10.8

1 files changed, 114 insertions, 0 deletions

diff --git a/zen/zlib_wrap.h b/zen/zlib_wrap.h
new file mode 100755
index 00000000..b92a8eba
--- /dev/null
+++ b/zen/zlib_wrap.h
@@ -0,0 +1,114 @@
+// *****************************************************************************
+// * This file is part of the FreeFileSync project. It is distributed under    *
+// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0          *
+// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
+// *****************************************************************************
+
+#ifndef ZLIB_WRAP_H_428597064566
+#define ZLIB_WRAP_H_428597064566
+
+#include "serialize.h"
+
+
+namespace zen
+{
+class ZlibInternalError {};
+
+// compression level must be between 0 and 9:
+// 0: no compression
+// 9: best compression
+template <class BinContainer> //as specified in serialize.h
+BinContainer compress(const BinContainer& stream, int level); //throw ZlibInternalError
+//caveat: output stream is physically larger than input! => strip additional reserved space if needed: "BinContainer(output.begin(), output.end())"
+
+template <class BinContainer>
+BinContainer decompress(const BinContainer& stream);          //throw ZlibInternalError
+
+
+
+
+
+
+
+
+
+
+
+//######################## implementation ##########################
+namespace impl
+{
+size_t zlib_compressBound(size_t len);
+size_t zlib_compress  (const void* src, size_t srcLen, void* trg, size_t trgLen, int level); //throw ZlibInternalError
+size_t zlib_decompress(const void* src, size_t srcLen, void* trg, size_t trgLen);            //throw ZlibInternalError
+}
+
+
+template <class BinContainer>
+BinContainer compress(const BinContainer& stream, int level) //throw ZlibInternalError
+{
+    BinContainer contOut;
+    if (!stream.empty()) //don't dereference iterator into empty container!
+    {
+        //save uncompressed stream size for decompression
+        const uint64_t uncompressedSize = stream.size(); //use portable number type!
+        contOut.resize(sizeof(uncompressedSize));
+        std::copy(reinterpret_cast<const std::byte*>(&uncompressedSize),
+                  reinterpret_cast<const std::byte*>(&uncompressedSize) + sizeof(uncompressedSize),
+                  &*contOut.begin());
+
+        const size_t bufferEstimate = impl::zlib_compressBound(stream.size()); //upper limit for buffer size, larger than input size!!!
+
+        contOut.resize(contOut.size() + bufferEstimate);
+
+        const size_t bytesWritten = impl::zlib_compress(&*stream.begin(),
+                                                        stream.size(),
+                                                        &*contOut.begin() + contOut.size() - bufferEstimate,
+                                                        bufferEstimate,
+                                                        level); //throw ZlibInternalError
+        if (bytesWritten < bufferEstimate)
+            contOut.resize(contOut.size() - (bufferEstimate - bytesWritten)); //caveat: unsigned arithmetics
+        //caveat: physical memory consumption still *unchanged*!
+    }
+    return contOut;
+}
+
+
+template <class BinContainer>
+BinContainer decompress(const BinContainer& stream) //throw ZlibInternalError
+{
+    BinContainer contOut;
+    if (!stream.empty()) //don't dereference iterator into empty container!
+    {
+        //retrieve size of uncompressed data
+        uint64_t uncompressedSize = 0; //use portable number type!
+        if (stream.size() < sizeof(uncompressedSize))
+            throw ZlibInternalError();
+        std::copy(&*stream.begin(),
+                  &*stream.begin() + sizeof(uncompressedSize),
+                  reinterpret_cast<std::byte*>(&uncompressedSize));
+        //attention: contOut MUST NOT be empty! Else it will pass a nullptr to zlib_decompress() => Z_STREAM_ERROR although "uncompressedSize == 0"!!!
+        //secondary bug: don't dereference iterator into empty container!
+        if (uncompressedSize == 0) //cannot be 0: compress() directly maps empty -> empty container skipping zlib!
+            throw ZlibInternalError();
+
+        try
+        {
+            contOut.resize(static_cast<size_t>(uncompressedSize)); //throw std::bad_alloc
+        }
+        catch (std::bad_alloc&) //most likely due to data corruption!
+        {
+            throw ZlibInternalError();
+        }
+
+        const size_t bytesWritten = impl::zlib_decompress(&*stream.begin() + sizeof(uncompressedSize),
+                                                          stream.size() - sizeof(uncompressedSize),
+                                                          &*contOut.begin(),
+                                                          static_cast<size_t>(uncompressedSize)); //throw ZlibInternalError
+        if (bytesWritten != static_cast<size_t>(uncompressedSize))
+            throw ZlibInternalError();
+    }
+    return contOut;
+}
+}
+
+#endif //ZLIB_WRAP_H_428597064566