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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 4/4] mingw: restrict file handle inheritance only on Windows 7 and later
Date: Fri, 22 Nov 2019 14:41:05 +0000
Message-ID: <85adb04e3d9a7a79e9b24ea50be71ac55dff6f65.1574433665.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.670.git.git.1574433665.gitgitgadget@gmail.com>

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

Turns out that it don't work so well on Vista, see
https://github.com/git-for-windows/git/issues/1742 for details.

According to https://devblogs.microsoft.com/oldnewthing/?p=8873, it
*should* work on Windows Vista and later.

But apparently there are issues on Windows Vista when pipes are
involved. Given that Windows Vista is past its end of life (official
support ended on April 11th, 2017), let's not spend *too* much time on
this issue and just disable the file handle inheritance restriction on
any Windows version earlier than Windows 7.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 Documentation/config/core.txt |  6 ++++++
 compat/mingw.c                | 22 +++++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt
index 852d2ba37a..ad4fa4dccd 100644
--- a/Documentation/config/core.txt
+++ b/Documentation/config/core.txt
@@ -559,6 +559,12 @@ core.unsetenvvars::
 	Defaults to `PERL5LIB` to account for the fact that Git for
 	Windows insists on using its own Perl interpreter.
 
+core.restrictinheritedhandles::
+	Windows-only: override whether spawned processes inherit only standard
+	file handles (`stdin`, `stdout` and `stderr`) or all handles. Can be
+	`auto`, `true` or `false`. Defaults to `auto`, which means `true` on
+	Windows 7 and later, and `false` on older Windows versions.
+
 core.createObject::
 	You can set this to 'link', in which case a hardlink followed by
 	a delete of the source are used to make sure that object creation
diff --git a/compat/mingw.c b/compat/mingw.c
index cac18cc3da..2b6eca2f56 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -212,6 +212,7 @@ enum hide_dotfiles_type {
 	HIDE_DOTFILES_DOTGITONLY
 };
 
+static int core_restrict_inherited_handles = -1;
 static enum hide_dotfiles_type hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
 static char *unset_environment_variables;
 
@@ -231,6 +232,15 @@ int mingw_core_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.restrictinheritedhandles")) {
+		if (value && !strcasecmp(value, "auto"))
+			core_restrict_inherited_handles = -1;
+		else
+			core_restrict_inherited_handles =
+				git_config_bool(var, value);
+		return 0;
+	}
+
 	return 0;
 }
 
@@ -1398,7 +1408,7 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 			      const char *dir,
 			      int prepend_cmd, int fhin, int fhout, int fherr)
 {
-	static int restrict_handle_inheritance = 1;
+	static int restrict_handle_inheritance = -1;
 	STARTUPINFOEXW si;
 	PROCESS_INFORMATION pi;
 	LPPROC_THREAD_ATTRIBUTE_LIST attr_list = NULL;
@@ -1413,6 +1423,16 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	const char *(*quote_arg)(const char *arg) =
 		is_msys2_sh(*argv) ? quote_arg_msys2 : quote_arg_msvc;
 
+	if (restrict_handle_inheritance < 0)
+		restrict_handle_inheritance = core_restrict_inherited_handles;
+	/*
+	 * The following code to restrict which handles are inherited seems
+	 * to work properly only on Windows 7 and later, so let's disable it
+	 * on Windows Vista and 2008.
+	 */
+	if (restrict_handle_inheritance < 0)
+		restrict_handle_inheritance = GetVersion() >> 16 >= 7601;
+
 	do_unset_environment_variables();
 
 	/* Determine whether or not we are associated to a console */
-- 
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 ` [PATCH 2/4] mingw: work around incorrect standard handles Johannes Schindelin via GitGitGadget
2019-11-22 14:41 ` [PATCH 3/4] mingw: spawned processes need to inherit only " 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 ` Johannes Schindelin via GitGitGadget [this message]
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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