log.cpp

/*
 * This file is part of the MAVLink Router project
 *
 * Copyright (C) 2017  Intel Corporation. All rights reserved.
 *
 * 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 "log.h"

#include <assert.h>
#include <limits.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <sys/uio.h>

#define COLOR_RED          "\033[31m"
#define COLOR_LIGHTBLUE    "\033[34;1m"
#define COLOR_YELLOW       "\033[33;1m"
#define COLOR_ORANGE       "\033[0;33m"
#define COLOR_WHITE        "\033[37;1m"
#define COLOR_RESET        "\033[0m"

Log::Level Log::_max_level = Level::INFO;
int Log::_target_fd = -1;
bool Log::_show_colors;

const char *Log::_get_color(Level level)
{
    if (!_show_colors)
        return nullptr;

    switch (level) {
    case Level::ERROR:
        return COLOR_RED;
    case Level::WARNING:
        return COLOR_ORANGE;
    case Level::NOTICE:
        return COLOR_YELLOW;
    case Level::INFO:
        return COLOR_WHITE;
    case Level::DEBUG:
        return COLOR_LIGHTBLUE;
    }

    return nullptr;
}

int Log::open()
{
    assert_or_return(_target_fd < 0, -1);

    /* for now, only logging is supported only to stderr */
    _target_fd =  STDERR_FILENO;

    if (isatty(_target_fd))
        _show_colors = true;

    return 0;
}

int Log::close()
{
    /* see _target_fd on open() */
    fflush(stderr);

    return 0;
}

void Log::set_max_level(Level level)
{
    _max_level = level;
}

void Log::logv(Level level, const char *format, va_list ap)
{
    struct iovec iovec[6] = { };
    const char *color;
    int n = 0;
    char buffer[LINE_MAX];
    int save_errno;

    if (_max_level < level)
        return;

    /* so %m works as expected */
    save_errno = errno;

    color = _get_color(level);

    if (color)
        IOVEC_SET_STRING(iovec[n++], color);

    errno = save_errno;
    vsnprintf(buffer, sizeof(buffer), format, ap);

    IOVEC_SET_STRING(iovec[n++], buffer);

    if (color)
        IOVEC_SET_STRING(iovec[n++], COLOR_RESET);

    IOVEC_SET_STRING(iovec[n++], "\n");

    (void)writev(_target_fd, iovec, n);
}

void Log::log(Level level, const char *format, ...)
{
    va_list ap;

    va_start(ap, format);
    logv(level, format, ap);
    va_end(ap);
}