Use "%zu" to print size_t, not "%"PRIu16.

[sliver-openvswitch.git] / lib / daemon.c

diff --git a/lib/daemon.c b/lib/daemon.c
index b597717..b8fc5af 100644 (file)
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -39,6 +39,7 @@
 #include <string.h>
 #include <unistd.h>
 #include "fatal-signal.h"
+#include "dirs.h"
 #include "util.h"
 
 #define THIS_MODULE VLM_daemon
@@ -50,14 +51,17 @@ static bool detach;
 /* Name of pidfile (null if none). */
 static char *pidfile;
 
+/* Create pidfile even if one already exists and is locked? */
+static bool force;
+
 /* Returns the file name that would be used for a pidfile if 'name' were
  * provided to set_pidfile().  The caller must free the returned string. */
 char *
 make_pidfile_name(const char *name) 
 {
-    return (!name ? xasprintf("%s/%s.pid", RUNDIR, program_name)
+    return (!name ? xasprintf("%s/%s.pid", ofp_rundir, program_name)
             : *name == '/' ? xstrdup(name)
-            : xasprintf("%s/%s", RUNDIR, name));
+            : xasprintf("%s/%s", ofp_rundir, name));
 }
 
 /* Sets up a following call to daemonize() to create a pidfile named 'name'.
@@ -73,6 +77,24 @@ set_pidfile(const char *name)
     pidfile = make_pidfile_name(name);
 }
 
+/* Returns an absolute path to the configured pidfile, or a null pointer if no
+ * pidfile is configured.  The caller must not modify or free the returned
+ * string. */
+const char *
+get_pidfile(void)
+{
+    return pidfile;
+}
+
+/* Normally, die_if_already_running() will terminate the program with a message
+ * if a locked pidfile already exists.  If this function is called,
+ * die_if_already_running() will merely log a warning. */
+void
+ignore_existing_pidfile(void)
+{
+    force = true;
+}
+
 /* Sets up a following call to daemonize() to detach from the foreground
  * session, running this process in the background.  */
 void
@@ -81,6 +103,47 @@ set_detach(void)
     detach = true;
 }
 
+/* If a pidfile has been configured and that pidfile already exists and is
+ * locked by a running process, returns the pid of the running process.
+ * Otherwise, returns 0. */
+static pid_t
+already_running(void)
+{
+    pid_t pid = 0;
+    if (pidfile) {
+        int fd = open(pidfile, O_RDWR);
+        if (fd >= 0) {
+            struct flock lck;
+            lck.l_type = F_WRLCK;
+            lck.l_whence = SEEK_SET;
+            lck.l_start = 0;
+            lck.l_len = 0;
+            if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
+                pid = lck.l_pid;
+            }
+            close(fd);
+        }
+    }
+    return pid;
+}
+
+/* If a locked pidfile exists, issue a warning message and, unless
+ * ignore_existing_pidfile() has been called, terminate the program. */
+void
+die_if_already_running(void)
+{
+    pid_t pid = already_running();
+    if (pid) {
+        if (!force) {
+            ofp_fatal(0, "%s: already running as pid %ld",
+                      get_pidfile(), (long int) pid);
+        } else {
+            VLOG_WARN("%s: %s already running as pid %ld",
+                      get_pidfile(), program_name, (long int) pid);
+        }
+    }
+}
+
 /* If a pidfile has been configured, creates it and stores the running process'
  * pid init.  Ensures that the pidfile will be deleted when the process
  * exits. */
@@ -103,7 +166,7 @@ make_pidfile(void)
             lck.l_whence = SEEK_SET;
             lck.l_start = 0;
             lck.l_len = 0;
-            if (fcntl(fd, F_SETLK, &lck) >= 0) {
+            if (fcntl(fd, F_SETLK, &lck) != -1) {
                 char *text = xasprintf("%ld\n", pid);
                 if (write(fd, text, strlen(text)) == strlen(text)) {
                     fatal_signal_add_file_to_unlink(pidfile);
@@ -142,7 +205,7 @@ daemonize(void)
         char c = 0;
         int fds[2];
         if (pipe(fds) < 0) {
-            fatal(errno, "pipe failed");
+            ofp_fatal(errno, "pipe failed");
         }
 
         switch (fork()) {
@@ -165,7 +228,7 @@ daemonize(void)
 
         case -1:
             /* Error. */
-            fatal(errno, "could not fork");
+            ofp_fatal(errno, "could not fork");
             break;
         }
     } else {
@@ -173,3 +236,61 @@ daemonize(void)
     }
 }
 
+void
+daemon_usage(void)
+{
+    printf(
+        "\nDaemon options:\n"
+        "  -D, --detach            run in background as daemon\n"
+        "  -P, --pidfile[=FILE]    create pidfile (default: %s/%s.pid)\n"
+        "  -f, --force             with -P, start even if already running\n",
+        ofp_rundir, program_name);
+}
+
+/* Opens and reads a PID from 'pidfile'.  Returns the nonnegative PID if
+ * successful, otherwise a negative errno value. */
+pid_t
+read_pidfile(const char *pidfile)
+{
+    char line[128];
+    struct flock lck;
+    FILE *file;
+    int error;
+
+    file = fopen(pidfile, "r");
+    if (!file) {
+        error = errno;
+        VLOG_WARN("%s: open: %s", pidfile, strerror(error));
+        goto error;
+    }
+
+    lck.l_type = F_WRLCK;
+    lck.l_whence = SEEK_SET;
+    lck.l_start = 0;
+    lck.l_len = 0;
+    if (fcntl(fileno(file), F_GETLK, &lck)) {
+        error = errno;
+        VLOG_WARN("%s: fcntl: %s", pidfile, strerror(error));
+        goto error;
+    }
+
+    if (!fgets(line, sizeof line, file)) {
+        error = errno;
+        VLOG_WARN("%s: read: %s", pidfile, strerror(error));
+        goto error;
+    }
+
+    if (lck.l_pid != strtoul(line, NULL, 10)) {
+        error = ESRCH;
+        VLOG_WARN("l_pid (%ld) != %s pid (%s)",
+                   (long int) lck.l_pid, pidfile, line);
+        goto error;
+    }
+
+    fclose(file);
+    return lck.l_pid;
+
+error:
+    fclose(file);
+    return -error;
+}