NC-Negate offset when ZIP_SOURCE_SEEK from SEEK_END (#74)

* Negate offset when ZIP_SOURCE_SEEK from SEEK_END 

custom_zip_source_callback from the zip library where the cmd is ZIP_SOURCE_SEEK and whence is SEEK_END specifies a negative offset.  pImportStream takes an unsigned positive value to indicate the distance to seek back.  The value must be negated between the two APIs.

* Assume unsigned argument for seekFromEnd

The API for CImportStream and CExportStream only allows unsigned input.
This commit handles this consistently in all seekFromEnd-functions
and adds some exceptions in custom_zip_source_callback.

* Support zip seeking backward from the current position.

* Update version

Author: kokuda

CMakeLists.txt

@@ -9,7 +9,7 @@ project (lib3MF)
 # Define Version
 set(LIB3MF_VERSION_MAJOR 1)				# increase on every backward-compatibility breaking change of the API
 set(LIB3MF_VERSION_MINOR 3)				# increase on every backward compatible change of the API
-set(LIB3MF_VERSION_MICRO 0)				# increase on on every change that does not alter the API
+set(LIB3MF_VERSION_MICRO 1)				# increase on on every change that does not alter the API
 
 set(CMAKE_INSTALL_BINDIR bin CACHE PATH "directory for installing binary files")
 set(CMAKE_INSTALL_LIBDIR lib CACHE PATH "directory for installing library files")

Source/Common/OPC/NMR_OpcPackageReader.cpp

@@ -62,13 +62,16 @@ namespace NMR {
 				argsSeek = * ((zip_source_args_seek *)data);
 				if (argsSeek.whence == SEEK_SET)
 					pImportStream->seekPosition(argsSeek.offset, true);
-				else if (argsSeek.whence == SEEK_CUR)
-					pImportStream->seekForward(argsSeek.offset, true);
+				else if (argsSeek.whence == SEEK_CUR) {
+					pImportStream->seekPosition(pImportStream->getPosition() + argsSeek.offset, true);
+				}
 				else if (argsSeek.whence == SEEK_END) {
-					pImportStream->seekFromEnd(argsSeek.offset, true);
+					if (argsSeek.offset > 0)
+						throw CNMRException(NMR_ERROR_ZIPCALLBACK);
+					pImportStream->seekFromEnd(-argsSeek.offset, true);
 				}
 				else
-					throw CNMRException(0);
+					throw CNMRException(NMR_ERROR_ZIPCALLBACK);
 				return 0;
 
 			case ZIP_SOURCE_OPEN:

Source/Common/Platform/NMR_ExportStream_GCC_Native.cpp

@@ -100,7 +100,7 @@ namespace NMR {
 
 	nfBool CExportStream_GCC_Native::seekFromEnd(_In_ nfUint64 bytes, _In_ nfBool bHasToSucceed)
 	{
-		std::streampos nStreamOffset = bytes;
+		std::streampos nStreamOffset = 0-bytes;
 		m_Stream.seekp(nStreamOffset, std::ios_base::end);
 
 		if (m_Stream.fail()) {

Source/Common/Platform/NMR_ImportStream_GCC_Native.cpp

@@ -96,7 +96,7 @@ namespace NMR {
 
 	nfBool CImportStream_GCC_Native::seekFromEnd(_In_ nfUint64 bytes, _In_ nfBool bHasToSucceed)
 	{
-		std::streampos nStreamOffset = bytes;
+		std::streampos nStreamOffset = 0-bytes;
 		m_Stream.seekg(nStreamOffset, std::ios_base::end);
 
 		if (m_Stream.fail()) {

Source/Common/Platform/NMR_ImportStream_Memory.cpp

@@ -156,11 +156,6 @@ namespace NMR {
 
 	nfBool CImportStream_Memory::seekFromEnd(_In_ nfUint64 cbBytes, _In_ nfBool bHasToSucceed)
 	{
-		// all seekFromEnd functions follow the calling conventions of fseek.
-		// fseek expects a negative number to seek from the end (SEEK_END).
-		// The program logic in this function requires a positive offset from the end.
-		cbBytes = 1+~cbBytes;
-
 		if (cbBytes > m_cbSize) {
 			if (bHasToSucceed)
 				throw CNMRException(NMR_ERROR_COULDNOTSEEKSTREAM);