auto-virtserial: Add guest SIGIO tests

The guest can receive the SIGIO signal on host connection and
disconnection events. This commit just adds a simple test for one
open/close event. A lot more are to be added, as explained in the
comments.

Signed-off-by: Amit Shah <amit.shah@redhat.com>

1 files changed, 108 insertions, 2 deletions

diff --git a/auto-virtserial-guest.c b/auto-virtserial-guest.c
index cef1d26..ce3e6e5 100644
--- a/auto-virtserial-guest.c
+++ b/auto-virtserial-guest.c
@@ -36,6 +36,7 @@
 #include "virtserial.h"
 
 #define CONTROL_PORT "/dev/vport0p1"
+#define MAX_PORTS 10
 
 /* The fd to work with for read / write requests. Set by the open message */
 static int g_fd;
@@ -47,7 +48,10 @@ static int g_length;
 static char g_sysfs_name[1024];
 /* The thread that performs a blocking read operation */
 static pthread_t g_read_thread_id;
-
+/* Array to hold fds of all open ports. Used for polling host connect events */
+static int g_open_fds[MAX_PORTS];
+/* Array to hold poll results of g_open_fds from the sigio_handler() */
+static int g_poll_results[MAX_PORTS];
 
 static ssize_t safewrite(int fd, const void *buf, size_t count)
 {
@@ -148,7 +152,7 @@ static char *get_port_dev(unsigned int nr)
 static int open_port(int nr)
 {
 	char *buf;
-	int fd;
+	int fd, ret;
 
 	buf = get_port_dev(nr);
 	if (!buf)
@@ -159,6 +163,19 @@ static int open_port(int nr)
 	if (fd == -1)
 		return -errno;
 	g_fd = fd;
+
+	ret = fcntl(fd, F_SETOWN, getpid());
+	if (ret < 0) {
+		perror("F_SETOWN");
+	}
+	ret = fcntl(fd, F_GETFL);
+	ret = fcntl(fd, F_SETFL, ret | O_ASYNC);
+	if (ret < 0) {
+		perror("F_SETFL");
+	}
+
+	if (nr < MAX_PORTS)
+		g_open_fds[nr] = fd;
 	return fd;
 }
 
@@ -220,6 +237,11 @@ static int close_port(int nr)
 	if (ret < 0)
 		ret = -errno;
 	g_length = 0;
+
+	if (nr < MAX_PORTS) {
+		g_open_fds[nr] = -1;
+		g_poll_results[nr] = 0;
+	}
 	return ret;
 }
 
@@ -462,6 +484,76 @@ static int join_read_thread(int nr)
 	return ret;
 }
 
+static int get_port_from_fd(int fd)
+{
+	unsigned int i;
+
+	for (i = 0; i < MAX_PORTS; i++) {
+		if (g_open_fds[i] == fd)
+			return i;
+	}
+	return -1;
+}
+
+static void sigio_handler(int signal)
+{
+	struct pollfd pollfds[MAX_PORTS];
+	unsigned int i, j;
+	int ret;
+
+	for (i = 0, j = 0; i < MAX_PORTS; i++) {
+		if (g_open_fds[i] > -1) {
+			pollfds[j].fd = g_open_fds[i];
+			pollfds[j++].events = POLLIN|POLLOUT;
+		}
+	}
+	ret = safepoll(pollfds, j, 0);
+	if (ret == -1) {
+		for (i = 0; i < MAX_PORTS; i++)
+			g_poll_results[i] = 0;
+		return;
+	}
+
+	for (i = 0; i < j; i++) {
+		int port;
+
+		port = get_port_from_fd(pollfds[i].fd);
+		if (port == -1)
+			continue;
+		g_poll_results[port] = pollfds[i].revents;
+	}
+}
+
+static int install_sigio_handler(void)
+{
+	struct sigaction action;
+	unsigned int i;
+	int ret;
+
+	action.sa_handler = sigio_handler;
+	action.sa_flags = 0;
+	ret = sigemptyset(&action.sa_mask);
+	if (ret) {
+		ret = -errno;
+		goto out;
+	}
+
+	ret = sigaction(SIGIO, &action, NULL);
+	if (ret)
+		ret = -errno;
+
+out:
+	for (i = 0; i < MAX_PORTS; i++)
+		g_poll_results[i] = 0;
+
+	return ret;
+}
+
+static int get_sigio_result(int nr)
+{
+	return g_poll_results[nr];
+}
+
 static void send_report(int cfd, int ret)
 {
 	struct guest_packet gpkt;
@@ -475,6 +567,7 @@ int main(int argc, char *argv[])
 {
 	struct guest_packet gpkt;
 	struct pollfd pollfd[1];
+	unsigned int i;
 	int ret, cfd;
 
 	/*
@@ -486,6 +579,12 @@ int main(int argc, char *argv[])
 	 */
 	spawn_console(0);
 
+	/*
+	 * Have to install it right away. Else we'll start getting
+	 * SIGIOs and the default action is to terminate the process.
+	 */
+	install_sigio_handler();
+
 	ret = access(CONTROL_PORT, R_OK|W_OK);
 	if (ret == -1)
 		error(errno, errno, "No control port found %s", CONTROL_PORT);
@@ -501,6 +600,9 @@ back_to_open:
 	if (ret < 0)
 		error(-ret, -ret, "write control port");
 
+	for (i = 0; i < MAX_PORTS; i++)
+		g_open_fds[i] = -1;
+
 	pollfd[0].fd = cfd;
 	pollfd[0].events = POLLIN;
 
@@ -596,6 +698,10 @@ back_to_open:
 			ret = join_read_thread(gpkt.value);
 			send_report(cfd, ret);
 			break;
+		case KEY_GET_SIGIO_RESULT:
+			ret = get_sigio_result(gpkt.value);
+			send_report(cfd, ret);
+			break;
 		default:
 			send_report(cfd, -ERANGE);
 			break;