tag-util: factor out rules for illegal tags, use in parse_tag_line

This will allow us to be consistent between batch tagging and command
line tagging as far as what is an illegal tag.

diff --git a/tag-util.c b/tag-util.c
index ca12b3b1eee5a574bd721979c47f39db5e4abd00..0a4fe789c61c90e0669f976801f348870ff5e541 100644 (file)
--- a/tag-util.c
+++ b/tag-util.c
@@ -31,6 +31,30 @@ line_error (tag_parse_status_t status,
     return status;
 }
 
+/*
+ * Test tags for some forbidden cases.
+ *
+ * return: NULL if OK,
+ *        explanatory message otherwise.
+ */
+
+static const char *
+illegal_tag (const char *tag, notmuch_bool_t remove)
+{
+
+    if (*tag == '\0' && ! remove)
+       return "empty tag forbidden";
+
+    /* This disallows adding the non-removable tag "-" and
+     * enables notmuch tag to take long options more easily.
+     */
+
+    if (*tag == '-' && ! remove)
+       return "tag starting with '-' forbidden";
+
+    return NULL;
+}
+
 tag_parse_status_t
 parse_tag_line (void *ctx, char *line,
                tag_op_flag_t flags,
@@ -95,11 +119,13 @@ parse_tag_line (void *ctx, char *line,
        remove = (*tok == '-');
        tag = tok + 1;
 
-       /* Maybe refuse empty tags. */
-       if (! (flags & TAG_FLAG_BE_GENEROUS) && *tag == '\0') {
-           ret = line_error (TAG_PARSE_INVALID, line_for_error,
-                             "empty tag");
-           goto DONE;
+       /* Maybe refuse illegal tags. */
+       if (! (flags & TAG_FLAG_BE_GENEROUS)) {
+           const char *msg = illegal_tag (tag, remove);
+           if (msg) {
+               ret = line_error (TAG_PARSE_INVALID, line_for_error, msg);
+               goto DONE;
+           }
        }
 
        /* Decode tag. */