Add new "notmuch tag" command for adding/removing tags.

This uses the same search functionality as "notmuch search" so
it should be quite powerful. And this global search might be
quick enough to be used for "automatic" adding of tags to new
messages.

Of course, this will all be a lot more useful when we can search
for actual text of messages and not just tags.

notmuch.c

@@ -635,6 +635,40 @@ new_command (unused (int argc), unused (char *argv[]))
     return ret;
 }
 
+/* Construct a single query string from the passed arguments, using
+ * 'ctx' as the talloc owner for all allocations.
+ *
+ * Currently, the arguments are just connected with space characters,
+ * but we might do more processing in the future, (such as inserting
+ * any AND operators needed to work around Xapian QueryParser bugs).
+ *
+ * This function returns NULL in case of insufficient memory.
+ */
+static char *
+query_string_from_args (void *ctx, int argc, char *argv[])
+{
+    char *query_string;
+    int i;
+
+    query_string = talloc_strdup (ctx, "");
+    if (query_string == NULL)
+	return NULL;
+
+    for (i = 0; i < argc; i++) {
+	if (i != 0) {
+	    query_string = talloc_strdup_append (query_string, " ");
+	    if (query_string == NULL)
+		return NULL;
+	}
+
+	query_string = talloc_strdup_append (query_string, argv[i]);
+	if (query_string == NULL)
+	    return NULL;
+    }
+
+    return query_string;
+}
+
 static int
 search_command (int argc, char *argv[])
 {
@@ -645,7 +679,6 @@ search_command (int argc, char *argv[])
     notmuch_thread_t *thread;
     notmuch_tags_t *tags;
     char *query_str;
-    int i;
     notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
 
     notmuch = notmuch_database_open (NULL);
@@ -654,15 +687,7 @@ search_command (int argc, char *argv[])
 	goto DONE;
     }
 
-    /* XXX: Should add xtalloc wrappers here and use them. */
-    query_str = talloc_strdup (local, "");
-
-    for (i = 0; i < argc; i++) {
-	if (i != 0)
-	    query_str = talloc_asprintf_append (query_str, " ");
-
-	query_str = talloc_asprintf_append (query_str, "%s", argv[i]);
-    }
+    query_str = query_string_from_args (local, argc, argv);
 
     query = notmuch_query_create (notmuch, query_str);
     if (query == NULL) {
@@ -715,6 +740,111 @@ show_command (unused (int argc), unused (char *argv[]))
     return 1;
 }
 
+static int
+tag_command (unused (int argc), unused (char *argv[]))
+{
+    void *local;
+    int *add_tags, *remove_tags;
+    int add_tags_count = 0;
+    int remove_tags_count = 0;
+    char *query_string;
+    notmuch_database_t *notmuch = NULL;
+    notmuch_query_t *query;
+    notmuch_message_results_t *results;
+    notmuch_message_t *message;
+    int ret = 0;
+    int i;
+
+    local = talloc_new (NULL);
+    if (local == NULL) {
+	ret = 1;
+	goto DONE;
+    }
+
+    add_tags = talloc_size (local, argc * sizeof (int));
+    if (add_tags == NULL) {
+	ret = 1;
+	goto DONE;
+    }
+
+    remove_tags = talloc_size (local, argc * sizeof (int));
+    if (remove_tags == NULL) {
+	ret = 1;
+	goto DONE;
+    }
+
+    for (i = 0; i < argc; i++) {
+	if (strcmp (argv[i], "--") == 0) {
+	    i++;
+	    break;
+	}
+	if (argv[i][0] == '+') {
+	    add_tags[add_tags_count++] = i;
+	} else if (argv[i][0] == '-') {
+	    remove_tags[remove_tags_count++] = i;
+	} else {
+	    break;
+	}
+    }
+
+    if (add_tags_count == 0 && remove_tags_count == 0) {
+	fprintf (stderr, "Error: 'notmuch tag' requires at least one tag to add or remove.\n");
+	ret = 1;
+	goto DONE;
+    }
+
+    if (i == argc) {
+	fprintf (stderr, "Error: 'notmuch tag' requires at least one search term.\n");
+	ret = 1;
+	goto DONE;
+    }
+
+    notmuch = notmuch_database_open (NULL);
+    if (notmuch == NULL) {
+	ret = 1;
+	goto DONE;
+    }
+
+    query_string = query_string_from_args (local, argc - i, &argv[i]);
+
+    query = notmuch_query_create (notmuch, query_string);
+    if (query == NULL) {
+	fprintf (stderr, "Out of memory.\n");
+	ret = 1;
+	goto DONE;
+    }
+
+    for (results = notmuch_query_search_messages (query);
+	 notmuch_message_results_has_more (results);
+	 notmuch_message_results_advance (results))
+    {
+	message = notmuch_message_results_get (results);
+
+	notmuch_message_freeze (message);
+
+	for (i = 0; i < remove_tags_count; i++)
+	    notmuch_message_remove_tag (message,
+					argv[remove_tags[i]] + 1);
+
+	for (i = 0; i < add_tags_count; i++)
+	    notmuch_message_add_tag (message, argv[add_tags[i]] + 1);
+
+	notmuch_message_thaw (message);
+
+	notmuch_message_destroy (message);
+    }
+
+    notmuch_query_destroy (query);
+
+  DONE:
+    if (notmuch)
+	notmuch_database_close (notmuch);
+
+    talloc_free (local);
+
+    return ret;
+}
+
 static int
 dump_command (int argc, char *argv[])
 {
@@ -922,6 +1052,19 @@ command_t commands[] = {
     { "show", show_command,
       "<thread-id>\n\n"
       "\t\tShow the thread with the given thread ID (see 'search')." },
+    { "tag", tag_command,
+      "+<tag>|-<tag> [...] [--] <search-term> [...]\n\n"
+      "\t\tAdd or remove the specified tags to all messages matching\n"
+      "\t\tthe specified search terms. The search terms are handled\n"
+      "\t\texactly as in 'search' so one can use that command first\n"
+      "\t\tto see what will be modified.\n\n"
+      "\t\tTags prefixed by '+' are added while those prefixed by '-' are\n"
+      "\t\tremoved. For each message, tag removal is before tag addition.\n\n"
+      "\t\tThe beginning of <search-terms> is recognized by the first\n"
+      "\t\targument that begins with neither '+' nor '-'. Support for\n"
+      "\t\tan initial search term beginning with '+' or '-' is provided\n"
+      "\t\tby allowing the user to specify a \"--\" argument to separate\n"
+      "\t\tthe tags from the search terms." },
     { "dump", dump_command,
       "[<filename>]\n\n"
       "\t\tCreate a plain-text dump of the tags for each message\n"