mike-jumper commented on code in PR #525:
URL: https://github.com/apache/guacamole-server/pull/525#discussion_r1778884987
##########
src/terminal/terminal-handlers.c:
##########
@@ -918,31 +1012,87 @@ int guac_terminal_csi(guac_terminal* term, unsigned char
c) {
break;
- /* h: Set Mode */
+ /* h: Set Mode (DECSET) */
case 'h':
-
- /* Look up flag and set */
+
+ /* Save cursor for later restoration */
+ if (argv[0] == GUAC_TERMINAL_DECSET_SAVE_CURSOR
+ || argv[0] ==
GUAC_TERMINAL_DECSET_USE_ALT_BUFFER_AND_SAVE_CURSOR_AND_CLEAR) {
+ term->saved_cursor_row = term->cursor_row;
+ term->saved_cursor_col = term->cursor_col;
+ }
+
+ if (term->current_buffer != term->alternate_buffer) {
+
+ /* Switch to alternate buffer */
+ if (argv[0] == GUAC_TERMINAL_DECSET_USE_ALT_BUFFER
+ || argv[0] ==
GUAC_TERMINAL_DECSET_USE_ALT_BUFFER_AND_CLEAR
+ || argv[0] ==
GUAC_TERMINAL_DECSET_USE_ALT_BUFFER_AND_SAVE_CURSOR_AND_CLEAR) {
+
+ term->current_buffer = term->alternate_buffer;
+
+ /* Update scrollbar bounds (the different buffers have
differing levels of scrollback) */
+ guac_terminal_scrollbar_set_bounds(term->scrollbar,
+ -guac_terminal_get_available_scroll(term), 0);
+
+ }
+
+ /* Clear alternate buffer only if we were previously using
+ * the normal buffer */
+ if (argv[0] ==
GUAC_TERMINAL_DECSET_USE_ALT_BUFFER_AND_CLEAR
+ || argv[0] ==
GUAC_TERMINAL_DECSET_USE_ALT_BUFFER_AND_SAVE_CURSOR_AND_CLEAR) {
+ guac_terminal_clear_range(term,
+ 0, 0, term->term_height - 1, term->term_width
- 1);
+ }
+
+ }
+
+ /* Look up flag and set */
flag = __guac_terminal_get_flag(term, argv[0],
private_mode_character);
if (flag != NULL)
*flag = true;
- /* Open alternate screen buffer */
- if (argv[0] == GUAC_TERMINAL_ALT_BUFFER)
- guac_terminal_switch_buffers(term, true);
-
break;
- /* l: Reset Mode */
+ /* l: Reset Mode (DECRST) */
case 'l':
-
- /* Look up flag and clear */
+
+ if (term->current_buffer != term->normal_buffer) {
+
+ /* Switch back to normal buffer */
+ if (argv[0] == GUAC_TERMINAL_DECRST_USE_NORMAL_BUFFER
+ || argv[0] ==
GUAC_TERMINAL_DECRST_USE_NORMAL_BUFFER_AND_CLEAR
+ || argv[0] ==
GUAC_TERMINAL_DECRST_USE_NORMAL_BUFFER_AND_RESTORE_CURSOR) {
+
+ term->current_buffer = term->normal_buffer;
+
+ /* Update scrollbar bounds (the different buffers have
differing levels of scrollback) */
+ guac_terminal_scrollbar_set_bounds(term->scrollbar,
+ -guac_terminal_get_available_scroll(term), 0);
+
+ }
+
+ /* Clear normal buffer only if we were previously using
+ * the alternate buffer */
+ if (argv[0] ==
GUAC_TERMINAL_DECRST_USE_NORMAL_BUFFER_AND_CLEAR) {
+ guac_terminal_clear_range(term,
+ 0, 0, term->term_height - 1, term->term_width
- 1);
+ }
Review Comment:
> I think we should check if we receive the code
`GUAC_TERMINAL_DECRST_USE_NORMAL_BUFFER_AND_RESTORE_CURSOR`.
We typically only receive that if `TERM` is set to `xterm-256color` within
the SSH session.
> However guac_terminal_clear_range completely clears the screen instead of
restoring the contents of the normal buffer so we have a black screen with only
the cursor row shown
I believe that's required behavior for this particular DECRST code (1047),
which is defined as clearing the normal buffer after switching to it. From
https://www.xfree86.org/current/ctlseqs.html:
> P s = 1 0 4 7 → Use Normal Screen Buffer, clearing screen first if in the
Alternate Screen (unless disabled by the titeInhibit resource)
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