/* environ.c -- library for manipulating environments for GNU.

  Copyright (C) 1986-2024 Free Software Foundation, Inc.

  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 "environ.h"
#include <algorithm>
#include <utility>

/* See gdbsupport/environ.h.  */

gdb_environ &
gdb_environ::operator= (gdb_environ &&e)
{
 /* Are we self-moving?  */
 if (&e == this)
   return *this;

 this->clear ();

 m_environ_vector = std::move (e.m_environ_vector);
 m_user_set_env = std::move (e.m_user_set_env);
 m_user_unset_env = std::move (e.m_user_unset_env);
 e.m_environ_vector.clear ();
 e.m_environ_vector.push_back (NULL);
 e.m_user_set_env.clear ();
 e.m_user_unset_env.clear ();
 return *this;
}

/* See gdbsupport/environ.h.  */

gdb_environ gdb_environ::from_host_environ ()
{
 extern char **environ;
 gdb_environ e;

 if (environ == NULL)
   return e;

 for (int i = 0; environ[i] != NULL; ++i)
   {
     /* Make sure we add the element before the last (NULL).  */
     e.m_environ_vector.insert (e.m_environ_vector.end () - 1,
                                xstrdup (environ[i]));
   }

 return e;
}

/* See gdbsupport/environ.h.  */

void
gdb_environ::clear ()
{
 for (char *v : m_environ_vector)
   xfree (v);
 m_environ_vector.clear ();
 /* Always add the NULL element.  */
 m_environ_vector.push_back (NULL);
 m_user_set_env.clear ();
 m_user_unset_env.clear ();
}

/* Helper function to check if STRING contains an environment variable
  assignment of VAR, i.e., if STRING starts with 'VAR='.  Return true
  if it contains, false otherwise.  */

static bool
match_var_in_string (const char *string, const char *var, size_t var_len)
{
 if (strncmp (string, var, var_len) == 0 && string[var_len] == '=')
   return true;

 return false;
}

/* See gdbsupport/environ.h.  */

const char *
gdb_environ::get (const char *var) const
{
 size_t len = strlen (var);

 for (char *el : m_environ_vector)
   if (el != NULL && match_var_in_string (el, var, len))
     return &el[len + 1];

 return NULL;
}

/* See gdbsupport/environ.h.  */

void
gdb_environ::set (const char *var, const char *value)
{
 char *fullvar = concat (var, "=", value, (char *) NULL);

 /* We have to unset the variable in the vector if it exists.  */
 unset (var, false);

 /* Insert the element before the last one, which is always NULL.  */
 m_environ_vector.insert (m_environ_vector.end () - 1, fullvar);

 /* Mark this environment variable as having been set by the user.
    This will be useful when we deal with setting environment
    variables on the remote target.  */
 m_user_set_env.insert (std::string (fullvar));

 /* If this environment variable is marked as unset by the user, then
    remove it from the list, because now the user wants to set
    it.  */
 m_user_unset_env.erase (std::string (var));
}

/* See gdbsupport/environ.h.  */

void
gdb_environ::unset (const char *var, bool update_unset_list)
{
 size_t len = strlen (var);
 std::vector<char *>::iterator it_env;

 /* We iterate until '.end () - 1' because the last element is
    always NULL.  */
 for (it_env = m_environ_vector.begin ();
      it_env != m_environ_vector.end () - 1;
      ++it_env)
   if (match_var_in_string (*it_env, var, len))
     break;

 if (it_env != m_environ_vector.end () - 1)
   {
     m_user_set_env.erase (std::string (*it_env));
     xfree (*it_env);

     m_environ_vector.erase (it_env);
   }

 if (update_unset_list)
   m_user_unset_env.insert (std::string (var));
}

/* See gdbsupport/environ.h.  */

void
gdb_environ::unset (const char *var)
{
 unset (var, true);
}

/* See gdbsupport/environ.h.  */

char **
gdb_environ::envp () const
{
 return const_cast<char **> (&m_environ_vector[0]);
}

/* See gdbsupport/environ.h.  */

const std::set<std::string> &
gdb_environ::user_set_env () const
{
 return m_user_set_env;
}

const std::set<std::string> &
gdb_environ::user_unset_env () const
{
 return m_user_unset_env;
}