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Commit 1975aaa5 authored by Andrei Homescu's avatar Andrei Homescu
Browse files

libbinder: replace RpcTransport::peek() with pollRead() 

peek uses MSG_PEEK internally which only works with sockets.
This refactors that function into a more specific pollRead()
which works for e.g. pipes and other files.

Bug: 224644083
Test: atest binderRpcTest
Change-Id: I340fa7ee7a7bb2077115fc28835bcadf67db03d9
parent 97c1356a

libs/binder/RpcState.cpp

+1 −4
Original line number Diff line number Diff line
@@ -661,13 +661,10 @@ status_t RpcState::getAndExecuteCommand(const sp<RpcSession::RpcConnection>& con 


status_t RpcState::drainCommands(const sp<RpcSession::RpcConnection>& connection,

                                 const sp<RpcSession>& session, CommandType type) {

    uint8_t buf;

    while (true) {

        size_t num_bytes;

        status_t status = connection->rpcTransport->peek(&buf, sizeof(buf), &num_bytes);

        status_t status = connection->rpcTransport->pollRead();

        if (status == WOULD_BLOCK) break;

        if (status != OK) return status;

        if (!num_bytes) break;



        status = getAndExecuteCommand(connection, session, type);

        if (status != OK) return status;

libs/binder/RpcTransportRaw.cpp

+7 −4
Original line number Diff line number Diff line
@@ -32,19 +32,22 @@ namespace { 
class RpcTransportRaw : public RpcTransport {

public:

    explicit RpcTransportRaw(android::base::unique_fd socket) : mSocket(std::move(socket)) {}

    status_t peek(void* buf, size_t size, size_t* out_size) override {

        ssize_t ret = TEMP_FAILURE_RETRY(::recv(mSocket.get(), buf, size, MSG_PEEK));

    status_t pollRead(void) override {

        uint8_t buf;

        ssize_t ret = TEMP_FAILURE_RETRY(

                ::recv(mSocket.get(), &buf, sizeof(buf), MSG_PEEK | MSG_DONTWAIT));

        if (ret < 0) {

            int savedErrno = errno;

            if (savedErrno == EAGAIN || savedErrno == EWOULDBLOCK) {

                return WOULD_BLOCK;

            }



            LOG_RPC_DETAIL("RpcTransport peek(): %s", strerror(savedErrno));

            LOG_RPC_DETAIL("RpcTransport poll(): %s", strerror(savedErrno));

            return -savedErrno;

        } else if (ret == 0) {

            return DEAD_OBJECT;

        }



        *out_size = static_cast<size_t>(ret);

        return OK;

    }

libs/binder/RpcTransportTls.cpp

+4 −5
Original line number Diff line number Diff line
@@ -277,7 +277,7 @@ class RpcTransportTls : public RpcTransport { 
public:

    RpcTransportTls(android::base::unique_fd socket, Ssl ssl)

          : mSocket(std::move(socket)), mSsl(std::move(ssl)) {}

    status_t peek(void* buf, size_t size, size_t* out_size) override;

    status_t pollRead(void) override;

    status_t interruptableWriteFully(FdTrigger* fdTrigger, iovec* iovs, int niovs,

                                     const std::function<status_t()>& altPoll) override;

    status_t interruptableReadFully(FdTrigger* fdTrigger, iovec* iovs, int niovs,
@@ -289,9 +289,9 @@ private: 
};



// Error code is errno.

status_t RpcTransportTls::peek(void* buf, size_t size, size_t* out_size) {

    size_t todo = std::min<size_t>(size, std::numeric_limits<int>::max());

    auto [ret, errorQueue] = mSsl.call(SSL_peek, buf, static_cast<int>(todo));

status_t RpcTransportTls::pollRead(void) {

    uint8_t buf;

    auto [ret, errorQueue] = mSsl.call(SSL_peek, &buf, sizeof(buf));

    if (ret < 0) {

        int err = mSsl.getError(ret);

        if (err == SSL_ERROR_WANT_WRITE || err == SSL_ERROR_WANT_READ) {
@@ -304,7 +304,6 @@ status_t RpcTransportTls::peek(void* buf, size_t size, size_t* out_size) { 
    }

    errorQueue.clear();

    LOG_TLS_DETAIL("TLS: Peeked %d bytes!", ret);

    *out_size = static_cast<size_t>(ret);

    return OK;

}

libs/binder/include/binder/RpcTransport.h

+9 −2
Original line number Diff line number Diff line
@@ -39,8 +39,15 @@ class RpcTransport { 
public:

    virtual ~RpcTransport() = default;



    // replacement of ::recv(MSG_PEEK). Error code may not be set if TLS is enabled.

    [[nodiscard]] virtual status_t peek(void *buf, size_t size, size_t *out_size) = 0;

    /**

     * Poll the transport to check whether there is any data ready to read.

     *

     * Return:

     *   OK - There is data available on this transport

     *   WOULDBLOCK - No data is available

     *   error - any other error

     */

    [[nodiscard]] virtual status_t pollRead(void) = 0;



    /**

     * Read (or write), but allow to be interrupted by a trigger.