Resolves: ofz#727 don't allow negative sizes or indexes

remove extra size in favour of vector size and don't resize
and memcpy data, just use vector::insert

Change-Id: I8efb91a8c11fbd862c0458042554cf7e94b813cd
Reviewed-on: https://gerrit.libreoffice.org/34891
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

hwpfilter/source/hstream.cxx

@@ -22,38 +22,37 @@
 #include "hstream.hxx"
 
 HStream::HStream()
-    : size(0)
+    : pos(0)
-    , pos(0)
 {
 }
 
-void HStream::addData(const byte *buf, int aToAdd)
+void HStream::addData(const byte *buf, size_t aToAdd)
 {
-    seq.resize(size + aToAdd);
+    seq.insert(seq.end(), buf, buf + aToAdd);
-    memcpy(seq.data() + size, buf, aToAdd);
-    size += aToAdd;
 }
 
-int HStream::readBytes(byte * buf, int aToRead)
+size_t HStream::readBytes(byte * buf, size_t aToRead)
 {
+    auto size = seq.size();
     if (aToRead >= (size - pos))
         aToRead = size - pos;
-    for (int i = 0; i < aToRead; i++)
+    for (size_t i = 0; i < aToRead; ++i)
         buf[i] = seq[pos++];
     return aToRead;
 }
 
-int HStream::skipBytes(int aToSkip)
+size_t HStream::skipBytes(size_t aToSkip)
 {
+    auto size = seq.size();
     if (aToSkip >= (size - pos))
         aToSkip = size - pos;
     pos += aToSkip;
     return aToSkip;
 }
 
-int HStream::available() const
+size_t HStream::available() const
 {
-    return size - pos;
+    return seq.size() - pos;
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

hwpfilter/source/hstream.hxx

@@ -34,24 +34,23 @@ class HStream
 /**
  *
  */
-        void addData( const byte *buf, int aToAdd);
+        void addData( const byte *buf, size_t aToAdd);
 /**
  * Read some byte to buf as given size
  */
-        int readBytes( byte *buf, int aToRead);
+        size_t readBytes( byte *buf, size_t aToRead);
 /**
  * Skip some byte from stream as given size
  */
-        int skipBytes( int aToSkip );
+        size_t skipBytes( size_t aToSkip );
 /**
  * @returns Size of remained stream
  */
-        int available() const;
+        size_t available() const;
 
     private:
-        int size;
         std::vector<byte> seq;
-        int pos;
+        size_t pos;
 };
 #endif