First pass at detecting ROM file size and not loading ROMs that are too large.

Note that this only works in UNIX for now; still TODO for Windows and ZIP files.
For the TODO, the current code still loads ROMs, but just doesn't ignore large files.

src/emucore/FSNode.cxx

@@ -328,6 +328,12 @@ bool FilesystemNode::rename(const string& newfile)
   return (_realNode && _realNode->exists()) ? _realNode->rename(newfile) : false;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+size_t FilesystemNode::getSize() const
+{
+  return (_realNode && _realNode->exists()) ? _realNode->getSize() : 0;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 size_t FilesystemNode::read(ByteBuffer& buffer, size_t size) const
 {

src/emucore/FSNode.hxx

@@ -243,6 +243,13 @@ class FilesystemNode
      */
     bool rename(const string& newfile);
 
+    /**
+     * Get the size of the current node path.
+     *
+     * @return  Size (in bytes) of the current node path.
+     */
+    size_t getSize() const;
+
     /**
      * Read data (binary format) into the given buffer.
      *
@@ -438,6 +445,13 @@ class AbstractFSNode
      */
     virtual bool rename(const string& newfile) = 0;
 
+    /**
+     * Get the size of the current node path.
+     *
+     * @return  Size (in bytes) of the current node path.
+     */
+    virtual size_t getSize() const { return 0; }
+
     /**
      * Read data (binary format) into the given buffer.
      *

src/emucore/OSystem.cxx

@@ -787,10 +787,22 @@ ByteBuffer OSystem::openROM(const FilesystemNode& rom, size_t& size,
   if(!isValidROM && showErrorMessage)
     throw runtime_error("Unrecognized ROM file type");
 
-  // Next check for a proper file size:
-  //   Streaming ROMs read only a portion of the file
-  //   TODO: Otherwise, cap the size to the maximum Cart size
+  // Next check for a proper file size
+  // Streaming ROMs read only a portion of the file
+  // Otherwise the size to read is 0 (meaning read the entire file)
   const size_t sizeToRead = CartDetector::isProbablyMVC(rom);
+  const bool isStreaming = sizeToRead > 0;
+
+  // Make sure we only read up to the maximum supported cart size
+  const bool isValidSize = isValidROM && (isStreaming ||
+                           rom.getSize() <= Cartridge::maxSize());
+  if(!isValidSize)
+  {
+    if(showErrorMessage)
+      throw runtime_error("ROM file too large");
+    else
+      return nullptr;
+  }
 
   // Now we can try to open the file
   ByteBuffer image;

src/unix/FSNodePOSIX.cxx

@@ -180,6 +180,13 @@ bool FilesystemNodePOSIX::getChildren(AbstractFSList& myList, ListMode mode) con
   return true;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+size_t FilesystemNodePOSIX::getSize() const
+{
+  struct stat st;
+  return (stat(_path.c_str(), &st) == 0) ? st.st_size : 0;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool FilesystemNodePOSIX::makeDir()
 {

src/unix/FSNodePOSIX.hxx

@@ -73,6 +73,7 @@ class FilesystemNodePOSIX : public AbstractFSNode
     bool makeDir() override;
     bool rename(const string& newfile) override;
 
+    size_t getSize() const override;
     bool getChildren(AbstractFSList& list, ListMode mode) const override;
     AbstractFSNodePtr getParent() const override;