[vte] parser: Ignore sequence with too many parameters

[Christian Persch <chpe src gnome org>]

commit e2bd1889ec229e718a2ad4ccd7c3e2fecfe3d1c8
Author: Christian Persch <chpe src gnome org>
Date:   Tue Mar 27 19:40:13 2018 +0200

    parser: Ignore sequence with too many parameters
    
    Also ignore sequences with too many default parameters.

 src/parser-test.cc |    4 ++--
 src/parser.cc      |    9 +++++++--
 2 files changed, 9 insertions(+), 4 deletions(-)
---
diff --git a/src/parser-test.cc b/src/parser-test.cc
index f70ba8b..89bdab1 100644
--- a/src/parser-test.cc
+++ b/src/parser-test.cc
@@ -1069,8 +1069,8 @@ test_seq_csi_max(void)
          * explicit value, or default, causes the sequence to be ignored.
          */
         str.pop_back(); /* erase final character */
-        test_seq_csi_max(str, U":"s, VTE_SEQ_CSI);
-        test_seq_csi_max(str, U";"s, VTE_SEQ_CSI);
+        test_seq_csi_max(str, U":"s);
+        test_seq_csi_max(str, U";"s);
         test_seq_csi_max(str, U":12345"s);
         test_seq_csi_max(str, U";12345"s);
         test_seq_csi_max(str, U":12345;"s);
diff --git a/src/parser.cc b/src/parser.cc
index 83f2e7d..e1c99d8 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -678,9 +678,14 @@ static void parser_params_overflow(struct vte_parser *parser, uint32_t raw)
                                     STATE_CSI_IGNORE : STATE_DCS_IGNORE);
 }
 
+/* The next two functions are only called when encountering a ';' or ':',
+ * so if there's already MAX-1 parameters, the ';' or ':' would finish
+ * the MAXth parameter and there would be a default or non-default
+ * MAX+1th parameter following it.
+ */
 static int parser_finish_param(struct vte_parser *parser, uint32_t raw)
 {
-        if (G_LIKELY(parser->seq.n_args < VTE_PARSER_ARG_MAX)) {
+        if (G_LIKELY(parser->seq.n_args < VTE_PARSER_ARG_MAX - 1)) {
                 vte_seq_arg_finish(&parser->seq.args[parser->seq.n_args], false);
                 ++parser->seq.n_args;
                 ++parser->seq.n_final_args;
@@ -692,7 +697,7 @@ static int parser_finish_param(struct vte_parser *parser, uint32_t raw)
 
 static int parser_finish_subparam(struct vte_parser *parser, uint32_t raw)
 {
-        if (G_LIKELY(parser->seq.n_args < VTE_PARSER_ARG_MAX)) {
+        if (G_LIKELY(parser->seq.n_args < VTE_PARSER_ARG_MAX - 1)) {
                 vte_seq_arg_finish(&parser->seq.args[parser->seq.n_args], true);
                 ++parser->seq.n_args;
         } else