Add config option "windows.appendatomically" support

Atomic append on windows is only supported on local disk files, and it may cause errors in other situations, e.g. pipeline and network file system. If that is the case, this config option should be used to turn atomic append off.

Signed-off-by: sunzhuoshi <[email protected]>
Co-Authored-By: Johannes Schindelin <[email protected]>

Author: sunzhuoshi

compat/mingw.c

@@ -741,50 +741,9 @@ static int is_local_named_pipe_path(const char *filename)
 		filename[9]);
 }
 
-static int is_local_disk_file(const char *filename)
-{
-	wchar_t wpath[MAX_LONG_PATH];
-	wchar_t wfullpath[MAX_LONG_PATH];
-	size_t windex;
-
-	if (is_local_named_pipe_path(filename))
-		return 0;
-
-	/*
-	 * Do everything in wide chars because the drive letter might be
-	 * a multi-byte sequence.  See win32_has_dos_drive_prefix().
-	 */
-	if (xutftowcs_long_path(wpath, filename) < 0)
-		return 0;
-
-	/*
-	 * GetDriveTypeW() requires a final slash.
-	 */
-	windex = wcslen(wpath) - 1;
-	while (windex > 0) {
-		if (is_dir_sep(wpath[windex]))
-			break;
-		windex--;
-	}
-	wpath[windex++] = L'\\';
-	wpath[windex] = 0;
-
-	/*
-	 * Normalize the path.  If nothing else, this converts forward
-	 * slashes to backslashes.  This is essential to get GetDriveTypeW()
-	 * correctly handle some UNC "\\server\share\..." paths.
-	 */
-	if (!GetFullPathNameW(wpath, MAX_LONG_PATH, wfullpath, NULL))
-		return 0;
-
-	if (GetDriveTypeW(wfullpath) == DRIVE_REMOTE)
-		return 0;
-
-	return 1;
-}
-
 int mingw_open (const char *filename, int oflags, ...)
 {
+	static int append_atomically = -1;
 	typedef int (*open_fn_t)(wchar_t const *wfilename, int oflags, ...);
 	va_list args;
 	unsigned mode;
@@ -801,7 +760,15 @@ int mingw_open (const char *filename, int oflags, ...)
 		return -1;
 	}
 
-	if ((oflags & O_APPEND) && is_local_disk_file(filename))
+	if (append_atomically < 0) {
+		append_atomically = 1; /* default to `true` */
+		if (the_repository)
+			git_config_get_bool("windows.appendatomically",
+					    &append_atomically);
+	}
+
+	if (append_atomically && (oflags & O_APPEND) &&
+	    !is_local_named_pipe_path(filename))
 		open_fn = mingw_open_append;
 	else
 		open_fn = _wopen;