platform_system_core/init/ueventd.cpp

/*
 * Copyright (C) 2010 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.
 */

#include "ueventd.h"

#include <ctype.h>
#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <selinux/selinux.h>

#include "devices.h"
#include "log.h"
#include "util.h"

int ueventd_main(int argc, char **argv)
{
    /*
     * init sets the umask to 077 for forked processes. We need to
     * create files with exact permissions, without modification by
     * the umask.
     */
    umask(000);

    /* Prevent fire-and-forget children from becoming zombies.
     * If we should need to wait() for some children in the future
     * (as opposed to none right now), double-forking here instead
     * of ignoring SIGCHLD may be the better solution.
     */
    signal(SIGCHLD, SIG_IGN);

    InitKernelLogging(argv);

    LOG(INFO) << "ueventd started!";

    selinux_callback cb;
    cb.func_log = selinux_klog_callback;
    selinux_set_callback(SELINUX_CB_LOG, cb);

    Parser& parser = Parser::GetInstance();
    parser.AddSectionParser("subsystem", std::make_unique<SubsystemParser>());
    using namespace std::placeholders;
    parser.AddSingleLineParser("/sys/", std::bind(ParsePermissionsLine, _1, _2, true));
    parser.AddSingleLineParser("/dev/", std::bind(ParsePermissionsLine, _1, _2, false));
    parser.ParseConfig("/ueventd.rc");
    parser.ParseConfig("/vendor/ueventd.rc");
    parser.ParseConfig("/odm/ueventd.rc");

    /*
     * keep the current product name base configuration so
     * we remain backwards compatible and allow it to override
     * everything
     * TODO: cleanup platform ueventd.rc to remove vendor specific
     * device node entries (b/34968103)
     */
    std::string hardware = android::base::GetProperty("ro.hardware", "");
    parser.ParseConfig("/ueventd." + hardware + ".rc");

    device_init();

    pollfd ufd;
    ufd.events = POLLIN;
    ufd.fd = get_device_fd();

    while (true) {
        ufd.revents = 0;
        int nr = poll(&ufd, 1, -1);
        if (nr <= 0) {
            continue;
        }
        if (ufd.revents & POLLIN) {
            handle_device_fd();
        }
    }

    return 0;
}