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Original console buffer is not restored when closing a secondary one #17817
Description
Windows Terminal version
1.22.240823002-preview
Windows build number
10.0.19045
Other Software
No response
Steps to reproduce
Reduced test code (by lhecker):
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
int main() {
const auto buffer = CreateConsoleScreenBuffer(GENERIC_READ | GENERIC_WRITE, 0, nullptr, CONSOLE_TEXTMODE_BUFFER, nullptr);
SetConsoleActiveScreenBuffer(buffer);
CloseHandle(buffer);
return 0;
}Run a program which creates and activates a new console screen buffer using CreateConsoleScreenBuffer and SetConsoleActiveScreenBuffer.
The following C program with argument value 0-4 does all combos:
// usage: *argv 0|1|2|3|4
// create+activate new screen buffer, print a message to it, sleep 1s, then before exit:
// 0: do nothing.
// 1: CloseHandle(newbuf).
// 2: SetConsoleActiveScreenBuffer(orig_con)
// 3: CloseHandle(newbuf), SetConsoleActiveScreenBuffer(orig_con)
// 4: SetConsoleActiveScreenBuffer(orig_con), CloseHandle(newbuf)
newbuf.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <windows.h>
#define writecon(h, s) WriteConsole(h, (s), strlen(s), 0, 0)
#define ERR_EXIT(...) (fprintf(stderr, __VA_ARGS__), exit(1), 0)
// usage: *argv 0|1|2|3|4
// create+activate new screen buffer, print a message to it, sleep 1s, then before exit:
// 0: do nothing.
// 1: CloseHandle(newbuf).
// 2: SetConsoleActiveScreenBuffer(orig_con)
// 3: CloseHandle(newbuf), SetConsoleActiveScreenBuffer(orig_con)
// 4: SetConsoleActiveScreenBuffer(orig_con), CloseHandle(newbuf)
int main(int argc, char **argv)
{
int mode = argc > 1 ? atoi(argv[1]) : 0;
HANDLE hcon = GetStdHandle(STD_OUTPUT_HANDLE);
if (hcon == INVALID_HANDLE_VALUE)
ERR_EXIT("can't get stdout handle\n");
if (!writecon(hcon, "orig screen buffer\n"))
ERR_EXIT("can't write to stdout console\n");
HANDLE hnewbuf = CreateConsoleScreenBuffer(
GENERIC_WRITE, FILE_SHARE_WRITE,
0, CONSOLE_TEXTMODE_BUFFER, 0);
if (hnewbuf == INVALID_HANDLE_VALUE)
ERR_EXIT("can't create new screen buf\n");
if (!SetConsoleActiveScreenBuffer(hnewbuf))
ERR_EXIT("can't activete new screen buf\n");
if (!writecon(hnewbuf, "new screen buffer\n"))
ERR_EXIT("can't write to new screen buf\n");
Sleep(1000);
// all combos of "close new buf" and "restore orig buff", + reverse order.
//
// expected result:
// - all combos restore the original buf on exit (maybe implicitly)
//
// actual result:
// - Working as expected in conhost.exe or OpenConsole.exe (including 1.22)
// or Windows Terminal (up to and including 1.21).
//
// - in Windows Terminal 1.22: only 2 and 4 work as expected
// ("restore orig buf" without or before "close new buf")
// - 0: no close and no manual restore: not restored.
// - 1: close only: not restored.
// - 3: close and restored manually: not restored.
switch (mode) {
case 0:
break;
case 1:
CloseHandle(hnewbuf);
break;
case 2:
if (!SetConsoleActiveScreenBuffer(hcon))
ERR_EXIT("can't restore orig screen buf\n");
break;
case 3:
CloseHandle(hnewbuf);
if (!SetConsoleActiveScreenBuffer(hcon))
ERR_EXIT("can't restore orig screen buf\n");
break;
case 4: // like 3 but in reverse order
if (!SetConsoleActiveScreenBuffer(hcon))
ERR_EXIT("can't restore orig screen buf\n");
CloseHandle(hnewbuf);
break;
}
return 0;
}Expected Behavior
Original screen buffer is restored when the application exits (its content and original cursor position), regardless if the new screen buffer handle is closed or not, and regardless if the original screen buffer is re-activated before exit.
Actual Behavior
No issue in conhost.exe or OpenConsole.exe (even of 1.22), or Windows terminal up to and including 1.21.
With Windows terminal 1.22 (preview):
- The original screen buffer is only restored if
SetConsoleActiveScreenBuffer(orig_con)is invoked without or beforeCloseHandle(h_newbuf). - Specifically, it's not restored if:
- Neither
CloseHandlenorSetConsoleActiveScreenBuffer(orig_con)are used. - Only
CloseHandleis used. - Both
CloseHandleandSetConsoleActiveScreenBuffer(orig_con)are used in that order.
- Neither
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avih commentedon Aug 28, 2024
While it's not mine to decide, and personally I can wait for a build with this fixed, I'd think it would be nice to fix it in 1.22, because it's still relatively early and only one preview build was released of 1.22, and it does affect the default behavior of existing applications, such as
less.exe, and I'm guessing possibly more editors and pagers.lhecker commentedon Aug 29, 2024
The milestone for us just indicates in what period we're working on it. Now that 1.22 was released we're in the 1.23 development period and so on. We usually spend the beginning of each period for fixing bugs in the just released versions. That will also be the case for this issue.
In short, I'm going to fix this soon. 🙂
avih commentedon Aug 29, 2024
Was it?
Yesterday 1.21 had the first stable release: "Terminal 1.21 is finally stable!...". and 1.22 had the first preview build.
Doesn't that mean that 1.21 is now ready for most users, but that there's still work to bugfix before 1.22 becomes stable and ready for public consumption? I.e. that "stable" is for most users, and that "preview" is for early adopters which can test it and report issues which would hopefully get fixed before 1.22 is considered "Ready" and distributed to the larger public?
The store page says about "Windows Terminal Preview":
I.e. that there's still work to be done before the preview version is considered "ready"?
That's nice, though my main concern was/is that there would be a "stable" version which is distributed to a large number of people which has this issue...
Or am I missing something with the "stable"/"preview" terminology and/or pipeline?
ehoogeveen-medweb commentedon Aug 29, 2024
This could be rephrased to something like "contains the latest features that we think are ready, but may not be entirely stable yet" (though there's a philosophical question about whether any software is ever truly "stable", as pretty much all software contains bugs 😄).
Basically, both "Windows Terminal" (current version
1.21.x) and "Windows Terminal Preview" (current version1.22.x) receive bugfixes, but new features are developed for the main branch. The Preview version can be used by anyone but is more likely to have issues, especially shortly after a release.avih commentedon Aug 29, 2024
Yeah, that's what I thought too.
So do you consider "restore screen buffer correctly like it behaved in 1.21" a new feature?
To me that's more like a bugfix in 1.22. Is it not?
(that's not to say that it must be fixed in 1.22. I marely expressed hope that it could get fixed in 1.22 before it becomes stable).
ehoogeveen-medweb commentedon Aug 29, 2024
Well, I would certainly consider it a bugfix (though I'm not part of the team), but I think the point is that the milestone just indicates that the fix will be developed on the branch for 1.23. It would then presumably be cherry-picked or backported to 1.22 assuming the fix isn't riskier than the impact of the bug.
1 remaining item
zadjii-msft commentedon Aug 29, 2024
That's all correct.
richardeid commentedon Aug 30, 2024
I'm on 1.21 and I can't get the buffer to restore. Open windows from a previous session is set. Am I doing something wrong?
avih commentedon Aug 30, 2024
This issue is not about restoring the content from a previous session when opening a new terminal window.
It's about restoring the screen content after an application (like an editor, or pager) creates and works in a new screen buffer, and then exits.
[-]Console buffer sometimes not restored[/-][+]Original console buffer is not restored when closing a secondary one[/+]lhecker commentedon Sep 3, 2024
richardeid If you still have this issue, please open a discussion or open another issue. We'll then try to help you.
richardeid commentedon Sep 3, 2024
Leonard Hecker (@lhecker) I think I misunderstood what this was. I was expecting my console history to restore. Thank you for following up
avih commentedon Sep 4, 2024
I can confirm that the build artifact of #17853 has this issue fixed.
Tested with the C test progam given above, and also other use cases with
less.exefor windows, which are broken in 1.22-preview but work OK in the PR artifact.avih commentedon Sep 6, 2024
Thanks. Confirmed build artifact of 544452d is fixed.
avih commentedon Sep 29, 2024
Can confirm this is fixed in the latest Preview v1.22.2702.0 .
Thanks!