I’m working on wrapping up the ugly innards of the FindFirstFile / FindNextFile loop

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Asked: May 14, 20262026-05-14T02:10:49+00:00 2026-05-14T02:10:49+00:00

I’m working on wrapping up the ugly innards of the FindFirstFile / FindNextFile loop

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I’m working on wrapping up the ugly innards of the FindFirstFile/FindNextFile loop (though my question applies to other similar APIs, such as RegEnumKeyEx or RegEnumValue, etc.) inside iterators that work in a manner similar to the Standard Template Library’s istream_iterators.

I have two problems here. The first is with the termination condition of most “foreach” style loops. STL style iterators typically use operator!= inside the exit condition of the for, i.e.

std::vector<int> test;
for(std::vector<int>::iterator it = test.begin(); it != test.end(); it++) {
 //Do stuff
}

My problem is I’m unsure how to implement operator!= with such a directory enumeration, because I do not know when the enumeration is complete until I’ve actually finished with it. I have sort of a hack together solution in place now that enumerates the entire directory at once, where each iterator simply tracks a reference counted vector, but this seems like a kludge which can be done a better way.

The second problem I have is that there are multiple pieces of data returned by the FindXFile APIs. For that reason, there’s no obvious way to overload operator* as required for iterator semantics. When I overload that item, do I return the file name? The size? The modified date? How might I convey the multiple pieces of data to which such an iterator must refer to later in an ideomatic way? I’ve tried ripping off the C# style MoveNext design but I’m concerned about not following the standard idioms here.

class SomeIterator {
public:
 bool next(); //Advances the iterator and returns true if successful, false if the iterator is at the end.
 std::wstring fileName() const;
 //other kinds of data....
};

EDIT: And the caller would look like:

SomeIterator x = ??; //Construct somehow
while(x.next()) {
    //Do stuff
}

Thanks!

Billy3

EDIT2: I have fixed some bugs and written some tests.

Implementation:

#pragma once
#include <queue>
#include <string>
#include <boost/noncopyable.hpp>
#include <boost/make_shared.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <Windows.h>
#include <Shlwapi.h>
#pragma comment(lib, "shlwapi.lib")
#include "../Exception.hpp"

namespace WindowsAPI { namespace FileSystem {

template <typename Filter_T = AllResults, typename Recurse_T = NonRecursiveEnumeration>
class DirectoryIterator;

//For unit testing
struct RealFindXFileFunctions
{
    static HANDLE FindFirst(LPCWSTR lpFileName, LPWIN32_FIND_DATAW lpFindFileData) {
        return FindFirstFile(lpFileName, lpFindFileData);
    };
    static BOOL FindNext(HANDLE hFindFile, LPWIN32_FIND_DATAW lpFindFileData) {
        return FindNextFile(hFindFile, lpFindFileData);
    };
    static BOOL Close(HANDLE hFindFile) {
        return FindClose(hFindFile);
    };
};

inline std::wstring::const_iterator GetLastSlash(std::wstring const&pathSpec) {
    return std::find(pathSpec.rbegin(), pathSpec.rend(), L'\\').base();
}

class Win32FindData {
    WIN32_FIND_DATA internalData;
    std::wstring rootPath;
public:
    Win32FindData(const std::wstring& root, const WIN32_FIND_DATA& data) :
        rootPath(root), internalData(data) {};
    DWORD GetAttributes() const {
        return internalData.dwFileAttributes;
    };
    bool IsDirectory() const {
        return (internalData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
    };
    bool IsFile() const {
        return !IsDirectory();
    };
    unsigned __int64 GetSize() const {
        ULARGE_INTEGER intValue;
        intValue.LowPart = internalData.nFileSizeLow;
        intValue.HighPart = internalData.nFileSizeHigh;
        return intValue.QuadPart;
    };
    std::wstring GetFolderPath() const {
        return rootPath;
    };
    std::wstring GetFileName() const {
        return internalData.cFileName;
    };
    std::wstring GetFullFileName() const {
        return rootPath + L"\\" + internalData.cFileName;
    };
    std::wstring GetShortFileName() const {
        return internalData.cAlternateFileName;
    };
    FILETIME GetCreationTime() const {
        return internalData.ftCreationTime;
    };
    FILETIME GetLastAccessTime() const {
        return internalData.ftLastAccessTime;
    };
    FILETIME GetLastWriteTime() const {
        return internalData.ftLastWriteTime;
    };
};

template <typename FindXFileFunctions_T>
class BasicNonRecursiveEnumeration : public boost::noncopyable
{
    WIN32_FIND_DATAW currentData;
    HANDLE hFind;
    std::wstring currentDirectory;
    void IncrementCurrentDirectory() {
        if (hFind == INVALID_HANDLE_VALUE) return;
        BOOL success =
            FindXFileFunctions_T::FindNext(hFind, &currentData);
        if (success)
            return;
        DWORD error = GetLastError();
        if (error == ERROR_NO_MORE_FILES) {
            FindXFileFunctions_T::Close(hFind);
            hFind = INVALID_HANDLE_VALUE;
        } else {
            WindowsApiException::Throw(error);
        }
    };
    bool IsValidDotDirectory()
    {
        return !Valid() &&
            (!wcscmp(currentData.cFileName, L".") || !wcscmp(currentData.cFileName, L".."));
    };
    void IncrementPastDotDirectories() {
        while (IsValidDotDirectory()) {
            IncrementCurrentDirectory();
        }
    };
    void PerformFindFirstFile(std::wstring const&pathSpec)
    {
        hFind = FindXFileFunctions_T::FindFirst(pathSpec.c_str(), &currentData);
        if (Valid()
            && GetLastError() != ERROR_PATH_NOT_FOUND
            && GetLastError() != ERROR_FILE_NOT_FOUND)
            WindowsApiException::ThrowFromLastError();
    };
public:
    BasicNonRecursiveEnumeration() : hFind(INVALID_HANDLE_VALUE) {};
    BasicNonRecursiveEnumeration(const std::wstring& pathSpec) :
        hFind(INVALID_HANDLE_VALUE) {
        std::wstring::const_iterator lastSlash = GetLastSlash(pathSpec);
        if (lastSlash != pathSpec.begin())
            currentDirectory.assign(pathSpec.begin(), lastSlash-1);
        PerformFindFirstFile(pathSpec);
        IncrementPastDotDirectories();
    };
    bool equal(const BasicNonRecursiveEnumeration<FindXFileFunctions_T>& other) const {
        if (this == &other)
            return true;
        return hFind == other.hFind;
    };
    Win32FindData dereference() {
        return Win32FindData(currentDirectory, currentData);
    };
    void increment() {
        IncrementCurrentDirectory();
    };
    bool Valid() {
        return hFind == INVALID_HANDLE_VALUE;
    };
    virtual ~BasicNonRecursiveEnumeration() {
        if (!Valid())
            FindXFileFunctions_T::Close(hFind);
    };
};

typedef BasicNonRecursiveEnumeration<RealFindXFileFunctions> NonRecursiveEnumeration;

template <typename FindXFileFunctions_T>
class BasicRecursiveEnumeration : public boost::noncopyable
{
    std::wstring fileSpec;
    std::deque<std::deque<Win32FindData> > enumeratedData;
    void EnumerateDirectory(const std::wstring& nextPathSpec) {
        std::deque<Win32FindData> newDeck;
        BasicNonRecursiveEnumeration<FindXFileFunctions_T> begin(nextPathSpec), end;
        for(; !begin.equal(end); begin.increment()) {
            newDeck.push_back(begin.dereference()); 
        }
        if (!newDeck.empty()) {
            enumeratedData.push_back(std::deque<Win32FindData>()); //Swaptimization
            enumeratedData.back().swap(newDeck);
        }
    };
    void PerformIncrement() {
        if (enumeratedData.empty()) return;
        if (enumeratedData.back().front().IsDirectory()) {
            std::wstring nextSpec(enumeratedData.back().front().GetFullFileName());
            nextSpec.append(L"\\*");
            enumeratedData.back().pop_front();
            EnumerateDirectory(nextSpec);
        } else {
            enumeratedData.back().pop_front();
        }
        while (Valid() && enumeratedData.back().empty())
            enumeratedData.pop_back();
    }
    bool CurrentPositionNoMatchFileSpec() const
    {
        return !enumeratedData.empty() && !PathMatchSpecW(enumeratedData.back().front().GetFileName().c_str(), fileSpec.c_str());
    }
public:
    BasicRecursiveEnumeration() {};
    BasicRecursiveEnumeration(const std::wstring& pathSpec) {
        std::wstring::const_iterator lastSlash = GetLastSlash(pathSpec);
        if (lastSlash == pathSpec.begin()) {
            fileSpec = pathSpec;
            EnumerateDirectory(L"*");
        } else {
            fileSpec.assign(lastSlash, pathSpec.end());
            std::wstring firstQuery(pathSpec.begin(), lastSlash);
            firstQuery.push_back(L'*');
            EnumerateDirectory(firstQuery);
            while (CurrentPositionNoMatchFileSpec())
                PerformIncrement();
        }
    };
    void increment() {
        do
        {
            PerformIncrement();
        } while (CurrentPositionNoMatchFileSpec());
    };
    bool equal(const BasicRecursiveEnumeration<FindXFileFunctions_T>& other) const {
        if (!Valid())
            return !other.Valid();
        if (!other.Valid())
            return false;
        return this == &other;
    };
    Win32FindData dereference() const {
        return enumeratedData.back().front();
    };
    bool Valid() const {
        return !enumeratedData.empty();
    };
};

typedef BasicRecursiveEnumeration<RealFindXFileFunctions> RecursiveEnumeration;

struct AllResults
{
    bool operator()(const Win32FindData&) {
        return true;
    };
}; 

struct FilesOnly
{
    bool operator()(const Win32FindData& arg) {
        return arg.IsFile();
    };
};

template <typename Filter_T, typename Recurse_T>
class DirectoryIterator : 
    public boost::iterator_facade<
        DirectoryIterator<Filter_T, Recurse_T>,
        Win32FindData,
        std::input_iterator_tag,
        Win32FindData
    >
{
    friend class boost::iterator_core_access;
    boost::shared_ptr<Recurse_T> impl;
    Filter_T filter;
    void increment() {
        do {
            impl->increment();
        } while (impl->Valid() && !filter(impl->dereference()));
    };
    bool equal(const DirectoryIterator& other) const {
        return impl->equal(*other.impl);
    };
    Win32FindData dereference() const {
        return impl->dereference();
    };
public:
    DirectoryIterator(Filter_T functor = Filter_T()) :
        impl(boost::make_shared<Recurse_T>()),
        filter(functor) {
    };
    explicit DirectoryIterator(const std::wstring& pathSpec, Filter_T functor = Filter_T()) :
        impl(boost::make_shared<Recurse_T>(pathSpec)),
        filter(functor) {
    };
};

}}

Tests:

#include <queue>
#include "../WideCharacterOutput.hpp"
#include <boost/test/unit_test.hpp>
#include "../../WindowsAPI++/FileSystem/Enumerator.hpp"
using namespace WindowsAPI::FileSystem;


struct SimpleFakeFindXFileFunctions
{
    static std::deque<WIN32_FIND_DATAW> fakeData;
    static std::wstring insertedFileName;

    static HANDLE FindFirst(LPCWSTR lpFileName, LPWIN32_FIND_DATAW lpFindFileData) {
        insertedFileName.assign(lpFileName);
        if (fakeData.empty()) {
            SetLastError(ERROR_PATH_NOT_FOUND);
            return INVALID_HANDLE_VALUE;
        }
        *lpFindFileData = fakeData.front();
        fakeData.pop_front();
        return reinterpret_cast<HANDLE>(42);
    };
    static BOOL FindNext(HANDLE hFindFile, LPWIN32_FIND_DATAW lpFindFileData) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        if (fakeData.empty()) {
            SetLastError(ERROR_NO_MORE_FILES);
            return 0;
        }
        *lpFindFileData = fakeData.front();
        fakeData.pop_front();
        return 1;
    };
    static BOOL Close(HANDLE hFindFile) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        return 1;
    };

};

std::deque<WIN32_FIND_DATAW> SimpleFakeFindXFileFunctions::fakeData;
std::wstring SimpleFakeFindXFileFunctions::insertedFileName;

struct ErroneousFindXFileFunctionFirst
{
    static HANDLE FindFirst(LPCWSTR, LPWIN32_FIND_DATAW) {
        SetLastError(ERROR_ACCESS_DENIED);
        return INVALID_HANDLE_VALUE;
    };
    static BOOL FindNext(HANDLE hFindFile, LPWIN32_FIND_DATAW) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        return 1;
    };
    static BOOL Close(HANDLE hFindFile) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        return 1;
    };
};

struct ErroneousFindXFileFunctionNext
{
    static HANDLE FindFirst(LPCWSTR, LPWIN32_FIND_DATAW) {
        return reinterpret_cast<HANDLE>(42);
    };
    static  BOOL FindNext(HANDLE hFindFile, LPWIN32_FIND_DATAW) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        SetLastError(ERROR_INVALID_PARAMETER);
        return 0;
    };
    static BOOL Close(HANDLE hFindFile) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        return 1;
    };
};

struct DirectoryIteratorTestsFixture
{
    typedef SimpleFakeFindXFileFunctions fakeFunctor;
    DirectoryIteratorTestsFixture() {
        WIN32_FIND_DATAW test;
        wcscpy_s(test.cFileName, L".");
        wcscpy_s(test.cAlternateFileName, L".");
        test.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
        GetSystemTimeAsFileTime(&test.ftCreationTime);
        test.ftLastWriteTime = test.ftCreationTime;
        test.ftLastAccessTime = test.ftCreationTime;
        test.nFileSizeHigh = 0;
        test.nFileSizeLow = 0;
        fakeFunctor::fakeData.push_back(test);

        wcscpy_s(test.cFileName, L"..");
        wcscpy_s(test.cAlternateFileName, L"..");
        fakeFunctor::fakeData.push_back(test);

        wcscpy_s(test.cFileName, L"File.txt");
        wcscpy_s(test.cAlternateFileName, L"FILE.TXT");
        test.nFileSizeLow = 1024;
        test.dwFileAttributes = FILE_ATTRIBUTE_NORMAL;
        fakeFunctor::fakeData.push_back(test);

        wcscpy_s(test.cFileName, L"System32");
        wcscpy_s(test.cAlternateFileName, L"SYSTEM32");
        test.nFileSizeLow = 0;
        test.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
        fakeFunctor::fakeData.push_back(test);
    };
    ~DirectoryIteratorTestsFixture() {
        fakeFunctor::fakeData.clear();
    };
};

BOOST_FIXTURE_TEST_SUITE( DirectoryIteratorTests, DirectoryIteratorTestsFixture )

template<typename fakeFunctor>
static void NonRecursiveIteratorAssertions()
{
    typedef DirectoryIterator<AllResults
        ,BasicNonRecursiveEnumeration<SimpleFakeFindXFileFunctions> > testType;
    testType begin(L"C:\\Windows\\*");
    testType end;
    BOOST_CHECK_EQUAL(fakeFunctor::insertedFileName, L"C:\\Windows\\*");
    BOOST_CHECK(begin->GetFolderPath() == L"C:\\Windows");
    BOOST_CHECK(begin->GetFileName() == L"File.txt");
    BOOST_CHECK(begin->GetFullFileName() == L"C:\\Windows\\File.txt");
    BOOST_CHECK(begin->GetShortFileName() == L"FILE.TXT");
    BOOST_CHECK_EQUAL(begin->GetSize(), 1024);
    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK(begin != end);
    begin++;
    BOOST_CHECK(begin->GetFileName() == L"System32");
    BOOST_CHECK(begin->GetFullFileName() == L"C:\\Windows\\System32");
    BOOST_CHECK(begin->GetShortFileName() == L"SYSTEM32");
    BOOST_CHECK_EQUAL(begin->GetSize(), 0);
    BOOST_CHECK(begin->IsDirectory());
    begin++;
    BOOST_CHECK(begin == end);
}

BOOST_AUTO_TEST_CASE( BasicEnumeration )
{
    NonRecursiveIteratorAssertions<fakeFunctor>();
}

BOOST_AUTO_TEST_CASE( NoRootDirectories )
{
    fakeFunctor::fakeData.pop_front();
    fakeFunctor::fakeData.pop_front();
    NonRecursiveIteratorAssertions<fakeFunctor>();
}

static void EmptyIteratorAssertions() {
    typedef DirectoryIterator<AllResults
        ,BasicNonRecursiveEnumeration<SimpleFakeFindXFileFunctions> > testType;
    testType begin(L"C:\\Windows\\*");
    testType end;
    BOOST_CHECK(begin == end);
}

BOOST_AUTO_TEST_CASE( Empty1 )
{
    fakeFunctor::fakeData.clear();
    EmptyIteratorAssertions();
}

BOOST_AUTO_TEST_CASE( Empty2 )
{
    fakeFunctor::fakeData.erase(fakeFunctor::fakeData.begin() + 2, fakeFunctor::fakeData.end());
    EmptyIteratorAssertions();
}

BOOST_AUTO_TEST_CASE( CorrectDestruction )
{
    typedef DirectoryIterator<AllResults
        ,BasicNonRecursiveEnumeration<SimpleFakeFindXFileFunctions> > testType;
    testType begin(L"C:\\Windows\\*");
    testType end;
}

BOOST_AUTO_TEST_CASE( Exceptions )
{
    typedef DirectoryIterator<AllResults,BasicNonRecursiveEnumeration<ErroneousFindXFileFunctionFirst> >
        firstFailType;
    BOOST_CHECK_THROW(firstFailType(L"C:\\Windows\\*"), WindowsAPI::ErrorAccessDeniedException);
    typedef DirectoryIterator<AllResults,BasicNonRecursiveEnumeration<ErroneousFindXFileFunctionNext> >
        nextFailType;
    nextFailType constructedOkay(L"C:\\Windows\\*");
    BOOST_CHECK_THROW(constructedOkay++, WindowsAPI::ErrorInvalidParameterException);
}

BOOST_AUTO_TEST_SUITE_END()

struct RecursiveFakeFindXFileFunctions
{
    static std::deque<std::pair<std::deque<WIN32_FIND_DATA> , std::wstring> >  fakeData;
    static std::size_t openHandles;
    static HANDLE FindFirst(LPCWSTR lpFileName, LPWIN32_FIND_DATAW lpFindFileData) {
        BOOST_REQUIRE(!fakeData.empty());
        BOOST_REQUIRE_EQUAL(lpFileName, fakeData.front().second);
        openHandles++;
        BOOST_REQUIRE_EQUAL(openHandles, 1);
        if (fakeData.front().first.empty()) {
            openHandles--;
            SetLastError(ERROR_PATH_NOT_FOUND);
            return INVALID_HANDLE_VALUE;
        }
        *lpFindFileData = fakeData.front().first.front();
        fakeData.front().first.pop_front();
        return reinterpret_cast<HANDLE>(42);
    };
    static BOOL FindNext(HANDLE hFindFile, LPWIN32_FIND_DATAW lpFindFileData) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        if (fakeData.front().first.empty()) {
            SetLastError(ERROR_NO_MORE_FILES);
            return 0;
        }
        *lpFindFileData = fakeData.front().first.front();
        fakeData.front().first.pop_front();
        return 1;
    };
    static BOOL Close(HANDLE hFindFile) {
        BOOST_CHECK_EQUAL(reinterpret_cast<HANDLE>(42), hFindFile);
        openHandles--;
        BOOST_REQUIRE_EQUAL(openHandles, 0);
        fakeData.pop_front();
        return 1;
    };
};

std::deque<std::pair<std::deque<WIN32_FIND_DATA> , std::wstring> > RecursiveFakeFindXFileFunctions::fakeData;
std::size_t RecursiveFakeFindXFileFunctions::openHandles;

struct RecursiveDirectoryFixture
{
    RecursiveDirectoryFixture() {
        WIN32_FIND_DATAW tempData;
        ZeroMemory(&tempData, sizeof(tempData));
        std::deque<WIN32_FIND_DATAW> dequeData;

        wcscpy_s(tempData.cFileName, L".");
        wcscpy_s(tempData.cAlternateFileName, L".");
        tempData.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
        GetSystemTimeAsFileTime(&tempData.ftCreationTime);
        tempData.ftLastWriteTime = tempData.ftCreationTime;
        tempData.ftLastAccessTime = tempData.ftCreationTime;
        dequeData.push_back(tempData);

        wcscpy_s(tempData.cFileName, L"..");
        wcscpy_s(tempData.cAlternateFileName, L"..");
        dequeData.push_back(tempData);

        wcscpy_s(tempData.cFileName, L"MySubDirectory");
        wcscpy_s(tempData.cAlternateFileName, L"MYSUBD~1");
        dequeData.push_back(tempData);

        wcscpy_s(tempData.cFileName, L"MyFile.txt");
        wcscpy_s(tempData.cAlternateFileName, L"MYFILE.TXT");
        tempData.nFileSizeLow = 500;
        tempData.dwFileAttributes = FILE_ATTRIBUTE_NORMAL;
        dequeData.push_back(tempData);

        RecursiveFakeFindXFileFunctions::fakeData.push_back
            (std::make_pair(dequeData, L"C:\\Windows\\*"));

        dequeData.clear();

        wcscpy_s(tempData.cFileName, L".");
        wcscpy_s(tempData.cAlternateFileName, L".");
        tempData.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
        GetSystemTimeAsFileTime(&tempData.ftCreationTime);
        tempData.ftLastWriteTime = tempData.ftCreationTime;
        tempData.ftLastAccessTime = tempData.ftCreationTime;
        dequeData.push_back(tempData);

        wcscpy_s(tempData.cFileName, L"..");
        wcscpy_s(tempData.cAlternateFileName, L"..");
        dequeData.push_back(tempData);

        wcscpy_s(tempData.cFileName, L"MyFile2.txt");
        wcscpy_s(tempData.cAlternateFileName, L"NYFILE2.TXT");
        tempData.nFileSizeLow = 1024;
        tempData.dwFileAttributes = FILE_ATTRIBUTE_NORMAL;
        dequeData.push_back(tempData);

        RecursiveFakeFindXFileFunctions::fakeData.push_back
            (std::make_pair(dequeData, L"C:\\Windows\\MySubDirectory\\*"));
    };
    ~RecursiveDirectoryFixture() {
        RecursiveFakeFindXFileFunctions::fakeData.clear();
    };
};

BOOST_AUTO_TEST_SUITE( RecursiveDirectoryIteratorTests )

BOOST_AUTO_TEST_CASE( BasicEnumerationTxt )
{
    RecursiveDirectoryFixture DataFixture;
    typedef DirectoryIterator<AllResults
        ,BasicRecursiveEnumeration<RecursiveFakeFindXFileFunctions> > testType;
    testType begin(L"C:\\Windows\\*.txt");
    testType end;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 1024);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows\\MySubDirectory");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MyFile2.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MySubDirectory\\MyFile2.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 500);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MyFile.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MyFile.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin == end);
}

BOOST_AUTO_TEST_CASE( BasicEnumerationAll )
{
    RecursiveDirectoryFixture DataFixture;
    typedef DirectoryIterator<AllResults
        ,BasicRecursiveEnumeration<RecursiveFakeFindXFileFunctions> > testType;
    testType begin(L"C:\\Windows\\*");
    testType end;

    BOOST_CHECK(begin->IsDirectory());
    BOOST_CHECK_EQUAL(begin->GetSize(), 0);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MySubDirectory");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MySubDirectory");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 1024);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows\\MySubDirectory");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MyFile2.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MySubDirectory\\MyFile2.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 500);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MyFile.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MyFile.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin == end);
}

BOOST_AUTO_TEST_CASE( RecursionOrderMaintained )
{
    WIN32_FIND_DATAW tempData;
    ZeroMemory(&tempData, sizeof(tempData));
    std::deque<WIN32_FIND_DATAW> dequeData;

    wcscpy_s(tempData.cFileName, L".");
    wcscpy_s(tempData.cAlternateFileName, L".");
    tempData.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
    GetSystemTimeAsFileTime(&tempData.ftCreationTime);
    tempData.ftLastWriteTime = tempData.ftCreationTime;
    tempData.ftLastAccessTime = tempData.ftCreationTime;
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"..");
    wcscpy_s(tempData.cAlternateFileName, L"..");
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"MySubDirectory");
    wcscpy_s(tempData.cAlternateFileName, L"MYSUBD~1");
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"MyFile.txt");
    wcscpy_s(tempData.cAlternateFileName, L"MYFILE.TXT");
    tempData.nFileSizeLow = 500;
    tempData.dwFileAttributes = FILE_ATTRIBUTE_NORMAL;
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"Zach");
    wcscpy_s(tempData.cAlternateFileName, L"ZACH");
    tempData.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
    tempData.nFileSizeLow = 0;
    dequeData.push_back(tempData);

    RecursiveFakeFindXFileFunctions::fakeData.push_back
        (std::make_pair(dequeData, L"C:\\Windows\\*"));

    dequeData.clear();

    wcscpy_s(tempData.cFileName, L".");
    wcscpy_s(tempData.cAlternateFileName, L".");
    tempData.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
    GetSystemTimeAsFileTime(&tempData.ftCreationTime);
    tempData.ftLastWriteTime = tempData.ftCreationTime;
    tempData.ftLastAccessTime = tempData.ftCreationTime;
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"..");
    wcscpy_s(tempData.cAlternateFileName, L"..");
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"MyFile2.txt");
    wcscpy_s(tempData.cAlternateFileName, L"NYFILE2.TXT");
    tempData.nFileSizeLow = 1024;
    tempData.dwFileAttributes = FILE_ATTRIBUTE_NORMAL;
    dequeData.push_back(tempData);

    RecursiveFakeFindXFileFunctions::fakeData.push_back
        (std::make_pair(dequeData, L"C:\\Windows\\MySubDirectory\\*"));

    dequeData.clear();
    wcscpy_s(tempData.cFileName, L".");
    wcscpy_s(tempData.cAlternateFileName, L".");
    tempData.dwFileAttributes = FILE_ATTRIBUTE_DIRECTORY;
    GetSystemTimeAsFileTime(&tempData.ftCreationTime);
    tempData.ftLastWriteTime = tempData.ftCreationTime;
    tempData.ftLastAccessTime = tempData.ftCreationTime;
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"..");
    wcscpy_s(tempData.cAlternateFileName, L"..");
    dequeData.push_back(tempData);

    wcscpy_s(tempData.cFileName, L"ZachFile.txt");
    wcscpy_s(tempData.cAlternateFileName, L"ZACHFILE.TXT");
    tempData.nFileSizeLow = 1024;
    tempData.dwFileAttributes = FILE_ATTRIBUTE_NORMAL;
    dequeData.push_back(tempData);

    RecursiveFakeFindXFileFunctions::fakeData.push_back
        (std::make_pair(dequeData, L"C:\\Windows\\Zach\\*"));

    typedef DirectoryIterator<AllResults
        ,BasicRecursiveEnumeration<RecursiveFakeFindXFileFunctions> > testType;
    testType begin(L"C:\\Windows\\*");
    testType end;

    BOOST_CHECK(begin->IsDirectory());
    BOOST_CHECK_EQUAL(begin->GetSize(), 0);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MySubDirectory");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MySubDirectory");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 1024);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows\\MySubDirectory");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MyFile2.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MySubDirectory\\MyFile2.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 500);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"MyFile.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\MyFile.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsDirectory());
    BOOST_CHECK_EQUAL(begin->GetSize(), 0);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"Zach");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\Zach");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin->IsFile());
    BOOST_CHECK_EQUAL(begin->GetSize(), 1024);
    BOOST_CHECK_EQUAL(begin->GetFolderPath(), L"C:\\Windows\\Zach");
    BOOST_CHECK_EQUAL(begin->GetFileName(), L"ZachFile.txt");
    BOOST_CHECK_EQUAL(begin->GetFullFileName(), L"C:\\Windows\\Zach\\ZachFile.txt");
    BOOST_CHECK(begin != end);

    begin++;

    BOOST_CHECK(begin == end);
}

BOOST_AUTO_TEST_CASE( Exceptions )
{
    typedef DirectoryIterator<AllResults,BasicRecursiveEnumeration<ErroneousFindXFileFunctionFirst> >
        firstFailType;
    BOOST_CHECK_THROW(firstFailType(L"C:\\Windows\\*"), WindowsAPI::ErrorAccessDeniedException);
    typedef DirectoryIterator<AllResults,BasicRecursiveEnumeration<ErroneousFindXFileFunctionNext> >
        nextFailType;
    BOOST_CHECK_THROW(nextFailType(L"C:\\Windows\\*"), WindowsAPI::ErrorInvalidParameterException);
}

BOOST_AUTO_TEST_SUITE_END()

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1 Answer

Editorial Team · Answer 1 · 2026-05-14T02:10:50+00:00

Interestingly, I had the same idea some time ago. Here’s what I wrote up:

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <string>
#include <iterator>
#include <exception>

#ifndef DIR_ITERATOR_H_INC
#define DIR_ITERATOR_H_INC

class dir_iterator

#if (!defined(_MSC_VER)) || (_MSC_VER > 1200)
    : public std::iterator<std::input_iterator_tag, 
                            std::string, 
                            int, 
                            std::string *, 
                            std::string &> 
#endif
{ 
    mutable HANDLE it;
    std::string mask;
    std::string path;
    WIN32_FIND_DATA data;
    bool done;
    DWORD require;
    DWORD prohibit;
public:
    WIN32_FIND_DATA operator*() { 
        return data;
    }

dir_iterator(dir_iterator const &other) :
    it(other.it),
    mask(other.mask),
    path(other.path),
    data(other.data),
    done(other.done),
    require(other.require),
    prohibit(other.prohibit)
{
    // Transfer the handle instead of just copying it.
    other.it=INVALID_HANDLE_VALUE;
}

    dir_iterator(std::string const &s, 
        DWORD must = 0,
        DWORD cant = FILE_ATTRIBUTE_DIRECTORY)
        : mask(s),
        require(must),
        prohibit(cant & ~must),
        done(false),
        it(INVALID_HANDLE_VALUE) // To fix bug spotted by Billy ONeal.
    { 
        int pos;
        if (std::string::npos != (pos=mask.find_last_of("\\/"))) 
            path = std::string(mask, 0, pos+1);

        it = FindFirstFile(mask.c_str(), &data);
        if (it == INVALID_HANDLE_VALUE)
            throw std::invalid_argument("Directory Inaccessible");

        while (!(((data.dwFileAttributes & require) == require) &&
                ((data.dwFileAttributes & prohibit) ==  0)))
        {
            if (done = (FindNextFile(it, &data)==0))
                break;
        }
    }

    dir_iterator() : done(true) {}

    dir_iterator &operator++() {
        do { 
            if (done = (FindNextFile(it, &data)==0))
                break;
        } while (!(((data.dwFileAttributes & require) == require) &&
            (data.dwFileAttributes & prohibit) == 0));

        return *this;
    }

    bool operator!=(dir_iterator const &other) { 
        return done != other.done;
    }
    bool operator==(dir_iterator const &other) { 
        return done == other.done;
    }

    ~dir_iterator() { 
        // The rest of the bug fix -- only close handle if it's open.
        if (it!=INVALID_HANDLE_VALUE)
            FindClose(it);
    }
};

#endif

And a quick demonstration of it:

#include "dir_iterator.h"
#include <iostream>
#include <algorithm>

namespace std { 
    std::ostream &operator<<(std::ostream &os, WIN32_FIND_DATA const &d) { 
        return os << d.cFileName;
    }
}

int main() { 
    std::copy(dir_iterator("*"), dir_iterator(), 
        std::ostream_iterator<WIN32_FIND_DATA>(std::cout, "\n"));

    std::cout << "\nDirectories:\n";
    std::copy(dir_iterator("*", FILE_ATTRIBUTE_DIRECTORY), dir_iterator(), 
        std::ostream_iterator<WIN32_FIND_DATA>(std::cout, "\n"));

    return 0;
}

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I’m working on wrapping up the ugly innards of the FindFirstFile / FindNextFile loop

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