From 0f037167c450edd55769eddbf113244082f54a1b Mon Sep 17 00:00:00 2001
From: JJ Roberts-White <computerfido@gmail.com>
Date: Fri, 22 Oct 2021 09:24:39 +1100
Subject: [PATCH] Kernel: Properly destroy PTYs after master is closed. Ensure
 signal stack alignment.

---
 Kernel/include/TTY/PTY.h          |  4 ++++
 Kernel/src/Arch/x86_64/Thread.cpp |  3 ++-
 Kernel/src/CharacterBuffer.cpp    |  6 ++++++
 Kernel/src/Device.cpp             | 20 +++++---------------
 Kernel/src/TTY/PTMX.cpp           | 12 ++++++++++++
 Kernel/src/TTY/PTY.cpp            | 25 +++++++++++++++++++++++++
 6 files changed, 54 insertions(+), 16 deletions(-)

diff --git a/Kernel/include/TTY/PTY.h b/Kernel/include/TTY/PTY.h
index 8f2eb391..a1a8cff6 100755
--- a/Kernel/include/TTY/PTY.h
+++ b/Kernel/include/TTY/PTY.h
@@ -38,6 +38,7 @@ class PTMultiplexor final : public Device {
     static inline PTMultiplexor& Instance() { return *m_instance; }
 
     UNIXFileDescriptor* Open(size_t flags) override;
+    void DestroyPTY(PTY* pt);
 
 private:
     static PTMultiplexor* m_instance;
@@ -58,6 +59,8 @@ class PTYDevice : public FsNode {
 
     PTYDevice();
 
+    void Close() override;
+
     ssize_t Read(size_t, size_t, uint8_t *) override;
     ssize_t Write(size_t, size_t, uint8_t *) override;
     int Ioctl(uint64_t cmd, uint64_t arg) override;
@@ -83,6 +86,7 @@ class PTY{
     termios tios;
 
     PTY(int id);
+    ~PTY();
 
     inline int GetID() const { return m_id; }
 
diff --git a/Kernel/src/Arch/x86_64/Thread.cpp b/Kernel/src/Arch/x86_64/Thread.cpp
index 4c2f33e3..c58bc897 100644
--- a/Kernel/src/Arch/x86_64/Thread.cpp
+++ b/Kernel/src/Arch/x86_64/Thread.cpp
@@ -163,7 +163,8 @@ void Thread::HandlePendingSignal(RegisterContext* regs) {
     //uint64_t* stack = reinterpret_cast<uint64_t*>(regs->rsp - sizeof(ucontext_t));
     //ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(stack);
 
-    uint64_t* stack = reinterpret_cast<uint64_t*>(regs->rsp - sizeof(RegisterContext));
+    // Ensure stack alignment
+    uint64_t* stack = reinterpret_cast<uint64_t*>((regs->rsp & (~0xfULL)) - sizeof(RegisterContext));
     *reinterpret_cast<RegisterContext*>(stack) = *regs;
 
     *(--stack) = oldSignalMask;
diff --git a/Kernel/src/CharacterBuffer.cpp b/Kernel/src/CharacterBuffer.cpp
index b8aa230a..1cc48c8d 100755
--- a/Kernel/src/CharacterBuffer.cpp
+++ b/Kernel/src/CharacterBuffer.cpp
@@ -12,6 +12,12 @@ CharacterBuffer::CharacterBuffer() {
     lines = 0;
 }
 
+CharacterBuffer::~CharacterBuffer() {
+    if(buffer){
+        delete buffer;
+    }
+}
+
 ssize_t CharacterBuffer::Write(char* _buffer, size_t size) {
     if (bufferPos + size > maxBufferSize) {
         size = maxBufferSize - bufferPos;
diff --git a/Kernel/src/Device.cpp b/Kernel/src/Device.cpp
index 76de35c0..6e930900 100644
--- a/Kernel/src/Device.cpp
+++ b/Kernel/src/Device.cpp
@@ -44,8 +44,7 @@ class TTY : public Device {
         SetDeviceName("Process Terminal");
     }
 
-    ssize_t Read(size_t, size_t, uint8_t*);
-    ssize_t Write(size_t, size_t, uint8_t*);
+    UNIXFileDescriptor* Open(size_t flags) override;
 };
 
 int Device::nextUnnamedDeviceNumber = 0;
@@ -131,23 +130,14 @@ ssize_t URandom::Read(size_t offset, size_t size, uint8_t* buffer) {
 
 ssize_t URandom::Write(size_t offset, size_t size, uint8_t* buffer) { return size; }
 
-
-ssize_t TTY::Read(size_t offset, size_t size, uint8_t* buffer) {
-    auto stdin = Scheduler::GetCurrentProcess()->GetFileDescriptor(0);
-
-    if(stdin && stdin->node){
-        return fs::Read(stdin->node, offset, size, buffer);
-    }
-    return -EBADF;
-}
-
-ssize_t TTY::Write(size_t offset, size_t size, uint8_t* buffer) {
+UNIXFileDescriptor* TTY::Open(size_t flags){
     auto stdout = Scheduler::GetCurrentProcess()->GetFileDescriptor(1);
 
     if(stdout && stdout->node){
-        return fs::Write(stdout->node, offset, size, buffer);
+        return stdout->node->Open(flags);
     }
-    return -EBADF;
+
+    return nullptr;
 }
 
 Null null = Null("null");
diff --git a/Kernel/src/TTY/PTMX.cpp b/Kernel/src/TTY/PTMX.cpp
index 213b9b34..ca46c52b 100644
--- a/Kernel/src/TTY/PTMX.cpp
+++ b/Kernel/src/TTY/PTMX.cpp
@@ -66,3 +66,15 @@ UNIXFileDescriptor* PTMultiplexor::Open(size_t flags){
 
     return pty->masterFile.Open(flags);
 }
+
+void PTMultiplexor::DestroyPTY(PTY* pt){
+    ScopedSpinLock lock(m_ptmxLock);
+    for(auto it = m_ptList.begin(); it != m_ptList.end(); it++) {
+        if(*it == pt){
+            m_ptList.remove(pt);
+            delete pt;
+
+            return;
+        }
+    }
+}
diff --git a/Kernel/src/TTY/PTY.cpp b/Kernel/src/TTY/PTY.cpp
index 23a50ccc..5fce5b8f 100755
--- a/Kernel/src/TTY/PTY.cpp
+++ b/Kernel/src/TTY/PTY.cpp
@@ -27,6 +27,14 @@ PTYDevice::PTYDevice() {
 
 }
 
+void PTYDevice::Close() {
+    handleCount--;
+
+    if(handleCount == 0 && device == PTYMasterDevice){
+        PTMultiplexor::Instance().DestroyPTY(pty);
+    }
+}
+
 ssize_t PTYDevice::Read(size_t offset, size_t size, uint8_t* buffer) {
     assert(pty);
     assert(device == PTYSlaveDevice || device == PTYMasterDevice);
@@ -99,6 +107,13 @@ int PTYDevice::Ioctl(uint64_t cmd, uint64_t arg) {
     assert(pty);
 
     switch (cmd) {
+    case TCGETS:
+        *((termios*)arg) = pty->tios;
+        break;
+    case TCSETS:
+        pty->tios = *((termios*)arg);
+        pty->slave.ignoreBackspace = !pty->IsCanonical();
+        break;
     case TIOCGWINSZ:
         *((winsz*)arg) = pty->wSz;
         break;
@@ -187,6 +202,16 @@ PTY::PTY(int id) : m_id(id) {
         tios.c_cc[i] = c_cc_default[i];
 }
 
+PTY::~PTY(){
+    while (m_watchingSlave.get_length()) {
+        m_watchingSlave.remove_at(0)->Signal(); // Signal all watching
+    }
+
+    while (m_watchingMaster.get_length()) {
+        m_watchingMaster.remove_at(0)->Signal(); // Signal all watching
+    }
+}
+
 ssize_t PTY::MasterRead(char* buffer, size_t count) { return master.Read(buffer, count); }
 
 ssize_t PTY::SlaveRead(char* buffer, size_t count) {