Merge pull request #787 from jsenn/feature/large-file-support

Added support for files larger than ~2GB

tinyxml2.cpp

@@ -100,6 +100,20 @@ distribution.
 	#define TIXML_SSCANF   sscanf
 #endif
 
+#if defined(_WIN64)
+	#define TIXML_FSEEK _fseeki64
+	#define TIXML_FTELL _ftelli64
+#elif defined(__APPLE__)
+	#define TIXML_FSEEK fseeko
+	#define TIXML_FTELL ftello
+#elif defined(__x86_64__)
+	#define TIXML_FSEEK fseeko64
+	#define TIXML_FTELL ftello64
+#else
+	#define TIXML_FSEEK fseek
+	#define TIXML_FTELL ftell
+#endif
+
 
 static const char LINE_FEED				= static_cast<char>(0x0a);			// all line endings are normalized to LF
 static const char LF = LINE_FEED;
@@ -2286,49 +2300,34 @@ XMLError XMLDocument::LoadFile( const char* filename )
     return _errorID;
 }
 
-// This is likely overengineered template art to have a check that unsigned long value incremented
-// by one still fits into size_t. If size_t type is larger than unsigned long type
-// (x86_64-w64-mingw32 target) then the check is redundant and gcc and clang emit
-// -Wtype-limits warning. This piece makes the compiler select code with a check when a check
-// is useful and code with no check when a check is redundant depending on how size_t and unsigned long
-// types sizes relate to each other.
-template
-<bool = (sizeof(unsigned long) >= sizeof(size_t))>
-struct LongFitsIntoSizeTMinusOne {
-    static bool Fits( unsigned long value )
-    {
-        return value < static_cast<size_t>(-1);
-    }
-};
-
-template <>
-struct LongFitsIntoSizeTMinusOne<false> {
-    static bool Fits( unsigned long )
-    {
-        return true;
-    }
-};
-
 XMLError XMLDocument::LoadFile( FILE* fp )
 {
     Clear();
 
-    fseek( fp, 0, SEEK_SET );
+    TIXML_FSEEK( fp, 0, SEEK_SET );
     if ( fgetc( fp ) == EOF && ferror( fp ) != 0 ) {
         SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );
         return _errorID;
     }
 
-    fseek( fp, 0, SEEK_END );
-    const long filelength = ftell( fp );
-    fseek( fp, 0, SEEK_SET );
-    if ( filelength == -1L ) {
-        SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );
-        return _errorID;
+    TIXML_FSEEK( fp, 0, SEEK_END );
+
+    unsigned long long filelength;
+    {
+        const long long fileLengthSigned = TIXML_FTELL( fp );
+        TIXML_FSEEK( fp, 0, SEEK_SET );
+        if ( fileLengthSigned == -1L ) {
+            SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );
+            return _errorID;
+        }
+        TIXMLASSERT( fileLengthSigned >= 0 );
+        filelength = static_cast<unsigned long long>(fileLengthSigned);
     }
-    TIXMLASSERT( filelength >= 0 );
 
-    if ( !LongFitsIntoSizeTMinusOne<>::Fits( filelength ) ) {
+    const size_t maxSizeT = static_cast<size_t>(-1);
+    // We'll do the comparison as an unsigned long long, because that's guaranteed to be at
+    // least 8 bytes, even on a 32-bit platform.
+    if ( filelength >= static_cast<unsigned long long>(maxSizeT) ) {
         // Cannot handle files which won't fit in buffer together with null terminator
         SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );
         return _errorID;
@@ -2339,7 +2338,7 @@ XMLError XMLDocument::LoadFile( FILE* fp )
         return _errorID;
     }
 
-    const size_t size = filelength;
+    const size_t size = static_cast<size_t>(filelength);
     TIXMLASSERT( _charBuffer == 0 );
     _charBuffer = new char[size+1];
     const size_t read = fread( _charBuffer, 1, size, fp );