4.5

6 files changed, 200 insertions, 99 deletions

diff --git a/zen/FindFilePlus/find_file_plus.cpp b/zen/FindFilePlus/find_file_plus.cpp
index becfe553..e613177b 100644
--- a/zen/FindFilePlus/find_file_plus.cpp
+++ b/zen/FindFilePlus/find_file_plus.cpp
@@ -10,16 +10,18 @@
 #include "load_dll.h"
 #include <zen/scope_guard.h>
 
+#include <cstdio>
+
 using namespace dll;
 using namespace findplus;
 
 
 namespace
 {
-struct FileError
+struct NtFileError //exception class
 {
-    FileError(ULONG errorCode) : win32Error(errorCode) {}
-    ULONG win32Error;
+    NtFileError(NTSTATUS errorCode) : ntError(errorCode) {}
+    NTSTATUS ntError;
 };
 
 
@@ -91,8 +93,8 @@ bool findplus::initDllBinding() //evaluate in ::DllMain() when attaching process
     //http://msdn.microsoft.com/en-us/library/ff563638(v=VS.85).aspx
 
     //verify dynamic dll binding
-    return ntOpenFile &&
-           ntClose    &&
+    return ntOpenFile            &&
+           ntClose               &&
            ntQueryDirectoryFile  &&
            rtlNtStatusToDosError &&
            rtlFreeUnicodeString  &&
@@ -108,9 +110,15 @@ public:
     FileSearcher(const wchar_t* dirname); //throw FileError
     ~FileSearcher();
 
-    void readdir(FileInformation& output); //throw FileError
+    void readDir(FileInformation& output) { (this->*readDirFun)(output); } //throw FileError
+
+    bool tryFallbackToDefaultQuery(); //call if readDir() throws STATUS_NOT_SUPPORTED or similar
 
 private:
+    template <class QueryPolicy> void readDirImpl(FileInformation& output); //throw FileError
+    //handle fallback, if retrieving file id is not supported by file system layer
+    void (FileSearcher::*readDirFun)(FileInformation& output);
+
     UNICODE_STRING ntPathName; //it seems hDir implicitly keeps a reference to this, at least ::FindFirstFile() does no cleanup before ::FindClose()!
     HANDLE hDir;
 
@@ -124,9 +132,43 @@ private:
 };
 
 
+namespace
+{
+/*
+Common C-style policy handling directory traversal:
+
+struct QueryPolicy
+{
+	typedef ... RawFileInfo;
+	static const FILE_INFORMATION_CLASS fileInformationClass = ...;
+	static void extractFileId(const RawFileInfo& rawInfo, FileInformation& fileInfo);
+};
+*/
+
+struct DirQueryDefault
+{
+    typedef FILE_BOTH_DIR_INFORMATION RawFileInfo;
+    static const FILE_INFORMATION_CLASS fileInformationClass = FileBothDirectoryInformation;
+    static void extractFileId(const RawFileInfo& rawInfo, FileInformation& fileInfo) { fileInfo.fileId.QuadPart = 0; }
+};
+
+struct DirQueryFileId
+{
+    typedef FILE_ID_BOTH_DIR_INFORMATION RawFileInfo;
+    static const FILE_INFORMATION_CLASS fileInformationClass = FileIdBothDirectoryInformation;
+    static void extractFileId(const RawFileInfo& rawInfo, FileInformation& fileInfo)
+    {
+        fileInfo.fileId.QuadPart = rawInfo.FileId.QuadPart; //may be 0 even in this context, e.g. for mapped FTP drive!
+        static_assert(sizeof(fileInfo.fileId) == sizeof(rawInfo.FileId), "dang!");
+    }
+};
+}
+
+
 FileSearcher::FileSearcher(const wchar_t* dirname) :
     hDir(NULL),
-    nextEntryOffset(0)
+    nextEntryOffset(0),
+    readDirFun(&FileSearcher::readDirImpl<DirQueryFileId>) //start optimistically
 {
     ntPathName.Buffer = NULL;
     ntPathName.Length = 0;
@@ -136,7 +178,8 @@ FileSearcher::FileSearcher(const wchar_t* dirname) :
     //--------------------------------------------------------------------------------------------------------------
 
     //convert dosFileName, e.g. C:\Users or \\?\C:\Users to ntFileName \??\C:\Users
-    //in contrast to ::FindFirstFile() we don't evaluate the relativeName, however tests indicate ntFileName is *always* filled with an absolute name, even if dosFileName is relative
+    //in contrast to ::FindFirstFile() implementation we don't evaluate the relativeName,
+    //however tests indicate ntFileName is *always* filled with an absolute name, even if dosFileName is relative
 
     //NOTE: RtlDosPathNameToNtPathName_U may be used on all XP/Win7/Win8 for compatibility
     //		RtlDosPathNameToNtPathName_U:         used by Windows XP          available with OS version 3.51 (Windows NT) and higher
@@ -145,7 +188,7 @@ FileSearcher::FileSearcher(const wchar_t* dirname) :
                                       &ntPathName, //__out ntFileName,
                                       NULL,        //__out_optFilePart,
                                       NULL))       //__out_opt relativeName - empty if dosFileName is absolute
-        throw FileError(rtlNtStatusToDosError(STATUS_OBJECT_PATH_NOT_FOUND)); //translates to ERROR_PATH_NOT_FOUND, same behavior like ::FindFirstFileEx()
+        throw NtFileError(STATUS_OBJECT_PATH_NOT_FOUND); //translates to ERROR_PATH_NOT_FOUND, same behavior like ::FindFirstFileEx()
 
     OBJECT_ATTRIBUTES objAttr = {};
     InitializeObjectAttributes(&objAttr,    //[out]           POBJECT_ATTRIBUTES initializedAttributes,
@@ -163,7 +206,7 @@ FileSearcher::FileSearcher(const wchar_t* dirname) :
                                  FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, //__in ULONG shareAccess, - 7 on Win7/Win8, 3 on XP
                                  FILE_DIRECTORY_FILE | FILE_SYNCHRONOUS_IO_NONALERT | FILE_OPEN_FOR_BACKUP_INTENT); //__in ULONG openOptions - 4021 used on all XP/Win7/Win8
         if (!NT_SUCCESS(rv))
-            throw FileError(rtlNtStatusToDosError(rv));
+            throw NtFileError(rv);
     }
 
     guardConstructor.dismiss();
@@ -179,16 +222,33 @@ FileSearcher::~FileSearcher()
 
     if (ntPathName.Buffer)
         rtlFreeUnicodeString(&ntPathName); //cleanup identical to ::FindFirstFile()
-    //note that most if this function seems inlined by the linker, so that its assembly looks equivalent to "RtlFreeHeap(GetProcessHeap(), 0, ntPathName.Buffer)"
+    //note that most of this function seems inlined by the linker, so that its assembly looks equivalent to "RtlFreeHeap(GetProcessHeap(), 0, ntPathName.Buffer)"
+}
+
+
+inline
+bool FileSearcher::tryFallbackToDefaultQuery()
+{
+    if (readDirFun == &FileSearcher::readDirImpl<DirQueryDefault>)
+        return false; //already default
+
+    //Note: NtQueryDirectoryFile() may not respect "restartScan" for some weird Win2000 file system drivers, so we won't bother
+    //Samba before v3.0.22 (Mar 30, 2006) seems to have a bug which sucessfully returns 128 elements via NtQueryDirectoryFile()
+    //and FileIdBothDirectoryInformation, then fails with STATUS_INVALID_LEVEL.
+    //Although traversal is NOT finished yet, it will further return STATUS_NO_MORE_FILES, even if falling back to FileBothDirectoryInformation!!!
+
+    readDirFun = &FileSearcher::readDirImpl<DirQueryDefault>;
+    return true;
 }
 
 
-void FileSearcher::readdir(FileInformation& output)
+template <class QueryPolicy>
+void FileSearcher::readDirImpl(FileInformation& output) //throw FileError
 {
     //although FILE_ID_FULL_DIR_INFORMATION should suffice for our purposes, there are problems on Windows XP for certain directories, e.g. "\\Vboxsvr\build"
     //making NtQueryDirectoryFile() return with STATUS_INVALID_PARAMETER while other directories, e.g. "C:\" work fine for some reason
     //FILE_ID_BOTH_DIR_INFORMATION on the other hand works on XP/Win7/Win8
-    //performance: there is no noticable difference between FILE_ID_BOTH_DIR_INFORMATION and FILE_ID_FULL_DIR_INFORMATION
+    //performance: there is no noticeable difference between FILE_ID_BOTH_DIR_INFORMATION and FILE_ID_FULL_DIR_INFORMATION
 
     /* corresponding first access in ::FindFirstFileW()
 
@@ -216,18 +276,26 @@ void FileSearcher::readdir(FileInformation& output)
                                            &status,     //__out PIO_STATUS_BLOCK ioStatusBlock,
                                            &buffer,     //__out_bcount(Length) PVOID fileInformation,
                                            BUFFER_SIZE, //__in ULONG length, ::FindNextFileW() on all XP/Win7/Win8 uses sizeof(FILE_BOTH_DIR_INFORMATION) + sizeof(TCHAR) * 2000 == 0x1000
-                                           FileIdBothDirectoryInformation, //__in FILE_INFORMATION_CLASS fileInformationClass - all XP/Win7/Win8 use "FileBothDirectoryInformation"
+                                           QueryPolicy::fileInformationClass, //__in FILE_INFORMATION_CLASS fileInformationClass - all XP/Win7/Win8 use "FileBothDirectoryInformation"
                                            false,       //__in BOOLEAN returnSingleEntry,
                                            NULL,        //__in_opt PUNICODE_STRING mask,
                                            false);      //__in BOOLEAN restartScan
         if (!NT_SUCCESS(rv))
-            throw FileError(rtlNtStatusToDosError(rv)); //throws STATUS_NO_MORE_FILES when finished
+        {
+            if (rv == STATUS_NO_SUCH_FILE) //harmonize ntQueryDirectoryFile() error handling! failure to find a file on first call returns STATUS_NO_SUCH_FILE,
+                rv = STATUS_NO_MORE_FILES; //while on subsequent accesses return STATUS_NO_MORE_FILES
+            //note: not all directories contain "., .." entries! E.g. a drive's root directory or NetDrive + ftp.gnu.org\CRYPTO.README"
+            //-> addon: this is NOT a directory, it looks like on in NetDrive, but it's a file in Opera
+
+            throw NtFileError(rv); //throws STATUS_NO_MORE_FILES when finished
+        }
 
-        if (status.Information == 0)                                        //except for the first call to call ::NtQueryDirectoryFile():
-            throw FileError(rtlNtStatusToDosError(STATUS_BUFFER_OVERFLOW)); //if buffer size is too small, return value is STATUS_SUCCESS and Information == 0 -> we don't expect this!
+        if (status.Information == 0)                   //except for the first call to call ::NtQueryDirectoryFile():
+            throw NtFileError(STATUS_BUFFER_OVERFLOW); //if buffer size is too small, return value is STATUS_SUCCESS and Information == 0 -> we don't expect this!
     }
 
-    const FILE_ID_BOTH_DIR_INFORMATION& dirInfo = *reinterpret_cast<FILE_ID_BOTH_DIR_INFORMATION*>(reinterpret_cast<char*>(buffer) + nextEntryOffset);
+    typedef typename QueryPolicy::RawFileInfo RawFileInfo;
+    const RawFileInfo& dirInfo = *reinterpret_cast<RawFileInfo*>(reinterpret_cast<char*>(buffer) + nextEntryOffset);
 
     if (dirInfo.NextEntryOffset == 0)
         nextEntryOffset = 0; //our offset is relative to the beginning of the buffer
@@ -241,15 +309,16 @@ void FileSearcher::readdir(FileInformation& output)
         return tmp;
     };
 
+    QueryPolicy::extractFileId(dirInfo, output);
+
     output.creationTime      = toFileTime(dirInfo.CreationTime);
     output.lastWriteTime     = toFileTime(dirInfo.LastWriteTime);
     output.fileSize.QuadPart = dirInfo.EndOfFile.QuadPart;
-    output.fileId.QuadPart   = dirInfo.FileId.QuadPart;
     output.fileAttributes    = dirInfo.FileAttributes;
     output.shortNameLength   = dirInfo.FileNameLength / sizeof(TCHAR); //FileNameLength is in bytes!
 
     if (dirInfo.FileNameLength + sizeof(TCHAR) > sizeof(output.shortName)) //this may actually happen if ::NtQueryDirectoryFile() decides to return a
-        throw FileError(rtlNtStatusToDosError(STATUS_BUFFER_OVERFLOW));    //short name of length MAX_PATH + 1, 0-termination is not required!
+        throw NtFileError(STATUS_BUFFER_OVERFLOW);    //short name of length MAX_PATH + 1, 0-termination is not required!
 
     ::memcpy(output.shortName, dirInfo.FileName, dirInfo.FileNameLength);
     output.shortName[output.shortNameLength] = 0; //NOTE: FILE_ID_BOTH_DIR_INFORMATION::FileName in general is NOT 0-terminated! It is on XP/Win7, but NOT on Win8!
@@ -257,7 +326,6 @@ void FileSearcher::readdir(FileInformation& output)
     static_assert(sizeof(output.creationTime)   == sizeof(dirInfo.CreationTime),   "dang!");
     static_assert(sizeof(output.lastWriteTime)  == sizeof(dirInfo.LastWriteTime),  "dang!");
     static_assert(sizeof(output.fileSize)       == sizeof(dirInfo.EndOfFile),      "dang!");
-    static_assert(sizeof(output.fileId)         == sizeof(dirInfo.FileId),         "dang!");
     static_assert(sizeof(output.fileAttributes) == sizeof(dirInfo.FileAttributes), "dang!");
 }
 
@@ -268,10 +336,10 @@ FindHandle findplus::openDir(const wchar_t* dirname)
     {
         return new FileSearcher(dirname); //throw FileError
     }
-    catch (const FileError& err)
+    catch (const NtFileError& e)
     {
-        setWin32Error(err.win32Error);
-        return NULL;
+        setWin32Error(rtlNtStatusToDosError(e.ntError));
+        return nullptr;
     }
 }
 
@@ -280,12 +348,28 @@ bool findplus::readDir(FindHandle hnd, FileInformation& output)
 {
     try
     {
-        hnd->readdir(output); //throw FileError
+        hnd->readDir(output); //throw FileError
         return true;
     }
-    catch (const FileError& err)
+    catch (const NtFileError& e)
     {
-        setWin32Error(err.win32Error);
+        /*
+        fallback to default directory query method, if FileIdBothDirectoryInformation is not properly implemented
+        this is required for NetDrive mounted Webdav, e.g. www.box.net and NT4, 2000 remote drives, et al.
+        */
+        if (e.ntError != STATUS_NO_MORE_FILES)
+            if (e.ntError == STATUS_INVALID_LEVEL            ||
+                e.ntError == STATUS_NOT_SUPPORTED            ||
+                e.ntError == STATUS_INVALID_PARAMETER        ||
+                e.ntError == STATUS_INVALID_NETWORK_RESPONSE ||
+                e.ntError == STATUS_INVALID_INFO_CLASS       ||
+                e.ntError == STATUS_ACCESS_VIOLATION) //FileIdBothDirectoryInformation on XP accessing UDF
+            {
+                if (hnd->tryFallbackToDefaultQuery())
+                    return readDir(hnd, output); //implementation of tryFallbackToDefaultQuery() promises, that we don't land in an endless recursion here!
+            }
+
+        setWin32Error(rtlNtStatusToDosError(e.ntError));
         return false;
     }
 }
@@ -293,6 +377,5 @@ bool findplus::readDir(FindHandle hnd, FileInformation& output)
 
 void findplus::closeDir(FindHandle hnd)
 {
-    if (hnd) //play a little "nice"
-        delete hnd;
+    delete hnd;
 }
diff --git a/zen/FindFilePlus/find_file_plus.h b/zen/FindFilePlus/find_file_plus.h
index 72b76dbb..33e9a178 100644
--- a/zen/FindFilePlus/find_file_plus.h
+++ b/zen/FindFilePlus/find_file_plus.h
@@ -34,7 +34,7 @@ struct FileInformation
     FILETIME creationTime;
     FILETIME lastWriteTime;
     ULARGE_INTEGER fileSize;
-    ULARGE_INTEGER fileId;
+    ULARGE_INTEGER fileId; //optional: may be 0 if not supported
     DWORD fileAttributes;
     DWORD shortNameLength;
     WCHAR shortName[MAX_PATH + 1]; //shortName is 0-terminated
diff --git a/zen/FindFilePlus/load_dll.h b/zen/FindFilePlus/load_dll.h
index 350de9f8..24ce7174 100644
--- a/zen/FindFilePlus/load_dll.h
+++ b/zen/FindFilePlus/load_dll.h
@@ -39,7 +39,6 @@ private:
 
 
 
-
 void* /*FARPROC*/ loadSymbol(const wchar_t* libraryName, const char* functionName);
 }
 
diff --git a/zen/file_handling.cpp b/zen/file_handling.cpp
index 1e44afb7..d6804e34 100644
--- a/zen/file_handling.cpp
+++ b/zen/file_handling.cpp
@@ -2008,12 +2008,12 @@ void rawCopyStream(const Zstring& sourceFile,
         FileOutput fileOut(targetFile, FileOutput::ACC_CREATE_NEW); //throw FileError, ErrorTargetPathMissing, ErrorTargetExisting
 
         std::vector<char>& buffer = []() -> std::vector<char>&
-       {
-               static boost::thread_specific_ptr<std::vector<char>> cpyBuf;
-        if (!cpyBuf.get())
-            cpyBuf.reset(new std::vector<char>(512 * 1024)); //512 kb seems to be a reasonable buffer size
+        {
+            static boost::thread_specific_ptr<std::vector<char>> cpyBuf;
+            if (!cpyBuf.get())
+                cpyBuf.reset(new std::vector<char>(512 * 1024)); //512 kb seems to be a reasonable buffer size
             return *cpyBuf;
-       }();
+        }();
 
         //copy contents of sourceFile to targetFile
         UInt64 totalBytesTransferred;
diff --git a/zen/file_id_def.h b/zen/file_id_def.h
index b2029879..7e729eb1 100644
--- a/zen/file_id_def.h
+++ b/zen/file_id_def.h
@@ -29,13 +29,16 @@ FileId extractFileID(const BY_HANDLE_FILE_INFORMATION& fileInfo)
     ULARGE_INTEGER uint = {};
     uint.HighPart = fileInfo.nFileIndexHigh;
     uint.LowPart  = fileInfo.nFileIndexLow;
-    return std::make_pair(fileInfo.dwVolumeSerialNumber, uint.QuadPart);
+
+    return fileInfo.dwVolumeSerialNumber != 0 && uint.QuadPart != 0 ?
+           FileId(fileInfo.dwVolumeSerialNumber, uint.QuadPart) : FileId();
 }
 
 inline
 FileId extractFileID(DWORD dwVolumeSerialNumber, ULARGE_INTEGER fileId)
 {
-    return std::make_pair(dwVolumeSerialNumber, fileId.QuadPart);
+    return dwVolumeSerialNumber != 0 && fileId.QuadPart != 0 ?
+           FileId(dwVolumeSerialNumber, fileId.QuadPart) : FileId();
 }
 
 namespace impl
@@ -57,7 +60,8 @@ typedef std::pair<decltype(impl::StatDummy::st_dev), decltype(impl::StatDummy::s
 inline
 FileId extractFileID(const struct stat& fileInfo)
 {
-    return std::make_pair(fileInfo.st_dev, fileInfo.st_ino);
+    return fileInfo.st_dev != 0 && fileInfo.st_ino != 0 ?
+           FileId(fileInfo.st_dev, fileInfo.st_ino) : FileId();
 }
 #endif
 }
diff --git a/zen/file_traverser.cpp b/zen/file_traverser.cpp
index 8a8a8b6f..236581a3 100644
--- a/zen/file_traverser.cpp
+++ b/zen/file_traverser.cpp
@@ -31,13 +31,13 @@ namespace
 //implement "retry" in a generic way:
 
 template <class Command> inline //function object expecting to throw FileError if operation fails
-void tryReportingError(Command cmd, zen::TraverseCallback& callback)
+bool tryReportingError(Command cmd, zen::TraverseCallback& callback) //return "true" on success, "false" if error was ignored
 {
     for (;;)
         try
         {
             cmd();
-            return;
+            return true;
         }
         catch (const FileError& e)
         {
@@ -46,7 +46,7 @@ void tryReportingError(Command cmd, zen::TraverseCallback& callback)
                 case TraverseCallback::TRAV_ERROR_RETRY:
                     break;
                 case TraverseCallback::TRAV_ERROR_IGNORE:
-                    return;
+                    return false;
                 default:
                     assert(false);
                     break;
@@ -119,18 +119,17 @@ const DllFun<findplus::OpenDirFunc>  openDir (findplus::getDllName(), findplus::
 const DllFun<findplus::ReadDirFunc>  readDir (findplus::getDllName(), findplus::readDirFuncName ); //load at startup: avoid pre C++11 static initialization MT issues
 const DllFun<findplus::CloseDirFunc> closeDir(findplus::getDllName(), findplus::closeDirFuncName); //
 
-
 /*
 Common C-style interface for Win32 FindFirstFile(), FindNextFile() and FileFilePlus openDir(), closeDir():
-struct X //see "policy based design"
+struct TraverserPolicy //see "policy based design"
 {
-typedef ... Handle;
+typedef ... DirHandle;
 typedef ... FindData;
-static Handle create(const Zstring& directoryPf, FindData& fileInfo); //throw FileError - concession to FindFirstFile(): implement two operations: 1. open handle, 2. retrieve first data set
-static void destroy(Handle hnd); //throw()
-static bool next(Handle hnd, const Zstring& directory, WIN32_FIND_DATA& fileInfo) //throw FileError
+static void create(const Zstring& directory, DirHandle& hnd); //throw FileError - *no* concession to FindFirstFile(): open handle only, *no* return of data!
+static void destroy(DirHandle hnd); //throw()
+static bool getEntry(DirHandle hnd, const Zstring& directory, FindData& fileInfo) //throw FileError
 
-//helper routines
+//FindData "member" functions
 static void extractFileInfo            (const FindData& fileInfo, const DWORD* volumeSerial, TraverseCallback::FileInfo& output);
 static Int64 getModTime                (const FindData& fileInfo);
 static const FILETIME& getModTimeRaw   (const FindData& fileInfo); //yet another concession to DST hack
@@ -140,35 +139,54 @@ static bool isDirectory                (const FindData& fileInfo);
 static bool isSymlink                  (const FindData& fileInfo);
 }
 
-Note: Win32 FindFirstFile(), FindNextFile() is a weaker abstraction than FileFilePlus openDir(), readDir(), closeDir() and Unix opendir(), closedir(), stat(),
-      so unfortunately we have to use former as a greatest common divisor
+Note: Win32 FindFirstFile(), FindNextFile() is a weaker abstraction than FileFilePlus openDir(), readDir(), closeDir() and Unix opendir(), closedir(), stat()
 */
 
 
 struct Win32Traverser
 {
-    typedef HANDLE Handle;
+    struct DirHandle
+    {
+        DirHandle() : searchHandle(NULL), firstRead(true) {}
+
+        HANDLE searchHandle;
+        bool firstRead;
+        WIN32_FIND_DATA firstData;
+    };
+
     typedef WIN32_FIND_DATA FindData;
 
-    static Handle create(const Zstring& directory, FindData& fileInfo) //throw FileError
+    static void create(const Zstring& directory, DirHandle& hnd) //throw FileError
     {
         const Zstring& directoryPf = endsWith(directory, FILE_NAME_SEPARATOR) ?
                                      directory :
                                      directory + FILE_NAME_SEPARATOR;
 
-        HANDLE output = ::FindFirstFile(applyLongPathPrefix(directoryPf + L'*').c_str(), &fileInfo);
+        hnd.searchHandle = ::FindFirstFile(applyLongPathPrefix(directoryPf + L'*').c_str(), &hnd.firstData);
         //no noticable performance difference compared to FindFirstFileEx with FindExInfoBasic, FIND_FIRST_EX_CASE_SENSITIVE and/or FIND_FIRST_EX_LARGE_FETCH
-        if (output == INVALID_HANDLE_VALUE)
+        if (hnd.searchHandle == INVALID_HANDLE_VALUE)
             throw FileError(_("Error traversing directory:") + L"\n\"" + directory + L"\"" + L"\n\n" + zen::getLastErrorFormatted());
-        //::GetLastError() == ERROR_FILE_NOT_FOUND -> actually NOT okay, even for an empty directory this should not occur (., ..)
-        return output;
+
+        //::GetLastError() == ERROR_FILE_NOT_FOUND -> *usually* NOT okay:
+        //however it is unclear whether this indicates a missing directory or a completely empty directory
+        //      note: not all directories contain "., .." entries! E.g. a drive's root directory or NetDrive + ftp.gnu.org\CRYPTO.README"
+        //      -> addon: this is NOT a directory, it looks like one in NetDrive, but it's a file in Opera!
+        //we have to guess it's former and let the error propagate
+        // -> FindFirstFile() is a nice example of violation of API design principle of single responsibility and its consequences
     }
 
-    static void destroy(Handle hnd) { ::FindClose(hnd); } //throw()
+    static void destroy(const DirHandle& hnd) { ::FindClose(hnd.searchHandle); } //throw()
 
-    static bool next(Handle hnd, const Zstring& directory, FindData& fileInfo) //throw FileError
+    static bool getEntry(DirHandle& hnd, const Zstring& directory, FindData& fileInfo) //throw FileError
     {
-        if (!::FindNextFile(hnd, &fileInfo))
+        if (hnd.firstRead)
+        {
+            hnd.firstRead = false;
+            ::memcpy(&fileInfo, &hnd.firstData, sizeof(fileInfo));
+            return true;
+        }
+
+        if (!::FindNextFile(hnd.searchHandle, &fileInfo))
         {
             if (::GetLastError() == ERROR_NO_MORE_FILES) //not an error situation
                 return false;
@@ -178,7 +196,6 @@ struct Win32Traverser
         return true;
     }
 
-    //helper routines
     template <class FindData>
     static void extractFileInfo(const FindData& fileInfo, const DWORD* volumeSerial, TraverseCallback::FileInfo& output)
     {
@@ -208,27 +225,27 @@ struct Win32Traverser
 
 struct FilePlusTraverser
 {
-    typedef findplus::FindHandle Handle;
+    struct DirHandle
+    {
+        DirHandle() : searchHandle(NULL) {}
+
+        findplus::FindHandle searchHandle;
+    };
+
     typedef findplus::FileInformation FindData;
 
-    static Handle create(const Zstring& directory, FindData& fileInfo) //throw FileError
+    static void create(const Zstring& directory, DirHandle& hnd) //throw FileError
     {
-        Handle output = ::openDir(applyLongPathPrefix(directory).c_str());
-        if (output == NULL)
+        hnd.searchHandle = ::openDir(applyLongPathPrefix(directory).c_str());
+        if (hnd.searchHandle == NULL)
             throw FileError(_("Error traversing directory:") + L"\n\"" + directory + L"\"" + L"\n\n" + zen::getLastErrorFormatted());
-
-        bool rv = next(output, directory, fileInfo); //throw FileError
-        if (!rv) //we expect at least two successful reads, even for an empty directory: ., ..
-            throw FileError(_("Error traversing directory:") + L"\n\"" + directory + L"\"" + L"\n\n" + zen::getLastErrorFormatted(ERROR_NO_MORE_FILES));
-
-        return output;
     }
 
-    static void destroy(Handle hnd) { ::closeDir(hnd); } //throw()
+    static void destroy(DirHandle hnd) { ::closeDir(hnd.searchHandle); } //throw()
 
-    static bool next(Handle hnd, const Zstring& directory, FindData& fileInfo) //throw FileError
+    static bool getEntry(DirHandle hnd, const Zstring& directory, FindData& fileInfo) //throw FileError
     {
-        if (!::readDir(hnd, fileInfo))
+        if (!::readDir(hnd.searchHandle, fileInfo))
         {
             if (::GetLastError() == ERROR_NO_MORE_FILES) //not an error situation
                 return false;
@@ -238,7 +255,6 @@ struct FilePlusTraverser
         return true;
     }
 
-    //helper routines
     template <class FindData>
     static void extractFileInfo(const FindData& fileInfo, const DWORD* volumeSerial, TraverseCallback::FileInfo& output)
     {
@@ -305,31 +321,43 @@ private:
                 throw FileError(_("Endless loop when traversing directory:") + L"\n\"" + directory + L"\"");
         }, sink);
 
-        typename Trav::FindData fileInfo = {};
-
-        typename Trav::Handle searchHandle = 0;
+        typename Trav::DirHandle searchHandle;
 
-        tryReportingError([&]
+        const bool openSuccess = tryReportingError([&]
         {
             typedef Trav Trav; //f u VS!
-            searchHandle = Trav::create(directory, fileInfo); //throw FileError
+            Trav::create(directory, searchHandle); //throw FileError
         }, sink);
 
-        if (searchHandle == 0)
+        if (!openSuccess)
             return; //ignored error
         ZEN_ON_BLOCK_EXIT(typedef Trav Trav; Trav::destroy(searchHandle));
 
-        do
+        typename Trav::FindData fileInfo = {};
+
+        while ([&]() -> bool
+    {
+        bool moreData = false;
+
+        typedef Trav Trav1; //f u VS!
+        tryReportingError([&]
         {
-            //don't return "." and ".."
+            typedef Trav1 Trav; //f u VS!
+            moreData = Trav::getEntry(searchHandle, directory, fileInfo); //throw FileError
+            }, sink);
+
+            return moreData;
+        }())
+        {
+            //skip "." and ".."
             const Zchar* const shortName = Trav::getShortName(fileInfo);
             if (shortName[0] == L'.' &&
-                (shortName[1] == L'\0' || (shortName[1] == L'.' && shortName[2] == L'\0')))
+            (shortName[1] == L'\0' || (shortName[1] == L'.' && shortName[2] == L'\0')))
                 continue;
 
             const Zstring& fullName = endsWith(directory, FILE_NAME_SEPARATOR) ?
-                                      directory + shortName :
-                                      directory + FILE_NAME_SEPARATOR + shortName;
+            directory + shortName :
+            directory + FILE_NAME_SEPARATOR + shortName;
 
             if (Trav::isSymlink(fileInfo) && !followSymlinks_) //evaluate symlink directly
             {
@@ -383,19 +411,6 @@ private:
                 sink.onFile(shortName, fullName, details);
             }
         }
-        while ([&]() -> bool
-    {
-        bool moreData = false;
-
-        typedef Trav Trav1; //f u VS!
-        tryReportingError([&]
-        {
-            typedef Trav1 Trav; //f u VS!
-            moreData = Trav::next(searchHandle, directory, fileInfo); //throw FileError
-            }, sink);
-
-            return moreData;
-        }());
     }