Line data    Source code

       1             : // Copyright (c) 2016-2023  Made to Order Software Corp.  All Rights Reserved
       2             : //
       3             : // https://snapwebsites.org/project/snapdev
       4             : // contact@m2osw.com
       5             : //
       6             : // This program is free software: you can redistribute it and/or modify
       7             : // it under the terms of the GNU General Public License as published by
       8             : // the Free Software Foundation, either version 3 of the License, or
       9             : // (at your option) any later version.
      10             : //
      11             : // This program is distributed in the hope that it will be useful,
      12             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             : // GNU General Public License for more details.
      15             : //
      16             : // You should have received a copy of the GNU General Public License
      17             : // along with this program.  If not, see <https://www.gnu.org/licenses/>.
      18             : #pragma once
      19             : 
      20             : /** \file
      21             :  * \brief Change the user and group ownership of a file.
      22             :  *
      23             :  * This implementation allows for changing the ownership of a file by name.
      24             :  * The default C system function requires the user identifier and the group
      25             :  * identifier. Our function accepts strings with the names and automatically
      26             :  * converts the names in a string.
      27             :  *
      28             :  * The chownnm() is defined four times to allow for the user and/or the
      29             :  * group to be passed either as a string or as an identifier.
      30             :  */
      31             : 
      32             : // C++
      33             : //
      34             : #include    <string>
      35             : #include    <stdexcept>
      36             : 
      37             : 
      38             : // C
      39             : //
      40             : #include    <grp.h>
      41             : #include    <pwd.h>
      42             : #include    <unistd.h>
      43             : 
      44             : 
      45             : 
      46             : namespace snapdev
      47             : {
      48             : 
      49             : 
      50             : constexpr uid_t     NO_UID = static_cast<uid_t>(-1);
      51             : constexpr uid_t     NO_GID = static_cast<gid_t>(-1);
      52             : 
      53             : 
      54             : /** \brief Convert a user name in its Unix uid_t.
      55             :  *
      56             :  * This function searches for a user identifier in /etc/passwd and return
      57             :  * the corresponding uid_t value.
      58             :  *
      59             :  * \param[in] user_name  The name of the user to search.
      60             :  *
      61             :  * \return The uid_t of the named user or NO_UID.
      62             :  */
      63          12 : inline uid_t getuid(std::string const & user_name)
      64             : {
      65          12 :     if(!user_name.empty())
      66             :     {
      67           0 :         struct passwd const * pwd(getpwnam(user_name.c_str()));
      68           0 :         if(pwd != nullptr)
      69             :         {
      70           0 :             return pwd->pw_uid;
      71             :         }
      72             :     }
      73             : 
      74          12 :     return NO_UID;
      75             : }
      76             : 
      77             : 
      78             : /** \brief Convert a group name in a gid_t.
      79             :  *
      80             :  * This function searches for the named group in /etc/group and return the
      81             :  * corresponding gid_t value.
      82             :  *
      83             :  * \param[in] group_name  The name of a group to convert to a gid_t.
      84             :  *
      85             :  * \return The gid_t of the named group or NO_GID.
      86             :  */
      87          12 : inline gid_t getgid(std::string const & group_name)
      88             : {
      89          12 :     if(!group_name.empty())
      90             :     {
      91           2 :         struct group const * grp(getgrnam(group_name.c_str()));
      92           2 :         if(grp != nullptr)
      93             :         {
      94           2 :             return grp->gr_gid;
      95             :         }
      96             :     }
      97             : 
      98          10 :     return NO_GID;
      99             : }
     100             : 
     101             : 
     102          12 : inline int chownnm(
     103             :       std::string const & path
     104             :     , uid_t uid
     105             :     , gid_t gid)
     106             : {
     107          12 :     if(path.empty())
     108             :     {
     109           0 :         throw std::invalid_argument("the path cannot be empty in snap::chownnm()");
     110             :     }
     111             : 
     112          12 :     if(uid != NO_UID
     113          12 :     || gid != NO_GID)
     114             :     {
     115           2 :         return chown(path.c_str(), uid, gid);
     116             :     }
     117             : 
     118             :     // in case both are undefined (it happens in the mkdir_p() function)
     119             :     //
     120          10 :     return 0;
     121             : }
     122             : 
     123             : 
     124             : /** \brief Set the owner and group of a file or directory.
     125             :  *
     126             :  * This function determines the user identifier and group identifier
     127             :  * from the specified names and use them to call chown().
     128             :  *
     129             :  * The function can fail if an identifier for the user or group names
     130             :  * cannot be determined.
     131             :  *
     132             :  * The function may fail if the path is invalid or permissions do not
     133             :  * allow for ownership modifications.
     134             :  *
     135             :  * \param[in] path  The path to the file or directory to change.
     136             :  * \param[in] user_name  The name of the user.
     137             :  * \param[in] group_name  The name of the group.
     138             :  *
     139             :  * \return 0 if chown succeeded,
     140             :  *         -1 if an error occurs (i.e. permissions denied, unknown user/group)
     141             :  *         and errno is set accordingly.
     142             :  */
     143          12 : inline int chownnm(
     144             :       std::string const & path
     145             :     , std::string const & user_name
     146             :     , std::string const & group_name)
     147             : {
     148          12 :     return chownnm(path, getuid(user_name), getgid(group_name));
     149             : }
     150             : 
     151             : 
     152             : inline int chownnm(
     153             :       std::string const & path
     154             :     , uid_t uid
     155             :     , std::string const & group_name)
     156             : {
     157             :     return chownnm(path, uid, getgid(group_name));
     158             : }
     159             : 
     160             : 
     161             : inline int chownnm(
     162             :       std::string const & path
     163             :     , std::string const & user_name
     164             :     , gid_t gid)
     165             : {
     166             :     return chownnm(path, getuid(user_name), gid);
     167             : }
     168             : 
     169             : 
     170             : 
     171             : } // namespace snapdev
     172             : // vim: ts=4 sw=4 et