/* Copyright (C) 1992,1995-2001,2004 Free Software Foundation, Inc.

 * This file is part of the GNU C Library.

 *

 * The GNU C Library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * The GNU C Library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this program; if not, see <https://gnu.org/licenses/>.

 * SPDX-License-Identifier: LGPL-2.1-or-later

 */

#if HAVE_CONFIG_H

# include <config.h>

#endif

#include <string.h>

#include <gpg-error.h>

#define __set_errno(ev) (gpg_err_set_errno (ev))

#if HAVE_ASSUAN_H

/* Fixme: Why do we need to include the assuan header and why the

   internal ones? */

#include "assuan-defs.h"

#endif /*HAVE_ASSUAN_H*/

#define __builtin_expect(cond,val) (cond)

#include <errno.h>

#if _LIBC || HAVE_STDLIB_H

# include <stdlib.h>

#endif

#if _LIBC || HAVE_STRING_H

# include <string.h>

#endif

#if _LIBC || HAVE_UNISTD_H

# include <unistd.h>

#endif

#if !_LIBC

# define __environ	environ

# ifndef HAVE_ENVIRON_DECL

extern char **environ;

# endif

#endif

#if _LIBC

/* This lock protects against simultaneous modifications of `environ'.  */

# include <bits/libc-lock.h>

__libc_lock_define_initialized (static, envlock)

# define LOCK	__libc_lock_lock (envlock)

# define UNLOCK	__libc_lock_unlock (envlock)

#else

# define LOCK

# define UNLOCK

#endif

/* In the GNU C library we must keep the namespace clean.  */

#ifdef _LIBC

# define setenv __setenv

# define unsetenv __unsetenv

# define clearenv __clearenv

# define tfind __tfind

# define tsearch __tsearch

#endif

/* In the GNU C library implementation we try to be more clever and

   allow arbitrarily many changes of the environment given that the used

   values are from a small set.  Outside glibc this will eat up all

   memory after a while.  */

#if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \

		      && defined __GNUC__)

# define USE_TSEARCH	1

# include <search.h>

/* This is a pointer to the root of the search tree with the known

   values.  */

static void *known_values;

# define KNOWN_VALUE(Str) \

  ({									      \

    void *value = tfind (Str, &known_values, (__compar_fn_t) strcmp);	      \

    value != NULL ? *(char **) value : NULL;				      \

  })

# define STORE_VALUE(Str) \

  tsearch (Str, &known_values, (__compar_fn_t) strcmp)

#else

# undef USE_TSEARCH

# define KNOWN_VALUE(Str) NULL

# define STORE_VALUE(Str) do { } while (0)

#endif

/* If this variable is not a null pointer we allocated the current

   environment.  */

static char **last_environ;

/* This function is used by `setenv' and `putenv'.  The difference between

   the two functions is that for the former must create a new string which

   is then placed in the environment, while the argument of `putenv'

   must be used directly.  This is all complicated by the fact that we try

   to reuse values once generated for a `setenv' call since we can never

   free the strings.  */

static int

__add_to_environ (const char *name, const char *value, const char *combined,

		  int replace)

{

  register char **ep;

  register size_t size;

  const size_t namelen = strlen (name);

  const size_t vallen = value != NULL ? strlen (value) + 1 : 0;

  LOCK;

  /* We have to get the pointer now that we have the lock and not earlier

     since another thread might have created a new environment.  */

  ep = __environ;

  size = 0;

  if (ep != NULL)

    {

      for (; *ep != NULL; ++ep)

	if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')

	  break;

	else

	  ++size;

    }

  if (ep == NULL || __builtin_expect (*ep == NULL, 1))

    {

      char **new_environ;

      /* We allocated this space; we can extend it.  */

      new_environ = (char **) realloc (last_environ,

				       (size + 2) * sizeof (char *));

      if (new_environ == NULL)

	{

	  UNLOCK;

	  return -1;

	}

      /* If the whole entry is given add it.  */

      if (combined != NULL)

	/* We must not add the string to the search tree since it belongs

	   to the user.  */

	new_environ[size] = (char *) combined;

      else

	{

	  /* See whether the value is already known.  */

#ifdef USE_TSEARCH

# ifdef __GNUC__

	  char new_value[namelen + 1 + vallen];

# else

	  char *new_value = (char *) alloca (namelen + 1 + vallen);

# endif

# ifdef _LIBC

	  __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),

		     value, vallen);

# else

	  memcpy (new_value, name, namelen);

	  new_value[namelen] = '=';

	  memcpy (&new_value[namelen + 1], value, vallen);

# endif

	  new_environ[size] = KNOWN_VALUE (new_value);

	  if (__builtin_expect (new_environ[size] == NULL, 1))

#endif

	    {

	      new_environ[size] = (char *) malloc (namelen + 1 + vallen);

	      if (__builtin_expect (new_environ[size] == NULL, 0))

		{

		  __set_errno (ENOMEM);

		  UNLOCK;

		  return -1;

		}

#ifdef USE_TSEARCH

	      memcpy (new_environ[size], new_value, namelen + 1 + vallen);

#else

	      memcpy (new_environ[size], name, namelen);

	      new_environ[size][namelen] = '=';

	      memcpy (&new_environ[size][namelen + 1], value, vallen);

#endif

	      /* And save the value now.  We cannot do this when we remove

		 the string since then we cannot decide whether it is a

		 user string or not.  */

	      STORE_VALUE (new_environ[size]);

	    }

	}

      if (__environ != last_environ)

	memcpy ((char *) new_environ, (char *) __environ,

		size * sizeof (char *));

      new_environ[size + 1] = NULL;

      last_environ = __environ = new_environ;

    }

  else if (replace)

    {

      char *np;

      /* Use the user string if given.  */

      if (combined != NULL)

	np = (char *) combined;

      else

	{

#ifdef USE_TSEARCH

# ifdef __GNUC__

	  char new_value[namelen + 1 + vallen];

# else

	  char *new_value = (char *) alloca (namelen + 1 + vallen);

# endif

# ifdef _LIBC

	  __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),

		     value, vallen);

# else

	  memcpy (new_value, name, namelen);

	  new_value[namelen] = '=';

	  memcpy (&new_value[namelen + 1], value, vallen);

# endif

	  np = KNOWN_VALUE (new_value);

	  if (__builtin_expect (np == NULL, 1))

#endif

	    {

	      np = malloc (namelen + 1 + vallen);

	      if (__builtin_expect (np == NULL, 0))

		{

		  UNLOCK;

		  return -1;

		}

#ifdef USE_TSEARCH

	      memcpy (np, new_value, namelen + 1 + vallen);

#else

	      memcpy (np, name, namelen);

	      np[namelen] = '=';

	      memcpy (&np[namelen + 1], value, vallen);

#endif

	      /* And remember the value.  */

	      STORE_VALUE (np);

	    }

	}

      *ep = np;

    }

  UNLOCK;

  return 0;

}

int

setenv (const char *name, const char *value, int replace)

{

  if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)

    {

      __set_errno (EINVAL);

      return -1;

    }

  return __add_to_environ (name, value, NULL, replace);

}

int

unsetenv (const char *name)

{

  size_t len;

  char **ep;

  if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)

    {

      __set_errno (EINVAL);

      return -1;

    }

  len = strlen (name);

  LOCK;

  ep = __environ;

  while (*ep != NULL)

    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')

      {

	/* Found it.  Remove this pointer by moving later ones back.  */

	char **dp = ep;

	do

	  dp[0] = dp[1];

	while (*dp++);

	/* Continue the loop in case NAME appears again.  */

      }

    else

      ++ep;

  UNLOCK;

  return 0;

}

/* The `clearenv' was planned to be added to POSIX.1 but probably

   never made it.  Nevertheless the POSIX.9 standard (POSIX bindings

   for Fortran 77) requires this function.  */

int

clearenv (void)

{

  LOCK;

  if (__environ == last_environ && __environ != NULL)

    {

      /* We allocated this environment so we can free it.  */

      free (__environ);

      last_environ = NULL;

    }

  /* Clear the environment pointer removes the whole environment.  */

  __environ = NULL;

  UNLOCK;

  return 0;

}

#ifdef _LIBC

libc_freeres_fn (free_mem)

{

  /* Remove all traces.  */

  clearenv ();

  /* Now remove the search tree.  */

  __tdestroy (known_values, free);

  known_values = NULL;

}

# undef setenv

# undef unsetenv

# undef clearenv

weak_alias (__setenv, setenv)

weak_alias (__unsetenv, unsetenv)

weak_alias (__clearenv, clearenv)

#endif