[PATCH 4/4] mingw: restrict file handle inheritance only on Windows 7 and later

From

Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>

Date

Nov 22, 2019, 14:41 UTC

Message-ID

<85adb04e3d9a7a79e9b24ea50be71ac55dff6f65.1574433665.git.gitgitgadget@gmail.com>

In-Reply-To

<pull.670.git.git.1574433665.gitgitgadget@gmail.com>

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

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 */

-- 
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