[v2,1/2] Add test-listen - a stress test for QEMU socket listen

diff --git a/tests/Makefile.include b/tests/Makefile.include
index f42f3df..a492285 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -127,6 +127,7 @@  check-unit-y += tests/test-bufferiszero$(EXESUF)
 gcov-files-check-bufferiszero-y = util/bufferiszero.c
 check-unit-y += tests/test-uuid$(EXESUF)
 check-unit-y += tests/ptimer-test$(EXESUF)
+#check-unit-y += tests/test-listen$(EXESUF)
 gcov-files-ptimer-test-y = hw/core/ptimer.c
 check-unit-y += tests/test-qapi-util$(EXESUF)
 gcov-files-test-qapi-util-y = qapi/qapi-util.c
@@ -760,6 +761,7 @@  tests/test-uuid$(EXESUF): tests/test-uuid.o $(test-util-obj-y)
 tests/test-arm-mptimer$(EXESUF): tests/test-arm-mptimer.o
 tests/test-qapi-util$(EXESUF): tests/test-qapi-util.o $(test-util-obj-y)
 tests/numa-test$(EXESUF): tests/numa-test.o
+tests/test-listen$(EXESUF): tests/test-listen.o $(test-util-obj-y)
 
 tests/migration/stress$(EXESUF): tests/migration/stress.o
 	$(call quiet-command, $(LINKPROG) -static -O3 $(PTHREAD_LIB) -o $@ $< ,"LINK","$(TARGET_DIR)$@")
diff --git a/tests/test-listen.c b/tests/test-listen.c
new file mode 100644
index 0000000..45fe9a8
--- /dev/null
+++ b/tests/test-listen.c
@@ -0,0 +1,141 @@ 
+/*
+ * Test parallel port listen configuration with
+ * dynamic port allocation
+ */
+
+#include "qemu/osdep.h"
+#include "libqtest.h"
+#include "qemu-common.h"
+#include "qemu/thread.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+
+#define NAME_LEN 1024
+#define PORT_LEN 16
+
+struct thr_info {
+    QemuThread thread;
+    int to_port;
+    int got_port;
+    int eno;
+    int fd;
+    const char *errstr;
+};
+
+static char hostname[NAME_LEN + 1];
+static char port[PORT_LEN + 1];
+
+static void *listener_thread(void *arg)
+{
+    struct thr_info *thr = (struct thr_info *)arg;
+    SocketAddress addr = {
+        .type = SOCKET_ADDRESS_TYPE_INET,
+        .u = {
+            .inet = {
+                .host = hostname,
+                .port = port,
+                .ipv4 = true,
+                .has_to = true,
+                .to = thr->to_port,
+            },
+        },
+    };
+    Error *err = NULL;
+    int fd;
+
+    fd = socket_listen(&addr, &err);
+    if (fd < 0) {
+        thr->eno = errno;
+        thr->errstr = error_get_pretty(err);
+    } else {
+        struct sockaddr_in a;
+        socklen_t a_len = sizeof(a);
+        g_assert_cmpint(getsockname(fd, (struct sockaddr *)&a, &a_len), ==, 0);
+        thr->got_port = ntohs(a.sin_port);
+        thr->fd = fd;
+    }
+    return arg;
+}
+
+
+static void listen_compete_nthr(bool threaded, int nthreads,
+                                int start_port, int max_offset)
+{
+    int i;
+    int failed_listens = 0;
+    size_t alloc_sz = sizeof(struct thr_info) * nthreads;
+    struct thr_info *thr = g_malloc(alloc_sz);
+    int used[max_offset + 1];
+    memset(used, 0, sizeof(used));
+    g_assert_nonnull(thr);
+    g_assert_cmpint(gethostname(hostname, NAME_LEN), == , 0);
+    snprintf(port, PORT_LEN, "%d", start_port);
+    memset(thr, 0, alloc_sz);
+
+    for (i = 0; i < nthreads; i++) {
+        thr[i].to_port = start_port + max_offset;
+        if (threaded) {
+            qemu_thread_create(&thr[i].thread, "listener",
+                               listener_thread, &thr[i],
+                               QEMU_THREAD_JOINABLE);
+        } else {
+            listener_thread(&thr[i]);
+        }
+    }
+
+    if (threaded) {
+        for (i = 0; i < nthreads; i++) {
+            qemu_thread_join(&thr[i].thread);
+        }
+    }
+    for (i = 0; i < nthreads; i++) {
+        if (thr[i].got_port) {
+            closesocket(thr[i].fd);
+        }
+    }
+
+    for (i = 0; i < nthreads; i++) {
+        if (thr[i].eno != 0) {
+            const char *m;
+            printf("** Failed to assign a port to thread %d (errno = %d)\n",
+                   i, thr[i].eno);
+            /* This is what we are interested in capturing -
+             * catch and report details if something unexpected happens:
+             */
+            m = strstr(thr[i].errstr, "Failed to listen on socket");
+            if (m != NULL) {
+                g_assert_cmpstr(thr[i].errstr, ==,
+                    "Failed to listen on socket: Address already in use");
+            }
+            failed_listens++;
+        } else {
+            int assigned_port = thr[i].got_port;
+            g_assert_cmpint(assigned_port, <= , thr[i].to_port);
+            g_assert_cmpint(used[assigned_port - start_port], == , 0);
+        }
+    }
+    g_assert_cmpint(failed_listens, ==, 0);
+    free(thr);
+}
+
+
+static void listen_compete(void)
+{
+    listen_compete_nthr(true, 200, 5920, 300);
+}
+
+static void listen_serial(void)
+{
+    listen_compete_nthr(false, 200, 6300, 300);
+}
+
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+
+    g_test_add_func("/socket/listen-serial", listen_serial);
+    g_test_add_func("/socket/listen-compete", listen_compete);
+
+    return g_test_run();
+}