qfilesystemiterator_unix.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant reason:default
 
#include "qplatformdefs.h"
#include "qfilesystemiterator_p.h"
 
#ifndef QT_NO_FILESYSTEMITERATOR
 
#include <qvarlengtharray.h>
 
#include <private/qstringconverter_p.h>
 
#include <stdlib.h>
#include <errno.h>
 
QT_BEGIN_NAMESPACE
 
/*
    Native filesystem iterator, which uses ::opendir()/readdir()/dirent from the system
    libraries to iterate over the directory represented by \a entry.
*/
QFileSystemIterator::QFileSystemIterator(const QFileSystemEntry &entry)
    : dirPath(entry.filePath())
{
    dir.reset(QT_OPENDIR(entry.nativeFilePath().constData()));
    if (!dir) {
        lastError = errno;
    } else {
        if (!dirPath.endsWith(u'/'))
            dirPath.append(u'/');
    }
}
 
QFileSystemIterator::QFileSystemIterator(const QFileSystemEntry &entry, QDirListing::IteratorFlags)
    : QFileSystemIterator(entry)
{}
 
QFileSystemIterator::QFileSystemIterator(const QFileSystemEntry &entry, QDir::Filters)
    : QFileSystemIterator(entry)
{
}
 
QFileSystemIterator::~QFileSystemIterator() = default;
 
QFileSystemNativeId QFileSystemIterator::nativeId() const
{
    if (!dir)
        return {};
#if QT_CONFIG(dirfd)
    // We can use dirfd() to fstat() the open directory - no race condition.
    return QFileSystemEngine::nativeId(dirfd(dir.get()));
#else
    // We must stat() the name - possible race condition, but already present
    // in QDirListing because we use full file names.
    return QFileSystemEngine::nativeId(
            QFileSystemEntry(dirPath, QFileSystemEntry::FromInternalPath()));
#endif
}
 
std::optional<QDirEntryInfo> QFileSystemIterator::advance()
{
    auto asFileEntry = [this](QStringView name) {
#ifdef Q_OS_DARWIN
        // must match QFile::decodeName
        QString normalized = name.toString().normalized(QString::NormalizationForm_C);
        name = normalized;
#endif
        return QFileSystemEntry(dirPath + name, QFileSystemEntry::FromInternalPath());
    };
    if (!dir)
        return std::nullopt;
 
    for (;;) {
        // From readdir man page:
        // If the end of the directory stream is reached, NULL is returned and errno is
        // not changed. If an error occurs, NULL is returned and errno is set to indicate
        // the error. To distinguish end of stream from an error, set errno to zero before
        // calling readdir() and then check the value of errno if NULL is returned.
        errno = 0;
        dirEntry = QT_READDIR(dir.get());
 
        if (dirEntry) {
            // POSIX allows readdir() to return a file name in struct dirent that
            // extends past the end of the d_name array (it's a char[1] array on QNX, for
            // example). Therefore, we *must* call strlen() on it to get the actual length
            // of the file name. See:
            // https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/dirent.h.html#tag_13_07_05
            QByteArrayView name(dirEntry->d_name, strlen(dirEntry->d_name));
            // name.size() is sufficient here, see QUtf8::convertToUnicode() for details
            QVarLengthArray<char16_t> buffer(name.size());
            QStringDecoder toUtf16(QStringDecoder::Utf8);
            auto *end = toUtf16.appendToBuffer(buffer.data(), name);
            buffer.resize(end - buffer.constData());
            if (!toUtf16.hasError()) {
                QFileSystemMetaData metaData;
                metaData.fillFromDirEnt(*dirEntry);
                return QDirEntryInfo{asFileEntry(buffer), std::move(metaData)};
            } else {
                errno = EILSEQ; // Invalid or incomplete multibyte or wide character
            }
        } else {
            break;
        }
    }
 
    lastError = errno;
    return std::nullopt;
}
 
QT_END_NAMESPACE
 
#endif // QT_NO_FILESYSTEMITERATOR