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win,tty: restore cursor after canceling line read

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When we send VK_RETURN to make ReadConsole return, a spurious new line
is echoed to the screen. This is pretty visible in Node.js, since it
calls uv_tty_read_start() and uv_tty_read_stop() in rapid succession
during startup.

With this change, we save the screen state just before sending
VK_RETURN, and restore the cursor position as soon as ReadConsole
returns.

PR-URL: https://github.com/libuv/libuv/pull/866
Reviewed-by: Bert Belder <bertbelder@gmail.com>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
This commit is contained in:
Alexis Campailla 2016-05-11 12:15:13 +02:00 committed by Saúl Ibarra Corretgé
parent 349aa6c0dd
commit 9eb1311971
1 changed files with 109 additions and 11 deletions
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120
src/win/tty.c
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@ -57,11 +57,23 @@
static void uv_tty_capture_initial_style(CONSOLE_SCREEN_BUFFER_INFO* info);
static void uv_tty_update_virtual_window(CONSOLE_SCREEN_BUFFER_INFO* info);
static int uv__cancel_read_console(uv_tty_t* handle);
/* Null uv_buf_t */
static const uv_buf_t uv_null_buf_ = { 0, NULL };
enum uv__read_console_status_e {
NOT_STARTED,
IN_PROGRESS,
TRAP_REQUESTED,
COMPLETED
};
static volatile LONG uv__read_console_status = NOT_STARTED;
static volatile LONG uv__restore_screen_state;
static CONSOLE_SCREEN_BUFFER_INFO uv__saved_screen_state;
/*
* The console virtual window.
@ -399,6 +411,8 @@ static DWORD CALLBACK uv_tty_line_read_thread(void* data) {
DWORD bytes, read_bytes;
WCHAR utf16[MAX_INPUT_BUFFER_LENGTH / 3];
DWORD chars, read_chars;
LONG status;
COORD pos;
assert(data);
@ -420,6 +434,14 @@ static DWORD CALLBACK uv_tty_line_read_thread(void* data) {
/* One utf-16 codeunit never takes more than 3 utf-8 codeunits to encode */
chars = bytes / 3;
status = InterlockedExchange(&uv__read_console_status, IN_PROGRESS);
if (status == TRAP_REQUESTED) {
SET_REQ_SUCCESS(req);
req->u.io.overlapped.InternalHigh = 0;
POST_COMPLETION_FOR_REQ(loop, req);
return 0;
}
if (ReadConsoleW(handle->handle,
(void*) utf16,
chars,
@ -439,6 +461,33 @@ static DWORD CALLBACK uv_tty_line_read_thread(void* data) {
SET_REQ_ERROR(req, GetLastError());
}
InterlockedExchange(&uv__read_console_status, COMPLETED);
/* If we canceled the read by sending a VK_RETURN event, restore the screen
state to undo the visual effect of the VK_RETURN*/
if (InterlockedOr(&uv__restore_screen_state, 0)) {
HANDLE active_screen_buffer = CreateFileA("conout$",
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (active_screen_buffer != INVALID_HANDLE_VALUE) {
pos = uv__saved_screen_state.dwCursorPosition;
/* If the cursor was at the bottom line of the screen buffer, the
VK_RETURN would have caused the buffer contents to scroll up by
one line. The right position to reset the cursor to is therefore one
line higher */
if (pos.Y == uv__saved_screen_state.dwSize.Y - 1)
pos.Y--;
SetConsoleCursorPosition(active_screen_buffer, pos);
CloseHandle(active_screen_buffer);
}
}
POST_COMPLETION_FOR_REQ(loop, req);
return 0;
}
@ -464,6 +513,11 @@ static void uv_tty_queue_read_line(uv_loop_t* loop, uv_tty_t* handle) {
}
assert(handle->tty.rd.read_line_buffer.base != NULL);
/* Reset flags No locking is required since there cannot be a line read
in progress. We are also relying on the memory barrier provided by
QueueUserWorkItem*/
uv__restore_screen_state = FALSE;
uv__read_console_status = NOT_STARTED;
r = QueueUserWorkItem(uv_tty_line_read_thread,
(void*) req,
WT_EXECUTELONGFUNCTION);
@ -923,7 +977,7 @@ int uv_tty_read_start(uv_tty_t* handle, uv_alloc_cb alloc_cb,
int uv_tty_read_stop(uv_tty_t* handle) {
INPUT_RECORD record;
DWORD written;
DWORD written, err;
handle->flags &= ~UV_HANDLE_READING;
DECREASE_ACTIVE_COUNT(handle->loop, handle);
@ -940,22 +994,66 @@ int uv_tty_read_stop(uv_tty_t* handle) {
}
} else if (!(handle->flags & UV_HANDLE_CANCELLATION_PENDING)) {
/* Cancel line-buffered read if not already pending */
/* Write enter key event to force the console wait to return. */
record.EventType = KEY_EVENT;
record.Event.KeyEvent.bKeyDown = TRUE;
record.Event.KeyEvent.wRepeatCount = 1;
record.Event.KeyEvent.wVirtualKeyCode = VK_RETURN;
record.Event.KeyEvent.wVirtualScanCode =
MapVirtualKeyW(VK_RETURN, MAPVK_VK_TO_VSC);
record.Event.KeyEvent.uChar.UnicodeChar = L'\r';
record.Event.KeyEvent.dwControlKeyState = 0;
WriteConsoleInputW(handle->handle, &record, 1, &written);
err = uv__cancel_read_console(handle);
if (err)
return err;
handle->flags |= UV_HANDLE_CANCELLATION_PENDING;
}
return 0;
}
static int uv__cancel_read_console(uv_tty_t* handle) {
HANDLE active_screen_buffer = INVALID_HANDLE_VALUE;
INPUT_RECORD record;
DWORD written;
DWORD err = 0;
LONG status;
assert(!(handle->flags & UV_HANDLE_CANCELLATION_PENDING));
status = InterlockedExchange(&uv__read_console_status, TRAP_REQUESTED);
if (status != IN_PROGRESS) {
/* Either we have managed to set a trap for the other thread before
ReadConsole is called, or ReadConsole has returned because the user
has pressed ENTER. In either case, there is nothing else to do. */
return 0;
}
/* Save screen state before sending the VK_RETURN event */
active_screen_buffer = CreateFileA("conout$",
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (active_screen_buffer != INVALID_HANDLE_VALUE &&
GetConsoleScreenBufferInfo(active_screen_buffer,
&uv__saved_screen_state)) {
InterlockedOr(&uv__restore_screen_state, 1);
}
/* Write enter key event to force the console wait to return. */
record.EventType = KEY_EVENT;
record.Event.KeyEvent.bKeyDown = TRUE;
record.Event.KeyEvent.wRepeatCount = 1;
record.Event.KeyEvent.wVirtualKeyCode = VK_RETURN;
record.Event.KeyEvent.wVirtualScanCode =
MapVirtualKeyW(VK_RETURN, MAPVK_VK_TO_VSC);
record.Event.KeyEvent.uChar.UnicodeChar = L'\r';
record.Event.KeyEvent.dwControlKeyState = 0;
if (!WriteConsoleInputW(handle->handle, &record, 1, &written))
err = GetLastError();
if (active_screen_buffer != INVALID_HANDLE_VALUE)
CloseHandle(active_screen_buffer);
return err;
}
static void uv_tty_update_virtual_window(CONSOLE_SCREEN_BUFFER_INFO* info) {
int old_virtual_width = uv_tty_virtual_width;