monitor: refine monitor_find_completion()

In order to support sub command in auto completion, a reentrant function
is needed, so monitor_find_completion() is split into two parts. The
first part does parsing of user input which need to be done only once,
the second part does the auto completion job according to the parsing
result, which contains the necessary code to support sub command and
works as the reentrant function. The global "info_cmds" is still used
in second part, which will be replaced by sub command code later.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

monitor.c

@@ -4230,53 +4230,36 @@ static const char *next_arg_type(const char *typestr)
     return (p != NULL ? ++p : typestr);
 }
 
-static void monitor_find_completion(Monitor *mon,
-                                    const char *cmdline)
+static void monitor_find_completion_by_table(Monitor *mon,
+                                             const mon_cmd_t *cmd_table,
+                                             char **args,
+                                             int nb_args)
 {
     const char *cmdname;
-    char *args[MAX_ARGS];
-    int nb_args, i, len;
+    int i;
     const char *ptype, *str;
     const mon_cmd_t *cmd;
     MonitorBlockComplete mbs;
 
-    if (parse_cmdline(cmdline, &nb_args, args) < 0) {
-        return;
-    }
-#ifdef DEBUG_COMPLETION
-    for (i = 0; i < nb_args; i++) {
-        monitor_printf(mon, "arg%d = '%s'\n", i, args[i]);
-    }
-#endif
-
-    /* if the line ends with a space, it means we want to complete the
-       next arg */
-    len = strlen(cmdline);
-    if (len > 0 && qemu_isspace(cmdline[len - 1])) {
-        if (nb_args >= MAX_ARGS) {
-            goto cleanup;
-        }
-        args[nb_args++] = g_strdup("");
-    }
     if (nb_args <= 1) {
         /* command completion */
         if (nb_args == 0)
             cmdname = "";
         else
             cmdname = args[0];
         readline_set_completion_index(mon->rs, strlen(cmdname));
-        for (cmd = mon->cmd_table; cmd->name != NULL; cmd++) {
+        for (cmd = cmd_table; cmd->name != NULL; cmd++) {
             cmd_completion(mon, cmdname, cmd->name);
         }
     } else {
         /* find the command */
-        for (cmd = mon->cmd_table; cmd->name != NULL; cmd++) {
+        for (cmd = cmd_table; cmd->name != NULL; cmd++) {
             if (compare_cmd(args[0], cmd->name)) {
                 break;
             }
         }
         if (!cmd->name) {
-            goto cleanup;
+            return;
         }
 
         ptype = next_arg_type(cmd->args_type);
@@ -4321,7 +4304,7 @@ static void monitor_find_completion(Monitor *mon,
                 }
             } else if (!strcmp(cmd->name, "help|?")) {
                 readline_set_completion_index(mon->rs, strlen(str));
-                for (cmd = mon->cmd_table; cmd->name != NULL; cmd++) {
+                for (cmd = cmd_table; cmd->name != NULL; cmd++) {
                     cmd_completion(mon, str, cmd->name);
                 }
             }
@@ -4330,6 +4313,36 @@ static void monitor_find_completion(Monitor *mon,
             break;
         }
     }
+}
+
+static void monitor_find_completion(Monitor *mon,
+                                    const char *cmdline)
+{
+    char *args[MAX_ARGS];
+    int nb_args, len;
+
+    /* 1. parse the cmdline */
+    if (parse_cmdline(cmdline, &nb_args, args) < 0) {
+        return;
+    }
+#ifdef DEBUG_COMPLETION
+    for (i = 0; i < nb_args; i++) {
+        monitor_printf(mon, "arg%d = '%s'\n", i, args[i]);
+    }
+#endif
+
+    /* if the line ends with a space, it means we want to complete the
+       next arg */
+    len = strlen(cmdline);
+    if (len > 0 && qemu_isspace(cmdline[len - 1])) {
+        if (nb_args >= MAX_ARGS) {
+            goto cleanup;
+        }
+        args[nb_args++] = g_strdup("");
+    }
+
+    /* 2. auto complete according to args */
+    monitor_find_completion_by_table(mon, mon->cmd_table, args, nb_args);
 
 cleanup:
     free_cmdline_args(args, nb_args);