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[PATCH] winansi_isatty(): fix when Git is used from CMD

From
Johannes Sixt <j6t@kdbg.org>
Date
Dec 18, 2016, 15:26 UTC
Message-ID
<ffc6a7a0-4ae4-b755-0b09-5bcd7114a2e6@kdbg.org>
In-Reply-To
<5977e71d-da58-7cb0-bc69-343bb3a1341d@kdbg.org>

The code in winansi.c emulates ANSI escape sequences when Git is connected to the "real" windows console, CMD.exe. The details are outline in eac14f8909d9 (Win32: Thread-safe windows console output, 2012-01-14). Essentially, it plugs a pipe between C code and the actual console output handle.

This commit also added an override for isatty(), but it was made unnecessary by fcd428f4a952 (Win32: fix broken pipe detection, 2012-03-01).

The new isatty() override implemented by cbb3f3c9b197 (mingw: intercept isatty() to handle /dev/null as Git expects it, 2016-12-11) does not take into account that _get_osfhandle() returns the handle visible by the C code, which is the pipe. But it actually wants to investigate the properties of the handle that is actually connected to the outside world. Fortunately, there is already winansi_get_osfhandle(), which returns exactly this handle. Use it.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
I was able to test the idea earlier than anticipated and it does work
for me.
 compat/winansi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/compat/winansi.c b/compat/winansi.c
index cb725fb02f..ba360be69b 100644
--- a/compat/winansi.c
+++ b/compat/winansi.c
@@ -586,7 +586,7 @@ int winansi_isatty(int fd)
 		 *
 		 * https://msdn.microsoft.com/en-us/library/f4s0ddew.aspx
 		 */
-		HANDLE handle = (HANDLE)_get_osfhandle(fd);
+		HANDLE handle = winansi_get_osfhandle(fd);
 		if (fd == STDIN_FILENO) {
 			DWORD dummy;
 
-- 
2.11.0.79.gf6b77ca
Previous: Johannes SchindelinNext: Johannes Sixt
Message 8 of 21 in “Fix a long-standing isatty() problem on Windows”
  1. 0/1 Fix a long-standing isatty() problem on WindowsJohannes Schindelin, Dec 11, 2016
  2. 1/1 mingw: intercept isatty() to handle /dev/null as Git expects itJohannes Schindelin, Dec 11, 2016
  3. Johannes SixtDec 16, 2016
  4. Junio C HamanoDec 16, 2016
  5. Johannes SixtDec 16, 2016
  6. Junio C HamanoDec 16, 2016
  7. Johannes SchindelinDec 21, 2016
  8. winansi_isatty(): fix when Git is used from CMDJohannes Sixt, Dec 18, 2016
  9. Johannes SixtDec 18, 2016
  10. Johannes SixtDec 19, 2016
  11. Johannes SchindelinDec 21, 2016
  12. Johannes SchindelinDec 20, 2016
  13. Junio C HamanoDec 19, 2016
  14. Johannes SchindelinDec 20, 2016
  15. Junio C HamanoDec 20, 2016
  16. Johannes SchindelinDec 21, 2016
  17. Junio C HamanoDec 21, 2016
  18. Johannes SchindelinDec 22, 2016
  19. Junio C HamanoDec 11, 2016
  20. Johannes SchindelinDec 12, 2016
  21. Junio C HamanoDec 12, 2016

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