Win32: reliably detect console pipe handles
As of "Win32: Thread-safe windows console output", child processes may
print to the console even if stdout has been redirected to a file. E.g.:
git config tar.cat.command "cat"
git archive -o test.cat HEAD
Detecting whether stdout / stderr point to our console pipe is currently
based on the assumption that OS HANDLE values are never reused. This is
apparently not true if stdout / stderr is replaced via dup2() (as in
builtin/archive.c:17).
Instead of comparing handle values, check if the file descriptor isatty()
backed by a pipe OS handle. This is only possible by swapping the handles
in MSVCRT's internal data structures, as we do in winansi_init().
Reported-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/compat/winansi.c b/compat/winansi.c
index f96d5c2..efc5bb3 100644
--- a/compat/winansi.c
+++ b/compat/winansi.c
@@ -20,7 +20,6 @@
static int negative;
static int non_ascii_used = 0;
static HANDLE hthread, hread, hwrite;
-static HANDLE hwrite1 = INVALID_HANDLE_VALUE, hwrite2 = INVALID_HANDLE_VALUE;
static HANDLE hconsole1, hconsole2;
#ifdef __MINGW32__
@@ -435,10 +434,6 @@
WaitForSingleObject(hthread, INFINITE);
/* cleanup handles... */
- if (hwrite1 != INVALID_HANDLE_VALUE)
- CloseHandle(hwrite1);
- if (hwrite2 != INVALID_HANDLE_VALUE)
- CloseHandle(hwrite2);
CloseHandle(hwrite);
CloseHandle(hthread);
}
@@ -565,14 +560,9 @@
/* redirect stdout / stderr to the pipe */
if (con1)
- hconsole1 = swap_osfhnd(1, hwrite1 = duplicate_handle(hwrite));
+ hconsole1 = swap_osfhnd(1, duplicate_handle(hwrite));
if (con2)
- hconsole2 = swap_osfhnd(2, hwrite2 = duplicate_handle(hwrite));
-}
-
-static int is_same_handle(HANDLE hnd, int fd)
-{
- return hnd != INVALID_HANDLE_VALUE && hnd == (HANDLE) _get_osfhandle(fd);
+ hconsole2 = swap_osfhnd(2, duplicate_handle(hwrite));
}
/*
@@ -581,10 +571,9 @@
*/
HANDLE winansi_get_osfhandle(int fd)
{
- if (fd == 1 && is_same_handle(hwrite1, 1))
- return hconsole1;
- else if (fd == 2 && is_same_handle(hwrite2, 2))
- return hconsole2;
- else
- return (HANDLE) _get_osfhandle(fd);
+ HANDLE hnd = (HANDLE) _get_osfhandle(fd);
+ if ((fd == 1 || fd == 2) && isatty(fd)
+ && GetFileType(hnd) == FILE_TYPE_PIPE)
+ return (fd == 1) ? hconsole1 : hconsole2;
+ return hnd;
}
