log.cpp

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/*
    Copyright (C) 2004 - 2022
    by Guillaume Melquiond <guillaume.melquiond@gmail.com>
    Copyright (C) 2003 by David White <dave@whitevine.net>
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/

    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 2 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.

    See the COPYING file for more details.
*/

/**
 * @file
 * Standard logging facilities (implementation).
 * See also the command line switches --logdomains and --log-@<level@>="domain".
 */

#include "log.hpp"

#include "filesystem.hpp"
#include "mt_rng.hpp"

#include <boost/algorithm/string.hpp>

#include <map>
#include <sstream>
#include <ctime>
#include <mutex>
#include <iostream>
#include <iomanip>

static lg::log_domain log_setup("logsetup");
#define ERR_LS LOG_STREAM(err,   log_setup)
#define WRN_LS LOG_STREAM(warn,  log_setup)
#define LOG_LS LOG_STREAM(info,  log_setup)
#define DBG_LS LOG_STREAM(debug, log_setup)

namespace {

class null_streambuf : public std::streambuf
{
    virtual int overflow(int c) { return std::char_traits< char >::not_eof(c); }
public:
    null_streambuf() {}
};

} // end anonymous namespace

static std::ostream null_ostream(new null_streambuf);
static int indent = 0;
static bool timestamp = true;
static bool precise_timestamp = false;
static std::mutex log_mutex;

static bool is_log_dir_writable_ = true;
static std::ostream *output_stream_ = nullptr;

static std::ostream& output()
{
    if(output_stream_) {
        return *output_stream_;
    }
    return std::cerr;
}

// custom deleter needed to reset cerr and cout
// otherwise wesnoth segfaults on closing (such as clicking the Quit button on the main menu)
// seems to be that there's a final flush done outside of wesnoth's code just before exiting
// but at that point the output_file_ has already been cleaned up
static std::unique_ptr<std::ostream, void(*)(std::ostream*)> output_file_(nullptr, [](std::ostream*){
    std::cerr.rdbuf(nullptr);
    std::cout.rdbuf(nullptr);
});
static std::string output_file_path_ = "";

namespace lg {

/** Helper function for rotate_logs. */
bool is_not_log_file(const std::string& fn)
{
    return !(boost::algorithm::istarts_with(fn, lg::log_file_prefix) &&
             boost::algorithm::iends_with(fn, lg::log_file_suffix));
}

/**
 * Deletes old log files from the log directory.
 */
void rotate_logs(const std::string& log_dir)
{
    // if logging to file is disabled, don't rotate the logs
    if(output_file_path_.empty()) {
        return;
    }

    std::vector<std::string> files;
    filesystem::get_files_in_dir(log_dir, &files);

    files.erase(std::remove_if(files.begin(), files.end(), is_not_log_file), files.end());

    if(files.size() <= lg::max_logs) {
        return;
    }

    // Sorting the file list and deleting all but the last max_logs items
    // should hopefully be faster than stat'ing every single file for its
    // time attributes (which aren't very reliable to begin with).

    std::sort(files.begin(), files.end());

    for(std::size_t j = 0; j < files.size() - lg::max_logs; ++j) {
        const std::string path = log_dir + '/' + files[j];
        LOG_LS << "rotate_logs(): delete " << path;
        if(!filesystem::delete_file(path)) {
            ERR_LS << "rotate_logs(): failed to delete " << path << "!";
        }
    }
}

/**
 * Generates a unique log file name.
 */
std::string unique_log_filename()
{
    std::ostringstream o;
    const std::time_t cur = std::time(nullptr);
    randomness::mt_rng rng;

    o << lg::log_file_prefix
      << std::put_time(std::localtime(&cur), "%Y%m%d-%H%M%S-")
      << rng.get_next_random()
      << lg::log_file_suffix;

    return o.str();
}

void check_log_dir_writable()
{
    std::string dummy_log = filesystem::get_logs_dir()+"/dummy.log";

    // log directory doesn't exist and can't be created
    if(!filesystem::file_exists(filesystem::get_logs_dir()) && !filesystem::make_directory(filesystem::get_logs_dir())) {
        is_log_dir_writable_ = false;
        return;
    }

    // can't create and write new log files
    try {
        filesystem::write_file(dummy_log, " ");
    } catch(const filesystem::io_exception&) {
        is_log_dir_writable_ = false;
        return;
    }

    // confirm that file exists and was written to
    if(filesystem::file_size(dummy_log) != 1) {
        is_log_dir_writable_ = false;
    }

    // can't delete files - prevents log rotation
    if(filesystem::file_exists(dummy_log) && !filesystem::delete_file(dummy_log)) {
        is_log_dir_writable_ = false;
        return;
    }

    is_log_dir_writable_ = true;
}

void set_log_to_file()
{
    check_log_dir_writable();
    // get the log file stream and assign cerr+cout to it
    if(is_log_dir_writable_) {
        output_file_path_ = filesystem::get_logs_dir()+"/"+unique_log_filename();
        output_file_.reset(filesystem::ostream_file(output_file_path_).release());
        std::cerr.rdbuf(output_file_.get()->rdbuf());
        std::cout.rdbuf(output_file_.get()->rdbuf());
    }
}

bool log_dir_writable()
{
    return is_log_dir_writable_;
}

std::string& get_log_file_path()
{
    return output_file_path_;
}
void set_log_file_path(const std::string& path)
{
    output_file_path_ = path;
}

redirect_output_setter::redirect_output_setter(std::ostream& stream)
    : old_stream_(output_stream_)
{
    output_stream_ = &stream;
}

redirect_output_setter::~redirect_output_setter()
{
    output_stream_ = old_stream_;
}

typedef std::map<std::string, int> domain_map;
static domain_map *domains;
static int strict_level_ = -1;
void timestamps(bool t) { timestamp = t; }
void precise_timestamps(bool pt) { precise_timestamp = pt; }

logger& err()
{
    static logger lg("error", 0);
    return lg;
}

logger& warn()
{
    static logger lg("warning", 1);
    return lg;
}

logger& info()
{
    static logger lg("info", 2);
    return lg;
}

logger& debug()
{
    static logger lg("debug", 3);
    return lg;
}

static log_domain dom("general");

log_domain& general()
{
    return dom;
}

log_domain::log_domain(char const *name, int severity)
    : domain_(nullptr)
{
    // Indirection to prevent initialization depending on link order.
    if (!domains) domains = new domain_map;
    domain_ = &*domains->insert(logd(name, severity)).first;
    domain_->second = severity;
}

bool set_log_domain_severity(const std::string& name, int severity)
{
    std::string::size_type s = name.size();
    if (name == "all") {
        for(logd &l : *domains) {
            l.second = severity;
        }
    } else if (s > 2 && name.compare(s - 2, 2, "/*") == 0) {
        for(logd &l : *domains) {
            if (l.first.compare(0, s - 1, name, 0, s - 1) == 0)
                l.second = severity;
        }
    } else {
        domain_map::iterator it = domains->find(name);
        if (it == domains->end())
            return false;
        it->second = severity;
    }
    return true;
}
bool set_log_domain_severity(const std::string& name, const logger &lg) {
    return set_log_domain_severity(name, lg.get_severity());
}

bool get_log_domain_severity(const std::string& name, int &severity)
{
    domain_map::iterator it = domains->find(name);
    if (it == domains->end())
        return false;
    severity = it->second;
    return true;
}

std::string list_logdomains(const std::string& filter)
{
    std::ostringstream res;
    for(logd &l : *domains) {
        if(l.first.find(filter) != std::string::npos)
            res << l.first << "\n";
    }
    return res.str();
}

void set_strict_severity(int severity) {
    strict_level_ = severity;
}

void set_strict_severity(const logger &lg) {
    set_strict_severity(lg.get_severity());
}

static bool strict_threw_ = false;

bool broke_strict() {
    return strict_threw_;
}

std::string get_timestamp(const std::time_t& t, const std::string& format) {
    std::ostringstream ss;

    ss << std::put_time(std::localtime(&t), format.c_str());

    return ss.str();
}
std::string get_timespan(const std::time_t& t) {
    std::ostringstream sout;
    // There doesn't seem to be any library function for this
    const std::time_t minutes = t / 60;
    const std::time_t days = minutes / 60 / 24;
    if(t <= 0) {
        sout << "expired";
    } else if(minutes == 0) {
        sout << t << " seconds";
    } else if(days == 0) {
        sout << minutes / 60 << " hours, " << minutes % 60 << " minutes";
    } else {
        sout << days << " days, " << (minutes / 60) % 24 << " hours, " << minutes % 60 << " minutes";
    }
    return sout.str();
}

static void print_precise_timestamp(std::ostream& out) noexcept
{
    try {
        int64_t micros = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::high_resolution_clock::now().time_since_epoch()).count();
        std::time_t seconds = micros/1'000'000;
        int fractional = micros-(seconds*1'000'000);
        char c = out.fill('0');
        out << std::put_time(std::localtime(&seconds), "%Y%m%d %H:%M:%S") << "." << std::setw(6) << fractional << ' ';
        out.fill(c);
    } catch(...) {}
}

std::string sanitize_log(const std::string& logstr)
{
    std::string str = logstr;

#ifdef _WIN32
    const char* user_name = getenv("USERNAME");
#else
    const char* user_name = getenv("USER");
#endif

    if(user_name != nullptr) {
        boost::replace_all(str, std::string("/") + user_name + "/", "/USER/");
        boost::replace_all(str, std::string("\\") + user_name + "\\", "\\USER\\");
    }

    return str;
}

log_in_progress logger::operator() (
    const log_domain& domain,
    bool show_names,
    bool do_indent,
    bool show_timestamps,
    bool break_strict,
    bool auto_newline) const
{
    if (severity_ > domain.domain_->second) {
        return null_ostream;
    } else {
        log_in_progress stream = output();
        if(do_indent) {
            stream.set_indent(indent);
        }
        if (timestamp && show_timestamps) {
            stream.enable_timestamp();
        }
        if (show_names) {
            stream.set_prefix(formatter() << name_ << ' ' << domain.domain_->first << ": ");
        }
        if (!strict_threw_ && severity_ <= strict_level_ && break_strict) {
            stream | formatter() << "Error (strict mode, strict_level = " << strict_level_ << "): wesnoth reported on channel " << name_ << " " << domain.domain_->first << std::endl;
            strict_threw_ = true;
        }
        stream.set_auto_newline(auto_newline);
        return stream;
    }
}

log_in_progress::log_in_progress(std::ostream& stream)
    : stream_(stream)
{}

void log_in_progress::operator|(formatter&& message)
{
    std::scoped_lock lock(log_mutex);
    for(int i = 0; i < indent; ++i)
        stream_ << "  ";
    if(timestamp_) {
        if(precise_timestamp) {
            print_precise_timestamp(stream_);
        } else {
            stream_ << get_timestamp(std::time(nullptr));
        }
    }
    stream_ << prefix_ << sanitize_log(message.str());
    if(auto_newline_) {
        stream_ << std::endl;
    }
}

void log_in_progress::set_indent(int level) {
    indent_ = level;
}

void log_in_progress::enable_timestamp() {
    timestamp_ = true;
}

void log_in_progress::set_prefix(const std::string& prefix) {
    prefix_ = prefix;
}

void log_in_progress::set_auto_newline(bool auto_newline) {
    auto_newline_ = auto_newline;
}

void scope_logger::do_log_entry(const std::string& str) noexcept
{
    str_ = str;
    try {
        ticks_ = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::high_resolution_clock::now().time_since_epoch()).count();
    } catch(...) {}
    debug()(domain_, false, true) | formatter() << "{ BEGIN: " << str_;
    ++indent;
}

void scope_logger::do_log_exit() noexcept
{
    long ticks = 0;
    try {
        ticks = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::high_resolution_clock::now().time_since_epoch()).count() - ticks_;
    } catch(...) {}
    --indent;
    auto output = debug()(domain_, false, true);
    output.set_indent(indent);
    if(timestamp) output.enable_timestamp();
    output | formatter() << "} END: " << str_ << " (took " << ticks << "us)";
}

std::stringstream& log_to_chat()
{
    static std::stringstream lg;
    return lg;
}

} // end namespace lg