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effects/screenshot: Ensure screenshot fd is nonblocking

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If the screenshot fd is blocking, the thread writing the screenshot to
the pipe can potentially get stuck in case something happens to the
client.
This commit is contained in:
Vlad Zahorodnii 2023-03-03 17:52:41 +02:00
parent 43a9add5fe
commit 83398dce7b
1 changed files with 18 additions and 5 deletions
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23
src/effects/screenshot/screenshotdbusinterface2.cpp
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@ -9,6 +9,7 @@
#include "screenshotdbusinterface2.h"
#include "screenshot2adaptor.h"
#include "screenshotlogging.h"
#include "utils/filedescriptor.h"
#include "utils/serviceutils.h"
#include <KLocalizedString>
@ -18,6 +19,7 @@
#include <QtConcurrent>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <string.h>
#include <unistd.h>
@ -47,11 +49,22 @@ static ScreenShotFlags screenShotFlagsFromOptions(const QVariantMap &options)
return flags;
}
static void writeBufferToPipe(int fileDescriptor, const QByteArray &buffer)
static void writeBufferToPipe(FileDescriptor fileDescriptor, const QByteArray &buffer)
{
const int flags = fcntl(fileDescriptor.get(), F_GETFL, 0);
if (flags == -1) {
qCWarning(KWIN_SCREENSHOT) << "failed to get screenshot fd flags:" << strerror(errno);
return;
}
if (!(flags & O_NONBLOCK)) {
if (fcntl(fileDescriptor.get(), F_SETFL, flags | O_NONBLOCK) == -1) {
qCWarning(KWIN_SCREENSHOT) << "failed to make screenshot fd non blocking:" << strerror(errno);
return;
}
}
QFile file;
if (!file.open(fileDescriptor, QIODevice::WriteOnly, QFileDevice::AutoCloseHandle)) {
close(fileDescriptor);
if (!file.open(fileDescriptor.get(), QIODevice::WriteOnly)) {
qCWarning(KWIN_SCREENSHOT) << Q_FUNC_INFO << "failed to open pipe:" << file.errorString();
return;
}
@ -59,7 +72,7 @@ static void writeBufferToPipe(int fileDescriptor, const QByteArray &buffer)
qint64 remainingSize = buffer.size();
pollfd pfds[1];
pfds[0].fd = fileDescriptor;
pfds[0].fd = fileDescriptor.get();
pfds[0].events = POLLOUT;
while (true) {
@ -251,7 +264,7 @@ void ScreenShotSinkPipe2::flush(const QImage &image)
QtConcurrent::run([](int fileDescriptor, const QImage &image) {
const QByteArray buffer(reinterpret_cast<const char *>(image.constBits()),
image.sizeInBytes());
writeBufferToPipe(fileDescriptor, buffer);
writeBufferToPipe(FileDescriptor(fileDescriptor), buffer);
},
m_fileDescriptor, image);