qt: Add data provider for list of file names

* lang/qt/src/Makefile.am: Add new files and corresponding camel-case
header.
* lang/qt/src/dataprovider.h: Include interface from gpgme++ when
not building.
* lang/qt/src/filelistdataprovider.cpp,
lang/qt/src/filelistdataprovider.h: New.
--

The new data provider simplifies providing a nul-separated list of
UTF-8-encoded filenames, e.g. for creating signed or encrypted
archives. It is a simple read-only proxy for QByteArrayDataProvider.

GnuPG-bug-id: 6342

1 files changed, 98 insertions, 0 deletions

diff --git a/lang/qt/src/filelistdataprovider.cpp b/lang/qt/src/filelistdataprovider.cpp
new file mode 100644
index 00000000..004854ef
--- /dev/null
+++ b/lang/qt/src/filelistdataprovider.cpp
@@ -0,0 +1,98 @@
+/*
+    filelistdataprovider.cpp
+
+    This file is part of qgpgme, the Qt API binding for gpgme
+    Copyright (c) 2023 g10 Code GmbH
+    Software engineering by Ingo Klöcker <[email protected]>
+
+    QGpgME is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.
+
+    QGpgME is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of this program with any edition of
+    the Qt library by Trolltech AS, Norway (or with modified versions
+    of Qt that use the same license as Qt), and distribute linked
+    combinations including the two.  You must obey the GNU General
+    Public License in all respects for all of the code used other than
+    Qt.  If you modify this file, you may extend this exception to
+    your version of the file, but you are not obligated to do so.  If
+    you do not wish to do so, delete this exception statement from
+    your version.
+*/
+
+#ifdef HAVE_CONFIG_H
+ #include "config.h"
+#endif
+
+#include "filelistdataprovider.h"
+
+#include "dataprovider.h"
+
+#include <QString>
+
+#include <gpgme++/error.h>
+
+#include <numeric>
+
+using namespace QGpgME;
+using namespace GpgME;
+
+static QByteArray encodeFilenames(const std::vector<QString> &filenames)
+{
+    QByteArray ret;
+    if (filenames.empty()) {
+        return ret;
+    }
+    // calculate and reserve the needed minimum size of the result
+    const auto addSize = [](unsigned int n, const QString &s) { return n + s.size(); };
+    const unsigned int minSize = filenames.size()
+        + std::accumulate(filenames.cbegin(), filenames.cend(), 0u, addSize);
+    ret.reserve(minSize);
+    // pack the filenames into the byte array
+    for (const auto &f : filenames) {
+        if (!f.isEmpty()) {
+            ret += f.toUtf8() + '\0';
+        }
+    }
+    ret.chop(1); // remove the trailing nul
+    return ret;
+}
+
+FileListDataProvider::FileListDataProvider(const std::vector<QString> &filenames)
+    : mProvider{new QByteArrayDataProvider{encodeFilenames(filenames)}}
+{
+}
+
+FileListDataProvider::~FileListDataProvider() = default;
+
+ssize_t FileListDataProvider::read(void* buffer, size_t bufSize)
+{
+    return mProvider->read(buffer, bufSize);
+}
+
+ssize_t FileListDataProvider::write(const void *, size_t)
+{
+    Error::setSystemError(GPG_ERR_EBADF);
+    return -1;
+}
+
+off_t FileListDataProvider::seek(off_t offset, int whence)
+{
+    return mProvider->seek(offset, whence);
+}
+
+void FileListDataProvider::release()
+{
+    mProvider->release();
+}