Lots of hacking to make a very simple "ls" utility.

I added a dead-simple malloc that only allows allocations < 4096 bytes.
It just forwards the request to mmap() every time.

I also added simplified versions of opendir() and readdir().

AK/BufferStream.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include "ByteBuffer.h"
+
+namespace AK {
+
+class BufferStream {
+public:
+    explicit BufferStream(ByteBuffer& buffer)
+        : m_buffer(buffer)
+    {
+    }
+
+    void operator<<(byte value)
+    {
+        m_buffer[m_offset++] = value & 0xffu;
+    }
+
+    void operator<<(word value)
+    {
+        m_buffer[m_offset++] = value & 0xffu;
+        m_buffer[m_offset++] = (byte)(value >> 8) & 0xffu;
+    }
+
+    void operator<<(dword value)
+    {
+        m_buffer[m_offset++] = value & 0xffu;
+        m_buffer[m_offset++] = (byte)(value >> 8) & 0xffu;
+        m_buffer[m_offset++] = (byte)(value >> 16) & 0xffu;
+        m_buffer[m_offset++] = (byte)(value >> 24) & 0xffu;
+    }
+
+    void operator<<(const String& value)
+    {
+        for (unsigned i = 0; i < value.length(); ++i)
+            m_buffer[m_offset++] = value[i];
+    }
+
+    void fillToEnd(byte ch)
+    {
+        while (m_offset < m_buffer.size())
+            m_buffer[m_offset++] = ch;
+    }
+
+    Unix::size_t offset() const { return m_offset; }
+
+private:
+    ByteBuffer& m_buffer;
+    Unix::size_t m_offset { 0 };
+};
+
+}
+
+using AK::BufferStream;