Merge branch 'dont-restrict-handles-on-vista'

It seems that our feature to restrict file handle inheritance to let
spawned processes inherit only the standard handles is a bit broken on
Vista.

This closes #1742

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

Documentation/config/core.txt

@@ -570,6 +570,12 @@ 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

compat/mingw.c

@@ -259,6 +259,7 @@ static enum hide_dotfiles_type hide_dotfiles = HIDE_DOTFILES_DOTGITONLY;
 static char *unset_environment_variables;
 int core_fscache;
 int core_long_paths;
+int core_restrict_inherited_handles = -1;
 
 int mingw_core_config(const char *var, const char *value, void *cb)
 {
@@ -286,6 +287,15 @@ 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;
 }
 
@@ -1674,7 +1684,7 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 			      const char *dir, const char *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;
@@ -1690,6 +1700,16 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 		is_msys2_sh(*argv) ? quote_arg_msys2 : quote_arg_msvc;
 	const char *strace_env;
 
+	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 */