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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* This program 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.
*/
#include "channel.hh"
namespace pdns::channel
{
Notifier::Notifier(FDWrapper&& descriptor) :
d_fd(std::move(descriptor))
{
}
bool Notifier::notify() const
{
char data = 'a';
while (true) {
auto sent = write(d_fd.getHandle(), &data, sizeof(data));
if (sent == 0) {
throw std::runtime_error("Unable to write to channel notifier pipe: remote end has been closed");
}
if (sent != sizeof(data)) {
if (errno == EINTR) {
continue;
}
if (errno == EAGAIN || errno == EWOULDBLOCK) {
return false;
}
throw std::runtime_error("Unable to write to channel notifier pipe: " + stringerror());
}
return true;
}
}
Waiter::Waiter(FDWrapper&& descriptor, bool throwOnEOF) :
d_fd(std::move(descriptor)), d_throwOnEOF(throwOnEOF)
{
}
void Waiter::clear()
{
ssize_t got{0};
do {
char data{0};
got = read(d_fd.getHandle(), &data, sizeof(data));
if (got == 0) {
d_closed = true;
if (!d_throwOnEOF) {
return;
}
throw std::runtime_error("EOF while clearing channel notifier pipe");
}
if (got == -1) {
if (errno == EINTR) {
continue;
}
if (errno == EAGAIN || errno == EWOULDBLOCK) {
break;
}
throw std::runtime_error("Error while clearing channel notifier pipe: " + stringerror());
}
} while (got > 0);
}
int Waiter::getDescriptor() const
{
return d_fd.getHandle();
}
std::pair<Notifier, Waiter> createNotificationQueue(bool nonBlocking, size_t pipeBufferSize, bool throwOnEOF)
{
std::array<int, 2> fds = {-1, -1};
if (pipe(fds.data()) < 0) {
throw std::runtime_error("Error creating notification channel pipe: " + stringerror());
}
FDWrapper sender(fds[1]);
FDWrapper receiver(fds[0]);
if (nonBlocking && !setNonBlocking(receiver.getHandle())) {
int err = errno;
throw std::runtime_error("Error making notification channel pipe non-blocking: " + stringerror(err));
}
if (nonBlocking && !setNonBlocking(sender.getHandle())) {
int err = errno;
throw std::runtime_error("Error making notification channel pipe non-blocking: " + stringerror(err));
}
if (pipeBufferSize > 0 && getPipeBufferSize(receiver.getHandle()) < pipeBufferSize) {
setPipeBufferSize(receiver.getHandle(), pipeBufferSize);
}
return {Notifier(std::move(sender)), Waiter(std::move(receiver), throwOnEOF)};
}
}
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