Add sys$ttyname_r and ttyname_r() + ttyname().

And print a greeting when sh starts up so we know which TTY we're on.

VirtualFileSystem/CharacterDevice.h

@@ -18,6 +18,8 @@ public:
     unsigned major() const { return m_major; }
     unsigned minor() const { return m_minor; }
 
+    virtual bool isTTY() const { return false; }
+
 protected:
     CharacterDevice(unsigned major, unsigned minor) : m_major(major), m_minor(minor) { }
 

VirtualFileSystem/FileHandle.cpp

@@ -3,6 +3,7 @@
 #include "CharacterDevice.h"
 #include "sys-errno.h"
 #include "UnixTypes.h"
+#include "TTY.h"
 #include <AK/BufferStream.h>
 
 FileHandle::FileHandle(RetainPtr<VirtualFileSystem::Node>&& vnode)
@@ -109,6 +110,7 @@ Unix::ssize_t FileHandle::write(const byte* data, Unix::size_t size)
     }
     // FIXME: Implement non-device writes.
     ASSERT_NOT_REACHED();
+    return -1;
 }
 
 bool FileHandle::hasDataAvailableForRead()
@@ -160,3 +162,17 @@ ssize_t FileHandle::get_dir_entries(byte* buffer, Unix::size_t size)
     memcpy(buffer, tempBuffer.pointer(), stream.offset());
     return stream.offset();
 }
+
+bool FileHandle::isTTY() const
+{
+    if (auto* device = m_vnode->characterDevice())
+        return device->isTTY();
+    return false;
+}
+
+const TTY* FileHandle::tty() const
+{
+    if (auto* device = m_vnode->characterDevice())
+        return static_cast<const TTY*>(device);
+    return nullptr;
+}

VirtualFileSystem/FileHandle.h

@@ -4,6 +4,8 @@
 #include "InodeMetadata.h"
 #include <AK/ByteBuffer.h>
 
+class TTY;
+
 class FileHandle {
 public:
     explicit FileHandle(RetainPtr<VirtualFileSystem::Node>&&);
@@ -24,6 +26,9 @@ public:
 
     bool isDirectory() const;
 
+    bool isTTY() const;
+    const TTY* tty() const;
+
     InodeMetadata metadata() const { return m_vnode->metadata(); }
 
     VirtualFileSystem::Node* vnode() { return m_vnode.ptr(); }

VirtualFileSystem/VirtualFileSystem.h

@@ -55,6 +55,7 @@ public:
 
         bool isCharacterDevice() const { return m_characterDevice; }
         CharacterDevice* characterDevice() { return m_characterDevice; }
+        const CharacterDevice* characterDevice() const { return m_characterDevice; }
 
         void retain();
         void release();