Add config option "windows.appendatomically"

Atomic append on windows is only supported on local disk files, and it may
cause errors in other situations, e.g. 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

Documentation/config.txt

@@ -500,4 +500,6 @@ include::config/versionsort.txt[]
 
 include::config/web.txt[]
 
+include::config/windows.txt[]
+
 include::config/worktree.txt[]

Documentation/config/windows.txt

@@ -0,0 +1,4 @@
+windows.appendatomically::
+	By default, append atomic API is used on windows. But it works only with
+	local disk files, if you're working on a network file system, you should
+	set it false to turn it off.

compat/mingw.c

@@ -743,6 +743,7 @@ static int is_local_named_pipe_path(const char *filename)
 
 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;
@@ -759,7 +760,13 @@ int mingw_open (const char *filename, int oflags, ...)
 		return -1;
 	}
 
-	if ((oflags & O_APPEND) && !is_local_named_pipe_path(filename))
+	if (append_atomically < 0 &&
+	    (!the_repository || git_config_get_bool("windows.appendatomically",
+						    &append_atomically)))
+		append_atomically = 1;
+
+	if (append_atomically && (oflags & O_APPEND) &&
+	    !is_local_named_pipe_path(filename))
 		open_fn = mingw_open_append;
 	else
 		open_fn = _wopen;