) {
+ perror(name);
+ printf("Can't create lockfile \"%s\"\n", tempfile);
+ free(tempfile);
+ free(lockfile);
+ return 1;
+ }
+ fprintf(fp, "%10u\n", getpid());
+ fclose(fp);
+
+ while (TRUE) {
+ if (link(tempfile, lockfile) == 0) {
+ unlink(tempfile);
+ free(tempfile);
+ free(lockfile);
+ return 0;
+ }
+ if ((fp = fopen(lockfile, "r")) == NULL) {
+ perror(name);
+ printf("Can't open lockfile \"%s\"\n", tempfile);
+ unlink(tempfile);
+ free(tempfile);
+ free(lockfile);
+ return 1;
+ }
+ if (fscanf(fp, "%u", &oldpid) != 1) {
+ perror(name);
+ printf("Can't read old pid from \"%s\"\n", tempfile);
+ fclose(fp);
+ unlink(tempfile);
+ free(tempfile);
+ free(lockfile);
+ return 1;
+ }
+ fclose(fp);
+ if (kill(oldpid,0) == -1) {
+ if (errno == ESRCH) {
+ printf("Stale lock found for pid %u\n", oldpid);
+ unlink(lockfile);
+ /* no return, try lock again */
+ } else {
+ perror(name);
+ printf("Kill for %u failed\n",oldpid);
+ unlink(tempfile);
+ free(tempfile);
+ free(lockfile);
+ return 1;
+ }
+ } else {
+ printf("Another %s is already running, pid=%u\n", name, oldpid);
+ unlink(tempfile);
+ free(tempfile);
+ free(lockfile);
+ return 1;
+ }
+ }
+}
+
+
+
+void ulockprog(char *name)
+{
+ char *lockfile;
+ pid_t oldpid;
+ FILE *fp;
+
+ lockfile = calloc(PATH_MAX, sizeof(char));
+ snprintf(lockfile, PATH_MAX, "/var/run/%s.pid", name);
+
+ if ((fp = fopen(lockfile, "r")) == NULL) {
+ syslog(LOG_NOTICE, "Can't open lockfile \"%s\"", lockfile);
+ free(lockfile);
+ return;
+ }
+
+ if (fscanf(fp, "%u", &oldpid) != 1) {
+ syslog(LOG_NOTICE, "Can't read old pid from \"%s\"", lockfile);
+ fclose(fp);
+ unlink(lockfile);
+ free(lockfile);
+ return;
+ }
+
+ fclose(fp);
+
+ if (oldpid == getpid()) {
+ (void)unlink(lockfile);
+ }
+
+ free(lockfile);
+}
+
+