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Fix std handle forwarding #1837

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merged 1 commit into from
Nov 13, 2025
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Fix std handle forwarding #1837

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24 changes: 20 additions & 4 deletions GVFS/GitHooksLoader/GitHooksLoader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -112,9 +112,25 @@ int ExecuteHook(const std::wstring &applicationName, wchar_t *hookName, int argc
PROCESS_INFORMATION pi;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
si.dwFlags = STARTF_USESTDHANDLES;
Comment on lines -115 to -117
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@dscho dscho May 13, 2025

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So what you're saying is that this explicit redirection of stdout/stderr currently does not work? This is puzzling because the GitHooksLoader.exe process should have the correct handles, and this way of creating the child process should work...

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@tyrielv tyrielv May 13, 2025 •
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Yes, it does not work. For example running git status on an unmounted gvfs repo displays only the standard fatal: pre-command hook aborted command message, and not the specific message about needing to mount.

The documentation for CREATE_NO_WINDOW says The process is a console application that is being run without a console window. Therefore, the console handle for the application is not set.

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@tyrielv tyrielv Nov 12, 2025

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I have updated this to more closely match how git-wrapper in microsoft/git works - checking explicitly for a console with CONOUT$, and if found then use default behavior (ie don't set CREATE_NO_WINDOW, don't explicitly forward handles as they are forwarded by default), falling back to the current behavior if CONOUT$ is not found (set CREATE_NO_WINDOW and explicitly forward handles)

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@dscho dscho Nov 13, 2025

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Excellent, thank you! Did you test this a bit, including running git status on an unmounted GVFS repo?

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@tyrielv tyrielv Nov 13, 2025

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Yes, it now displays The repo does not appear to be mounted. Use 'gvfs status' to check. fatal: pre-command hook aborted command
instead of just the fatal line.

DWORD creationFlags = 0;
HANDLE consoleHandle;

/* If we have a console, use it (ie allow default behavior)*/
if ((consoleHandle = CreateFile(L"CONOUT$", GENERIC_WRITE,
FILE_SHARE_WRITE, NULL, OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL, NULL)) !=
INVALID_HANDLE_VALUE)
CloseHandle(consoleHandle);
else {
/* Otherwise, forward stdout/err in case they were redirected,
* but do not allow creating a window.*/
si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
/* Git disallows stdin from hooks */
si.dwFlags = STARTF_USESTDHANDLES;

creationFlags |= CREATE_NO_WINDOW;
}

ZeroMemory(&pi, sizeof(pi));

Expand All @@ -135,7 +151,7 @@ int ExecuteHook(const std::wstring &applicationName, wchar_t *hookName, int argc
NULL, // Process handle not inheritable
NULL, // Thread handle not inheritable
TRUE, // Set handle inheritance to TRUE
CREATE_NO_WINDOW, // Process creation flags
creationFlags , // Process creation flags
NULL, // Use parent's environment block
NULL, // Use parent's starting directory
&si, // Pointer to STARTUPINFO structure
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