From eea4a7f4b3620df1b0bd3c1eb1d27e6fd4cb2ff5 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Fri, 22 Nov 2019 14:41:02 +0000
Subject: mingw: demonstrate that all file handles are inherited by child
 processes

When spawning child processes, we really should be careful which file
handles we let them inherit.

This is doubly important on Windows, where we cannot rename, delete, or
modify files if there is still a file handle open.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/helper/test-run-command.c b/t/helper/test-run-command.c
index ead6dc6..40ec4db 100644
--- a/t/helper/test-run-command.c
+++ b/t/helper/test-run-command.c
@@ -200,6 +200,46 @@ static int testsuite(int argc, const char **argv)
 	return !!ret;
 }
 
+static int inherit_handle(const char *argv0)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	char path[PATH_MAX];
+	int tmp;
+
+	/* First, open an inheritable handle */
+	xsnprintf(path, sizeof(path), "out-XXXXXX");
+	tmp = xmkstemp(path);
+
+	argv_array_pushl(&cp.args,
+			 "test-tool", argv0, "inherited-handle-child", NULL);
+	cp.in = -1;
+	cp.no_stdout = cp.no_stderr = 1;
+	if (start_command(&cp) < 0)
+		die("Could not start child process");
+
+	/* Then close it, and try to delete it. */
+	close(tmp);
+	if (unlink(path))
+		die("Could not delete '%s'", path);
+
+	if (close(cp.in) < 0 || finish_command(&cp) < 0)
+		die("Child did not finish");
+
+	return 0;
+}
+
+static int inherit_handle_child(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	if (strbuf_read(&buf, 0, 0) < 0)
+		die("Could not read stdin");
+	printf("Received %s\n", buf.buf);
+	strbuf_release(&buf);
+
+	return 0;
+}
+
 int cmd__run_command(int argc, const char **argv)
 {
 	struct child_process proc = CHILD_PROCESS_INIT;
@@ -207,6 +247,10 @@ int cmd__run_command(int argc, const char **argv)
 
 	if (argc > 1 && !strcmp(argv[1], "testsuite"))
 		exit(testsuite(argc - 1, argv + 1));
+	if (!strcmp(argv[1], "inherited-handle"))
+		exit(inherit_handle(argv[0]));
+	if (!strcmp(argv[1], "inherited-handle-child"))
+		exit(inherit_handle_child());
 
 	if (argc < 3)
 		return 1;
diff --git a/t/t0061-run-command.sh b/t/t0061-run-command.sh
index 17c9c0f..473a340 100755
--- a/t/t0061-run-command.sh
+++ b/t/t0061-run-command.sh
@@ -12,6 +12,10 @@ cat >hello-script <<-EOF
 	cat hello-script
 EOF
 
+test_expect_failure MINGW 'subprocess inherits only std handles' '
+	test-tool run-command inherited-handle
+'
+
 test_expect_success 'start_command reports ENOENT (slash)' '
 	test-tool run-command start-command-ENOENT ./does-not-exist 2>err &&
 	test_i18ngrep "\./does-not-exist" err
-- 
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