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From: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Johannes Schindelin <johannes.schindelin@gmx.de>,
	Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: [PATCH 2/4] mingw: work around incorrect standard handles
Date: Fri, 22 Nov 2019 14:41:03 +0000
Message-ID: <f68b4094a2985217a0229fd6432cece9d91b25e5.1574433665.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.670.git.git.1574433665.gitgitgadget@gmail.com>

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

For some reason, when being called via TortoiseGit the standard handles,
or at least what is returned by _get_osfhandle(0) for standard input,
can take on the value (HANDLE)-2 (which is not a legal value, according
to the documentation).

Even if this value is not documented anywhere, CreateProcess() seems to
work fine without complaints if hStdInput set to this value.

In contrast, the upcoming code to restrict which file handles get
inherited by spawned processes would result in `ERROR_INVALID_PARAMETER`
when including such handle values in the list.

To help this, special-case the value (HANDLE)-2 returned by
_get_osfhandle() and replace it with INVALID_HANDLE_VALUE, which will
hopefully let the handle inheritance restriction work even when called
from TortoiseGit.

This fixes https://github.com/git-for-windows/git/issues/1481

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/winansi.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/compat/winansi.c b/compat/winansi.c
index 54fd701cbf..c27b20a79d 100644
--- a/compat/winansi.c
+++ b/compat/winansi.c
@@ -662,10 +662,20 @@ void winansi_init(void)
  */
 HANDLE winansi_get_osfhandle(int fd)
 {
+	HANDLE ret;
+
 	if (fd == 1 && (fd_is_interactive[1] & FD_SWAPPED))
 		return hconsole1;
 	if (fd == 2 && (fd_is_interactive[2] & FD_SWAPPED))
 		return hconsole2;
 
-	return (HANDLE)_get_osfhandle(fd);
+	ret = (HANDLE)_get_osfhandle(fd);
+
+	/*
+	 * There are obviously circumstances under which _get_osfhandle()
+	 * returns (HANDLE)-2. This is not documented anywhere, but that is so
+	 * clearly an invalid handle value that we can just work around this
+	 * and return the correct value for invalid handles.
+	 */
+	return ret == (HANDLE)-2 ? INVALID_HANDLE_VALUE : ret;
 }
-- 
gitgitgadget


  parent reply	other threads:[~2019-11-22 14:41 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-22 14:41 [PATCH 0/4] On Windows, limit which file handles are inherited by spawned child processes Johannes Schindelin via GitGitGadget
2019-11-22 14:41 ` [PATCH 1/4] mingw: demonstrate that all file handles are inherited by " Johannes Schindelin via GitGitGadget
2019-11-22 14:41 ` Johannes Schindelin via GitGitGadget [this message]
2019-11-22 14:41 ` [PATCH 3/4] mingw: spawned processes need to inherit only standard handles Johannes Schindelin via GitGitGadget
2019-11-28 21:48   ` Johannes Sixt
2019-11-29 13:52     ` Johannes Schindelin
2019-11-29 20:40       ` Johannes Schindelin
2019-11-29 22:19       ` Johannes Sixt
2019-11-29 22:37       ` Johannes Sixt
2019-11-30 22:10         ` Johannes Schindelin
2019-11-22 14:41 ` [PATCH 4/4] mingw: restrict file handle inheritance only on Windows 7 and later Johannes Schindelin via GitGitGadget
2019-11-25  5:42 ` [PATCH 0/4] On Windows, limit which file handles are inherited by spawned child processes Junio C Hamano
2019-11-25 16:29   ` Johannes Schindelin

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