Merge branch 'SmallAllocationFixInFBXLoader' of https://github.com/FlorianBorn71/assimp into FlorianBorn71-SmallAllocationFixInFBXLoader

code/AssetLib/FBX/FBXBinaryTokenizer.cpp

@@ -341,8 +341,7 @@ void ReadData(const char*& sbegin_out, const char*& send_out, const char* input,
 
 
 // ------------------------------------------------------------------------------------------------
-bool ReadScope(TokenList& output_tokens, const char* input, const char*& cursor, const char* end, bool const is64bits)
+bool ReadScope(TokenList &output_tokens, StackAllocator &token_allocator, const char *input, const char *&cursor, const char *end, bool const is64bits) {
-{
     // the first word contains the offset at which this block ends
 	const uint64_t end_offset = is64bits ? ReadDoubleWord(input, cursor, end) : ReadWord(input, cursor, end);
 
@@ -408,7 +407,7 @@ bool ReadScope(TokenList& output_tokens, const char* input, const char*& cursor,
 
         // XXX this is vulnerable to stack overflowing ..
         while(Offset(input, cursor) < end_offset - sentinel_block_length) {
-			ReadScope(output_tokens, input, cursor, input + end_offset - sentinel_block_length, is64bits);
+            ReadScope(output_tokens, token_allocator, input, cursor, input + end_offset - sentinel_block_length, is64bits);
         }
         output_tokens.push_back(new_Token(cursor, cursor + 1, TokenType_CLOSE_BRACKET, Offset(input, cursor) ));
 
@@ -431,8 +430,7 @@ bool ReadScope(TokenList& output_tokens, const char* input, const char*& cursor,
 
 // ------------------------------------------------------------------------------------------------
 // TODO: Test FBX Binary files newer than the 7500 version to check if the 64 bits address behaviour is consistent
-void TokenizeBinary(TokenList& output_tokens, const char* input, size_t length)
+void TokenizeBinary(TokenList &output_tokens, const char *input, size_t length, StackAllocator &token_allocator) {
-{
 	ai_assert(input);
 	ASSIMP_LOG_DEBUG("Tokenizing binary FBX file");
 
@@ -465,7 +463,7 @@ void TokenizeBinary(TokenList& output_tokens, const char* input, size_t length)
     try
     {
         while (cursor < end ) {
-		    if (!ReadScope(output_tokens, input, cursor, input + length, is64bits)) {
+            if (!ReadScope(output_tokens, token_allocator, input, cursor, input + length, is64bits)) {
                 break;
             }
         }

code/AssetLib/FBX/FBXDocument.cpp

@@ -243,7 +243,7 @@ FileGlobalSettings::FileGlobalSettings(const Document &doc, std::shared_ptr<cons
 }
 
 // ------------------------------------------------------------------------------------------------
-Document::Document(const Parser& parser, const ImportSettings& settings) :
+Document::Document(Parser& parser, const ImportSettings& settings) :
      settings(settings), parser(parser) {
 	ASSIMP_LOG_DEBUG("Creating FBX Document");
 
@@ -265,13 +265,17 @@ Document::Document(const Parser& parser, const ImportSettings& settings) :
 }
 
 // ------------------------------------------------------------------------------------------------
-Document::~Document() {
+Document::~Document()
-    for(ObjectMap::value_type& v : objects) {
+{
-        delete v.second;
+	// The document does not own the memory for the following objects, but we need to call their d'tor
+	// so they can properly free memory like string members:
+	
+    for (ObjectMap::value_type &v : objects) {
+        delete_LazyObject(v.second);
     }
 
-    for(ConnectionMap::value_type& v : src_connections) {
+    for (ConnectionMap::value_type &v : src_connections) {
-        delete v.second;
+        delete_Connection(v.second);
     }
     // |dest_connections| contain the same Connection objects as the |src_connections|
 }
@@ -356,9 +360,11 @@ void Document::ReadObjects() {
         DOMError("no Objects dictionary found");
     }
 
+    StackAllocator &allocator = parser.GetAllocator();
+
     // add a dummy entry to represent the Model::RootNode object (id 0),
     // which is only indirectly defined in the input file
-    objects[0] = new LazyObject(0L, *eobjects, *this);
+    objects[0] = new_LazyObject(0L, *eobjects, *this);
 
     const Scope& sobjects = *eobjects->Compound();
     for(const ElementMap::value_type& el : sobjects.Elements()) {
@@ -387,7 +393,7 @@ void Document::ReadObjects() {
             delete foundObject->second;
         }
 
-        objects[id] = new LazyObject(id, *el.second, *this);
+        objects[id] = new_LazyObject(id, *el.second, *this);
 
         // grab all animation stacks upfront since there is no listing of them
         if(!strcmp(el.first.c_str(),"AnimationStack")) {
@@ -454,8 +460,10 @@ void Document::ReadPropertyTemplates() {
 }
 
 // ------------------------------------------------------------------------------------------------
-void Document::ReadConnections() {
+void Document::ReadConnections()
-    const Scope& sc = parser.GetRootScope();
+{
+    StackAllocator &allocator = parser.GetAllocator();
+    const Scope &sc = parser.GetRootScope();
     // read property templates from "Definitions" section
     const Element* const econns = sc["Connections"];
     if(!econns || !econns->Compound()) {
@@ -494,7 +502,7 @@ void Document::ReadConnections() {
         }
 
         // add new connection
-        const Connection* const c = new Connection(insertionOrder++,src,dest,prop,*this);
+        const Connection* const c = new_Connection(insertionOrder++,src,dest,prop,*this);
         src_connections.insert(ConnectionMap::value_type(src,c));
         dest_connections.insert(ConnectionMap::value_type(dest,c));
     }

code/AssetLib/FBX/FBXDocument.h

@@ -81,6 +81,10 @@ class BlendShape;
 class Skin;
 class Cluster;
 
+#define new_LazyObject new (allocator.Allocate(sizeof(LazyObject))) LazyObject
+#define new_Connection new (allocator.Allocate(sizeof(Connection))) Connection
+#define delete_LazyObject(_p) (_p)->~LazyObject()
+#define delete_Connection(_p) (_p)->~Connection()
 
 /** Represents a delay-parsed FBX objects. Many objects in the scene
  *  are not needed by assimp, so it makes no sense to parse them
@@ -1073,7 +1077,7 @@ private:
 /** DOM root for a FBX file */
 class Document {
 public:
-    Document(const Parser& parser, const ImportSettings& settings);
+    Document(Parser& parser, const ImportSettings& settings);
 
     ~Document();
 
@@ -1157,7 +1161,7 @@ private:
     const ImportSettings& settings;
 
     ObjectMap objects;
-    const Parser& parser;
+    Parser& parser;
 
     PropertyTemplateMap templates;
     ConnectionMap src_connections;

code/AssetLib/FBX/FBXImporter.cpp

@@ -152,19 +152,19 @@ void FBXImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 	// broad-phase tokenized pass in which we identify the core
 	// syntax elements of FBX (brackets, commas, key:value mappings)
 	TokenList tokens;
-	try {
+    Assimp::StackAllocator tempAllocator;
-
+    try {
 		bool is_binary = false;
 		if (!strncmp(begin, "Kaydara FBX Binary", 18)) {
 			is_binary = true;
-			TokenizeBinary(tokens, begin, contents.size());
+            TokenizeBinary(tokens, begin, contents.size(), tempAllocator);
 		} else {
-			Tokenize(tokens, begin);
+            Tokenize(tokens, begin, tempAllocator);
 		}
 
 		// use this information to construct a very rudimentary
 		// parse-tree representing the FBX scope structure
-		Parser parser(tokens, is_binary);
+        Parser parser(tokens, tempAllocator, is_binary);
 
 		// take the raw parse-tree and convert it to a FBX DOM
 		Document doc(parser, mSettings);
@@ -183,10 +183,12 @@ void FBXImporter::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 		// assimp universal format (M)
 		SetFileScale(size_relative_to_cm * 0.01f);
 
-		std::for_each(tokens.begin(), tokens.end(), Util::delete_fun<Token>());
+		// This collection does not own the memory for the tokens, but we need to call their d'tor
-	} catch (std::exception &) {
+        std::for_each(tokens.begin(), tokens.end(), Util::destructor_fun<Token>());
-		std::for_each(tokens.begin(), tokens.end(), Util::delete_fun<Token>());
+
-		throw;
+    } catch (std::exception &) {
+        std::for_each(tokens.begin(), tokens.end(), Util::destructor_fun<Token>());
+        throw;
 	}
 }
 

code/AssetLib/FBX/FBXParser.cpp

@@ -115,8 +115,11 @@ namespace Assimp {
 namespace FBX {
 
 // ------------------------------------------------------------------------------------------------
-Element::Element(const Token& key_token, Parser& parser) : key_token(key_token) {
+Element::Element(const Token& key_token, Parser& parser) :
+    key_token(key_token), compound(nullptr)
+{
     TokenPtr n = nullptr;
+    StackAllocator &allocator = parser.GetAllocator();
     do {
         n = parser.AdvanceToNextToken();
         if(!n) {
@@ -145,7 +148,7 @@ Element::Element(const Token& key_token, Parser& parser) : key_token(key_token)
         }
 
         if (n->Type() == TokenType_OPEN_BRACKET) {
-            compound.reset(new Scope(parser));
+            compound = new_Scope(parser);
 
             // current token should be a TOK_CLOSE_BRACKET
             n = parser.CurrentToken();
@@ -163,6 +166,15 @@ Element::Element(const Token& key_token, Parser& parser) : key_token(key_token)
 }
 
 // ------------------------------------------------------------------------------------------------
+Element::~Element()
+{
+    if (compound) {
+        delete_Scope(compound);
+    }
+
+     // no need to delete tokens, they are owned by the parser
+}
+
 Scope::Scope(Parser& parser,bool topLevel)
 {
     if(!topLevel) {
@@ -172,6 +184,7 @@ Scope::Scope(Parser& parser,bool topLevel)
         }
     }
 
+    StackAllocator &allocator = parser.GetAllocator();
     TokenPtr n = parser.AdvanceToNextToken();
     if (n == nullptr) {
         ParseError("unexpected end of file");
@@ -206,22 +219,27 @@ Scope::Scope(Parser& parser,bool topLevel)
 }
 
 // ------------------------------------------------------------------------------------------------
-Scope::~Scope() {
+Scope::~Scope()
-    for(ElementMap::value_type& v : elements) {
+{
-        delete v.second;
+	// This collection does not own the memory for the elements, but we need to call their d'tor:
+
+    for (ElementMap::value_type &v : elements) {
+        delete_Element(v.second);
     }
 }
 
 // ------------------------------------------------------------------------------------------------
-Parser::Parser (const TokenList& tokens, bool is_binary)
+Parser::Parser(const TokenList &tokens, StackAllocator &allocator, bool is_binary) :
-: tokens(tokens)
+        tokens(tokens), allocator(allocator), last(), current(), cursor(tokens.begin()), is_binary(is_binary)
-, last()
-, current()
-, cursor(tokens.begin())
-, is_binary(is_binary)
 {
     ASSIMP_LOG_DEBUG("Parsing FBX tokens");
-    root.reset(new Scope(*this,true));
+    root = new_Scope(*this, true);
+}
+
+// ------------------------------------------------------------------------------------------------
+Parser::~Parser()
+{
+    delete_Scope(root);
 }
 
 // ------------------------------------------------------------------------------------------------

code/AssetLib/FBX/FBXParser.h

@@ -52,6 +52,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/LogAux.h>
 #include <assimp/fast_atof.h>
 
+#include "Common/StackAllocator.h"
 #include "FBXCompileConfig.h"
 #include "FBXTokenizer.h"
 
@@ -68,9 +69,10 @@ typedef std::fbx_unordered_multimap< std::string, Element* > ElementMap;
 
 typedef std::pair<ElementMap::const_iterator,ElementMap::const_iterator> ElementCollection;
 
-#   define new_Scope new Scope
+#define new_Scope new (allocator.Allocate(sizeof(Scope))) Scope
-#   define new_Element new Element
+#define new_Element new (allocator.Allocate(sizeof(Element))) Element
-
+#define delete_Scope(_p) (_p)->~Scope()
+#define delete_Element(_p) (_p)->~Element()
 
 /** FBX data entity that consists of a key:value tuple.
  *
@@ -87,10 +89,10 @@ class Element
 {
 public:
     Element(const Token& key_token, Parser& parser);
-    ~Element() = default;
+    ~Element():
 
     const Scope* Compound() const {
-        return compound.get();
+        return compound;
     }
 
     const Token& KeyToken() const {
@@ -104,7 +106,7 @@ public:
 private:
     const Token& key_token;
     TokenList tokens;
-    std::unique_ptr<Scope> compound;
+    Scope* compound;
 };
 
 /** FBX data entity that consists of a 'scope', a collection
@@ -159,8 +161,8 @@ class Parser
 public:
     /** Parse given a token list. Does not take ownership of the tokens -
      *  the objects must persist during the entire parser lifetime */
-    Parser (const TokenList& tokens,bool is_binary);
+    Parser(const TokenList &tokens, StackAllocator &allocator, bool is_binary);
-    ~Parser() = default;
+    ~Parser();
 
     const Scope& GetRootScope() const {
         return *root;
@@ -170,6 +172,10 @@ public:
         return is_binary;
     }
 
+    StackAllocator &GetAllocator() {
+        return allocator;
+    }
+
 private:
     friend class Scope;
     friend class Element;
@@ -180,10 +186,10 @@ private:
 
 private:
     const TokenList& tokens;
-
+    StackAllocator &allocator;
     TokenPtr last, current;
     TokenList::const_iterator cursor;
-    std::unique_ptr<Scope> root;
+    Scope *root;
 
     const bool is_binary;
 };

code/AssetLib/FBX/FBXTokenizer.cpp

@@ -94,7 +94,8 @@ AI_WONT_RETURN void TokenizeError(const std::string& message, unsigned int line,
 
 // process a potential data token up to 'cur', adding it to 'output_tokens'.
 // ------------------------------------------------------------------------------------------------
-void ProcessDataToken( TokenList& output_tokens, const char*& start, const char*& end,
+void ProcessDataToken(TokenList &output_tokens, StackAllocator &token_allocator,
+                      const char*& start, const char*& end,
                       unsigned int line,
                       unsigned int column,
                       TokenType type = TokenType_DATA,
@@ -131,8 +132,7 @@ void ProcessDataToken( TokenList& output_tokens, const char*& start, const char*
 }
 
 // ------------------------------------------------------------------------------------------------
-void Tokenize(TokenList& output_tokens, const char* input)
+void Tokenize(TokenList &output_tokens, const char *input, StackAllocator &token_allocator) {
-{
 	ai_assert(input);
 	ASSIMP_LOG_DEBUG("Tokenizing ASCII FBX file");
 
@@ -164,7 +164,7 @@ void Tokenize(TokenList& output_tokens, const char* input)
                 in_double_quotes = false;
                 token_end = cur;
 
-                ProcessDataToken(output_tokens,token_begin,token_end,line,column);
+                ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column);
                 pending_data_token = false;
             }
             continue;
@@ -181,30 +181,30 @@ void Tokenize(TokenList& output_tokens, const char* input)
             continue;
 
         case ';':
-            ProcessDataToken(output_tokens,token_begin,token_end,line,column);
+            ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column);
             comment = true;
             continue;
 
         case '{':
-            ProcessDataToken(output_tokens,token_begin,token_end, line, column);
+            ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column);
             output_tokens.push_back(new_Token(cur,cur+1,TokenType_OPEN_BRACKET,line,column));
             continue;
 
         case '}':
-            ProcessDataToken(output_tokens,token_begin,token_end,line,column);
+            ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column);
             output_tokens.push_back(new_Token(cur,cur+1,TokenType_CLOSE_BRACKET,line,column));
             continue;
 
         case ',':
             if (pending_data_token) {
-                ProcessDataToken(output_tokens,token_begin,token_end,line,column,TokenType_DATA,true);
+                ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column, TokenType_DATA, true);
             }
             output_tokens.push_back(new_Token(cur,cur+1,TokenType_COMMA,line,column));
             continue;
 
         case ':':
             if (pending_data_token) {
-                ProcessDataToken(output_tokens,token_begin,token_end,line,column,TokenType_KEY,true);
+                ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column, TokenType_KEY, true);
             }
             else {
                 TokenizeError("unexpected colon", line, column);
@@ -226,7 +226,7 @@ void Tokenize(TokenList& output_tokens, const char* input)
                     }
                 }
 
-                ProcessDataToken(output_tokens,token_begin,token_end,line,column,type);
+                ProcessDataToken(output_tokens, token_allocator, token_begin, token_end, line, column, type);
             }
 
             pending_data_token = false;

code/AssetLib/FBX/FBXTokenizer.h

@@ -47,6 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define INCLUDED_AI_FBX_TOKENIZER_H
 
 #include "FBXCompileConfig.h"
+#include "Common/StackAllocator.h"
 #include <assimp/ai_assert.h>
 #include <assimp/defs.h>
 #include <vector>
@@ -157,7 +158,8 @@ private:
 typedef const Token* TokenPtr;
 typedef std::vector< TokenPtr > TokenList;
 
-#define new_Token new Token
+#define new_Token new (token_allocator.Allocate(sizeof(Token))) Token
+#define delete_Token(_p) (_p)->~Token()
 
 
 /** Main FBX tokenizer function. Transform input buffer into a list of preprocessed tokens.
@@ -167,7 +169,7 @@ typedef std::vector< TokenPtr > TokenList;
  * @param output_tokens Receives a list of all tokens in the input data.
  * @param input_buffer Textual input buffer to be processed, 0-terminated.
  * @throw DeadlyImportError if something goes wrong */
-void Tokenize(TokenList& output_tokens, const char* input);
+void Tokenize(TokenList &output_tokens, const char *input, StackAllocator &tokenAllocator);
 
 
 /** Tokenizer function for binary FBX files.
@@ -178,7 +180,7 @@ void Tokenize(TokenList& output_tokens, const char* input);
  * @param input_buffer Binary input buffer to be processed.
  * @param length Length of input buffer, in bytes. There is no 0-terminal.
  * @throw DeadlyImportError if something goes wrong */
-void TokenizeBinary(TokenList& output_tokens, const char* input, size_t length);
+void TokenizeBinary(TokenList &output_tokens, const char *input, size_t length, StackAllocator &tokenAllocator);
 
 
 } // ! FBX

code/AssetLib/FBX/FBXUtil.h

@@ -66,6 +66,17 @@ struct delete_fun
     }
 };
 
+/** helper for std::for_each to call the destructor on all items in a container without freeing their heap*/
+template <typename T>
+struct destructor_fun {
+    void operator()(const volatile T* del) {
+        if (del) {
+            del->~T();
+        }
+    }
+};
+
+
 /** Get a string representation for a #TokenType. */
 const char* TokenTypeString(TokenType t);
 

code/CMakeLists.txt

@@ -194,6 +194,8 @@ SET( Common_SRCS
   Common/ScenePreprocessor.cpp
   Common/ScenePreprocessor.h
   Common/SkeletonMeshBuilder.cpp
+  Common/StackAllocator.h
+  Common/StackAllocator.inl
   Common/StandardShapes.cpp
   Common/TargetAnimation.cpp
   Common/TargetAnimation.h

code/Common/StackAllocator.h

@@ -0,0 +1,96 @@
+/*
+Open Asset Import Library (assimp)
+----------------------------------------------------------------------
+
+Copyright (c) 2006-2022, assimp team
+
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the
+following conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----------------------------------------------------------------------
+*/
+
+/** @file  StackAllocator.h
+ *  @brief A very bare-bone allocator class that is suitable when
+ *      allocating many small objects, e.g. during parsing.
+ *      Individual objects are not freed, instead only the whole memory
+ *      can be deallocated.
+ */
+#ifndef AI_STACK_ALLOCATOR_H_INC
+#define AI_STACK_ALLOCATOR_H_INC
+
+
+#include <deque>
+#include <stdint.h>
+
+namespace Assimp
+{
+
+/** @brief A very bare-bone allocator class that is suitable when
+ *      allocating many small objects, e.g. during parsing.
+ *      Individual objects are not freed, instead only the whole memory
+ *      can be deallocated.
+*/
+class StackAllocator {
+public:
+    // Constructs the allocator
+    inline StackAllocator();
+    // Destructs the allocator and frees all memory
+    inline ~StackAllocator();
+
+    // non copyable
+    StackAllocator(const StackAllocator &) = delete;
+    StackAllocator &operator=(const StackAllocator &) = delete;
+
+    // Returns a pointer to byteSize bytes of heap memory that persists
+    // for the lifetime of the allocator (or until FreeAll is called).
+    inline void *Allocate(size_t byteSize);
+
+    // Releases all the memory owned by this allocator.
+    // Memory provided through function Allocate is not valid anymore after this function has been called.
+    inline void FreeAll();
+
+private:
+    constexpr const static size_t g_maxBytesPerBlock = 64 * 1024 * 1024; // The maximum size (in bytes) of a block
+    constexpr const static size_t g_startBytesPerBlock = 16 * 1024;  // Size of the first block. Next blocks will double in size until maximum size of g_maxBytesPerBlock
+    size_t m_blockAllocationSize = g_startBytesPerBlock; // Block size of the current block
+    size_t m_subIndex = g_maxBytesPerBlock; // The current byte offset in the current block
+    std::deque<uint8_t *> m_storageBlocks;  // A list of blocks
+};
+
+
+} // namespace Assimp
+
+#include "StackAllocator.inl"
+
+#endif // include guard

code/Common/StackAllocator.inl

@@ -0,0 +1,84 @@
+/*
+Open Asset Import Library (assimp)
+----------------------------------------------------------------------
+
+Copyright (c) 2006-2022, assimp team
+
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the
+following conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----------------------------------------------------------------------
+*/
+
+#include "StackAllocator.h"
+#include <assimp/ai_assert.h>
+
+using namespace Assimp;
+
+
+inline StackAllocator::StackAllocator() {
+}
+
+inline StackAllocator::~StackAllocator() {
+    FreeAll();
+}
+
+inline void *StackAllocator::Allocate(size_t byteSize) {
+    if (m_subIndex + byteSize > m_blockAllocationSize) // start a new block
+    {
+        // double block size every time, up to maximum of g_maxBytesPerBlock.
+        // Block size must be at least as large as byteSize, but we want to use this for small allocations anyway.
+        m_blockAllocationSize = std::max(std::min(m_blockAllocationSize * 2, g_maxBytesPerBlock), byteSize);
+        uint8_t *data = new uint8_t[m_blockAllocationSize];
+        m_storageBlocks.push_back(data);
+        m_subIndex = byteSize;
+        return data;
+    }
+
+    uint8_t *data = m_storageBlocks.back();
+    data += m_subIndex;
+    m_subIndex += byteSize;
+
+    return data;
+}
+
+inline void StackAllocator::FreeAll() {
+    for (size_t i = 0; i < m_storageBlocks.size(); i++) {
+        delete [] m_storageBlocks[i];
+    }
+    std::deque<uint8_t *> empty;
+    m_storageBlocks.swap(empty);
+    // start over:
+    m_blockAllocationSize = g_startBytesPerBlock;
+    m_subIndex = g_maxBytesPerBlock;
+}