Tracer.cpp

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#include "utils/Tracer.hpp"
 
#include "Version.h"
 
#include "client/crash_report_database.h"
#include "client/crashpad_client.h"
#include "client/settings.h"
#include <spdlog/spdlog.h>
 
#include <algorithm>
#include <array>
#include <fstream>
#include <sstream>
 
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
 
constexpr int SLEEP_INTERVAL_MS = 50;
 
void Tracer::startHandler()
{
    // Path to crashpad executable
    const base::FilePath handler(_handlerPath);
 
    // Must be writable or crashpad_handler will crash
    const base::FilePath reportsDir(_reportPath);
    const base::FilePath metricsDir(_reportPath);
 
    // Initialize Crashpad database
    auto database = crashpad::CrashReportDatabase::Initialize(reportsDir);
    if (database == nullptr)
    {
        throw std::ios_base::failure("Can't initialize crash report database");
    }
 
    // Enable automated crash uploads
    auto *settings = database->GetSettings();
    if (settings == nullptr)
    {
        throw std::ios_base::failure("Can't get crash report database settings");
    }
    settings->SetUploadsEnabled(true);
 
    // Start crash handler
    if (!_clientHandler->StartHandler(handler, reportsDir, metricsDir, _serverPath, _serverProxy, _annotations,
                                      {"--no-rate-limit"}, true, false, _attachments))
    {
        throw std::ios_base::failure("Can't start crash handler");
    }
 
    _thread = std::make_unique<std::thread>(&Tracer::threadFunc, this);
}
 
void Tracer::threadFunc() noexcept
{
    while (!_shouldStop._M_i)
    {
        try
        {
            if (!isRunning())
            {
                // NOTICE: Worked before but currently restarting the handler raises an error
                // due to changes in the crashpad library
                restart();
                spdlog::warn("Crashpad handler restarted");
            }
            if (_checkFlag)
            {
                _checkFlag->test_and_set();
            }
        }
        catch (const std::exception &e)
        {
            spdlog::error("Crashpad failed: {}", e.what());
        }
        std::this_thread::sleep_for(std::chrono::milliseconds(SLEEP_INTERVAL_MS));
    }
}
 
bool Tracer::checkPidIsRunning(pid_t processId) { return kill(processId, 0) == 0; }
 
bool Tracer::checkSocketIsRunning(int sockId)
{
    int error = 0;
    socklen_t len = sizeof(error);
 
    char buff = 0;
    const int result = getsockopt(sockId, SOL_SOCKET, SO_ERROR, &error, &len);
    return result == 0 && error == 0 && recv(sockId, &buff, 1, MSG_PEEK | MSG_DONTWAIT) != 0;
}
 
std::string Tracer::getSelfExecutableDir()
{
    std::array<char, FILENAME_MAX> pathBuffer{'\0'};
    auto bytes = readlink("/proc/self/exe", pathBuffer.data(), sizeof(pathBuffer));
 
    auto path = std::string(pathBuffer.data(), bytes == -1 ? 0 : static_cast<size_t>(bytes));
    auto lastDelimPos = path.find_last_of('/');
    return (lastDelimPos == std::string::npos) ? "" : path.substr(0, lastDelimPos);
}
 
bool Tracer::isRunning()
{
    int sockId{-1};
    pid_t processId{-1};
 
    if (!crashpad::CrashpadClient::GetHandlerSocket(&sockId, &processId))
    {
        return false;
    }
 
    if (sockId >= 0 && !checkSocketIsRunning(sockId))
    {
        return false;
    }
    if (processId > 0 && !checkPidIsRunning(processId))
    {
        return false;
    }
    return true;
}
 
void Tracer::restart()
{
    if (!isRunning())
    {
        startHandler();
    }
}
 
void Tracer::dumpSharedLibraryInfo(const std::string &filePath)
{
    // Open the output file
    std::ofstream ofile(filePath);
    if (!ofile.is_open())
    {
        throw std::invalid_argument("Can't open file: " + filePath);
    }
 
    // Get the shared library information
    std::ifstream maps("/proc/self/maps");
 
    std::string line;
    while (std::getline(maps, line))
    {
        // The format of each line is: address perms offset dev inode pathname
        // We only care about the address and the pathname, which are the first and last fields
        std::istringstream iss(line);
        std::string address;
        std::string perms;
        std::string offset;
        std::string dev;
        std::string inode;
        std::string pathname;
        iss >> address >> perms >> offset >> dev >> inode >> pathname;
 
        // We only want the shared libraries, which have the .so extension and the read and execute permissions
        if (pathname.find(".so") != std::string::npos && perms.find("r-x") != std::string::npos)
        {
            // The address field is in the form of start-end, we only need the start address
            const std::string start = address.substr(0, address.find('-'));
 
            // Convert the start address from hexadecimal string to unsigned long
            const unsigned long addr = std::stoul(start, nullptr, 16);
 
            ofile << pathname << " " << addr << '\n';
        }
    }
}
 
Tracer::Tracer(std::shared_ptr<std::atomic_flag> checkFlag, std::string serverPath, std::string serverProxy,
               const std::string &crashpadHandlerPath, const std::string &reportPath,
               std::vector<base::FilePath> attachments)
    : _checkFlag(std::move(checkFlag)), _serverPath(std::move(serverPath)), _serverProxy(std::move(serverProxy)),
      _attachments(std::move(attachments))
{
    auto selfDir = getSelfExecutableDir();
 
    _handlerPath = crashpadHandlerPath.empty() ? selfDir + "/crashpad_handler" : crashpadHandlerPath;
    _reportPath = reportPath.empty() ? selfDir : reportPath;
    _clientHandler = std::make_unique<crashpad::CrashpadClient>();
 
    _annotations = std::map<std::string, std::string>(
        {{"name", PROJECT_NAME},
         {"version", PROJECT_FULL_REVISION},
         {"build_info", PROJECT_BUILD_DATE + std::string(" ") + PROJECT_BUILD_TIME + std::string(" ") + BUILD_TYPE},
         {"compiler_info", COMPILER_NAME + std::string(" ") + COMPILER_VERSION}});
 
    // Dump shared library information and add as attachment
    dumpSharedLibraryInfo(_reportPath + "/shared_libs.txt");
    _attachments.emplace_back(_reportPath + "/shared_libs.txt");
 
    startHandler();
}
 
Tracer::~Tracer()
{
    _shouldStop._M_i = true;
    if (_thread && _thread->joinable())
    {
        _thread->join();
    }
}