/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1998  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

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

 *

 * This 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.

 *

 * This 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 library; if not, see <http://www.gnu.org/licenses/>.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/. 

 */

#include "config.h"

#include "genviron.h"

#include <stdlib.h>

#include <string.h>

#ifdef HAVE_CRT_EXTERNS_H

#include <crt_externs.h> /* for _NSGetEnviron */

#endif

#ifdef G_OS_WIN32

#include <windows.h>

#endif

#include "glib-private.h"

#include "gmem.h"

#include "gmessages.h"

#include "gstrfuncs.h"

#include "gunicode.h"

#include "gconvert.h"

#include "gquark.h"

#include "gthreadprivate.h"

/* Environ array functions {{{1 */

static gboolean

g_environ_matches (const gchar *env, const gchar *variable, gsize len)

{

#ifdef G_OS_WIN32

    /* TODO handle Unicode environment variable names */

    /* Like filesystem paths, environment variables are case-insensitive. */

    return g_ascii_strncasecmp (env, variable, len) == 0 && env[len] == '=';

#else

    return strncmp (env, variable, len) == 0 && env[len] == '=';

#endif

}

static gint

g_environ_find (gchar       **envp,

                const gchar  *variable)

{

  gsize len;

  gint i;

  if (envp == NULL)

    return -1;

  len = strlen (variable);

  for (i = 0; envp[i]; i++)

    {

      if (g_environ_matches (envp[i], variable, len))

        return i;

    }

  return -1;

}

/**

 * g_environ_getenv:

 * @envp: (nullable) (array zero-terminated=1) (transfer none) (element-type filename):

 *     an environment list (eg, as returned from g_get_environ()), or %NULL

 *     for an empty environment list

 * @variable: (type filename): the environment variable to get

 *

 * Returns the value of the environment variable @variable in the

 * provided list @envp.

 *

 * Returns: (type filename) (nullable): the value of the environment variable, or %NULL if

 *     the environment variable is not set in @envp. The returned

 *     string is owned by @envp, and will be freed if @variable is

 *     set or unset again.

 *

 * Since: 2.32

 */

const gchar *

g_environ_getenv (gchar       **envp,

                  const gchar  *variable)

{

  gint index;

  g_return_val_if_fail (variable != NULL, NULL);

  index = g_environ_find (envp, variable);

  if (index != -1)

    return envp[index] + strlen (variable) + 1;

  else

    return NULL;

}

/**

 * g_environ_setenv:

 * @envp: (nullable) (array zero-terminated=1) (element-type filename) (transfer full):

 *     an environment list that can be freed using g_strfreev() (e.g., as

 *     returned from g_get_environ()), or %NULL for an empty

 *     environment list

 * @variable: (type filename): the environment variable to set, must not

 *     contain '='

 * @value: (type filename): the value for to set the variable to

 * @overwrite: whether to change the variable if it already exists

 *

 * Sets the environment variable @variable in the provided list

 * @envp to @value.

 *

 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):

 *     the updated environment list. Free it using g_strfreev().

 *

 * Since: 2.32

 */

gchar **

g_environ_setenv (gchar       **envp,

                  const gchar  *variable,

                  const gchar  *value,

                  gboolean      overwrite)

{

  gint index;

  g_return_val_if_fail (variable != NULL, NULL);

  g_return_val_if_fail (strchr (variable, '=') == NULL, NULL);

  g_return_val_if_fail (value != NULL, NULL);

  index = g_environ_find (envp, variable);

  if (index != -1)

    {

      if (overwrite)

        {

          g_free (envp[index]);

          envp[index] = g_strdup_printf ("%s=%s", variable, value);

        }

    }

  else

    {

      gint length;

      length = envp ? g_strv_length (envp) : 0;

      envp = g_renew (gchar *, envp, length + 2);

      envp[length] = g_strdup_printf ("%s=%s", variable, value);

      envp[length + 1] = NULL;

    }

  return envp;

}

static gchar **

g_environ_unsetenv_internal (gchar        **envp,

                             const gchar   *variable,

                             gboolean       free_value)

{

  gsize len;

  gchar **e, **f;

  len = strlen (variable);

  /* Note that we remove *all* environment entries for

   * the variable name, not just the first.

   */

  e = f = envp;

  while (*e != NULL)

    {

      if (!g_environ_matches (*e, variable, len))

        {

          *f = *e;

          f++;

        }

      else

        {

          if (free_value)

            g_free (*e);

        }

      e++;

    }

  *f = NULL;

  return envp;

}

/**

 * g_environ_unsetenv:

 * @envp: (nullable) (array zero-terminated=1) (element-type filename) (transfer full):

 *     an environment list that can be freed using g_strfreev() (e.g., as

 *     returned from g_get_environ()), or %NULL for an empty environment list

 * @variable: (type filename): the environment variable to remove, must not

 *     contain '='

 *

 * Removes the environment variable @variable from the provided

 * environment @envp.

 *

 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):

 *     the updated environment list. Free it using g_strfreev().

 *

 * Since: 2.32

 */

gchar **

g_environ_unsetenv (gchar       **envp,

                    const gchar  *variable)

{

  g_return_val_if_fail (variable != NULL, NULL);

  g_return_val_if_fail (strchr (variable, '=') == NULL, NULL);

  if (envp == NULL)

    return NULL;

  return g_environ_unsetenv_internal (envp, variable, TRUE);

}

/* UNIX implementation {{{1 */

#ifndef G_OS_WIN32

/**

 * g_getenv:

 * @variable: (type filename): the environment variable to get

 *

 * Returns the value of an environment variable.

 *

 * On UNIX, the name and value are byte strings which might or might not

 * be in some consistent character set and encoding. On Windows, they are

 * in UTF-8.

 * On Windows, in case the environment variable's value contains

 * references to other environment variables, they are expanded.

 *

 * Returns: (type filename) (nullable): the value of the environment variable, or %NULL if

 *     the environment variable is not found. The returned string

 *     may be overwritten by the next call to g_getenv(), g_setenv()

 *     or g_unsetenv().

 */

const gchar *

g_getenv (const gchar *variable)

{

  g_return_val_if_fail (variable != NULL, NULL);

  return getenv (variable);

}

/**

 * g_setenv:

 * @variable: (type filename): the environment variable to set, must not

 *     contain '='.

 * @value: (type filename): the value for to set the variable to.

 * @overwrite: whether to change the variable if it already exists.

 *

 * Sets an environment variable. On UNIX, both the variable's name and

 * value can be arbitrary byte strings, except that the variable's name

 * cannot contain '='. On Windows, they should be in UTF-8.

 *

 * Note that on some systems, when variables are overwritten, the memory

 * used for the previous variables and its value isn't reclaimed.

 *

 * You should be mindful of the fact that environment variable handling

 * in UNIX is not thread-safe, and your program may crash if one thread

 * calls g_setenv() while another thread is calling getenv(). (And note

 * that many functions, such as gettext(), call getenv() internally.)

 * This function is only safe to use at the very start of your program,

 * before creating any other threads (or creating objects that create

 * worker threads of their own).

 *

 * If you need to set up the environment for a child process, you can

 * use g_get_environ() to get an environment array, modify that with

 * g_environ_setenv() and g_environ_unsetenv(), and then pass that

 * array directly to execvpe(), g_spawn_async(), or the like.

 *

 * Returns: %FALSE if the environment variable couldn't be set.

 *

 * Since: 2.4

 */

gboolean

g_setenv (const gchar *variable,

          const gchar *value,

          gboolean     overwrite)

{

  gint result;

#ifndef HAVE_SETENV

  gchar *string;

#endif

  g_return_val_if_fail (variable != NULL, FALSE);

  g_return_val_if_fail (strchr (variable, '=') == NULL, FALSE);

  g_return_val_if_fail (value != NULL, FALSE);

#ifndef G_DISABLE_CHECKS

  /* FIXME: This will be upgraded to a g_warning() in a future release of GLib.

   * See https://gitlab.gnome.org/GNOME/glib/issues/715 */

  if (g_thread_n_created () > 0)

    g_debug ("setenv()/putenv() are not thread-safe and should not be used after threads are created");

#endif

#ifdef HAVE_SETENV

  result = setenv (variable, value, overwrite);

#else

  if (!overwrite && getenv (variable) != NULL)

    return TRUE;

  /* This results in a leak when you overwrite existing

   * settings. It would be fairly easy to fix this by keeping

   * our own parallel array or hash table.

   */

  string = g_strconcat (variable, "=", value, NULL);

  result = putenv (string);

#endif

  return result == 0;

}

#ifdef HAVE__NSGETENVIRON

#define environ (*_NSGetEnviron())

#else

/* According to the Single Unix Specification, environ is not

 * in any system header, although unistd.h often declares it.

 */

extern char **environ;

#endif

/**

 * g_unsetenv:

 * @variable: (type filename): the environment variable to remove, must

 *     not contain '='

 *

 * Removes an environment variable from the environment.

 *

 * Note that on some systems, when variables are overwritten, the

 * memory used for the previous variables and its value isn't reclaimed.

 *

 * You should be mindful of the fact that environment variable handling

 * in UNIX is not thread-safe, and your program may crash if one thread

 * calls g_unsetenv() while another thread is calling getenv(). (And note

 * that many functions, such as gettext(), call getenv() internally.) This

 * function is only safe to use at the very start of your program, before

 * creating any other threads (or creating objects that create worker

 * threads of their own).

 * 

 * If you need to set up the environment for a child process, you can

 * use g_get_environ() to get an environment array, modify that with

 * g_environ_setenv() and g_environ_unsetenv(), and then pass that

 * array directly to execvpe(), g_spawn_async(), or the like.

 *

 * Since: 2.4

 */

void

g_unsetenv (const gchar *variable)

{

  g_return_if_fail (variable != NULL);

  g_return_if_fail (strchr (variable, '=') == NULL);

#ifndef G_DISABLE_CHECKS

  /* FIXME: This will be upgraded to a g_warning() in a future release of GLib.

   * See https://gitlab.gnome.org/GNOME/glib/issues/715 */

  if (g_thread_n_created () > 0)

    g_debug ("unsetenv() is not thread-safe and should not be used after threads are created");

#endif

#ifdef HAVE_UNSETENV

  unsetenv (variable);

#else /* !HAVE_UNSETENV */

  /* Mess directly with the environ array.

   * This seems to be the only portable way to do this.

   */

  g_environ_unsetenv_internal (environ, variable, FALSE);

#endif /* !HAVE_UNSETENV */

}

/**

 * g_listenv:

 *

 * Gets the names of all variables set in the environment.

 *

 * Programs that want to be portable to Windows should typically use

 * this function and g_getenv() instead of using the environ array

 * from the C library directly. On Windows, the strings in the environ

 * array are in system codepage encoding, while in most of the typical

 * use cases for environment variables in GLib-using programs you want

 * the UTF-8 encoding that this function and g_getenv() provide.

 *

 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):

 *     a %NULL-terminated list of strings which must be freed with

 *     g_strfreev().

 *

 * Since: 2.8

 */

gchar **

g_listenv (void)

{

  gchar **result, *eq;

  gint len, i, j;

  len = g_strv_length (environ);

  result = g_new0 (gchar *, len + 1);

  j = 0;

  for (i = 0; i < len; i++)

    {

      eq = strchr (environ[i], '=');

      if (eq)

        result[j++] = g_strndup (environ[i], eq - environ[i]);

    }

  result[j] = NULL;

  return result;

}

/**

 * g_get_environ:

 *

 * Gets the list of environment variables for the current process.

 *

 * The list is %NULL terminated and each item in the list is of the

 * form 'NAME=VALUE'.

 *

 * This is equivalent to direct access to the 'environ' global variable,

 * except portable.

 *

 * The return value is freshly allocated and it should be freed with

 * g_strfreev() when it is no longer needed.

 *

 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):

 *     the list of environment variables

 *

 * Since: 2.28

 */

gchar **

g_get_environ (void)

{

  return g_strdupv (environ);

}

/* Win32 implementation {{{1 */

#else   /* G_OS_WIN32 */

const gchar *

g_getenv (const gchar *variable)

{

  GQuark quark;

  gchar *value;

  wchar_t dummy[2], *wname, *wvalue;

  DWORD len;

  g_return_val_if_fail (variable != NULL, NULL);

  g_return_val_if_fail (g_utf8_validate (variable, -1, NULL), NULL);

  /* On Windows NT, it is relatively typical that environment

   * variables contain references to other environment variables. If

   * so, use ExpandEnvironmentStrings(). (In an ideal world, such

   * environment variables would be stored in the Registry as

   * REG_EXPAND_SZ type values, and would then get automatically

   * expanded before a program sees them. But there is broken software

   * that stores environment variables as REG_SZ values even if they

   * contain references to other environment variables.)

   */

  wname = g_utf8_to_utf16 (variable, -1, NULL, NULL, NULL);

  len = GetEnvironmentVariableW (wname, dummy, 2);

  if (len == 0)

    {

      g_free (wname);

      if (GetLastError () == ERROR_ENVVAR_NOT_FOUND)

        return NULL;

      quark = g_quark_from_static_string ("");

      return g_quark_to_string (quark);

    }

  else if (len == 1)

    len = 2;

  wvalue = g_new (wchar_t, len);

  if (GetEnvironmentVariableW (wname, wvalue, len) != len - 1)

    {

      g_free (wname);

      g_free (wvalue);

      return NULL;

    }

  if (wcschr (wvalue, L'%') != NULL)

    {

      wchar_t *tem = wvalue;

      len = ExpandEnvironmentStringsW (wvalue, dummy, 2);

      if (len > 0)

        {

          wvalue = g_new (wchar_t, len);

          if (ExpandEnvironmentStringsW (tem, wvalue, len) != len)

            {

              g_free (wvalue);

              wvalue = tem;

            }

          else

            g_free (tem);

        }

    }

  value = g_utf16_to_utf8 (wvalue, -1, NULL, NULL, NULL);

  g_free (wname);

  g_free (wvalue);

  quark = g_quark_from_string (value);

  g_free (value);

  return g_quark_to_string (quark);

}

gboolean

g_setenv (const gchar *variable,

          const gchar *value,

          gboolean     overwrite)

{

  gboolean retval;

  wchar_t *wname, *wvalue, *wassignment;

  gchar *tem;

  g_return_val_if_fail (variable != NULL, FALSE);

  g_return_val_if_fail (strchr (variable, '=') == NULL, FALSE);

  g_return_val_if_fail (value != NULL, FALSE);

  g_return_val_if_fail (g_utf8_validate (variable, -1, NULL), FALSE);

  g_return_val_if_fail (g_utf8_validate (value, -1, NULL), FALSE);

  if (!overwrite && g_getenv (variable) != NULL)

    return TRUE;

  /* We want to (if possible) set both the environment variable copy

   * kept by the C runtime and the one kept by the system.

   *

   * We can't use only the C runtime's putenv or _wputenv() as that

   * won't work for arbitrary Unicode strings in a "non-Unicode" app

   * (with main() and not wmain()). In a "main()" app the C runtime

   * initializes the C runtime's environment table by converting the

   * real (wide char) environment variables to system codepage, thus

   * breaking those that aren't representable in the system codepage.

   *

   * As the C runtime's putenv() will also set the system copy, we do

   * the putenv() first, then call SetEnvironmentValueW ourselves.

   */

  wname = g_utf8_to_utf16 (variable, -1, NULL, NULL, NULL);

  wvalue = g_utf8_to_utf16 (value, -1, NULL, NULL, NULL);

  tem = g_strconcat (variable, "=", value, NULL);

  wassignment = g_utf8_to_utf16 (tem, -1, NULL, NULL, NULL);

  g_free (tem);

  _wputenv (wassignment);

  g_free (wassignment);

  retval = (SetEnvironmentVariableW (wname, wvalue) != 0);

  g_free (wname);

  g_free (wvalue);

  return retval;

}

void

g_unsetenv (const gchar *variable)

{

  wchar_t *wname, *wassignment;

  gchar *tem;

  g_return_if_fail (variable != NULL);

  g_return_if_fail (strchr (variable, '=') == NULL);

  g_return_if_fail (g_utf8_validate (variable, -1, NULL));

  wname = g_utf8_to_utf16 (variable, -1, NULL, NULL, NULL);

  tem = g_strconcat (variable, "=", NULL);

  wassignment = g_utf8_to_utf16 (tem, -1, NULL, NULL, NULL);

  g_free (tem);

  _wputenv (wassignment);

  g_free (wassignment);

  SetEnvironmentVariableW (wname, NULL);

  g_free (wname);

}

gchar **

g_listenv (void)

{

  gchar **result, *eq;

  gint len = 0, j;

  wchar_t *p, *q;

  p = (wchar_t *) GetEnvironmentStringsW ();

  if (p != NULL)

    {

      q = p;

      while (*q)

        {

          q += wcslen (q) + 1;

          len++;

        }

    }

  result = g_new0 (gchar *, len + 1);

  j = 0;

  q = p;

  while (*q)

    {

      result[j] = g_utf16_to_utf8 (q, -1, NULL, NULL, NULL);

      if (result[j] != NULL)

        {

          eq = strchr (result[j], '=');

          if (eq && eq > result[j])

            {

              *eq = '\0';

              j++;

            }

          else

            g_free (result[j]);

        }

      q += wcslen (q) + 1;

    }

  result[j] = NULL;

  FreeEnvironmentStringsW (p);

  return result;

}

gchar **

g_get_environ (void)

{

  gunichar2 *strings;

  gchar **result;

  gint i, n;

  strings = GetEnvironmentStringsW ();

  for (n = 0, i = 0; strings[n]; i++)

    n += wcslen (strings + n) + 1;

  result = g_new (char *, i + 1);

  for (n = 0, i = 0; strings[n]; i++)

    {

      result[i] = g_utf16_to_utf8 (strings + n, -1, NULL, NULL, NULL);

      n += wcslen (strings + n) + 1;

    }

  FreeEnvironmentStringsW (strings);

  result[i] = NULL;

  return result;

}

#endif  /* G_OS_WIN32 */

#ifdef G_OS_WIN32

/* Binary compatibility versions. Not for newly compiled code. */

_GLIB_EXTERN const gchar *g_getenv_utf8   (const gchar  *variable);

_GLIB_EXTERN gboolean     g_setenv_utf8   (const gchar  *variable,

                                           const gchar  *value,

                                           gboolean      overwrite);

_GLIB_EXTERN void         g_unsetenv_utf8 (const gchar  *variable);

const gchar *

g_getenv_utf8 (const gchar *variable)

{

  return g_getenv (variable);

}

gboolean

g_setenv_utf8 (const gchar *variable,

               const gchar *value,

               gboolean     overwrite)

{

  return g_setenv (variable, value, overwrite);

}

void

g_unsetenv_utf8 (const gchar *variable)

{

  g_unsetenv (variable);

}

#endif

/* Epilogue {{{1 */

/* vim: set foldmethod=marker: */