[PATCH v4 3/3] conhost: Fix delayed wrapping around when ENABLE_VIRTUAL_TERMINAL_PROCESSING is set.

Gabriel Ivăncescu gabrielopcode at gmail.com
Fri Apr 2 12:07:14 CDT 2021


Remember the fact we completed the entire line but normalize the cursor
otherwise. A newline is delayed so it wraps when writing a new character
if the cursor is outside the width.

This can happen in practice when writing one character at a time to the
console; right now it will keep overwriting the last character on the line.

Signed-off-by: Gabriel Ivăncescu <gabrielopcode at gmail.com>
---
 programs/conhost/conhost.c   | 30 +++++++++++----
 programs/conhost/conhost.h   |  5 +++
 programs/conhost/tests/tty.c | 73 ++++++++++++++++++++++++++++++++++++
 programs/conhost/window.c    |  8 ++--
 4 files changed, 104 insertions(+), 12 deletions(-)

diff --git a/programs/conhost/conhost.c b/programs/conhost/conhost.c
index 7cd36e2..74ea1f9 100644
--- a/programs/conhost/conhost.c
+++ b/programs/conhost/conhost.c
@@ -278,7 +278,7 @@ static void tty_sync( struct console *console )
 
     if (console->active->cursor_visible)
     {
-        set_tty_cursor( console, console->active->cursor_x, console->active->cursor_y );
+        set_tty_cursor( console, get_bounded_cursor_x(console->active), console->active->cursor_y );
         if (!console->tty_cursor_visible)
         {
             tty_write( console, "\x1b[?25h", 6 ); /* show cursor */
@@ -307,11 +307,12 @@ static void scroll_to_cursor( struct screen_buffer *screen_buffer )
 {
     int w = screen_buffer->win.right - screen_buffer->win.left + 1;
     int h = screen_buffer->win.bottom - screen_buffer->win.top + 1;
+    unsigned int cursor_x = get_bounded_cursor_x(screen_buffer);
 
-    if (screen_buffer->cursor_x < screen_buffer->win.left)
-        screen_buffer->win.left = min( screen_buffer->cursor_x, screen_buffer->width - w );
-    else if (screen_buffer->cursor_x > screen_buffer->win.right)
-        screen_buffer->win.left = max( screen_buffer->cursor_x, w ) - w + 1;
+    if (cursor_x < screen_buffer->win.left)
+        screen_buffer->win.left = min( cursor_x, screen_buffer->width - w );
+    else if (cursor_x > screen_buffer->win.right)
+        screen_buffer->win.left = max( cursor_x, w ) - w + 1;
     screen_buffer->win.right = screen_buffer->win.left + w - 1;
 
     if (screen_buffer->cursor_y < screen_buffer->win.top)
@@ -1359,6 +1360,11 @@ static NTSTATUS read_console( struct console *console, unsigned int ioctl, size_
     console->edit_line.home_x = console->active->cursor_x;
     console->edit_line.home_y = console->active->cursor_y;
     console->edit_line.status = STATUS_PENDING;
+    if (console->active->cursor_x >= console->active->width)
+    {
+        console->edit_line.home_x = 0;
+        console->edit_line.home_y++;
+    }
     if (edit_line_grow( console, 1 )) console->edit_line.buf[0] = 0;
 
     console->pending_read = out_size;
@@ -1716,7 +1722,7 @@ static NTSTATUS get_output_info( struct screen_buffer *screen_buffer, size_t *ou
 
     info->cursor_size    = screen_buffer->cursor_size;
     info->cursor_visible = screen_buffer->cursor_visible;
-    info->cursor_x       = screen_buffer->cursor_x;
+    info->cursor_x       = get_bounded_cursor_x(screen_buffer);
     info->cursor_y       = screen_buffer->cursor_y;
     info->width          = screen_buffer->width;
     info->height         = screen_buffer->height;
@@ -1903,6 +1909,7 @@ static NTSTATUS set_output_info( struct screen_buffer *screen_buffer,
 
 static NTSTATUS write_console( struct screen_buffer *screen_buffer, const WCHAR *buffer, size_t len )
 {
+    unsigned int orig_x = screen_buffer->cursor_x, orig_y = screen_buffer->cursor_y;
     RECT update_rect;
     size_t i, j;
 
@@ -1917,10 +1924,12 @@ static NTSTATUS write_console( struct screen_buffer *screen_buffer, const WCHAR
             switch (buffer[i])
             {
             case '\b':
+                if (screen_buffer->cursor_x == screen_buffer->width) screen_buffer->cursor_x--;
                 if (screen_buffer->cursor_x) screen_buffer->cursor_x--;
                 continue;
             case '\t':
-                j = min( screen_buffer->width - screen_buffer->cursor_x, 8 - (screen_buffer->cursor_x % 8) );
+                j = screen_buffer->cursor_x < screen_buffer->width ? screen_buffer->cursor_x : 0;
+                j = min( screen_buffer->width - j, 8 - (j % 8) );
                 while (j--) write_char( screen_buffer, ' ', &update_rect, NULL );
                 continue;
             case '\n':
@@ -1956,13 +1965,18 @@ static NTSTATUS write_console( struct screen_buffer *screen_buffer, const WCHAR
                 if (++screen_buffer->cursor_y == screen_buffer->height)
                     new_line( screen_buffer, &update_rect );
             }
-            else screen_buffer->cursor_x--;
         }
         else screen_buffer->cursor_x = update_rect.left;
     }
 
     scroll_to_cursor( screen_buffer );
     update_output( screen_buffer, &update_rect );
+
+    /* Windows doesn't put a \b if only one position changed for some reason */
+    if (screen_buffer->cursor_x == screen_buffer->width)
+        if (orig_x == screen_buffer->cursor_x - 1 && orig_y == screen_buffer->cursor_y)
+            screen_buffer->console->tty_cursor_x--;
+
     tty_sync( screen_buffer->console );
     update_window_config( screen_buffer->console, TRUE );
     return STATUS_SUCCESS;
diff --git a/programs/conhost/conhost.h b/programs/conhost/conhost.h
index 6446cd1..c773ce4 100644
--- a/programs/conhost/conhost.h
+++ b/programs/conhost/conhost.h
@@ -140,6 +140,11 @@ NTSTATUS write_console_input( struct console *console, const INPUT_RECORD *recor
 void notify_screen_buffer_size( struct screen_buffer *screen_buffer );
 NTSTATUS change_screen_buffer_size( struct screen_buffer *screen_buffer, int new_width, int new_height );
 
+static inline unsigned int get_bounded_cursor_x( struct screen_buffer *screen_buffer )
+{
+    return min(screen_buffer->cursor_x, screen_buffer->width - 1);
+}
+
 static inline void empty_update_rect( struct screen_buffer *screen_buffer, RECT *rect )
 {
     SetRect( rect, screen_buffer->width, screen_buffer->height, 0, 0 );
diff --git a/programs/conhost/tests/tty.c b/programs/conhost/tests/tty.c
index 122e8a9..f0b36b1 100644
--- a/programs/conhost/tests/tty.c
+++ b/programs/conhost/tests/tty.c
@@ -781,6 +781,79 @@ static void test_write_console(void)
     skip_sequence("\x1b[?25h");               /* show cursor */
     expect_empty_output();
 
+    child_set_output_mode(ENABLE_PROCESSED_OUTPUT | ENABLE_WRAP_AT_EOL_OUTPUT | ENABLE_VIRTUAL_TERMINAL_PROCESSING);
+
+    child_set_cursor(28, 12);
+    skip_hide_cursor();
+    expect_output_sequence("\x1b[28C");       /* move cursor to the end of the line */
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+
+    child_string_request(REQ_WRITE_CONSOLE, L"ab");
+    skip_hide_cursor();
+    expect_output_sequence("ab");
+    expect_output_sequence("\b");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(29, 12);
+
+    child_string_request(REQ_WRITE_CONSOLE, L"c");
+    skip_hide_cursor();
+    expect_output_sequence("\r\n");
+    expect_output_sequence("c");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(1, 13);
+
+    child_set_cursor(28, 14);
+    skip_hide_cursor();
+    expect_output_sequence("\x1b[15;29H");    /* set cursor */
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+
+    child_string_request(REQ_WRITE_CONSOLE, L"x");
+    skip_hide_cursor();
+    expect_output_sequence("x");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(29, 14);
+
+    child_string_request(REQ_WRITE_CONSOLE, L"y");
+    skip_hide_cursor();
+    expect_output_sequence("y");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(29, 14);
+
+    child_string_request(REQ_WRITE_CONSOLE, L"\b");
+    skip_hide_cursor();
+    expect_output_sequence("\b");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(28, 14);
+
+    child_string_request(REQ_WRITE_CONSOLE, L"z");
+    skip_hide_cursor();
+    expect_output_sequence("z");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(29, 14);
+
+    child_string_request(REQ_WRITE_CONSOLE, L"w");
+    skip_hide_cursor();
+    expect_output_sequence("w");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(29, 14);
+
+    child_string_request(REQ_WRITE_CONSOLE, L"X");
+    skip_hide_cursor();
+    expect_output_sequence("\r\n");
+    expect_output_sequence("X");
+    skip_sequence("\x1b[?25h");               /* show cursor */
+    expect_empty_output();
+    test_cursor_pos(1, 15);
+
     child_set_output_mode(ENABLE_PROCESSED_OUTPUT | ENABLE_WRAP_AT_EOL_OUTPUT);
 
     child_set_cursor(28, 20);
diff --git a/programs/conhost/window.c b/programs/conhost/window.c
index 0ea929d..12437bb 100644
--- a/programs/conhost/window.c
+++ b/programs/conhost/window.c
@@ -430,8 +430,8 @@ static void update_window_cursor( struct console *console )
 {
     if (console->win != GetFocus() || !console->active->cursor_visible) return;
 
-    SetCaretPos( (console->active->cursor_x - console->active->win.left) * console->active->font.width,
-                 (console->active->cursor_y - console->active->win.top)  * console->active->font.height );
+    SetCaretPos( (get_bounded_cursor_x(console->active) - console->active->win.left) * console->active->font.width,
+                 (console->active->cursor_y - console->active->win.top) * console->active->font.height );
     ShowCaret( console->win );
 }
 
@@ -607,10 +607,10 @@ static void update_window( struct console *console )
         }
     }
 
-    if (update_all || console->active->cursor_x != console->window->cursor_pos.X ||
+    if (update_all || get_bounded_cursor_x(console->active) != console->window->cursor_pos.X ||
         console->active->cursor_y != console->window->cursor_pos.Y)
     {
-        console->window->cursor_pos.X = console->active->cursor_x;
+        console->window->cursor_pos.X = get_bounded_cursor_x(console->active);
         console->window->cursor_pos.Y = console->active->cursor_y;
         update_window_cursor( console );
     }
-- 
2.30.0




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