User.hpp

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// @formatter:off
//
// Balau core C++ library
//
// Copyright (C) 2008 Bora Software (contact@borasoftware.com)
//
// Licensed under the Boost Software License - Version 1.0 - August 17th, 2003.
// See the LICENSE file for the full license text.
//


#ifndef COM_BORA_SOFTWARE__BALAU_UTIL__USER
#define COM_BORA_SOFTWARE__BALAU_UTIL__USER

#include <Balau/Exception/ResourceExceptions.hpp>
#include <Balau/Resource/File.hpp>

#include <pwd.h>

namespace Balau::Util {

struct User final {
    static std::string getUserName() {
        #if BOOST_OS_UNIX
            const uid_t uid = geteuid();
            const passwd * pw = getpwuid(uid);

            if (pw) {
                return std::string(pw->pw_name);
            } else {
                ThrowBalauException(
                      Exception::NotFoundException
                    , "Failed to obtain the user name: user entry not found in passwd."
                );
            }
        #elif BOOST_OS_WINDOWS
            #error "The Windows platform is not yet implemented."
        #else
            #error "Platform not implemented."
        #endif
    }

    static Resource::File getHomeDirectory() {
        // Best effort approach.
        #if BOOST_OS_UNIX
            const char * home = std::getenv("HOME");

            if (home != nullptr && !Util::Strings::trim(home).empty()) {
                return Resource::File(Util::Strings::trim(home));
            }

            passwd pwd {};
            passwd * result;
            int s;
            size_t bufferSize = 512;
            std::vector<char> buffer(bufferSize);
            bool repeat = false;

            do {
                s = getpwuid_r(getuid(), &pwd, buffer.data(), bufferSize, &result);

                if (result == nullptr) {
                    if (s == 0) {
                        ThrowBalauException(
                              Exception::NotFoundException
                            , "Failed to locate the user home directory: user entry not found in passwd."
                        );
                    } else if (errno == ERANGE) {
                        // Give up at 1MB buffer size.
                        if (bufferSize >= 1048576) {
                            ThrowBalauException(
                                  Exception::NotFoundException
                                , "Failed to locate the user home directory with buffer size of 1MB."
                            );
                        }

                        bufferSize *= 2;
                        buffer.resize(bufferSize, 0);
                        repeat = true;
                    } else {
                        ThrowBalauException(
                              Exception::NotFoundException
                            , "Failed to locate the user home directory: getpwnam_r raised an error, errno = " +
                              ::toString(errno)
                        );
                    }
                }
            } while (!repeat);

            if (result == nullptr || result->pw_dir == nullptr) {
                ThrowBalauException(
                      Exception::NotFoundException
                    , ::toString("Failed to locate the user home directory: getpwnam_r raised an error, errno = ", errno)
                );
            }

            return Resource::File(result->pw_dir);
        #elif BOOST_OS_WINDOWS
            #error "The Windows platform is not yet implemented."

            // TODO verify
            const char * up = std::getenv("USERPROFILE");

            if (up != nullptr && !Util::Strings::trim(up).empty()) {
                return Resource::File(up);
            }

            const char * hd = std::getenv("HOMEDRIVE");
            const char * hp = std::getenv("HOMEPATH");

            if (hd != nullptr && hp != nullptr && !Util::Strings::trim(hd).empty() && !std::string(hp).empty()) {
                // TODO
                return Resource::File(h);
            }
        #else
            #error "Platform not implemented."
        #endif
    }


    User() = delete;
    User(const User &) = delete;
    User & operator = (const User &) = delete;
};

} // namespace Balau::Util

#endif // COM_BORA_SOFTWARE__BALAU_UTIL__USER