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[PATCH v2 2/3] mingw: optionally redirect stderr/stdout via the same handle

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Nov 1, 2017, 17:10 UTC
Message-ID
<d98f6a9a6eeb01f68f4bc853952ca675e97940bd.1509556153.git.johannes.schindelin@gmx.de>
In-Reply-To
<cover.1509556153.git.johannes.schindelin@gmx.de>

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 <johannes.schindelin@gmx.de>
---
 compat/mingw.c  | 15 +++++++++++++++
 t/t0001-init.sh |  8 +++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/compat/mingw.c b/compat/mingw.c
index 6c6c7795a70..2d44d21aca8 100644
--- 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
index 0fd2fc45385..c413bff9cf1 100755
--- 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
-- 
2.15.0.windows.1
Previous: Johannes SchindelinNext: Johannes Schindelin
Message 21 of 22 in “mingw: introduce a way to avoid std handle inheritance”
  1. 0/3 mingw: introduce a way to avoid std handle inheritanceJohannes Schindelin, Oct 30, 2017
  2. 1/3 mingw: add experimental feature to redirect standard handlesJohannes Schindelin, Oct 30, 2017
  3. 2/3 mingw: special-case GIT_REDIRECT_STDERR=2>&1Johannes Schindelin, Oct 30, 2017
  4. 3/3 mingw: document the experimental standard handle redirectionJohannes Schindelin, Oct 30, 2017
  5. Eric SunshineOct 30, 2017
  6. Johannes SchindelinOct 31, 2017
  7. Junio C HamanoNov 1, 2017
  8. Johannes SchindelinNov 1, 2017
  9. Junio C HamanoNov 2, 2017
  10. Johannes SchindelinNov 2, 2017
  11. Junio C HamanoNov 3, 2017
  12. Johannes SchindelinNov 3, 2017
  13. Jonathan NiederOct 30, 2017
  14. Junio C HamanoOct 31, 2017
  15. Johannes SchindelinOct 31, 2017
  16. Jonathan NiederOct 31, 2017
  17. Johannes SchindelinNov 1, 2017
  18. Stefan BellerNov 1, 2017
  19. 0/3 mingw: introduce a way to avoid std handle inheritanceJohannes Schindelin, Nov 1, 2017
  20. 1/3 mingw: add experimental feature to redirect standard handlesJohannes Schindelin, Nov 1, 2017
  21. 2/3 mingw: optionally redirect stderr/stdout via the same handleJohannes Schindelin, Nov 1, 2017
  22. 3/3 mingw: document the standard handle redirectionJohannes Schindelin, Nov 1, 2017

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