[PATCH v2 1/2] mingw: ensure `getcwd()` reports the correct case

From: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Date: Oct 24, 2018, 09:19 UTC
Message-ID: <e13ae233822c8e4a4504e3294adf3e0de38a1990.1540372778.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.54.v2.git.gitgitgadget@gmail.com>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

When switching the current working directory, say, in PowerShell, it is quite possible to use a different capitalization than the one that is recorded on disk. While doing the same in `cmd.exe` adjusts the capitalization magically, that does not happen in PowerShell so that `getcwd()` returns the current directory in a different way than is recorded on disk.

Typically this creates no problems except when you call

	git log .

in a subdirectory called, say, "GIT/" but you switched to "Git/" and your `getcwd()` reports the latter, then Git won't understand that you wanted to see the history as per the `GIT/` subdirectory but it thinks you wanted to see the history of some directory that may have existed in the past (but actually never did).

So let's be extra careful to adjust the capitalization of the current directory before working with it.

Reported by a few PowerShell power users ;-)

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 18caf2196..2c3e27ce9 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -917,8 +917,15 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
 
 char *mingw_getcwd(char *pointer, int len)
 {
-	wchar_t wpointer[MAX_PATH];
-	if (!_wgetcwd(wpointer, ARRAY_SIZE(wpointer)))
+	wchar_t cwd[MAX_PATH], wpointer[MAX_PATH];
+	DWORD ret = GetCurrentDirectoryW(ARRAY_SIZE(cwd), cwd);
+
+	if (!ret || ret >= ARRAY_SIZE(cwd)) {
+		errno = ret ? ENAMETOOLONG : err_win_to_posix(GetLastError());
+		return NULL;
+	}
+	ret = GetLongPathNameW(cwd, wpointer, ARRAY_SIZE(wpointer));
+	if (!ret || ret >= ARRAY_SIZE(wpointer))
 		return NULL;
 	if (xwcstoutf(pointer, wpointer, len) < 0)
 		return NULL;

-- 
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