From d2f83b599df069b99123e247482efc09528a1235 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Fri, 26 Jan 2018 16:34:59 +0100
Subject: [PATCH] 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.

Sadly, we have to guard this test inside #ifdef WIN32: we need to use
the value of the HANDLE directly, and that concept does not exist on
Linux/Unix.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 t/helper/test-run-command.c | 48 +++++++++++++++++++++++++++++++++++++
 t/t0061-run-command.sh      |  4 ++++
 2 files changed, 52 insertions(+)

diff --git a/t/helper/test-run-command.c b/t/helper/test-run-command.c
index 02f9692924..84284d7e2d 100644
--- a/t/helper/test-run-command.c
+++ b/t/helper/test-run-command.c
@@ -190,6 +190,46 @@ 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;
@@ -197,6 +237,14 @@ int cmd__run_command(int argc, const char **argv)
 
 	if (argc > 1 && !strcmp(argv[1], "testsuite"))
 		exit(testsuite(argc - 1, argv + 1));
+
+	if (argc < 2)
+		return 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;
 	while (!strcmp(argv[1], "env")) {
diff --git a/t/t0061-run-command.sh b/t/t0061-run-command.sh
index 55b4de2db9..10e1bc23ec 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' '
 	test-tool run-command start-command-ENOENT ./does-not-exist
 '