Fix file content malloc to avoid reading beyond buffer

Add another byte to avoid lexer going into unallocated
memory land. End of file handling was always pretty poor
with libsass. This is just another hack and no real fix.

Author: mgreter

src/file.cpp

@@ -394,9 +394,11 @@ namespace Sass {
         DWORD dwFileLength = GetFileSize(hFile, NULL);
         if (dwFileLength == INVALID_FILE_SIZE) return 0;
         // allocate an extra byte for the null char
-        pBuffer = (BYTE*)malloc((dwFileLength+1)*sizeof(BYTE));
+        // and another one for edge-cases in lexer
+        pBuffer = (BYTE*)malloc((dwFileLength+2)*sizeof(BYTE));
         ReadFile(hFile, pBuffer, dwFileLength, &dwBytes, NULL);
-        pBuffer[dwFileLength] = '\0';
+        pBuffer[dwFileLength+0] = '\0';
+        pBuffer[dwFileLength+1] = '\0';
         CloseHandle(hFile);
         // just convert from unsigned char*
         char* contents = (char*) pBuffer;
@@ -408,10 +410,12 @@ namespace Sass {
         if (file.is_open()) {
           size_t size = file.tellg();
           // allocate an extra byte for the null char
-          contents = (char*) malloc((size+1)*sizeof(char));
+          // and another one for edge-cases in lexer
+          contents = (char*) malloc((size+2)*sizeof(char));
           file.seekg(0, std::ios::beg);
           file.read(contents, size);
-          contents[size] = '\0';
+          contents[size+0] = '\0';
+          contents[size+0] = '\0';
           file.close();
         }
       #endif