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mingw: optionally use legacy (non-POSIX) delete semantics 

At some point between Windows 10 Build 17134.1304 and Build 18363.657,
the default behavior of `DeleteFileW()` was changed to use POSIX
semantics (https://stackoverflow.com/a/60512798). Under those semantics,
a file can be deleted even when another process holds an active
`MapViewOfFile` view on it: the directory entry is removed immediately,
but the underlying data persists until the last handle is closed.

On older Windows versions (and Windows 10 builds before that change),
`DeleteFileW()` uses legacy semantics where deletion fails outright if
any process holds a file mapping.

To allow testing code paths that depend on the legacy behavior, introduce
a `GIT_TEST_LEGACY_DELETE` environment variable. When set, `mingw_unlink()`
uses `SetFileInformationByHandle()` with `FileDispositionInfo` (the
non-POSIX variant) instead of `DeleteFileW()`, forcing legacy delete
semantics regardless of the Windows version.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
main
Johannes Schindelin 2026-05-07 12:51:12 +00:00 committed by Junio C Hamano
parent 94f057755b
commit 69ed0e35a7
1 changed files with 45 additions and 2 deletions
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47
compat/mingw.c
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@ -449,20 +449,63 @@ static wchar_t *normalize_ntpath(wchar_t *wbuf)
return wbuf;
}

/*
* Use SetFileInformationByHandle(FileDispositionInfo) to force legacy
* (non-POSIX) delete semantics. On Windows 11, DeleteFileW() uses POSIX
* delete semantics internally, allowing deletion even with active
* MapViewOfFile views. This helper simulates Windows 10 behavior where
* deletion fails if a file mapping exists.
*
* Returns nonzero on success (like DeleteFileW), 0 on failure.
*/
static int legacy_delete_file(const wchar_t *wpathname)
{
FILE_DISPOSITION_INFO fdi = { TRUE };
DWORD gle;
HANDLE h = CreateFileW(wpathname, DELETE,
FILE_SHARE_READ | FILE_SHARE_WRITE |
FILE_SHARE_DELETE,
NULL, OPEN_EXISTING,
FILE_FLAG_OPEN_REPARSE_POINT, NULL);
if (h == INVALID_HANDLE_VALUE)
return 0;

if (SetFileInformationByHandle(h, FileDispositionInfo,
&fdi, sizeof(fdi))) {
CloseHandle(h);
return 1;
}
gle = GetLastError();
CloseHandle(h);
SetLastError(gle);
return 0;
}

static int try_delete_file(const wchar_t *wpathname, int use_legacy)
{
if (use_legacy)
return legacy_delete_file(wpathname);
return DeleteFileW(wpathname);
}

int mingw_unlink(const char *pathname, int handle_in_use_error)
{
static int use_legacy_delete = -1;
int tries = 0;
wchar_t wpathname[MAX_PATH];
if (xutftowcs_path(wpathname, pathname) < 0)
return -1;

if (DeleteFileW(wpathname))
if (use_legacy_delete < 0)
use_legacy_delete = git_env_bool("GIT_TEST_LEGACY_DELETE", 0);

if (try_delete_file(wpathname, use_legacy_delete))
return 0;

do {
/* read-only files cannot be removed */
_wchmod(wpathname, 0666);
if (!_wunlink(wpathname))
if (try_delete_file(wpathname, use_legacy_delete))
return 0;
if (!is_file_in_use_error(GetLastError()))
break;