mingw: handle non-ASCII PATH components correctly

We need to be careful on Windows: there are "ANSI" versions of the API functions that take char *, and "Unicode" versions that take "wchar_t ` strings as parameters. The ANSI versions are subject to the current codepage, i.e. almost guaranteed to *not handle UTF-8. Internally, we do want to use UTF-8, though, at least in compat/mingw.c, so we really have to use the Unicode versions of the Win32 API.

Adam Roben (1):
mingw: fix launching of externals from Unicode paths

 compat/mingw.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

base-commit: 8104ec994ea3849a968b4667d072fedd1e688642
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-135%2Fdscho%2Ffix-externals-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-135/dscho/fix-externals-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/135

gitgitgadget

From: Adam Roben <[email protected]>

If Git were installed in a path containing non-ASCII characters, commands such as git am and git submodule, which are implemented as externals, would fail to launch with the following error:

This was due to lookup_prog not being Unicode-aware. It was somehow missed in 85faec9d3a (Win32: Unicode file name support (except dirent), 2012-03-15).

Note that the only problem in this function was calling GetFileAttributes() instead of GetFileAttributesW(). The calls to access() were fine because access() is a macro which resolves to mingw_access(), which already handles Unicode correctly. But lookup_prog() was changed to use _waccess() directly so that we only convert the path to UTF-16 once.

To make things work correctly, we have to maintain UTF-8 and UTF-16 versions in tandem in lookup_prog().

---
 compat/mingw.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

index 8141f77189..9f02403ebf 100644
@@ -1161,14 +1161,21 @@ static char *lookup_prog(const char *dir, int dirlen, const char *cmd,
 			 int isexe, int exe_only)
 {
 	char path[MAX_PATH];
+	wchar_t wpath[MAX_PATH];
 	snprintf(path, sizeof(path), "%.*s\\%s.exe", dirlen, dir, cmd);
 
-	if (!isexe && access(path, F_OK) == 0)
+	if (xutftowcs_path(wpath, path) < 0)
+		return NULL;
+
+	if (!isexe && _waccess(wpath, F_OK) == 0)
 		return xstrdup(path);
-	path[strlen(path)-4] = '\0';
-	if ((!exe_only || isexe) && access(path, F_OK) == 0)
-		if (!(GetFileAttributes(path) & FILE_ATTRIBUTE_DIRECTORY))
+	wpath[wcslen(wpath)-4] = '\0';
+	if ((!exe_only || isexe) && _waccess(wpath, F_OK) == 0) {
+		if (!(GetFileAttributesW(wpath) & FILE_ATTRIBUTE_DIRECTORY)) {
+			path[strlen(path)-4] = '\0';
 			return xstrdup(path);
+		}
+	}
 	return NULL;
 }
 

gitgitgadget

Nicely explained. Thanks.