master: Check PID file existence at startup before doing anything.

--HG--
branch : HEAD

diff --git a/src/master/main.c b/src/master/main.c
index 030ede9ba4b50e111b6134035c4bcb948f3fd627..aa8bacba725c2a38a28e483e356b8090d1b0406a 100644 (file)
--- a/src/master/main.c
+++ b/src/master/main.c
@@ -21,6 +21,8 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 
+#define MASTER_PID_FILE_NAME "master.pid"
+
 struct master_service *master_service;
 uid_t master_uid;
 gid_t master_gid;
@@ -64,6 +66,42 @@ void process_exec(const char *cmd, const char *extra_args[])
        i_fatal_status(FATAL_EXEC, "execv(%s) failed: %m", executable);
 }
 
+static void pid_file_check_running(const char *path)
+{
+       char buf[32];
+       int fd;
+       ssize_t ret;
+
+       fd = open(path, O_RDONLY);
+       if (fd == -1) {
+               if (errno == ENOENT)
+                       return;
+               i_fatal("open(%s) failed: %m", path);
+       }
+
+       ret = read(fd, buf, sizeof(buf));
+       if (ret <= 0) {
+               if (ret == 0)
+                       i_error("Empty PID file in %s, overriding", path);
+               else
+                       i_fatal("read(%s) failed: %m", path);
+       } else {
+               pid_t pid;
+
+               if (buf[ret-1] == '\n')
+                       ret--;
+               buf[ret] = '\0';
+               pid = atoi(buf);
+               if (pid == getpid() || (kill(pid, 0) < 0 && errno == ESRCH)) {
+                       /* doesn't exist */
+               } else {
+                       i_fatal("Dovecot is already running with PID %s "
+                               "(read from %s)", buf, path);
+               }
+       }
+       (void)close(fd);
+}
+
 static void create_pid_file(const char *path)
 {
        const char *pid;
@@ -171,7 +209,6 @@ static void main_init(const struct master_settings *set, bool log_error)
         lib_signals_set_handler(SIGINT, TRUE, sig_die, NULL);
         lib_signals_set_handler(SIGTERM, TRUE, sig_die, NULL);
 
-        pidfile_path = i_strconcat(set->base_dir, "/master.pid", NULL);
        create_pid_file(pidfile_path);
 
        services_monitor_start(services);
@@ -401,9 +438,12 @@ int main(int argc, char *argv[])
        sets = master_service_settings_get_others(master_service);
        set = sets[0];
 
-       master_service_init_log(master_service, "dovecot: ", 0);
-       if (!log_error)
+       pidfile_path =
+               i_strconcat(set->base_dir, "/"MASTER_PID_FILE_NAME, NULL);
+       if (!log_error) {
+               pid_file_check_running(pidfile_path);
                master_settings_do_fixes(set);
+       }
 
 #if 0 // FIXME
        if (ask_key_pass) {
@@ -446,6 +486,7 @@ int main(int argc, char *argv[])
        if (services_listen(services) <= 0)
                return FATAL_DEFAULT;
 
+       master_service_init_log(master_service, "dovecot: ", 0);
        if (!foreground)
                daemonize();
        if (chdir(set->base_dir) < 0)