Merge branch '10.8' into 'master'10.8

10.8

See merge request opensource-tracking/FreeFileSync!5

16 files changed, 318 insertions, 83 deletions

diff --git a/zen/file_access.cpp b/zen/file_access.cpp
index ea19b6c7..d257b7c2 100755
--- a/zen/file_access.cpp
+++ b/zen/file_access.cpp
@@ -170,16 +170,6 @@ namespace
 }
 
 
-uint64_t zen::getFileSize(const Zstring& filePath) //throw FileError
-{
-    struct ::stat fileInfo = {};
-    if (::stat(filePath.c_str(), &fileInfo) != 0)
-        THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtPath(filePath)), L"stat");
-
-    return fileInfo.st_size;
-}
-
-
 uint64_t zen::getFreeDiskSpace(const Zstring& path) //throw FileError, returns 0 if not available
 {
     struct ::statfs info = {};
@@ -190,13 +180,19 @@ uint64_t zen::getFreeDiskSpace(const Zstring& path) //throw FileError, returns 0
 }
 
 
-FileId /*optional*/ zen::getFileId(const Zstring& itemPath) //throw FileError
+FileDetails zen::getFileDetails(const Zstring& itemPath) //throw FileError
 {
     struct ::stat fileInfo = {};
     if (::stat(itemPath.c_str(), &fileInfo) != 0)
         THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtPath(itemPath)), L"stat");
 
-    return extractFileId(fileInfo);
+    return
+    {
+        makeUnsigned(fileInfo.st_size),
+        fileInfo.st_mtime,
+        fileInfo.st_dev,        
+	//FileIndex fileIndex = fileInfo.st_ino;
+    };
 }
 
 
@@ -301,19 +297,14 @@ namespace
 
 /* Usage overview: (avoid circular pattern!)
 
-  renameFile()  -->  renameFile_sub()
-      |               /|\
-     \|/               |
-      Fix8Dot3NameClash()
+  moveAndRenameItem()  -->  moveAndRenameFileSub()
+      |                              /|\
+     \|/                              |
+             Fix8Dot3NameClash()
 */
 //wrapper for file system rename function:
-void renameFile_sub(const Zstring& pathSource, const Zstring& pathTarget) //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
+void moveAndRenameFileSub(const Zstring& pathSource, const Zstring& pathTarget, bool replaceExisting) //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
 {
-    //rename() will never fail with EEXIST, but always (atomically) overwrite!
-    //=> equivalent to SetFileInformationByHandle() + FILE_RENAME_INFO::ReplaceIfExists or ::MoveFileEx + MOVEFILE_REPLACE_EXISTING
-    //Linux: renameat2() with RENAME_NOREPLACE -> still new, probably buggy
-    //macOS: no solution
-
     auto throwException = [&](int ec)
     {
         const std::wstring errorMsg = replaceCpy(replaceCpy(_("Cannot move file %x to %y."), L"%x", L"\n" + fmtPath(pathSource)), L"%y", L"\n" + fmtPath(pathTarget));
@@ -326,19 +317,27 @@ void renameFile_sub(const Zstring& pathSource, const Zstring& pathTarget) //thro
         throw FileError(errorMsg, errorDescr);
     };
 
-    struct ::stat infoSrc = {};
-    if (::lstat(pathSource.c_str(), &infoSrc) != 0)
-        THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtPath(pathSource)), L"stat");
+    //rename() will never fail with EEXIST, but always (atomically) overwrite!
+    //=> equivalent to SetFileInformationByHandle() + FILE_RENAME_INFO::ReplaceIfExists or ::MoveFileEx() + MOVEFILE_REPLACE_EXISTING
+    //Linux: renameat2() with RENAME_NOREPLACE -> still new, probably buggy
+    //macOS: no solution https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man2/rename.2.html
+    if (!replaceExisting)
+    {
+        struct ::stat infoSrc = {};
+        if (::lstat(pathSource.c_str(), &infoSrc) != 0)
+            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtPath(pathSource)), L"stat");
 
-	struct ::stat infoTrg = {};
-    if (::lstat(pathTarget.c_str(), &infoTrg) == 0)
-	{
-		if (infoSrc.st_dev != infoTrg.st_dev ||
-		    infoSrc.st_ino != infoTrg.st_ino)
-			throwException(EEXIST); //that's what we're really here for
-		//else: continue with a rename in case
-	}
-	//else: not existing or access error (hopefully ::rename will also fail!)
+        struct ::stat infoTrg = {};
+        if (::lstat(pathTarget.c_str(), &infoTrg) == 0)
+        {
+            if (infoSrc.st_dev != infoTrg.st_dev ||
+                infoSrc.st_ino != infoTrg.st_ino)
+                throwException(EEXIST); //that's what we're really here for
+            //else: continue with a rename in case
+			//caveat: if we have a hardlink referenced by two different paths, the source one will be unlinked => fine, but not exactly a "rename"...
+        }
+        //else: not existing or access error (hopefully ::rename will also fail!)
+    }
 
     if (::rename(pathSource.c_str(), pathTarget.c_str()) != 0)
         throwException(errno);
@@ -349,11 +348,11 @@ void renameFile_sub(const Zstring& pathSource, const Zstring& pathTarget) //thro
 
 
 //rename file: no copying!!!
-void zen::renameFile(const Zstring& pathSource, const Zstring& pathTarget) //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
+void zen::moveAndRenameItem(const Zstring& pathSource, const Zstring& pathTarget, bool replaceExisting) //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
 {
     try
     {
-        renameFile_sub(pathSource, pathTarget); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
+        moveAndRenameFileSub(pathSource, pathTarget, replaceExisting); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
     }
     catch (ErrorTargetExisting&)
     {
@@ -369,9 +368,9 @@ void zen::renameFile(const Zstring& pathSource, const Zstring& pathTarget) //thr
                 return; //non-sensical request
 
             const Zstring tempFilePath = getTemporaryPath8Dot3(pathSource); //throw FileError
-            renameFile_sub(pathSource, tempFilePath); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
-            ZEN_ON_SCOPE_FAIL(renameFile_sub(tempFilePath, pathSource)); //"try" our best to be "atomic" :>
-            renameFile_sub(tempFilePath, pathTarget); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
+            moveAndRenameFileSub(pathSource, tempFilePath); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
+            ZEN_ON_SCOPE_FAIL(moveAndRenameFileSub(tempFilePath, pathSource)); //"try" our best to be "atomic" :>
+            moveAndRenameFileSub(tempFilePath, pathTarget); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
             return;
         }
 #endif
@@ -398,7 +397,7 @@ void setWriteTimeNative(const Zstring& itemPath, const struct ::timespec& modTim
     struct ::timespec newTimes[2] = {};
     newTimes[0].tv_sec = ::time(nullptr); //access time; using UTIME_OMIT for tv_nsec would trigger even more bugs: https://freefilesync.org/forum/viewtopic.php?t=1701
     newTimes[1] = modTime; //modification time
-	//test: even modTime == 0 is correctly applied (no NOOP!) test2: same behavior for "utime()"
+    //test: even modTime == 0 is correctly applied (no NOOP!) test2: same behavior for "utime()"
 
     if (procSl == ProcSymlink::FOLLOW)
     {
@@ -680,8 +679,8 @@ FileCopyResult copyFileOsSpecific(const Zstring& sourceFile, //throw FileError,
     FileCopyResult result;
     result.fileSize = sourceInfo.st_size;
     result.modTime = sourceInfo.st_mtim.tv_sec; //
-    result.sourceFileId = extractFileId(sourceInfo);
-    result.targetFileId = extractFileId(targetInfo);
+    result.sourceFileId = generateFileId(sourceInfo);
+    result.targetFileId = generateFileId(targetInfo);
     result.errorModTime = errorModTime;
     return result;
 }
@@ -700,10 +699,10 @@ copyFileWindowsDefault(::CopyFileEx)  copyFileWindowsStream(::BackupRead/::Backu
 }
 
 
-FileCopyResult zen::copyNewFile(const Zstring& sourceFile, const Zstring& targetFile, bool copyFilePermissions, //throw FileError, ErrorTargetExisting, ErrorFileLocked
-                                const IOCallback& notifyUnbufferedIO)
+FileCopyResult zen::copyNewFile(const Zstring& sourceFile, const Zstring& targetFile, bool copyFilePermissions, //throw FileError, ErrorTargetExisting, ErrorFileLocked, X
+                                const IOCallback& notifyUnbufferedIO /*throw X*/)
 {
-    const FileCopyResult result = copyFileOsSpecific(sourceFile, targetFile, notifyUnbufferedIO); //throw FileError, ErrorTargetExisting, ErrorFileLocked
+    const FileCopyResult result = copyFileOsSpecific(sourceFile, targetFile, notifyUnbufferedIO); //throw FileError, ErrorTargetExisting, ErrorFileLocked, X
 
     //at this point we know we created a new file, so it's fine to delete it for cleanup!
     ZEN_ON_SCOPE_FAIL(try { removeFilePlain(targetFile); }
diff --git a/zen/file_access.h b/zen/file_access.h
index 514d798e..d981dcc3 100755
--- a/zen/file_access.h
+++ b/zen/file_access.h
@@ -52,10 +52,17 @@ enum class ProcSymlink
 };
 void setFileTime(const Zstring& filePath, time_t modTime, ProcSymlink procSl); //throw FileError
 
-//symlink handling: always evaluate target
-uint64_t getFileSize(const Zstring& filePath); //throw FileError
+//symlink handling: always follow
 uint64_t getFreeDiskSpace(const Zstring& path); //throw FileError, returns 0 if not available
-FileId /*optional*/ getFileId(const Zstring& itemPath); //throw FileError
+
+struct FileDetails
+{
+    uint64_t  fileSize  = 0;
+    time_t    modTime   = 0; //number of seconds since Jan. 1st 1970 UTC
+    VolumeId  volumeId  = 0;
+};
+//symlink handling: always follow
+FileDetails getFileDetails(const Zstring& itemPath); //throw FileError
 
 //get per-user directory designated for temporary files:
 Zstring getTempFolderPath(); //throw FileError
@@ -65,8 +72,7 @@ void removeSymlinkPlain  (const Zstring& linkPath);         //throw FileError; E
 void removeDirectoryPlain(const Zstring& dirPath );         //throw FileError; ERROR if not existing
 void removeDirectoryPlainRecursion(const Zstring& dirPath); //throw FileError; ERROR if not existing
 
-//rename file or directory: no copying!!!
-void renameFile(const Zstring& itemPathOld, const Zstring& itemPathNew); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
+void moveAndRenameItem(const Zstring& itemPathOld, const Zstring& itemPathNew, bool replaceExisting); //throw FileError, ErrorDifferentVolume, ErrorTargetExisting
 
 bool supportsPermissions(const Zstring& dirPath); //throw FileError, follows symlinks
 //copy permissions for files, directories or symbolic links: requires admin rights
@@ -94,9 +100,9 @@ struct FileCopyResult
     std::optional<FileError> errorModTime; //failure to set modification time
 };
 
-FileCopyResult copyNewFile(const Zstring& sourceFile, const Zstring& targetFile, bool copyFilePermissions, //throw FileError, ErrorTargetExisting, ErrorFileLocked
+FileCopyResult copyNewFile(const Zstring& sourceFile, const Zstring& targetFile, bool copyFilePermissions, //throw FileError, ErrorTargetExisting, ErrorFileLocked, X
                            //accummulated delta != file size! consider ADS, sparse, compressed files
-                           const IOCallback& notifyUnbufferedIO); //may be nullptr; throw X!
+                           const IOCallback& notifyUnbufferedIO /*throw X*/); 
 }
 
 #endif //FILE_ACCESS_H_8017341345614857
diff --git a/zen/file_id_def.h b/zen/file_id_def.h
index f58cb479..55ee77f5 100755
--- a/zen/file_id_def.h
+++ b/zen/file_id_def.h
@@ -21,7 +21,14 @@ using FileIndex = decltype(impl::StatDummy::st_ino);
 struct FileId //always available on Linux, and *generally* available on Windows)
 {
     FileId() {}
-    FileId(VolumeId volId, FileIndex fIdx) : volumeId(volId), fileIndex(fIdx) {}
+    FileId(VolumeId volId, FileIndex fIdx) : volumeId(volId), fileIndex(fIdx)
+    {
+        if (volId == 0 || fIdx == 0)
+        {
+            volumeId  = 0;
+            fileIndex = 0;
+        }
+    }
     VolumeId  volumeId  = 0;
     FileIndex fileIndex = 0;
 };
@@ -29,10 +36,9 @@ inline bool operator==(const FileId& lhs, const FileId& rhs) { return lhs.volume
 
 
 inline
-FileId extractFileId(const struct ::stat& fileInfo)
+FileId generateFileId(const struct ::stat& fileInfo)
 {
-    return fileInfo.st_dev != 0 && fileInfo.st_ino != 0 ?
-           FileId(fileInfo.st_dev, fileInfo.st_ino) : FileId();
+    return FileId(fileInfo.st_dev, fileInfo.st_ino);
 }
 }
 
diff --git a/zen/file_io.cpp b/zen/file_io.cpp
index 80fb3153..1c6ab6f2 100755
--- a/zen/file_io.cpp
+++ b/zen/file_io.cpp
@@ -128,7 +128,7 @@ size_t FileInput::tryRead(void* buffer, size_t bytesToRead) //throw FileError, E
     return bytesRead; //"zero indicates end of file"
 }
 
- 
+
 size_t FileInput::read(void* buffer, size_t bytesToRead) //throw FileError, ErrorFileLocked, X; return "bytesToRead" bytes unless end of stream!
 {
     /*
@@ -203,7 +203,7 @@ FileOutput::FileOutput(FileHandle handle, const Zstring& filePath, const IOCallb
     FileBase(handle, filePath), notifyUnbufferedIO_(notifyUnbufferedIO) {}
 
 
-FileOutput::FileOutput(const Zstring& filePath, AccessFlag access, const IOCallback& notifyUnbufferedIO) :
+FileOutput::FileOutput(AccessFlag access, const Zstring& filePath, const IOCallback& notifyUnbufferedIO) :
     FileBase(openHandleForWrite(filePath, access), filePath), notifyUnbufferedIO_(notifyUnbufferedIO) {} //throw FileError, ErrorTargetExisting
 
 
diff --git a/zen/file_io.h b/zen/file_io.h
index d05d97db..bf23d22c 100755
--- a/zen/file_io.h
+++ b/zen/file_io.h
@@ -56,8 +56,8 @@ private:
 class FileInput : public FileBase
 {
 public:
-    FileInput(const Zstring& filePath, const IOCallback& notifyUnbufferedIO); //throw FileError, ErrorFileLocked
-    FileInput(FileHandle handle, const Zstring& filePath, const IOCallback& notifyUnbufferedIO); //takes ownership!
+    FileInput(                   const Zstring& filePath, const IOCallback& notifyUnbufferedIO /*throw X*/); //throw FileError, ErrorFileLocked
+    FileInput(FileHandle handle, const Zstring& filePath, const IOCallback& notifyUnbufferedIO /*throw X*/); //takes ownership!
 
     size_t read(void* buffer, size_t bytesToRead); //throw FileError, ErrorFileLocked, X; return "bytesToRead" bytes unless end of stream!
 
@@ -80,8 +80,8 @@ public:
         ACC_OVERWRITE,
         ACC_CREATE_NEW
     };
-    FileOutput(const Zstring& filePath, AccessFlag access, const IOCallback& notifyUnbufferedIO); //throw FileError, ErrorTargetExisting
-    FileOutput(FileHandle handle, const Zstring& filePath, const IOCallback& notifyUnbufferedIO); //takes ownership!
+    FileOutput(AccessFlag access, const Zstring& filePath, const IOCallback& notifyUnbufferedIO /*throw X*/); //throw FileError, ErrorTargetExisting
+    FileOutput(FileHandle handle, const Zstring& filePath, const IOCallback& notifyUnbufferedIO /*throw X*/); //takes ownership!
     ~FileOutput();
 
     void preAllocateSpaceBestEffort(uint64_t expectedSize); //throw FileError
@@ -105,8 +105,7 @@ private:
 //native stream I/O convenience functions:
 
 template <class BinContainer> inline
-BinContainer loadBinContainer(const Zstring& filePath, //throw FileError
-                              const IOCallback& notifyUnbufferedIO)
+BinContainer loadBinContainer(const Zstring& filePath, const IOCallback& notifyUnbufferedIO /*throw X*/) //throw FileError, X
 {
     FileInput streamIn(filePath, notifyUnbufferedIO); //throw FileError, ErrorFileLocked
     return bufferedLoad<BinContainer>(streamIn); //throw FileError, X;
@@ -114,10 +113,9 @@ BinContainer loadBinContainer(const Zstring& filePath, //throw FileError
 
 
 template <class BinContainer> inline
-void saveBinContainer(const Zstring& filePath, const BinContainer& buffer, //throw FileError
-                      const IOCallback& notifyUnbufferedIO)
+void saveBinContainer(const Zstring& filePath, const BinContainer& buffer, const IOCallback& notifyUnbufferedIO /*throw X*/) //throw FileError, X
 {
-    FileOutput fileOut(filePath, FileOutput::ACC_OVERWRITE, notifyUnbufferedIO); //throw FileError, (ErrorTargetExisting)
+    FileOutput fileOut(FileOutput::ACC_OVERWRITE, filePath, notifyUnbufferedIO); //throw FileError, (ErrorTargetExisting)
     if (!buffer.empty())
     {
         /*snake oil?*/ fileOut.preAllocateSpaceBestEffort(buffer.size()); //throw FileError
diff --git a/zen/format_unit.h b/zen/format_unit.h
index 3686f39c..de5a0811 100755
--- a/zen/format_unit.h
+++ b/zen/format_unit.h
@@ -24,7 +24,6 @@ std::wstring formatThreeDigitPrecision(double value); //(unless value is too lar
 
 std::wstring formatNumber(int64_t n); //format integer number including thousands separator
 
-
 }
 
 #endif
diff --git a/zen/legacy_compiler.h b/zen/legacy_compiler.h
index bebf5a05..54605945 100755
--- a/zen/legacy_compiler.h
+++ b/zen/legacy_compiler.h
@@ -27,10 +27,10 @@ public:
 
     template <class Container>
     span(Container& cont) : span(cont.begin(), cont.end()) {}
-    
+
     using iterator        = T*;
     using const_iterator  = const T*;
-       
+
     iterator begin() { return data_; }
     iterator end  () { return data_ + size_; }
 
diff --git a/zen/shutdown.cpp b/zen/shutdown.cpp
index 1794e4a8..a25e9c64 100755
--- a/zen/shutdown.cpp
+++ b/zen/shutdown.cpp
@@ -18,8 +18,7 @@ void zen::shutdownSystem() //throw FileError
     //https://linux.die.net/man/2/reboot => needs admin rights!
 
     //"systemctl" should work without admin rights:
-    shellExecute("sleep 1; systemctl poweroff", ExecutionType::ASYNC); //throw FileError
-    //sleep 1: give FFS some time to properly shut down!
+    shellExecute("systemctl poweroff", ExecutionType::SYNC); //throw FileError
 
 }
 
@@ -27,10 +26,20 @@ void zen::shutdownSystem() //throw FileError
 void zen::suspendSystem() //throw FileError
 {
     //"systemctl" should work without admin rights:
-    shellExecute("systemctl suspend", ExecutionType::ASYNC); //throw FileError
+    shellExecute("systemctl suspend", ExecutionType::SYNC); //throw FileError
 
 }
 
+
+void zen::terminateProcess(int exitCode)
+{
+    std::exit(exitCode); //[[noreturn]]; "Stack is not unwound: destructors of variables with automatic storage duration are not called." => perfect
+    //don't use std::abort() => crashes process with "EXC_CRASH (SIGABRT)" on macOS
+    for (;;) //why still here?? => crash deliberately!
+        *reinterpret_cast<volatile int*>(0) = 0; //crude but at least we'll get crash dumps if it happens
+}
+
+
 /*
 Command line alternatives:
 
diff --git a/zen/shutdown.h b/zen/shutdown.h
index df2314f8..2d66d1e8 100755
--- a/zen/shutdown.h
+++ b/zen/shutdown.h
@@ -14,6 +14,7 @@ namespace zen
 {
 void shutdownSystem(); //throw FileError
 void suspendSystem();  //
+void terminateProcess(int exitCode); //will NOT return!
 }
 
 #endif //SHUTDOWN_H_3423847870238407783265
diff --git a/zen/stl_tools.h b/zen/stl_tools.h
index d8bda888..f1ab7c16 100755
--- a/zen/stl_tools.h
+++ b/zen/stl_tools.h
@@ -57,7 +57,15 @@ BidirectionalIterator findLast(BidirectionalIterator first, BidirectionalIterato
 //replacement for std::find_end taking advantage of bidirectional iterators (and giving the algorithm a reasonable name)
 template <class BidirectionalIterator1, class BidirectionalIterator2>
 BidirectionalIterator1 searchLast(BidirectionalIterator1 first1, BidirectionalIterator1 last1,
-                                   BidirectionalIterator2 first2, BidirectionalIterator2 last2);
+                                  BidirectionalIterator2 first2, BidirectionalIterator2 last2);
+
+
+//read-only variant of std::merge; input: two sorted ranges
+template <class Iterator, class FunctionLeftOnly, class FunctionBoth, class FunctionRightOnly>
+void mergeTraversal(Iterator first1, Iterator last1,
+                    Iterator first2, Iterator last2,
+                    FunctionLeftOnly lo, FunctionBoth bo, FunctionRightOnly ro);
+
 
 template <class Num, class ByteIterator> Num hashBytes                   (ByteIterator first, ByteIterator last);
 template <class Num, class ByteIterator> Num hashBytesAppend(Num hashVal, ByteIterator first, ByteIterator last);
@@ -109,11 +117,13 @@ private:
 };
 
 template <class T, class... Args> inline
-SharedRef<T> makeSharedRef(Args&&... args) { return SharedRef<T>(std::make_shared<T>(std::forward<Args>(args)...)); }
+SharedRef<T> makeSharedRef(Args&& ... args) { return SharedRef<T>(std::make_shared<T>(std::forward<Args>(args)...)); }
 //===========================================================================
 
 
 
+
+
 //######################## implementation ########################
 
 template <class T, class Alloc, class Predicate> inline
@@ -208,7 +218,7 @@ BidirectionalIterator findLast(const BidirectionalIterator first, const Bidirect
 
 template <class BidirectionalIterator1, class BidirectionalIterator2> inline
 BidirectionalIterator1 searchLast(const BidirectionalIterator1 first1,       BidirectionalIterator1 last1,
-                                   const BidirectionalIterator2 first2, const BidirectionalIterator2 last2)
+                                  const BidirectionalIterator2 first2, const BidirectionalIterator2 last2)
 {
     const BidirectionalIterator1 itNotFound = last1;
 
@@ -233,6 +243,46 @@ BidirectionalIterator1 searchLast(const BidirectionalIterator1 first1,       Bid
 }
 
 
+//read-only variant of std::merge; input: two sorted ranges
+template <class Iterator, class FunctionLeftOnly, class FunctionBoth, class FunctionRightOnly> inline
+void mergeTraversal(Iterator first1, Iterator last1,
+                    Iterator first2, Iterator last2,
+                    FunctionLeftOnly lo, FunctionBoth bo, FunctionRightOnly ro)
+{
+    auto itL = first1;
+    auto itR = first2;
+
+    auto finishLeft  = [&] { std::for_each(itL, last1, lo); };
+    auto finishRight = [&] { std::for_each(itR, last2, ro); };
+
+    if (itL == last1) return finishRight();
+    if (itR == last2) return finishLeft ();
+
+    for (;;)
+        if (itL->first < itR->first)
+        {
+            lo(*itL);
+            if (++itL == last1)
+                return finishRight();
+        }
+        else if (itR->first < itL->first)
+        {
+            ro(*itR);
+            if (++itR == last2)
+                return finishLeft();
+        }
+        else
+        {
+            bo(*itL, *itR);
+            ++itL; //
+            ++itR; //increment BOTH before checking for end of range!
+            if (itL == last1) return finishRight();
+            if (itR == last2) return finishLeft ();
+            //simplify loop by placing both EOB checks at the beginning? => slightly slower
+        }
+}
+
+
 //FNV-1a: http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
 template <class Num, class ByteIterator> inline
 Num hashBytes(ByteIterator first, ByteIterator last)
diff --git a/zen/string_base.h b/zen/string_base.h
index 91a6d5bd..2247f93a 100755
--- a/zen/string_base.h
+++ b/zen/string_base.h
@@ -423,7 +423,7 @@ size_t Zbase<Char, SP>::rfind(const Char* str, size_t pos) const
     const size_t len = length();
     const Char* currEnd = begin() + (pos == npos ? len : std::min(pos + strLen, len));
     const Char* it = searchLast(begin(), currEnd,
-                                 str, str + strLen);
+                                str, str + strLen);
     return it == currEnd ? npos : it - begin();
 }
 
diff --git a/zen/string_tools.h b/zen/string_tools.h
index 8579a460..c3970d05 100755
--- a/zen/string_tools.h
+++ b/zen/string_tools.h
@@ -300,7 +300,7 @@ S afterLast(const S& str, const T& term, FailureReturnVal rv)
     const auto* const termFirst = strBegin(term);
 
     const auto* it = searchLast(strFirst, strLast,
-                                 termFirst, termFirst + termLen);
+                                termFirst, termFirst + termLen);
     if (it == strLast)
         return rv == IF_MISSING_RETURN_ALL ? str : S();
 
@@ -321,7 +321,7 @@ S beforeLast(const S& str, const T& term, FailureReturnVal rv)
     const auto* const termFirst = strBegin(term);
 
     const auto* it = searchLast(strFirst, strLast,
-                                 termFirst, termFirst + termLen);
+                                termFirst, termFirst + termLen);
     if (it == strLast)
         return rv == IF_MISSING_RETURN_ALL ? str : S();
 
diff --git a/zen/thread.h b/zen/thread.h
index 8a9adc87..5e298ba1 100755
--- a/zen/thread.h
+++ b/zen/thread.h
@@ -119,7 +119,7 @@ class Protected
 public:
     Protected() {}
     Protected(T& value) : value_(value) {}
-    //Protected(      T&& tmp ) : value_(std::move(tmp)) {} <- wait until needed
+    //Protected(T&& tmp ) : value_(std::move(tmp)) {} <- wait until needed
 
     template <class Function>
     auto access(Function fun) //-> decltype(fun(std::declval<T&>()))
diff --git a/zen/zlib_wrap.cpp b/zen/zlib_wrap.cpp
new file mode 100755
index 00000000..fbbe2f09
--- /dev/null
+++ b/zen/zlib_wrap.cpp
@@ -0,0 +1,53 @@
+// *****************************************************************************
+// * 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 *
+// *****************************************************************************
+
+#include "zlib_wrap.h"
+//Windows:     use the SAME zlib version that wxWidgets is linking against! //C:\Data\Projects\wxWidgets\Source\src\zlib\zlib.h
+//Linux/macOS: use zlib system header for both wxWidgets and Curl (zlib is required for HTTP)
+//             => don't compile wxWidgets with: --with-zlib=builtin
+#include <zlib.h>
+
+using namespace zen;
+
+
+size_t zen::impl::zlib_compressBound(size_t len)
+{
+    return ::compressBound(static_cast<uLong>(len)); //upper limit for buffer size, larger than input size!!!
+}
+
+
+size_t zen::impl::zlib_compress(const void* src, size_t srcLen, void* trg, size_t trgLen, int level) //throw ZlibInternalError
+{
+    uLongf bufferSize = static_cast<uLong>(trgLen);
+    const int rv = ::compress2(static_cast<Bytef*>(trg),       //Bytef* dest,
+                               &bufferSize,                    //uLongf* destLen,
+                               static_cast<const Bytef*>(src), //const Bytef* source,
+                               static_cast<uLong>(srcLen),     //uLong sourceLen,
+                               level);                         //int level
+    // Z_OK: success
+    // Z_MEM_ERROR: not enough memory
+    // Z_BUF_ERROR: not enough room in the output buffer
+    if (rv != Z_OK || bufferSize > trgLen)
+        throw ZlibInternalError();
+    return bufferSize;
+}
+
+
+size_t zen::impl::zlib_decompress(const void* src, size_t srcLen, void* trg, size_t trgLen) //throw ZlibInternalError
+{
+    uLongf bufferSize = static_cast<uLong>(trgLen);
+    const int rv = ::uncompress(static_cast<Bytef*>(trg),       //Bytef* dest,
+                                &bufferSize,                    //uLongf* destLen,
+                                static_cast<const Bytef*>(src), //const Bytef* source,
+                                static_cast<uLong>(srcLen));    //uLong sourceLen
+    // Z_OK: success
+    // Z_MEM_ERROR: not enough memory
+    // Z_BUF_ERROR: not enough room in the output buffer
+    // Z_DATA_ERROR: input data was corrupted or incomplete
+    if (rv != Z_OK || bufferSize > trgLen)
+        throw ZlibInternalError();
+    return bufferSize;
+}
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
diff --git a/zen/zstring.h b/zen/zstring.h
index a511e4e0..6727253b 100755
--- a/zen/zstring.h
+++ b/zen/zstring.h
@@ -32,9 +32,9 @@ Zstring makeUpperCopy(const Zstring& str);
 //Windows, Linux: precomposed
 //macOS: decomposed
 Zstring getUnicodeNormalForm(const Zstring& str);
-//	"In fact, Unicode declares that there is an equivalence relationship between decomposed and composed sequences, 
-//	and conformant software should not treat canonically equivalent sequences, whether composed or decomposed or something inbetween, as different."
-//																							http://www.win.tue.nl/~aeb/linux/uc/nfc_vs_nfd.html
+//  "In fact, Unicode declares that there is an equivalence relationship between decomposed and composed sequences,
+//  and conformant software should not treat canonically equivalent sequences, whether composed or decomposed or something inbetween, as different."
+//                                                                                          http://www.win.tue.nl/~aeb/linux/uc/nfc_vs_nfd.html
 
 struct LessUnicodeNormal { bool operator()(const Zstring& lhs, const Zstring& rhs) const { return getUnicodeNormalForm(lhs) < getUnicodeNormalForm(rhs);} };