main.cpp

/**
 * Copyright 2017 Google Inc.
 *
 * 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.
 */

#include <fcntl.h>
#include <getopt.h>
#include <poll.h>
#include <unistd.h>

#include <array>
#include <cstdint>
#include <iostream>
#include <memory>
#include <thread>

#include "lpcsnoop/snoop.hpp"

static const char* snoopFilename = "/dev/aspeed-lpc-snoop0";
static size_t codeSize = 1; /* Size of each POST code in bytes */

/*
 * 256 bytes is a nice amount.  It's improbable we'd need this many, but its
 * gives us leg room in the event the driver poll doesn't return in a timely
 * fashion.  So, mostly arbitrarily chosen.
 */
static constexpr size_t BUFFER_SIZE = 256;

/*
 * Process any incoming dbus inquiries, which include introspection etc.
 */
void ProcessDbus(sdbusplus::bus::bus& bus)
{
    while (true)
    {
        bus.process_discard();
        bus.wait(); // wait indefinitely
    }

    return;
}

static void usage(const char* name)
{
    fprintf(stderr,
            "Usage: %s [-d <DEVICE>]\n"
            "  -b, --bytes <SIZE>     set POST code length to <SIZE> bytes. "
            "Default is %zu\n"
            "  -d, --device <DEVICE>  use <DEVICE> file. Default is '%s'\n\n",
            name, codeSize, snoopFilename);
}

static uint64_t assembleBytes(std::array<uint8_t, BUFFER_SIZE> buf, int start,
                              int size)
{
    uint64_t result = 0;

    for (int i = start + size - 1; i >= start; i--)
    {
        result <<= 8;
        result |= buf[i];
    }

    return result;
}

/*
 * TODO(venture): this only listens one of the possible snoop ports, but
 * doesn't share the namespace.
 *
 * This polls() the lpc snoop character device and it owns the dbus object
 * whose value is the latest port 80h value.
 */
int main(int argc, char* argv[])
{
    int rc = 0;
    int opt;
    struct pollfd pollset;
    int pollr;
    int readb;
    int postFd = -1;
    std::array<uint8_t, BUFFER_SIZE> buffer;

    /*
     * These string constants are only used in this method within this object
     * and this object is the only object feeding into the final binary.
     *
     * If however, another object is added to this binary it would be proper
     * to move these declarations to be global and extern to the other object.
     */
    const char* snoopObject = SNOOP_OBJECTPATH;
    const char* snoopDbus = SNOOP_BUSNAME;

    bool deferSignals = true;

    static const struct option long_options[] = {
        {"bytes", required_argument, NULL, 'b'},
        {"device", required_argument, NULL, 'd'},
        {0, 0, 0, 0}};

    while ((opt = getopt_long(argc, argv, "b:d:", long_options, NULL)) != -1)
    {
        switch (opt)
        {
            case 0:
                break;
            case 'b':
                codeSize = atoi(optarg);

                if (codeSize < 1 || codeSize > 8)
                {
                    fprintf(stderr,
                            "Invalid POST code size '%s'. Must be "
                            "an integer from 1 to 8.\n",
                            optarg);
                    exit(EXIT_FAILURE);
                }
                break;
            case 'd':
                snoopFilename = optarg;
                break;
            default:
                usage(argv[0]);
                exit(EXIT_FAILURE);
        }
    }

    postFd = open(snoopFilename, 0);
    if (postFd < 0)
    {
        fprintf(stderr, "Unable to open: %s\n", snoopFilename);
        return -1;
    }

    pollset.fd = postFd;
    pollset.events |= POLLIN;

    auto bus = sdbusplus::bus::new_default();

    // Add systemd object manager.
    sdbusplus::server::manager::manager(bus, snoopObject);

    PostReporter reporter(bus, snoopObject, deferSignals);
    reporter.emit_object_added();

    bus.request_name(snoopDbus);

    /*
     * I don't see a public interface for getting the underlying sd_bus*
     * so instead of poll(bus, driver), I'll just create a separate thread.
     *
     * TODO(venture): There may be a way to use sdevent to poll both the file
     * and the dbus in the same event loop.  If I could get the sdbus pointer
     * from bus directly, I'd grab a file handler from it, and then just poll on
     * both in one loop.  From a cursory look at sdevent, I should be able to do
     * something similar with that at some point.
     */
    std::thread lt(ProcessDbus, std::ref(bus));

    /* infinitely listen for POST codes and broadcast. */
    while (true)
    {
        pollr = poll(&pollset, 1, -1); /* polls indefinitely. */
        if (pollr < 0)
        {
            /* poll returned error. */
            rc = -errno;
            goto exit;
        }

        if (pollr > 0)
        {
            if (pollset.revents & POLLIN)
            {
                readb = read(postFd, buffer.data(), buffer.size());
                if (readb < 0)
                {
                    /* Read failure. */
                    rc = readb;
                    goto exit;
                }
                else
                {
                    if (readb % codeSize != 0)
                    {
                        fprintf(stderr,
                                "Warning: read size %d not a multiple of "
                                "POST code length %zu. Some codes may be "
                                "corrupt or missing\n",
                                readb, codeSize);
                        readb -= (readb % codeSize);
                    }

                    /* Broadcast the values read. */
                    for (int i = 0; i < readb; i += codeSize)
                    {
                        reporter.value(assembleBytes(buffer, i, codeSize));
                    }
                }
            }
        }
    }

exit:
    if (postFd > -1)
    {
        close(postFd);
    }

    lt.join();

    return rc;
}