From 1b4079536d15df78c592e0a491104fa0e7ed17b5 Mon Sep 17 00:00:00 2001
From: Ted John <ted@brambles.org>
Date: Tue, 28 Jun 2016 21:16:09 +0100
Subject: [PATCH] try to read objects with bad image tables

---
 src/core/FileStream.hpp   | 19 ++++++++++++++++---
 src/core/IStream.hpp      |  2 ++
 src/core/MemoryStream.cpp |  8 ++++++++
 src/core/MemoryStream.h   |  2 ++
 src/object/ImageTable.cpp | 14 +++++++++++++-
 5 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/src/core/FileStream.hpp b/src/core/FileStream.hpp
index 9a0bca777d..4716222a79 100644
--- a/src/core/FileStream.hpp
+++ b/src/core/FileStream.hpp
@@ -37,6 +37,7 @@ private:
     bool        _canRead;
     bool        _canWrite;
     bool        _disposed;
+    uint64      _fileSize;
 
 public:
     FileStream(const utf8 * path, int fileMode)
@@ -64,6 +65,7 @@ public:
         }
 
         _disposed = false;
+        _fileSize = SDL_RWsize(_file);
     }
 
     ~FileStream()
@@ -78,7 +80,7 @@ public:
     bool CanRead()  const override { return _canRead;  }
     bool CanWrite() const override { return _canWrite; }
 
-    uint64 GetLength()   const override { return SDL_RWsize(_file); }
+    uint64 GetLength()   const override { return _fileSize; }
     uint64 GetPosition() const override { return SDL_RWtell(_file); }
 
     void SetPosition(uint64 position) override
@@ -103,10 +105,15 @@ public:
 
     void Read(void * buffer, uint64 length) override
     {
-        if (SDL_RWread(_file, buffer, (size_t)length, 1) != 1)
+        uint64 remainingBytes = GetLength() - GetPosition();
+        if (length <= remainingBytes)
         {
-            throw IOException("Attempted to read past end of file.");
+            if (SDL_RWread(_file, buffer, (size_t)length, 1) == 1)
+            {
+                return;
+            }
         }
+        throw IOException("Attempted to read past end of file.");
     }
 
     void Write(const void * buffer, uint64 length) override
@@ -116,4 +123,10 @@ public:
             throw IOException("Unable to write to file.");
         }
     }
+
+    uint64 TryRead(void * buffer, uint64 length) override
+    {
+        size_t readBytes = SDL_RWread(_file, buffer, 1, (size_t)length);
+        return readBytes;
+    }
 };
diff --git a/src/core/IStream.hpp b/src/core/IStream.hpp
index 697cadfe75..4bf2e3e878 100644
--- a/src/core/IStream.hpp
+++ b/src/core/IStream.hpp
@@ -47,6 +47,8 @@ interface IStream
     virtual void    Read(void * buffer, uint64 length)              abstract;
     virtual void    Write(const void * buffer, uint64 length)       abstract;
 
+    virtual uint64  TryRead(void * buffer, uint64 length)           abstract;
+
     ///////////////////////////////////////////////////////////////////////////
     // Helper methods
     ///////////////////////////////////////////////////////////////////////////
diff --git a/src/core/MemoryStream.cpp b/src/core/MemoryStream.cpp
index cf3855938b..35364fab0f 100644
--- a/src/core/MemoryStream.cpp
+++ b/src/core/MemoryStream.cpp
@@ -149,6 +149,14 @@ void MemoryStream::Read(void * buffer, uint64 length)
     _position = (void*)((uintptr_t)_position + length);
 }
 
+uint64 MemoryStream::TryRead(void * buffer, uint64 length)
+{
+    uint64 remainingBytes = GetLength() - GetPosition();
+    uint64 bytesToRead = Math::Min(length, remainingBytes);
+    Read(buffer, bytesToRead);
+    return bytesToRead;
+}
+
 void MemoryStream::Write(const void * buffer, uint64 length)
 {
     uint64 position = GetPosition();
diff --git a/src/core/MemoryStream.h b/src/core/MemoryStream.h
index c7a2a0763b..82a2fcfe5e 100644
--- a/src/core/MemoryStream.h
+++ b/src/core/MemoryStream.h
@@ -63,6 +63,8 @@ public:
     void    Read(void * buffer, uint64 length)              override;
     void    Write(const void * buffer, uint64 length)       override;
 
+    uint64  TryRead(void * buffer, uint64 length)           override;
+
 private:
     void EnsureCapacity(size_t capacity);
 };
diff --git a/src/object/ImageTable.cpp b/src/object/ImageTable.cpp
index ebd877dbd7..1b4ec16fa8 100644
--- a/src/object/ImageTable.cpp
+++ b/src/object/ImageTable.cpp
@@ -14,6 +14,7 @@
  *****************************************************************************/
 #pragma endregion
 
+#include "../core/Console.hpp"
 #include "../core/IStream.hpp"
 #include "../core/Memory.hpp"
 #include "ImageTable.h"
@@ -53,5 +54,16 @@ void ImageTable::Read(IStream * stream)
     }
 
     // Read g1 element data
-    stream->Read(_data, _dataSize);
+    size_t readBytes = (size_t)stream->TryRead(_data, _dataSize);
+
+    // If data is shorter than expected (some custom objects are unfortunately like that)
+    size_t unreadBytes = _dataSize - readBytes;
+    if (unreadBytes > 0)
+    {
+        void * ptr = (void*)(((uintptr_t)_data) + readBytes);
+        Memory::Set(ptr, 0, unreadBytes);
+
+        Console::Error::WriteFormat("Warning: Image table size shorter than expected.");
+        Console::Error::WriteLine();
+    }
 }