mingw: optionally redirect stderr/stdout via the same handle

The "2>&1" notation in Powershell and in Unix shells implies that stderr is redirected to the same handle into which stdout is already written. Let's use this special value to allow the same trick with GIT_REDIRECT_STDERR and GIT_REDIRECT_STDOUT: if the former's value is `2>&1`, then stderr will simply be written to the same handle as stdout. The functionality was suggested by Jeff Hostetler. Signed-off-by: Johannes Schindelin <[email protected]> Signed-off-by: Junio C Hamano <[email protected]>
zkat · Nov 2, 2017 · 1a172e4 · 1a172e4
1 parent 3f94442
commit 1a172e4
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diff --git a/compat/mingw.c b/compat/mingw.c
@@ -2160,6 +2160,21 @@ static void maybe_redirect_std_handle(const wchar_t *key, DWORD std_id, int fd,
 			CloseHandle(handle);
 		return;
 	}
+	if (std_id == STD_ERROR_HANDLE && !wcscmp(buf, L"2>&1")) {
+		handle = GetStdHandle(STD_OUTPUT_HANDLE);
+		if (handle == INVALID_HANDLE_VALUE) {
+			close(fd);
+			handle = GetStdHandle(std_id);
+			if (handle != INVALID_HANDLE_VALUE)
+				CloseHandle(handle);
+		} else {
+			int new_fd = _open_osfhandle((intptr_t)handle, O_BINARY);
+			SetStdHandle(std_id, handle);
+			dup2(new_fd, fd);
+			/* do *not* close the new_fd: that would close stdout */
+		}
+		return;
+	}
 	handle = CreateFileW(buf, desired_access, 0, NULL, create_flag,
 			     flags, NULL);
 	if (handle != INVALID_HANDLE_VALUE) {

diff --git a/t/t0001-init.sh b/t/t0001-init.sh
@@ -456,7 +456,13 @@ test_expect_success 're-init from a linked worktree' '
 test_expect_success MINGW 'redirect std handles' '
 	GIT_REDIRECT_STDOUT=output.txt git rev-parse --git-dir &&
 	test .git = "$(cat output.txt)" &&
-	test -z "$(GIT_REDIRECT_STDOUT=off git rev-parse --git-dir)"
+	test -z "$(GIT_REDIRECT_STDOUT=off git rev-parse --git-dir)" &&
+	test_must_fail env \
+		GIT_REDIRECT_STDOUT=output.txt \
+		GIT_REDIRECT_STDERR="2>&1" \
+		git rev-parse --git-dir --verify refs/invalid &&
+	printf ".git\nfatal: Needed a single revision\n" >expect &&
+	test_cmp expect output.txt
 '
 
 test_done