[RFC PATCH v5 09/11] trace-cmd: Make setup-guest auto attach FIFOs to the guest VM config

[Slavomir Kaslev <kaslevs@vmware.com>]

This patch tries to attach the newly created FIFOs for guest tracing as virtio
serial devices to libvirt managed guests.

Signed-off-by: Slavomir Kaslev <kaslevs@vmware.com>
---
 tracecmd/trace-setup-guest.c | 41 ++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/tracecmd/trace-setup-guest.c b/tracecmd/trace-setup-guest.c
index bcd8f40..3176b7e 100644
--- a/tracecmd/trace-setup-guest.c
+++ b/tracecmd/trace-setup-guest.c
@@ -118,6 +118,43 @@ static int get_guest_cpu_count(const char *guest)
 	return nr_cpus;
 }
 
+static int attach_guest_fifos(const char *guest, int nr_cpus)
+{
+	const char *cmd_fmt =
+		"virsh attach-device --config '%s' '%s' >/dev/null 2>/dev/null";
+	const char *xml_fmt =
+		"<channel type='pipe'>\n"
+		"  <source path='%s'/>\n"
+		"  <target type='virtio' name='%s%d'/>\n"
+		"</channel>";
+	char tmp_path[PATH_MAX], path[PATH_MAX];
+	char cmd[PATH_MAX], xml[PATH_MAX];
+	int i, fd, ret = 0;
+
+	strcpy(tmp_path, "/tmp/pipexmlXXXXXX");
+	fd = mkstemp(tmp_path);
+	if (fd < 0)
+		return fd;
+
+	for (i = 0; i < nr_cpus; i++) {
+		snprintf(path, sizeof(path), GUEST_FIFO_FMT, guest, i);
+		snprintf(xml, sizeof(xml), xml_fmt, path, GUEST_PIPE_NAME, i);
+		pwrite(fd, xml, strlen(xml), 0);
+
+		snprintf(cmd, sizeof(cmd), cmd_fmt, guest, tmp_path);
+		errno = 0;
+		if (system(cmd) != 0) {
+			ret = -1;
+			break;
+		}
+	}
+
+	close(fd);
+	unlink(tmp_path);
+
+	return ret;
+}
+
 static void do_setup_guest(const char *guest, int nr_cpus, mode_t mode, gid_t gid)
 {
 	gid_t save_egid;
@@ -136,6 +173,10 @@ static void do_setup_guest(const char *guest, int nr_cpus, mode_t mode, gid_t gi
 	if (ret < 0)
 		pdie("failed to create FIFOs for %s", guest);
 
+	ret = attach_guest_fifos(guest, nr_cpus);
+	if (ret < 0)
+		warning("failed to attach FIFOs to %s", guest);
+
 	ret = setegid(save_egid);
 	if (ret < 0)
 		pdie("failed to restore effective group ID");
-- 
2.19.1