Kernel: Add a new block state for accept() on a blocking socket

Rather than asserting, which really ruins everyone's day.

Kernel/Process.cpp

@@ -2120,8 +2120,13 @@ int Process::sys$accept(int accepting_socket_fd, sockaddr* address, socklen_t* a
         return -ENOTSOCK;
     auto& socket = *accepting_socket_description->socket();
     if (!socket.can_accept()) {
-        ASSERT(!accepting_socket_description->is_blocking());
-        return -EAGAIN;
+        if (accepting_socket_description->is_blocking()) {
+            current->block(Thread::State::BlockedAccept, *accepting_socket_description);
+            if (current->m_was_interrupted_while_blocked)
+                return -EINTR;
+        } else {
+            return -EAGAIN;
+        }
     }
     auto accepted_socket = socket.accept();
     ASSERT(accepted_socket);

Kernel/Scheduler.cpp

@@ -137,6 +137,18 @@ bool Scheduler::pick_next()
             return IterationDecision::Continue;
         }
 
+        if (thread.state() == Thread::BlockedAccept) {
+            auto& description = *thread.m_blocked_description;
+            auto& socket = *description.socket();
+
+            if (socket.can_accept()) {
+                thread.unblock();
+                return IterationDecision::Continue;
+            }
+
+            return IterationDecision::Continue;
+        }
+
         if (thread.state() == Thread::BlockedSelect) {
             if (thread.m_select_has_timeout) {
                 if (now_sec > thread.m_select_timeout.tv_sec || (now_sec == thread.m_select_timeout.tv_sec && now_usec >= thread.m_select_timeout.tv_usec)) {

Kernel/Thread.cpp

@@ -179,6 +179,8 @@ const char* to_string(Thread::State state)
         return "Connect";
     case Thread::BlockedReceive:
         return "Receive";
+    case Thread::BlockedAccept:
+        return "Accepting";
     case Thread::BlockedCondition:
         return "Condition";
     case Thread::__Begin_Blocked_States__:

Kernel/Thread.h

@@ -73,6 +73,7 @@ public:
         BlockedSelect,
         BlockedConnect,
         BlockedReceive,
+        BlockedAccept,
         BlockedCondition,
         __End_Blocked_States__
     };