57 lines
2.5 KiB
C++
57 lines
2.5 KiB
C++
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#include <TestCommon.h>
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const int SC_CONSOLE_MARK = 0xFFF2;
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const int SC_CONSOLE_SELECT_ALL = 0xFFF5;
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int main() {
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SpawnParams sp;
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sp.bInheritHandles = TRUE;
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trace("----------------------------------");
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Worker p;
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p.getStdout().write("<-- origBuffer -->");
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auto c = p.child();
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auto cb = c.newBuffer();
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cb.activate();
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cb.write("<-- cb -->");
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// This is what the winpty-agent would want to do:
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// - It tries to "freeze" the console with "Select All", which blocks
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// WriteConsole but little else. Closing a screen buffer is not
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// blocked.
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// - Then, winpty wants to get the buffer info, then read screen content.
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// - If the child process closes its special screen buffer during the
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// scraping, then on Windows 7, conhost can start reading freed memory
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// and crash. In this test case, `info2` is frequently garbage.
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// Somehow winpty-agent needs to avoid this situation, but options seem
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// scarce:
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// - The Windows 7 bug only happens with `CloseHandle` AFAICT. If a
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// buffer handle goes away implicitly from `FreeConsole` or process
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// exit, then the buffer is reference counted properly. If app
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// developers avoid closing their buffer handle, winpty can work.
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// - Be really careful about when to scrape. Pay close attention to
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// the kinds of WinEvents a full-screen app generates just before it
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// exits, and try to fast-path everything such that no scraping is
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// necessary.
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// - Start interfering with the user processes attached to the console.
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// - e.g. inject a DLL inside the processes and open CONOUT$, or
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// override APIs, etc.
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// - Attach to the right console process before opening CONOUT$. If
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// that console's buffer handle is inheritable, then opening CONOUT$
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// will then produce a safe handle.
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// - Accept a certain amount of unreliability.
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SendMessage(p.consoleWindow(), WM_SYSCOMMAND, SC_CONSOLE_SELECT_ALL, 0);
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auto scrape = p.openConout();
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auto info1 = scrape.screenBufferInfo();
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cb.close();
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Sleep(200); // Helps the test fail more often.
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auto info2 = scrape.screenBufferInfo();
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SendMessage(p.consoleWindow(), WM_CHAR, 27, 0x00010001);
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trace("%d %d %d %d", info1.srWindow.Left, info1.srWindow.Top, info1.srWindow.Right, info1.srWindow.Bottom);
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trace("%d %d %d %d", info2.srWindow.Left, info2.srWindow.Top, info2.srWindow.Right, info2.srWindow.Bottom);
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Sleep(300000);
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}
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