snapcast/server/streamreader/process_stream.cpp

/***
    This file is part of snapcast
    Copyright (C) 2014-2019  Johannes Pohl

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    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, see <http://www.gnu.org/licenses/>.
***/


#include "process_stream.hpp"
#include "common/aixlog.hpp"
#include "common/snap_exception.hpp"
#include "common/utils.hpp"
#include "common/utils/string_utils.hpp"
#include <fcntl.h>
#include <limits.h>
#include <sys/stat.h>


using namespace std;



ProcessStream::ProcessStream(PcmListener* pcmListener, boost::asio::io_context& ioc, const StreamUri& uri)
    : PcmStream(pcmListener, ioc, uri), path_(""), process_(nullptr)
{
    params_ = uri_.getQuery("params");
    logStderr_ = (uri_.getQuery("logStderr", "false") == "true");
}


ProcessStream::~ProcessStream()
{
    if (process_)
        process_->kill();
}


bool ProcessStream::fileExists(const std::string& filename)
{
    struct stat buffer;
    return (stat(filename.c_str(), &buffer) == 0);
}


std::string ProcessStream::findExe(const std::string& filename)
{
    /// check if filename exists
    if (fileExists(filename))
        return filename;

    std::string exe = filename;
    if (exe.find("/") != string::npos)
        exe = exe.substr(exe.find_last_of("/") + 1);

    /// check with "which"
    string which = execGetOutput("which " + exe);
    if (!which.empty())
        return which;

    /// check in the same path as this binary
    char buff[PATH_MAX];
    char szTmp[32];
    sprintf(szTmp, "/proc/%d/exe", getpid());
    ssize_t len = readlink(szTmp, buff, sizeof(buff) - 1);
    if (len != -1)
    {
        buff[len] = '\0';
        return string(buff) + "/" + exe;
    }

    return "";
}


void ProcessStream::initExeAndPath(const std::string& filename)
{
    path_ = "";
    exe_ = findExe(filename);
    if (exe_.find("/") != string::npos)
    {
        path_ = exe_.substr(0, exe_.find_last_of("/") + 1);
        exe_ = exe_.substr(exe_.find_last_of("/") + 1);
    }

    if (!fileExists(path_ + exe_))
        throw SnapException("file not found: \"" + filename + "\"");
}


void ProcessStream::start()
{
    initExeAndPath(uri_.path);
    PcmStream::start();
}


void ProcessStream::stop()
{
    if (process_)
        process_->kill();
    PcmStream::stop();

    /// thread is detached, so it is not joinable
    if (stderrReaderThread_.joinable())
        stderrReaderThread_.join();
}


void ProcessStream::onStderrMsg(const char* buffer, size_t n)
{
    if (logStderr_)
    {
        string line = utils::string::trim_copy(string(buffer, n));
        if ((line.find('\0') == string::npos) && !line.empty())
            LOG(INFO) << "(" << getName() << ") " << line << "\n";
    }
}


void ProcessStream::stderrReader()
{
    size_t buffer_size = 8192;
    auto buffer = std::unique_ptr<char[]>(new char[buffer_size]);
    ssize_t n;
    stringstream message;
    while (active_ && (n = read(process_->getStderr(), buffer.get(), buffer_size)) > 0)
        onStderrMsg(buffer.get(), n);
}


void ProcessStream::worker()
{
    timeval tvChunk;
    std::unique_ptr<msg::PcmChunk> chunk(new msg::PcmChunk(sampleFormat_, pcmReadMs_));
    setState(kPlaying);
    string lastException = "";

    while (active_)
    {
        process_.reset(new Process(path_ + exe_ + " " + params_, path_));
        int flags = fcntl(process_->getStdout(), F_GETFL, 0);
        fcntl(process_->getStdout(), F_SETFL, flags | O_NONBLOCK);

        stderrReaderThread_ = thread(&ProcessStream::stderrReader, this);
        stderrReaderThread_.detach();

        chronos::systemtimeofday(&tvChunk);
        tvEncodedChunk_ = tvChunk;
        long nextTick = chronos::getTickCount();
        int idleBytes = 0;
        int maxIdleBytes = sampleFormat_.rate * sampleFormat_.frameSize * dryoutMs_ / 1000;
        try
        {
            while (active_)
            {
                chunk->timestamp.sec = tvChunk.tv_sec;
                chunk->timestamp.usec = tvChunk.tv_usec;
                int toRead = chunk->payloadSize;
                int len = 0;
                do
                {
                    int count = read(process_->getStdout(), chunk->payload + len, toRead - len);
                    if (count < 0 && idleBytes < maxIdleBytes)
                    {
                        memset(chunk->payload + len, 0, toRead - len);
                        idleBytes += toRead - len;
                        len += toRead - len;
                        continue;
                    }
                    if (count < 0)
                    {
                        setState(kIdle);
                        if (!sleep(100))
                            break;
                    }
                    else if (count == 0)
                        throw SnapException("end of file");
                    else
                    {
                        len += count;
                        idleBytes = 0;
                    }
                } while ((len < toRead) && active_);

                if (!active_)
                    break;

                encoder_->encode(chunk.get());

                if (!active_)
                    break;

                nextTick += pcmReadMs_;
                chronos::addUs(tvChunk, pcmReadMs_ * 1000);
                long currentTick = chronos::getTickCount();

                if (nextTick >= currentTick)
                {
                    setState(kPlaying);
                    if (!sleep(nextTick - currentTick))
                        break;
                }
                else
                {
                    chronos::systemtimeofday(&tvChunk);
                    tvEncodedChunk_ = tvChunk;
                    pcmListener_->onResync(this, currentTick - nextTick);
                    nextTick = currentTick;
                }

                lastException = "";
            }
        }
        catch (const std::exception& e)
        {
            if (lastException != e.what())
            {
                LOG(ERROR) << "(PipeStream) Exception: " << e.what() << std::endl;
                lastException = e.what();
            }
            process_->kill();
            if (!sleep(30000))
                break;
        }
    }
}