Fixed a bug in mysqladmin, when it could hang while waiting for

pid file to disappear, when MySQL was already re-started.

client/mysqladmin.c

@@ -69,7 +69,8 @@ static void print_relative_header();
 static void print_relative_line();
 static void truncate_names();
 static my_bool get_pidfile(MYSQL *mysql, char *pidfile);
-static void wait_pidfile(char *pidfile);
+static void wait_pidfile(char *pidfile, my_bool check_pidfile_status,
+			 time_t last_modified, struct stat pidfile_status);
 static void store_values(MYSQL_RES *result);
 
 /*
@@ -453,13 +454,23 @@ static int execute_commands(MYSQL *mysql,int argc, char **argv)
     case ADMIN_SHUTDOWN:
     {
       char pidfile[FN_REFLEN];
-      my_bool got_pidfile=0;
+      my_bool got_pidfile= 0;
+      time_t last_modified= 0; /* to keep compiler happy */
+      struct stat pidfile_status;
+      my_bool check_pidfile_status= 1;
+
       /*
 	Only wait for pidfile on local connections
 	If pidfile doesn't exist, continue without pid file checking
       */
       if (mysql->unix_socket)
 	got_pidfile= !get_pidfile(mysql, pidfile);
+      
+      if (got_pidfile && stat(pidfile, &pidfile_status))
+	check_pidfile_status= 0;
+      else
+	last_modified= pidfile_status.st_mtime;
+
       if (mysql_shutdown(mysql))
       {
 	my_printf_error(0,"shutdown failed; error: '%s'",MYF(ME_BELL),
@@ -471,7 +482,10 @@ static int execute_commands(MYSQL *mysql,int argc, char **argv)
       {
 	if (opt_verbose)
 	  printf("Shutdown signal sent to server;  Waiting for pid file to disappear\n");
-	wait_pidfile(pidfile); /* Wait until pid file is gone */
+
+	/* Wait until pid file is gone */
+	wait_pidfile(pidfile, check_pidfile_status, last_modified,
+		     pidfile_status);
       }
       break;
     }
@@ -1101,19 +1115,25 @@ static my_bool get_pidfile(MYSQL *mysql, char *pidfile)
 }
 
 
-static void wait_pidfile(char *pidfile)
+static void wait_pidfile(char *pidfile, my_bool check_pidfile_status,
+			 time_t last_modified, struct stat pidfile_status)
 {
   char buff[FN_REFLEN];
   int fd;
   uint count=0;
 
-  system_filename(buff,pidfile);
+  system_filename(buff, pidfile);
   while ((fd = my_open(buff, O_RDONLY, MYF(0))) >= 0 &&
-	 count++ < opt_shutdown_timeout && !interrupted)
+	 count++ < opt_shutdown_timeout && !interrupted &&
+	 (!check_pidfile_status || (last_modified == pidfile_status.st_mtime)))
   {
     my_close(fd,MYF(0));
     sleep(1);
+    if (stat(pidfile, &pidfile_status))
+      check_pidfile_status= 0;
   }
+  if (check_pidfile_status && (last_modified != pidfile_status.st_mtime))
+    printf("Warning;  pid file changed while waiting for it to disappear!\n");
   if (fd >= 0)
   {
     my_close(fd,MYF(0));