auto-test: guest: Cope with EINTR and EAGAIN for read/write/poll

Introduce wrappers for read(), write() and poll() that handle EINTR and
EAGAIN properly. For EINTR, just re-do the operation. For EAGAIN, if
it's a non-blocking port, let the host know about it.

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

1 files changed, 111 insertions, 38 deletions

diff --git a/auto-virtserial-guest.c b/auto-virtserial-guest.c
index 6776874..eebf1f0 100644
--- a/auto-virtserial-guest.c
+++ b/auto-virtserial-guest.c
@@ -45,6 +45,93 @@ static int g_length;
 /* The 'name' field in the sysfs port info */
 static char g_sysfs_name[1024];
 
+
+static ssize_t safewrite(int fd, const void *buf, size_t count)
+{
+	size_t ret, len;
+	int flags;
+	bool nonblock;
+
+	nonblock = false;
+	flags = fcntl(fd, F_GETFL);
+	if (flags > 0 && flags & O_NONBLOCK)
+		nonblock = true;
+
+	len = count;
+	while (len > 0) {
+		ret = write(fd, buf, len);
+		if (ret == -1) {
+			if (errno == EINTR)
+				continue;
+
+			if (errno == EAGAIN) {
+				if (nonblock) {
+					return -EAGAIN;
+				} else {
+					continue;
+				}
+			}
+			return -errno;
+		} else if (ret == 0) {
+			break;
+		} else {
+			buf += ret;
+			len -= ret;
+		}
+	}
+	return count - len;
+}
+
+static ssize_t saferead(int fd, void *buf, size_t count)
+{
+	size_t ret, len;
+	int flags;
+	bool nonblock;
+
+	nonblock = false;
+	flags = fcntl(fd, F_GETFL);
+	if (flags > 0 && flags & O_NONBLOCK)
+		nonblock = true;
+
+	len = count;
+	while (len > 0) {
+		ret = read(fd, buf, len);
+		if (ret == -1) {
+			if (errno == EINTR)
+				continue;
+
+			if (errno == EAGAIN) {
+				if (nonblock) {
+					return -EAGAIN;
+				} else {
+					continue;
+				}
+			}
+			return -errno;
+		} else if (ret == 0) {
+			break;
+		} else {
+			buf += ret;
+			len -= ret;
+		}
+	}
+	return count - len;
+}
+
+static int safepoll(struct pollfd *fds, nfds_t nfds, int timeout)
+{
+	int ret;
+
+	do {
+		ret = poll(fds, nfds, timeout);
+	} while (ret == -1 && errno == EINTR);
+
+	if (ret == -1)
+		ret = -errno;
+
+	return ret;
+}
+
 static char *get_port_dev(unsigned int nr)
 {
 	char *buf;
@@ -77,11 +164,10 @@ static int poll_port(int timeout)
 
 	pollfds[0].fd = g_fd;
 	pollfds[0].events = POLLIN | POLLOUT;
-	ret = poll(pollfds, 1, timeout);
-	if (ret == -1)
-		return -errno;
-	if (ret == 0)
+	ret = safepoll(pollfds, 1, timeout);
+	if (ret <= 0)
 		return ret;
+
 	return pollfds[0].revents;
 }
 
@@ -100,11 +186,8 @@ static int read_port(int nr)
 	buf = malloc(g_length);
 	if (!buf)
 		return -ENOMEM;
-	ret = read(g_fd, buf, g_length);
+	ret = saferead(g_fd, buf, g_length);
 	free(buf);
-	if (ret == -1)
-		ret = -errno;
-
 	return ret;
 }
 
@@ -119,11 +202,8 @@ static int write_port(int nr)
 	buf = malloc(g_length);
 	if (!buf)
 		return -ENOMEM;
-	ret = write(g_fd, buf, g_length);
+	ret = safewrite(g_fd, buf, g_length);
 	free(buf);
-	if (ret == -1)
-		ret = -errno;
-
 	return ret;
 }
 
@@ -191,8 +271,8 @@ static int recv_bytestream(int val)
 	if (!buf)
 		return -ENOMEM;
 
-	while((ret = read(g_fd, buf, g_length))) {
-		ret = write(g_bigfile_fd, buf, ret);
+	while((ret = saferead(g_fd, buf, g_length)) > 0) {
+		ret = safewrite(g_bigfile_fd, buf, ret);
 		if (ret < 0)
 			break;
 	}
@@ -220,12 +300,11 @@ static int send_host_csum(int nr)
 	if (!csum_fd) {
 		return -errno;
 	}
-	ret = read(csum_fd, buf, g_length);
+	ret = saferead(csum_fd, buf, g_length);
 	close(csum_fd);
 
-	ret = write(g_fd, buf, ret);
-	if (ret < 0)
-		ret = -errno;
+	if (ret > 0)
+		ret = safewrite(g_fd, buf, ret);
 	free(buf);
 	return ret;
 }
@@ -247,17 +326,14 @@ static int send_bytestream(int val)
 	if (!buf)
 		return -ENOMEM;
 
-	while((ret = read(g_bigfile_fd, buf, g_length)) > 0) {
-
-		ret = write(g_fd, buf, ret);
+	while((ret = saferead(g_bigfile_fd, buf, g_length)) > 0) {
+		ret = safewrite(g_fd, buf, ret);
 		if (ret < 0)
 			break;
 	}
 	free(buf);
 	close(g_bigfile_fd);
 	close(g_fd);
-	if (ret < 0)
-		ret = -errno;
 	return ret;
 }
 
@@ -280,12 +356,11 @@ static int send_guest_csum(int nr)
 	if (!csum_fd) {
 		return -errno;
 	}
-	ret = read(csum_fd, buf, g_length);
+	ret = saferead(csum_fd, buf, g_length);
 	close(csum_fd);
 
-	ret = write(g_fd, buf, ret);
-	if (ret < 0)
-		ret = -errno;
+	if (ret > 0)
+		ret = safewrite(g_fd, buf, ret);
 	free(buf);
 	return ret;
 }
@@ -300,11 +375,9 @@ static int check_sysfs(int nr)
 	if (fd < 0)
 		return -errno;
 
-	ret = read(fd, g_sysfs_name, 1024);
-	if (ret < 0) {
-		ret = -errno;
+	ret = saferead(fd, g_sysfs_name, 1024);
+	if (ret < 0)
 		goto out_close;
-	}
 	ret = 0;
 
 out_close:
@@ -346,7 +419,7 @@ static void send_report(int cfd, int ret)
 
 	gpkt.key = KEY_RESULT;
 	gpkt.value = ret;
-	write(cfd, &gpkt, sizeof(gpkt));
+	safewrite(cfd, &gpkt, sizeof(gpkt));
 }
 
 int main(int argc, char *argv[])
@@ -375,22 +448,22 @@ back_to_open:
 
 	gpkt.key = KEY_STATUS_OK;
 	gpkt.value = 1;
-	ret = write(cfd, &gpkt, sizeof(gpkt));
-	if (ret == -1)
-		error(errno, errno, "write control port");
+	ret = safewrite(cfd, &gpkt, sizeof(gpkt));
+	if (ret < 0)
+		error(-ret, -ret, "write control port");
 
 	pollfd[0].fd = cfd;
 	pollfd[0].events = POLLIN;
 
 	while (1) {
-		ret = poll(pollfd, 1, -1);
-		if (ret == -1)
+		ret = safepoll(pollfd, 1, -1);
+		if (ret < 0)
 			error(errno, errno, "poll");
 
 		if (!(pollfd[0].revents & POLLIN))
 			continue;
 
-		ret = read(cfd, &gpkt, sizeof(gpkt));
+		ret = saferead(cfd, &gpkt, sizeof(gpkt));
 		if (ret < sizeof(gpkt)) {
 			/*
 			 * Out of sync with host. Close port and start over.