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/*
* Copyright (C) 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <android-base/unique_fd.h>
#include <poll.h>
#include "FdTrigger.h"
#include "RpcState.h"
namespace android {
template <typename SendOrReceive>
status_t interruptableReadOrWrite(
const android::RpcTransportFd& socket, FdTrigger* fdTrigger, iovec* iovs, int niovs,
SendOrReceive sendOrReceiveFun, const char* funName, int16_t event,
const std::optional<android::base::function_ref<status_t()>>& altPoll) {
MAYBE_WAIT_IN_FLAKE_MODE;
if (niovs < 0) {
return BAD_VALUE;
}
// Since we didn't poll, we need to manually check to see if it was triggered. Otherwise, we
// may never know we should be shutting down.
if (fdTrigger->isTriggered()) {
return DEAD_OBJECT;
}
// If iovs has one or more empty vectors at the end and
// we somehow advance past all the preceding vectors and
// pass some or all of the empty ones to sendmsg/recvmsg,
// the call will return processSize == 0. In that case
// we should be returning OK but instead return DEAD_OBJECT.
// To avoid this problem, we make sure here that the last
// vector at iovs[niovs - 1] has a non-zero length.
while (niovs > 0 && iovs[niovs - 1].iov_len == 0) {
niovs--;
}
if (niovs == 0) {
// The vectors are all empty, so we have nothing to send.
return OK;
}
bool havePolled = false;
while (true) {
ssize_t processSize = sendOrReceiveFun(iovs, niovs);
if (processSize < 0) {
int savedErrno = errno;
// Still return the error on later passes, since it would expose
// a problem with polling
if (havePolled || (savedErrno != EAGAIN && savedErrno != EWOULDBLOCK)) {
LOG_RPC_DETAIL("RpcTransport %s(): %s", funName, strerror(savedErrno));
return -savedErrno;
}
} else if (processSize == 0) {
return DEAD_OBJECT;
} else {
while (processSize > 0 && niovs > 0) {
auto& iov = iovs[0];
if (static_cast<size_t>(processSize) < iov.iov_len) {
// Advance the base of the current iovec
iov.iov_base = reinterpret_cast<char*>(iov.iov_base) + processSize;
iov.iov_len -= processSize;
break;
}
// The current iovec was fully written
processSize -= iov.iov_len;
iovs++;
niovs--;
}
if (niovs == 0) {
LOG_ALWAYS_FATAL_IF(processSize > 0,
"Reached the end of iovecs "
"with %zd bytes remaining",
processSize);
return OK;
}
}
if (altPoll) {
if (status_t status = (*altPoll)(); status != OK) return status;
if (fdTrigger->isTriggered()) {
return DEAD_OBJECT;
}
} else {
if (status_t status = fdTrigger->triggerablePoll(socket, event); status != OK)
return status;
if (!havePolled) havePolled = true;
}
}
}
} // namespace android
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