Re: [PATCH 1/2] t/helper/test-chmtime: update mingw to support chmtime on directories

From
Junio C Hamano <hidden>
Date
2022-02-28 22:00:31
"Tao Klerks via GitGitGadget" [off-list ref] writes:
From: Tao Klerks <redacted>

The mingw_utime implementation in mingw.c does not support
directories. This means that "test-tool chmtime" fails on Windows when
targeting directories. This has previously been noted and sidestepped
by Jeff Hostetler, in "t/helper/test-chmtime: skip directories
on Windows" in the "Builtin FSMonitor Part 2" work.
I was expecting that this will be applicable _before_ FSMonitor Part
2 and later.  This mention would probably belong to the comment
after three-dashes?
It would make sense to backdate file and folder changes in untracked
cache tests, to avoid needing to insert explicit delays/pauses in the
tests.

Add support for directory date manipulation in mingw_utime by calling
CreateFileW() explicitly to create the directory handle, and
CloseHandle() to close it.
OK.
quoted hunk
@@ -964,6 +964,8 @@ int mingw_utime (const char *file_name, const struct utimbuf *times)
 	int fh, rc;
 	DWORD attrs;
 	wchar_t wfilename[MAX_PATH];
+	HANDLE osfilehandle;
The variable is not initialized here, but that is perfectly OK.
We'll set it in both branches for directories and files.
quoted hunk
 	if (xutftowcs_path(wfilename, file_name) < 0)
 		return -1;
 
@@ -975,9 +977,26 @@ int mingw_utime (const char *file_name, const struct utimbuf *times)
 		SetFileAttributesW(wfilename, attrs & ~FILE_ATTRIBUTE_READONLY);
 	}
 
-	if ((fh = _wopen(wfilename, O_RDWR | O_BINARY)) < 0) {
-		rc = -1;
-		goto revert_attrs;
+	if (attrs & FILE_ATTRIBUTE_DIRECTORY) {
Excellent.  We can reuse existing attrs without any extra calls to
introduce the new codepath to deal with directories.
+		fh = 0;
This should be

		fh = -1;

instead.  More on this later.
quoted hunk
+		osfilehandle = CreateFileW(wfilename,
+					   0x100 /*FILE_WRITE_ATTRIBUTES*/,
+					   0 /*FileShare.None*/,
+					   NULL,
+					   OPEN_EXISTING,
+					   FILE_FLAG_BACKUP_SEMANTICS,
+					   NULL);
+		if (osfilehandle == INVALID_HANDLE_VALUE) {
+			errno = err_win_to_posix(GetLastError());
+			rc = -1;
+			goto revert_attrs;
+		}
Upon an error, we'll jump to revert_attrs but otherwise, we will
have a valid osfilehandle (which presumably is not NULL).
quoted hunk
+	} else {
+		if ((fh = _wopen(wfilename, O_RDWR | O_BINARY)) < 0) {
+			rc = -1;
+			goto revert_attrs;
+		}
+		osfilehandle = (HANDLE)_get_osfhandle(fh);
This side is the same as before.  This code assumes that, as long as
_wopen() gives us a usable fh, _get_osfhandle(fh) would always give
us a valid handle.  This assumption should be safe, as the original
code has been relying on it anyway.
quoted hunk
@@ -987,12 +1006,16 @@ int mingw_utime (const char *file_name, const struct utimbuf *times)
 		GetSystemTimeAsFileTime(&mft);
 		aft = mft;
 	}
-	if (!SetFileTime((HANDLE)_get_osfhandle(fh), NULL, &aft, &mft)) {
+	if (!SetFileTime(osfilehandle, NULL, &aft, &mft)) {
And we use the osfilehandle we obtained, either from the code that
is identical to the original for files or from the new code for
directories.  Good.
quoted hunk
 		errno = EINVAL;
 		rc = -1;
 	} else
 		rc = 0;
-	close(fh);
+
+	if (fh)
+		close(fh);
+	else if (osfilehandle)
+		CloseHandle(osfilehandle);
In the context of "git" process, I do not think we would ever close
FD#0, so it may be safe to assume that _wopen() above will never
yield FD#0, so this is not quite wrong per-se, but to be
future-proof, it would be even safer to instead do:

	if (0 <= fh)
		close(fh);
	else if (osfilehandle)
		CloseHandle(osfilehandle);

here.  That is consistent with the error checking done where
_wopen() was called to obtain it above, i.e.

	if ((fh = _wopen(...)) < 0)
		... error ...
 revert_attrs:
 	if (attrs != INVALID_FILE_ATTRIBUTES &&
Thread (2 messages) 2 messages, 2 authors, last reply 2022-03-01
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