Merge "binder: FdTrigger ensure POLLERR / POLLNVAL is checked"

#define LOG_TAG "FdTrigger"

#include <log/log.h>

#include "FdTrigger.h"

#include <poll.h>

#include <android-base/macros.h>

#include "FdTrigger.h"

#include "RpcState.h"

namespace android {

std::unique_ptr<FdTrigger> FdTrigger::make() {

}

status_t FdTrigger::triggerablePoll(base::borrowed_fd fd, int16_t event) {

    while (true) {

    LOG_ALWAYS_FATAL_IF(event == 0, "triggerablePoll %d with event 0 is not allowed", fd.get());

    pollfd pfd[]{{.fd = fd.get(), .events = static_cast<int16_t>(event), .revents = 0},

                 {.fd = mRead.get(), .events = 0, .revents = 0}};

    int ret = TEMP_FAILURE_RETRY(poll(pfd, arraysize(pfd), -1));

    if (ret < 0) {

        return -errno;

    }

        if (ret == 0) {

            continue;

        }

    LOG_ALWAYS_FATAL_IF(ret == 0, "poll(%d) returns 0 with infinite timeout", fd.get());

    // At least one FD has events. Check them.

    // Detect explicit trigger(): DEAD_OBJECT

    if (pfd[1].revents & POLLHUP) {

        return DEAD_OBJECT;

    }

        return pfd[0].revents & event ? OK : DEAD_OBJECT;

    // See unknown flags in trigger FD's revents (POLLERR / POLLNVAL).

    // Treat this error condition as UNKNOWN_ERROR.

    if (pfd[1].revents != 0) {

        ALOGE("Unknown revents on trigger FD %d: revents = %d", pfd[1].fd, pfd[1].revents);

        return UNKNOWN_ERROR;

    }

    // pfd[1].revents is 0, hence pfd[0].revents must be set, and only possible values are

    // a subset of event | POLLHUP | POLLERR | POLLNVAL.

    // POLLNVAL: invalid FD number, e.g. not opened.

    if (pfd[0].revents & POLLNVAL) {

        return BAD_VALUE;

    }

    // Error condition. It wouldn't be possible to do I/O on |fd| afterwards.

    // Note: If this is the write end of a pipe then POLLHUP may also be set simultaneously. We

    //   still want DEAD_OBJECT in this case.

    if (pfd[0].revents & POLLERR) {

        LOG_RPC_DETAIL("poll() incoming FD %d results in revents = %d", pfd[0].fd, pfd[0].revents);

        return DEAD_OBJECT;

    }

    // Success condition; event flag(s) set. Even though POLLHUP may also be set,

    // treat it as a success condition to ensure data is drained.

    if (pfd[0].revents & event) {

        return OK;

    }

    // POLLHUP: Peer closed connection. Treat as DEAD_OBJECT.

    // This is a very common case, so don't log.

    return DEAD_OBJECT;

}

} // namespace android