From b3a1671f1a7bf667d3d51ded95757cbb455ceeb9 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Mon, 20 May 2019 03:44:45 +0200
Subject: [PATCH] Kernel: Add support for recv() with MSG_DONTWAIT.

Passing this flag to recv() temporarily puts the file descriptor into
non-blocking mode.

Also implement LocalSocket::recv() as a simple forwarding to read().
---
 Kernel/Net/LocalSocket.cpp |  4 ++--
 Kernel/Process.cpp         | 12 ++++++++++--
 Kernel/Scheduler.cpp       | 10 +++++++---
 Kernel/UnixTypes.h         |  2 ++
 LibC/sys/socket.h          |  2 ++
 5 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/Kernel/Net/LocalSocket.cpp b/Kernel/Net/LocalSocket.cpp
index 8fa85c3606..c05f977ba5 100644
--- a/Kernel/Net/LocalSocket.cpp
+++ b/Kernel/Net/LocalSocket.cpp
@@ -204,7 +204,7 @@ ssize_t LocalSocket::sendto(FileDescriptor&, const void*, size_t, int, const soc
     ASSERT_NOT_REACHED();
 }
 
-ssize_t LocalSocket::recvfrom(FileDescriptor&, void*, size_t, int flags, sockaddr*, socklen_t*)
+ssize_t LocalSocket::recvfrom(FileDescriptor& descriptor, void* buffer, size_t buffer_size, int, sockaddr*, socklen_t*)
 {
-    ASSERT_NOT_REACHED();
+    return read(descriptor, (byte*)buffer, buffer_size);
 }
diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index bf4e0ed0dc..9866a5d087 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -2213,8 +2213,16 @@ ssize_t Process::sys$recvfrom(const Syscall::SC_recvfrom_params* params)
     if (!descriptor->is_socket())
         return -ENOTSOCK;
     auto& socket = *descriptor->socket();
-    kprintf("recvfrom %p (%u), flags=%u, addr: %p (%p)\n", buffer, buffer_length, flags, addr, addr_length);
-    return socket.recvfrom(*descriptor, buffer, buffer_length, flags, addr, addr_length);
+
+    bool original_blocking = descriptor->is_blocking();
+    if (flags & MSG_DONTWAIT)
+        descriptor->set_blocking(false);
+
+    auto nrecv = socket.recvfrom(*descriptor, buffer, buffer_length, flags, addr, addr_length);
+    if (flags & MSG_DONTWAIT)
+        descriptor->set_blocking(original_blocking);
+
+    return nrecv;
 }
 
 int Process::sys$getsockname(int sockfd, sockaddr* addr, socklen_t* addrlen)
diff --git a/Kernel/Scheduler.cpp b/Kernel/Scheduler.cpp
index 4f6b55e048..98c357e6b1 100644
--- a/Kernel/Scheduler.cpp
+++ b/Kernel/Scheduler.cpp
@@ -223,10 +223,14 @@ bool Scheduler::pick_next()
     });
 
 #ifdef SCHEDULER_DEBUG
-    dbgprintf("Scheduler choices: (runnable threads: %p)\n", g_runnable_threads);
+    dbgprintf("Non-runnables:\n");
+    for (auto* thread = g_nonrunnable_threads->head(); thread; thread = thread->next()) {
+        auto* process = &thread->process();
+        dbgprintf("[K%x] % 12s %s(%u:%u) @ %w:%x\n", process, to_string(thread->state()), process->name().characters(), process->pid(), thread->tid(), thread->tss().cs, thread->tss().eip);
+    }
+
+    dbgprintf("Runnables:\n");
     for (auto* thread = g_runnable_threads->head(); thread; thread = thread->next()) {
-        //if (process->state() == Thread::BlockedWait || process->state() == Thread::BlockedSleep)
-//            continue;
         auto* process = &thread->process();
         dbgprintf("[K%x] % 12s %s(%u:%u) @ %w:%x\n", process, to_string(thread->state()), process->name().characters(), process->pid(), thread->tid(), thread->tss().cs, thread->tss().eip);
     }
diff --git a/Kernel/UnixTypes.h b/Kernel/UnixTypes.h
index ab3669e70b..62ed18d1c6 100644
--- a/Kernel/UnixTypes.h
+++ b/Kernel/UnixTypes.h
@@ -329,6 +329,8 @@ struct pollfd {
 #define SOCK_NONBLOCK 04000
 #define SOCK_CLOEXEC 02000000
 
+#define MSG_DONTWAIT 0x40
+
 #define SOL_SOCKET 1
 
 #define SO_RCVTIMEO 1
diff --git a/LibC/sys/socket.h b/LibC/sys/socket.h
index 4e4f3227bf..06e59e527d 100644
--- a/LibC/sys/socket.h
+++ b/LibC/sys/socket.h
@@ -26,6 +26,8 @@ __BEGIN_DECLS
 #define IPPROTO_TCP 6
 #define IPPROTO_UDP 17
 
+#define MSG_DONTWAIT 0x40
+
 struct sockaddr {
     uint16_t sa_family;
     char sa_data[14];