tests/qtest: Use send/recv for socket communication

Socket communication in the libqtest and libqmp codes uses read()
and write() which work on any file descriptor on *nix, and sockets
in *nix are an example of a file descriptor.

However sockets on Windows do not use *nix-style file descriptors,
so read() and write() cannot be used on sockets on Windows.
Switch over to use send() and recv() instead which work on both
Windows and *nix.

Signed-off-by: Xuzhou Cheng <xuzhou.cheng@windriver.com>
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20221028045736.679903-3-bin.meng@windriver.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

include/qemu/sockets.h

@@ -33,6 +33,19 @@ int qemu_socketpair(int domain, int type, int protocol, int sv[2]);
 #endif
 
 int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen);
+/*
+ * A variant of send(2) which handles partial send.
+ *
+ * Return the number of bytes transferred over the socket.
+ * Set errno if fewer than `count' bytes are sent.
+ *
+ * This function don't work with non-blocking socket's.
+ * Any of the possibilities with non-blocking socket's is bad:
+ *   - return a short write (then name is wrong)
+ *   - busy wait adding (errno == EAGAIN) to the loop
+ */
+ssize_t qemu_send_full(int s, const void *buf, size_t count)
+    G_GNUC_WARN_UNUSED_RESULT;
 int socket_set_cork(int fd, int v);
 int socket_set_nodelay(int fd);
 void qemu_socket_set_block(int fd);

tests/qtest/libqmp.c

@@ -23,6 +23,7 @@
 #endif
 
 #include "qemu/cutils.h"
+#include "qemu/sockets.h"
 #include "qapi/error.h"
 #include "qapi/qmp/json-parser.h"
 #include "qapi/qmp/qjson.h"
@@ -36,7 +37,7 @@ typedef struct {
 
 static void socket_send(int fd, const char *buf, size_t size)
 {
-    size_t res = qemu_write_full(fd, buf, size);
+    ssize_t res = qemu_send_full(fd, buf, size);
 
     assert(res == size);
 }
@@ -69,7 +70,7 @@ QDict *qmp_fd_receive(int fd)
         ssize_t len;
         char c;
 
-        len = read(fd, &c, 1);
+        len = recv(fd, &c, 1, 0);
         if (len == -1 && errno == EINTR) {
             continue;
         }

tests/qtest/libqtest.c

@@ -27,6 +27,7 @@
 #include "libqmp.h"
 #include "qemu/ctype.h"
 #include "qemu/cutils.h"
+#include "qemu/sockets.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qjson.h"
 #include "qapi/qmp/qlist.h"
@@ -428,7 +429,7 @@ void qtest_quit(QTestState *s)
 
 static void socket_send(int fd, const char *buf, size_t size)
 {
-    size_t res = qemu_write_full(fd, buf, size);
+    ssize_t res = qemu_send_full(fd, buf, size);
 
     assert(res == size);
 }
@@ -460,7 +461,7 @@ static GString *qtest_client_socket_recv_line(QTestState *s)
         ssize_t len;
         char buffer[1024];
 
-        len = read(s->fd, buffer, sizeof(buffer));
+        len = recv(s->fd, buffer, sizeof(buffer), 0);
         if (len == -1 && errno == EINTR) {
             continue;
         }

util/osdep.c

@@ -502,6 +502,28 @@ int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
     return ret;
 }
 
+ssize_t qemu_send_full(int s, const void *buf, size_t count)
+{
+    ssize_t ret = 0;
+    ssize_t total = 0;
+
+    while (count) {
+        ret = send(s, buf, count, 0);
+        if (ret < 0) {
+            if (errno == EINTR) {
+                continue;
+            }
+            break;
+        }
+
+        count -= ret;
+        buf += ret;
+        total += ret;
+    }
+
+    return total;
+}
+
 void qemu_set_hw_version(const char *version)
 {
     hw_version = version;