[PATCH BlueZ v1 2/2] test-runner: Share build directory writable on coverage builds

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

The root filesystem is shared read-only with the guest so gcov is not
able to write the .gcda files of binaries run by test-runner, e.g. by
the functional tests. Share the build directory writable over 9p and
mount it over the read-only one when coverage is enabled.

Assisted-by: Claude:claude-opus-5.5
---
 Makefile.tools      |  3 +++
 tools/test-runner.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/Makefile.tools b/Makefile.tools
index 671b40fb0e42..658f92d7b9db 100644
--- a/Makefile.tools
+++ b/Makefile.tools
@@ -325,6 +325,9 @@ tools_btgatt_server_LDADD = src/libshared-mainloop.la \
 						lib/libbluetooth-internal.la
 
 tools_test_runner_CFLAGS = $(WARNING_CFLAGS)
+if COVERAGE
+tools_test_runner_CFLAGS += -DHAVE_COVERAGE
+endif
 tools_test_runner_LDFLAGS =
 
 tools_rctest_LDADD = lib/libbluetooth-internal.la
diff --git a/tools/test-runner.c b/tools/test-runner.c
index 338e5b9da544..674ce072d959 100644
--- a/tools/test-runner.c
+++ b/tools/test-runner.c
@@ -577,6 +577,46 @@ static void terminate_signal(int sig)
 	terminate = 1;
 }
 
+#define COVERAGE_TAG "bluez-coverage"
+
+static bool coverage_enabled(void)
+{
+#ifdef HAVE_COVERAGE
+	return true;
+#else
+	return false;
+#endif
+}
+
+/* The root filesystem is shared read-only, so gcov would be unable to write
+ * the .gcda files of the binaries run inside the guest. Share the build
+ * directory writable so it can be mounted over the read-only one.
+ */
+static void coverage_setup(struct strv *argv, const char *dir)
+{
+	if (!coverage_enabled())
+		return;
+
+	strv_append(argv, "-fsdev");
+	strv_append(argv, "local,id=fsdev-coverage,path=%s,readonly=off,"
+				"security_model=none,multidevs=remap", dir);
+	strv_append(argv, "-device");
+	strv_append(argv, "virtio-9p-pci,fsdev=fsdev-coverage,"
+					"mount_tag=" COVERAGE_TAG);
+}
+
+static void coverage_mount(const char *dir)
+{
+	if (!coverage_enabled())
+		return;
+
+	printf("Mounting %s writable for coverage\n", dir);
+
+	if (mount(COVERAGE_TAG, dir, "9p", 0,
+				"trans=virtio,version=9p2000.L") < 0)
+		perror("Failed to mount coverage directory");
+}
+
 static bool rootfs_setup(struct rootfs *r, struct strv *argv)
 {
 	const char *mem = "256M";
@@ -826,6 +866,8 @@ static int start_qemu(void)
 	strv_append(&argv, "-append");
 	strv_append(&argv, "%s", cmdline);
 
+	coverage_setup(&argv, cwd);
+
 	for (i = 0; i < num_devs; i++) {
 		strv_append(&argv, "-chardev");
 		strv_append(&argv, "socket,path=%s,id=bt%d", device_path, i);
@@ -1456,6 +1498,9 @@ static void run_command(char *cmdname, char *home)
 		return;
 	}
 
+	/* home is "HOME=<dir>" */
+	coverage_mount(home + 5);
+
 	if (num_devs) {
 		const char *node = "/dev/hvc1";
 		unsigned int basic_flags, extra_flags;
-- 
2.55.0