From 37a1ebfc27cfb85e1527507722dc580cd5d7855f Mon Sep 17 00:00:00 2001
From: Yury Popov <github@phoenix.dj>
Date: Tue, 28 May 2019 00:25:43 +0300
Subject: [PATCH] Fix process exit handling

---
 src/kernlib/include/list.hpp           |  3 +++
 src/process/include/processmanager.hpp |  3 ++-
 src/process/process.cpp                | 33 ++++++++++++--------------
 src/process/processmanager.cpp         | 10 +++++++-
 4 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/src/kernlib/include/list.hpp b/src/kernlib/include/list.hpp
index 4af3755..c1b3358 100644
--- a/src/kernlib/include/list.hpp
+++ b/src/kernlib/include/list.hpp
@@ -20,6 +20,9 @@ class List {
     }
     return items[count++];
   }
+  void remove(size_t idx) {
+    Memory::copy(items + idx, items + idx + 1, sizeof(Item) * ((--count) - idx));
+  }
 
   void add(const Item &item) { insert() = item; }
 
diff --git a/src/process/include/processmanager.hpp b/src/process/include/processmanager.hpp
index 298451f..9368f20 100644
--- a/src/process/include/processmanager.hpp
+++ b/src/process/include/processmanager.hpp
@@ -29,7 +29,8 @@ class ProcessManager {
   static bool FaultHandler(uint8_t intr, uint32_t code, Interrupts::CallbackRegs *regs);
 
  public:
-  uint64_t RegisterProcess(Process *process);
+  uint64_t registerProcess(Process *process);
+  void exitProcess(Process *process, int code);
   void queueThread(Process *process, Thread *thread);
   void dequeueThread(Thread *thread);
   Process *currentProcess();
diff --git a/src/process/process.cpp b/src/process/process.cpp
index fc033e6..099971b 100644
--- a/src/process/process.cpp
+++ b/src/process/process.cpp
@@ -77,26 +77,22 @@ PTE* Process::addPage(uintptr_t vaddr, void* paddr, uint8_t flags) {
     pagetable = static_cast<PTE*>(Pagetable::alloc());
     addPage(uintptr_t(pagetable), pagetable, 5);
   }
-  PTE pte = pagetable[ptx];
-  if (!pte.present) {
-    pagetable[ptx] = pte = PTE(Pagetable::alloc(), 7);
-    addPage(pte.getUintPtr(), pte.getPtr(), 5);
+  if (!pagetable[ptx].present) {
+    pagetable[ptx] = PTE(Pagetable::alloc(), 7);
+    addPage(pagetable[ptx].getUintPtr(), pagetable[ptx].getPtr(), 5);
   }
-  PTE *pde = pte.getPTE();
-  pte = pde[pdx];
-  if (!pte.present) {
-    pde[pdx] = pte = PTE(Pagetable::alloc(), 7);
-    addPage(pte.getUintPtr(), pte.getPtr(), 5);
+  PTE *pde = pagetable[ptx].getPTE();
+  if (!pde[pdx].present) {
+    pde[pdx] = PTE(Pagetable::alloc(), 7);
+    addPage(pde[pdx].getUintPtr(), pde[pdx].getPtr(), 5);
   }
-  PTE *pdpe = pte.getPTE();
-  pte = pdpe[pdpx];
-  if (!pte.present) {
-    pdpe[pdpx] = pte = PTE(Pagetable::alloc(), 7);
-    addPage(pte.getUintPtr(), pte.getPtr(), 5);
+  PTE *pdpe = pde[pdx].getPTE();
+  if (!pdpe[pdpx].present) {
+    pdpe[pdpx] = PTE(Pagetable::alloc(), 7);
+    addPage(pdpe[pdpx].getUintPtr(), pdpe[pdpx].getPtr(), 5);
   }
-  PTE *pml4e = pte.getPTE();
-  flags |= 1;
-  pml4e[pml4x] = PTE(paddr, flags);
+  PTE *pml4e = pdpe[pdpx].getPTE();
+  pml4e[pml4x] = PTE(paddr, flags | 1);
   return &pml4e[pml4x];
 }
 
@@ -329,7 +325,7 @@ void Process::startup() {
   Thread *thread = new Thread();
   thread->regs.rip = entry;
   thread->regs.rflags = 0;
-  id = (ProcessManager::getManager())->RegisterProcess(this);
+  id = (ProcessManager::getManager())->registerProcess(this);
   addThread(thread, false);
 }
 
@@ -338,6 +334,7 @@ void Process::exit(int code) {
   for (size_t i = 0; i < threads.getCount(); i++) {
     ProcessManager::getManager()->dequeueThread(threads[i]);
   }
+  ProcessManager::getManager()->exitProcess(this, code);
   delete this;
 }
 
diff --git a/src/process/processmanager.cpp b/src/process/processmanager.cpp
index 9c38621..032e4c2 100644
--- a/src/process/processmanager.cpp
+++ b/src/process/processmanager.cpp
@@ -104,7 +104,7 @@ bool ProcessManager::HandleFault(uint8_t intr, uint32_t code, Interrupts::Callba
   return true;
 }
 
-uint64_t ProcessManager::RegisterProcess(Process *process) {
+uint64_t ProcessManager::registerProcess(Process *process) {
   Mutex::CriticalLock lock(processSwitchMutex);
   uint64_t pid = 1;
   for (size_t i = 0; i < processes.getCount(); i++) {
@@ -114,6 +114,14 @@ uint64_t ProcessManager::RegisterProcess(Process *process) {
   return pid;
 }
 
+void ProcessManager::exitProcess(Process *process, int code) {
+  (void)code;  // TODO: handle
+  Mutex::CriticalLock lock(processSwitchMutex);
+  for (size_t i = processes.getCount(); i > 0; i--) {
+    if (processes[i-1] == process) processes.remove(i-1);
+  }
+}
+
 void ProcessManager::queueThread(Process *process, Thread *thread) {
   QueuedThread *q = new QueuedThread();
   q->process = process;