ZipArchiveIOSystem should be sorted, fix ZipFile::Read()

Q3BSP relies on the sort order
Read() should return number of elements read, not count of bytes
Read() should clip to the file size and return elements actually read,
instead of aborting if try to read too much

code/Common/ZipArchiveIOSystem.cpp

@@ -45,7 +45,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <assimp/ai_assert.h>
 
-#include <unordered_map>
+#include <map>
 #include <memory>
 
 #ifdef ASSIMP_USE_HUNTER
@@ -55,7 +55,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 namespace Assimp {
-
     // ----------------------------------------------------------------
     // Wraps an existing Assimp::IOSystem for unzip
     class IOSystem2Unzip {
@@ -247,14 +246,25 @@ namespace Assimp {
     }
 
     size_t ZipFile::Read(void* pvBuffer, size_t pSize, size_t pCount) {
-        const size_t size = pSize * pCount;
-        ai_assert((size + m_SeekPtr) <= m_Size);
+        // Should be impossible
+        ai_assert(m_Buffer != nullptr);
+        ai_assert(NULL != pvBuffer && 0 != pSize && 0 != pCount);
 
-        std::memcpy(pvBuffer, m_Buffer.get() + m_SeekPtr, size);
+        // Clip down to file size
+        size_t byteSize = pSize * pCount;
+        if ((byteSize + m_SeekPtr) > m_Size)
+        {
+            pCount = (m_Size - m_SeekPtr) / pSize;
+            byteSize = pSize * pCount;
+            if (byteSize == 0)
+                return 0;
+        }
 
-        m_SeekPtr += size;
+        std::memcpy(pvBuffer, m_Buffer.get() + m_SeekPtr, byteSize);
 
-        return size;
+        m_SeekPtr += byteSize;
+
+        return pCount;
     }
 
     size_t ZipFile::FileSize() const {
@@ -312,9 +322,10 @@ namespace Assimp {
         void MapArchive();
 
     private:
+        typedef std::map<std::string, ZipFileInfo> ZipFileInfoMap;
+
         unzFile m_ZipFileHandle = nullptr;
-        typedef std::unordered_map<std::string, ZipFileInfo> ZipFileMap;
-        ZipFileMap m_ArchiveMap;
+        ZipFileInfoMap m_ArchiveMap;
     };
 
     ZipArchiveIOSystem::Implement::Implement(IOSystem* pIOHandler, const char* pFilename, const char* pMode) {
@@ -388,7 +399,7 @@ namespace Assimp {
     bool ZipArchiveIOSystem::Implement::Exists(std::string& filename) {
         MapArchive();
 
-        ZipFileMap::const_iterator it = m_ArchiveMap.find(filename);
+        ZipFileInfoMap::const_iterator it = m_ArchiveMap.find(filename);
         return (it != m_ArchiveMap.end());
     }
 
@@ -398,7 +409,7 @@ namespace Assimp {
         SimplifyFilename(filename);
 
         // Find in the map
-        ZipFileMap::const_iterator zip_it = m_ArchiveMap.find(filename);
+        ZipFileInfoMap::const_iterator zip_it = m_ArchiveMap.find(filename);
         if (zip_it == m_ArchiveMap.cend())
             return nullptr;