userInfo.cpp

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/*
 * $Id: userInfo.cpp 4 2015-12-04 13:55:56Z wejaeger $
 *
 * File:   userInfo.cpp
 * Author: Werner Jaeger
 *
 * Created on November 26, 2015, 8:54 PM
 *
 * Copyright 2015 Werner Jaeger.
 *
 * 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 3 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; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include "userInfo.h"

using namespace std;

UserInfo::UserInfo(const char* pcUserInfo)
{
    parseUserInfoString(pcUserInfo);
}

int UserInfo::access(const int iUid, const int iGid, const unsigned int uiRawMode, const int iMask) const
{
    int iRet((m_iUid == 0 && m_iGid == 0) ? 0 : EACCES); // root has all permissions

    if (m_iUid == iUid)
        iRet = testAccesss((uiRawMode & S_IRWXU) >> 6, iMask);
    else if (belongs2Group(iGid))
        iRet = testAccesss((uiRawMode & S_IRWXG) >> 3, iMask);
    else
        iRet = testAccesss(uiRawMode & S_IRWXO, iMask);

    return(iRet);
}

bool UserInfo::belongs2Group(const int iGuid) const
{
    return(m_iGid == iGuid || m_Groups.find(iGuid) != m_Groups.end());
}

int UserInfo::testAccesss(const int iMode, const int iMask) const
{
    int iTestMode(iMode & iMask);
    return(iTestMode == iMask ? 0 : EACCES);
}

void UserInfo::parseUserInfoString(const char* pcUserInfo)
{
    if (pcUserInfo)
    {
        const char* pcEqualDelim = "= ";
        const char* pcUid = "uid";
        const char* pcGroups = "groups";

        const int iLen(::strlen(pcUserInfo) + 1);

        char acTokens[iLen];
        ::strncpy(acTokens, pcUserInfo, iLen);

        char* pcSave;
        char* pch = ::strtok_r(acTokens, pcEqualDelim, &pcSave);
        if (pch && ::strcmp(pch, pcUid) == 0)
        {
            pch = ::strtok_r(NULL, pcEqualDelim, &pcSave);
            if (pch)
            {
                m_iUid = ::atoi(pch);
                pch = ::strtok_r(NULL, pcEqualDelim, &pcSave);
                const char* pcGid = "gid";
                if (pch && ::strcmp(pch, pcGid) == 0)
                {
                    pch = ::strtok_r(NULL, pcEqualDelim, &pcSave);
                    if (pch)
                    {
                        m_iGid = ::atoi(pch);
                        pch = ::strtok_r(NULL, pcEqualDelim, &pcSave);
                    }
                }
            }
        }

        if (pch && ::strcmp(pch, pcGroups) == 0)
        {
            const char* pcCommaDelim = ",";
            pch = ::strtok_r(NULL, pcCommaDelim, &pcSave);
            while (pch != NULL)
            {
                m_Groups.insert(::atoi(pch));
                pch = ::strtok_r(NULL, pcCommaDelim, &pcSave);
            }
        }
    }
}