From 4330cdee74c86a383055d788de43fd4ae2bd7bc2 Mon Sep 17 00:00:00 2001
From: Dan Klishch <danilklishch@gmail.com>
Date: Mon, 29 Jan 2024 19:48:51 -0500
Subject: [PATCH] Tests/Kernel: Properly synchronize threads in TestTCPSocket

We should wait for a server thread to actually listen(2) a server socket
before trying to connect to it. This hopefully should make the test less
flaky.
---
 Tests/Kernel/TestTCPSocket.cpp | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/Tests/Kernel/TestTCPSocket.cpp b/Tests/Kernel/TestTCPSocket.cpp
index fcabcd1504..3451033c50 100644
--- a/Tests/Kernel/TestTCPSocket.cpp
+++ b/Tests/Kernel/TestTCPSocket.cpp
@@ -9,11 +9,12 @@
 #include <LibTest/TestCase.h>
 #include <netinet/in.h>
 #include <pthread.h>
+#include <semaphore.h>
 #include <sys/socket.h>
 
 static constexpr u16 port = 1337;
 
-static void* server_handler(void*)
+static void* server_handler(void* accept_semaphore)
 {
     int server_fd = socket(AF_INET, SOCK_STREAM, 0);
     EXPECT(server_fd >= 0);
@@ -28,6 +29,9 @@ static void* server_handler(void*)
     rc = listen(server_fd, 1);
     EXPECT_EQ(rc, 0);
 
+    rc = sem_post(reinterpret_cast<sem_t*>(accept_semaphore));
+    VERIFY(rc == 0);
+
     int client_fd = accept(server_fd, nullptr, nullptr);
     EXPECT(client_fd >= 0);
 
@@ -49,8 +53,16 @@ static void* server_handler(void*)
 static pthread_t start_tcp_server()
 {
     pthread_t thread;
-    int rc = pthread_create(&thread, nullptr, server_handler, nullptr);
-    EXPECT_EQ(rc, 0);
+    sem_t accept_semaphore;
+
+    int rc = sem_init(&accept_semaphore, 0, 0);
+    VERIFY(rc == 0);
+    rc = pthread_create(&thread, nullptr, server_handler, &accept_semaphore);
+    VERIFY(rc == 0);
+    rc = sem_wait(&accept_semaphore);
+    VERIFY(rc == 0);
+    rc = sem_destroy(&accept_semaphore);
+    VERIFY(rc == 0);
     return thread;
 }