From a4f6db7ec9199f6313299277655caf6197e4de9b Mon Sep 17 00:00:00 2001
From: J Reece Wilson <me@reece.sx>
Date: Sat, 16 Sep 2023 23:30:10 +0100
Subject: [PATCH] [*] Linux IPC reliability: finally got around to closing #48

---
 Source/IO/IPC/AuIPCPipe.Unix.cpp | 45 +++++++++++++++++++++++++++++---
 Source/IO/IPC/AuIPCPipe.Unix.hpp |  2 ++
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/Source/IO/IPC/AuIPCPipe.Unix.cpp b/Source/IO/IPC/AuIPCPipe.Unix.cpp
index 5fc00c31..181b3a00 100644
--- a/Source/IO/IPC/AuIPCPipe.Unix.cpp
+++ b/Source/IO/IPC/AuIPCPipe.Unix.cpp
@@ -60,7 +60,40 @@ namespace Aurora::IO::IPC
     
     void IPCPipeImpl::DrainOtherFd()
     {
-        // TODO (Reece): urgent
+    #if defined(FIONREAD)
+
+        int available {};
+        if (::ioctl(fds[1], FIONREAD, &available) < 0)
+        {
+            return;
+        }
+        
+        if (!available)
+        {
+            return;
+        }
+
+        AuByteBuffer temp(available);
+        SysAssert(temp);
+        
+        AuUInt uCounter {};
+        while (this->ReadEx({temp, uCounter}, true, false))
+        {
+            temp.writePtr = temp.readPtr = temp.base;
+        }
+
+    #else
+
+        AuByteBuffer temp(4096 * 10);
+        SysAssert(temp);
+
+        AuUInt uCounter {};
+        while (this->ReadEx({temp, uCounter}, true, false))
+        {
+            temp.writePtr = temp.readPtr = temp.base;
+        }
+
+    #endif
     }
 
     AuUInt IPCPipeImpl::GetPreemptFd()
@@ -77,8 +110,7 @@ namespace Aurora::IO::IPC
 
         #if defined(FIONREAD)
             int available {};
-            int res = ::ioctl(fds[0], FIONREAD, &available) ;
-            if (res< 0)
+            if (::ioctl(fds[0], FIONREAD, &available) < 0)
             {
                 return false;
             }
@@ -162,7 +194,12 @@ namespace Aurora::IO::IPC
 
     bool IPCPipeImpl::Read(const Memory::MemoryViewStreamWrite &write, bool nonblock)
     {
-        auto handle = fds[0];
+        return this->ReadEx(write, nonblock, true);   
+    }
+
+    bool IPCPipeImpl::ReadEx(const Memory::MemoryViewStreamWrite &write, bool nonblock, bool bSide)
+    {
+        auto handle = bSide ? fds[0] : fds[1];
         auto control = ::fcntl(handle, F_GETFL);
         auto ref = control;
 
diff --git a/Source/IO/IPC/AuIPCPipe.Unix.hpp b/Source/IO/IPC/AuIPCPipe.Unix.hpp
index b60fe671..0290fcb5 100644
--- a/Source/IO/IPC/AuIPCPipe.Unix.hpp
+++ b/Source/IO/IPC/AuIPCPipe.Unix.hpp
@@ -62,6 +62,8 @@ namespace Aurora::IO::IPC
         virtual bool Write(const Memory::MemoryViewStreamRead &read) override;
         virtual AuString ExportToString() override;
 
+        bool ReadEx(const Memory::MemoryViewStreamWrite &write, bool nonblock, bool bSide);
+        
         bool IsSignaled() override;
         bool WaitOn(AuUInt32 timeout) override;
         Loop::ELoopSource GetType() override;