1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1998 Peter Mattis, Spencer Kimball and Josh MacDonald
3 *
4 * SPDX-License-Identifier: LGPL-2.1-or-later
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library 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 GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 /*
21 * Modified by the GLib Team and others 1997-2000. See the AUTHORS
22 * file for a list of people on the GLib Team. See the ChangeLog
23 * files for a list of changes. These files are distributed with
24 * GLib at ftp://ftp.gtk.org/pub/gtk/.
25 */
26
27 #include "config.h"
28
29 #include "genviron.h"
30
31 #include <stdlib.h>
32 #include <string.h>
33 #ifdef HAVE_CRT_EXTERNS_H
34 #include <crt_externs.h> /* for _NSGetEnviron */
35 #endif
36 #ifdef G_OS_WIN32
37 #include <windows.h>
38 #endif
39
40 #include "glib-private.h"
41 #include "gmem.h"
42 #include "gmessages.h"
43 #include "gstrfuncs.h"
44 #include "gunicode.h"
45 #include "gconvert.h"
46 #include "gquark.h"
47 #include "gthreadprivate.h"
48
49 /* Environ array functions {{{1 */
50 static gboolean
51 g_environ_matches (const gchar *env, const gchar *variable, gsize len)
52 {
53 #ifdef G_OS_WIN32
54 /* TODO handle Unicode environment variable names */
55 /* Like filesystem paths, environment variables are case-insensitive. */
56 return g_ascii_strncasecmp (env, variable, len) == 0 && env[len] == '=';
57 #else
58 return strncmp (env, variable, len) == 0 && env[len] == '=';
59 #endif
60 }
61
62 static gint
63 g_environ_find (gchar **envp,
64 const gchar *variable)
65 {
66 gsize len;
67 gint i;
68
69 if (envp == NULL)
70 return -1;
71
72 len = strlen (variable);
73
74 for (i = 0; envp[i]; i++)
75 {
76 if (g_environ_matches (envp[i], variable, len))
77 return i;
78 }
79
80 return -1;
81 }
82
83 /**
84 * g_environ_getenv:
85 * @envp: (nullable) (array zero-terminated=1) (transfer none) (element-type filename):
86 * an environment list (eg, as returned from g_get_environ()), or %NULL
87 * for an empty environment list
88 * @variable: (type filename): the environment variable to get
89 *
90 * Returns the value of the environment variable @variable in the
91 * provided list @envp.
92 *
93 * Returns: (type filename) (nullable): the value of the environment variable, or %NULL if
94 * the environment variable is not set in @envp. The returned
95 * string is owned by @envp, and will be freed if @variable is
96 * set or unset again.
97 *
98 * Since: 2.32
99 */
100 const gchar *
101 g_environ_getenv (gchar **envp,
102 const gchar *variable)
103 {
104 gint index;
105
106 g_return_val_if_fail (variable != NULL, NULL);
107
108 index = g_environ_find (envp, variable);
109 if (index != -1)
110 return envp[index] + strlen (variable) + 1;
111 else
112 return NULL;
113 }
114
115 /**
116 * g_environ_setenv:
117 * @envp: (nullable) (array zero-terminated=1) (element-type filename) (transfer full):
118 * an environment list that can be freed using g_strfreev() (e.g., as
119 * returned from g_get_environ()), or %NULL for an empty
120 * environment list
121 * @variable: (type filename): the environment variable to set, must not
122 * contain '='
123 * @value: (type filename): the value for to set the variable to
124 * @overwrite: whether to change the variable if it already exists
125 *
126 * Sets the environment variable @variable in the provided list
127 * @envp to @value.
128 *
129 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):
130 * the updated environment list. Free it using g_strfreev().
131 *
132 * Since: 2.32
133 */
134 gchar **
135 g_environ_setenv (gchar **envp,
136 const gchar *variable,
137 const gchar *value,
138 gboolean overwrite)
139 {
140 gint index;
141
142 g_return_val_if_fail (variable != NULL, NULL);
143 g_return_val_if_fail (strchr (variable, '=') == NULL, NULL);
144 g_return_val_if_fail (value != NULL, NULL);
145
146 index = g_environ_find (envp, variable);
147 if (index != -1)
148 {
149 if (overwrite)
150 {
151 g_free (envp[index]);
152 envp[index] = g_strdup_printf ("%s=%s", variable, value);
153 }
154 }
155 else
156 {
157 gint length;
158
159 length = envp ? g_strv_length (envp) : 0;
160 envp = g_renew (gchar *, envp, length + 2);
161 envp[length] = g_strdup_printf ("%s=%s", variable, value);
162 envp[length + 1] = NULL;
163 }
164
165 return envp;
166 }
167
168 static gchar **
169 g_environ_unsetenv_internal (gchar **envp,
170 const gchar *variable,
171 gboolean free_value)
172 {
173 gsize len;
174 gchar **e, **f;
175
176 len = strlen (variable);
177
178 /* Note that we remove *all* environment entries for
179 * the variable name, not just the first.
180 */
181 e = f = envp;
182 while (*e != NULL)
183 {
184 if (!g_environ_matches (*e, variable, len))
185 {
186 *f = *e;
187 f++;
188 }
189 else
190 {
191 if (free_value)
192 g_free (*e);
193 }
194
195 e++;
196 }
197 *f = NULL;
198
199 return envp;
200 }
201
202
203 /**
204 * g_environ_unsetenv:
205 * @envp: (nullable) (array zero-terminated=1) (element-type filename) (transfer full):
206 * an environment list that can be freed using g_strfreev() (e.g., as
207 * returned from g_get_environ()), or %NULL for an empty environment list
208 * @variable: (type filename): the environment variable to remove, must not
209 * contain '='
210 *
211 * Removes the environment variable @variable from the provided
212 * environment @envp.
213 *
214 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):
215 * the updated environment list. Free it using g_strfreev().
216 *
217 * Since: 2.32
218 */
219 gchar **
220 g_environ_unsetenv (gchar **envp,
221 const gchar *variable)
222 {
223 g_return_val_if_fail (variable != NULL, NULL);
224 g_return_val_if_fail (strchr (variable, '=') == NULL, NULL);
225
226 if (envp == NULL)
227 return NULL;
228
229 return g_environ_unsetenv_internal (envp, variable, TRUE);
230 }
231
232 /* UNIX implementation {{{1 */
233 #ifndef G_OS_WIN32
234
235 /**
236 * g_getenv:
237 * @variable: (type filename): the environment variable to get
238 *
239 * Returns the value of an environment variable.
240 *
241 * On UNIX, the name and value are byte strings which might or might not
242 * be in some consistent character set and encoding. On Windows, they are
243 * in UTF-8.
244 * On Windows, in case the environment variable's value contains
245 * references to other environment variables, they are expanded.
246 *
247 * Returns: (type filename) (nullable): the value of the environment variable, or %NULL if
248 * the environment variable is not found. The returned string
249 * may be overwritten by the next call to g_getenv(), g_setenv()
250 * or g_unsetenv().
251 */
252 const gchar *
253 g_getenv (const gchar *variable)
254 {
255 g_return_val_if_fail (variable != NULL, NULL);
256
257 return getenv (variable);
258 }
259
260 /**
261 * g_setenv:
262 * @variable: (type filename): the environment variable to set, must not
263 * contain '='.
264 * @value: (type filename): the value for to set the variable to.
265 * @overwrite: whether to change the variable if it already exists.
266 *
267 * Sets an environment variable. On UNIX, both the variable's name and
268 * value can be arbitrary byte strings, except that the variable's name
269 * cannot contain '='. On Windows, they should be in UTF-8.
270 *
271 * Note that on some systems, when variables are overwritten, the memory
272 * used for the previous variables and its value isn't reclaimed.
273 *
274 * You should be mindful of the fact that environment variable handling
275 * in UNIX is not thread-safe, and your program may crash if one thread
276 * calls g_setenv() while another thread is calling getenv(). (And note
277 * that many functions, such as gettext(), call getenv() internally.)
278 * This function is only safe to use at the very start of your program,
279 * before creating any other threads (or creating objects that create
280 * worker threads of their own).
281 *
282 * If you need to set up the environment for a child process, you can
283 * use g_get_environ() to get an environment array, modify that with
284 * g_environ_setenv() and g_environ_unsetenv(), and then pass that
285 * array directly to execvpe(), g_spawn_async(), or the like.
286 *
287 * Returns: %FALSE if the environment variable couldn't be set.
288 *
289 * Since: 2.4
290 */
291 gboolean
292 g_setenv (const gchar *variable,
293 const gchar *value,
294 gboolean overwrite)
295 {
296 gint result;
297 #ifndef HAVE_SETENV
298 gchar *string;
299 #endif
300
301 g_return_val_if_fail (variable != NULL, FALSE);
302 g_return_val_if_fail (strchr (variable, '=') == NULL, FALSE);
303 g_return_val_if_fail (value != NULL, FALSE);
304
305 #ifndef G_DISABLE_CHECKS
306 /* FIXME: This will be upgraded to a g_warning() in a future release of GLib.
307 * See https://gitlab.gnome.org/GNOME/glib/issues/715 */
308 if (g_thread_n_created () > 0)
309 g_debug ("setenv()/putenv() are not thread-safe and should not be used after threads are created");
310 #endif
311
312 #ifdef HAVE_SETENV
313 result = setenv (variable, value, overwrite);
314 #else
315 if (!overwrite && getenv (variable) != NULL)
316 return TRUE;
317
318 /* This results in a leak when you overwrite existing
319 * settings. It would be fairly easy to fix this by keeping
320 * our own parallel array or hash table.
321 */
322 string = g_strconcat (variable, "=", value, NULL);
323 result = putenv (string);
324 #endif
325 return result == 0;
326 }
327
328 #ifdef HAVE__NSGETENVIRON
329 #define environ (*_NSGetEnviron())
330 #else
331 /* According to the Single Unix Specification, environ is not
332 * in any system header, although unistd.h often declares it.
333 */
334 extern char **environ;
335 #endif
336
337 /**
338 * g_unsetenv:
339 * @variable: (type filename): the environment variable to remove, must
340 * not contain '='
341 *
342 * Removes an environment variable from the environment.
343 *
344 * Note that on some systems, when variables are overwritten, the
345 * memory used for the previous variables and its value isn't reclaimed.
346 *
347 * You should be mindful of the fact that environment variable handling
348 * in UNIX is not thread-safe, and your program may crash if one thread
349 * calls g_unsetenv() while another thread is calling getenv(). (And note
350 * that many functions, such as gettext(), call getenv() internally.) This
351 * function is only safe to use at the very start of your program, before
352 * creating any other threads (or creating objects that create worker
353 * threads of their own).
354 *
355 * If you need to set up the environment for a child process, you can
356 * use g_get_environ() to get an environment array, modify that with
357 * g_environ_setenv() and g_environ_unsetenv(), and then pass that
358 * array directly to execvpe(), g_spawn_async(), or the like.
359 *
360 * Since: 2.4
361 */
362 void
363 g_unsetenv (const gchar *variable)
364 {
365 g_return_if_fail (variable != NULL);
366 g_return_if_fail (strchr (variable, '=') == NULL);
367
368 #ifndef G_DISABLE_CHECKS
369 /* FIXME: This will be upgraded to a g_warning() in a future release of GLib.
370 * See https://gitlab.gnome.org/GNOME/glib/issues/715 */
371 if (g_thread_n_created () > 0)
372 g_debug ("unsetenv() is not thread-safe and should not be used after threads are created");
373 #endif
374
375 #ifdef HAVE_UNSETENV
376 unsetenv (variable);
377 #else /* !HAVE_UNSETENV */
378 /* Mess directly with the environ array.
379 * This seems to be the only portable way to do this.
380 */
381 g_environ_unsetenv_internal (environ, variable, FALSE);
382 #endif /* !HAVE_UNSETENV */
383 }
384
385 /**
386 * g_listenv:
387 *
388 * Gets the names of all variables set in the environment.
389 *
390 * Programs that want to be portable to Windows should typically use
391 * this function and g_getenv() instead of using the environ array
392 * from the C library directly. On Windows, the strings in the environ
393 * array are in system codepage encoding, while in most of the typical
394 * use cases for environment variables in GLib-using programs you want
395 * the UTF-8 encoding that this function and g_getenv() provide.
396 *
397 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):
398 * a %NULL-terminated list of strings which must be freed with
399 * g_strfreev().
400 *
401 * Since: 2.8
402 */
403 gchar **
404 g_listenv (void)
405 {
406 gchar **result, *eq;
407 gint len, i, j;
408
409 len = g_strv_length (environ);
410 result = g_new0 (gchar *, len + 1);
411
412 j = 0;
413 for (i = 0; i < len; i++)
414 {
415 eq = strchr (environ[i], '=');
416 if (eq)
417 result[j++] = g_strndup (environ[i], eq - environ[i]);
418 }
419
420 result[j] = NULL;
421
422 return result;
423 }
424
425 /**
426 * g_get_environ:
427 *
428 * Gets the list of environment variables for the current process.
429 *
430 * The list is %NULL terminated and each item in the list is of the
431 * form 'NAME=VALUE'.
432 *
433 * This is equivalent to direct access to the 'environ' global variable,
434 * except portable.
435 *
436 * The return value is freshly allocated and it should be freed with
437 * g_strfreev() when it is no longer needed.
438 *
439 * Returns: (array zero-terminated=1) (element-type filename) (transfer full):
440 * the list of environment variables
441 *
442 * Since: 2.28
443 */
444 gchar **
445 g_get_environ (void)
446 {
447 return g_strdupv (environ);
448 }
449
450 /* Win32 implementation {{{1 */
451 #else /* G_OS_WIN32 */
452
453 const gchar *
454 g_getenv (const gchar *variable)
455 {
456 GQuark quark;
457 gchar *value;
458 wchar_t dummy[2], *wname, *wvalue;
459 DWORD len;
460
461 g_return_val_if_fail (variable != NULL, NULL);
462 g_return_val_if_fail (g_utf8_validate (variable, -1, NULL), NULL);
463
464 /* On Windows NT, it is relatively typical that environment
465 * variables contain references to other environment variables. If
466 * so, use ExpandEnvironmentStrings(). (In an ideal world, such
467 * environment variables would be stored in the Registry as
468 * REG_EXPAND_SZ type values, and would then get automatically
469 * expanded before a program sees them. But there is broken software
470 * that stores environment variables as REG_SZ values even if they
471 * contain references to other environment variables.)
472 */
473
474 wname = g_utf8_to_utf16 (variable, -1, NULL, NULL, NULL);
475
476 len = GetEnvironmentVariableW (wname, dummy, 2);
477
478 if (len == 0)
479 {
480 g_free (wname);
481 if (GetLastError () == ERROR_ENVVAR_NOT_FOUND)
482 return NULL;
483
484 quark = g_quark_from_static_string ("");
485 return g_quark_to_string (quark);
486 }
487 else if (len == 1)
488 len = 2;
489
490 wvalue = g_new (wchar_t, len);
491
492 if (GetEnvironmentVariableW (wname, wvalue, len) != len - 1)
493 {
494 g_free (wname);
495 g_free (wvalue);
496 return NULL;
497 }
498
499 if (wcschr (wvalue, L'%') != NULL)
500 {
501 wchar_t *tem = wvalue;
502
503 len = ExpandEnvironmentStringsW (wvalue, dummy, 2);
504
505 if (len > 0)
506 {
507 wvalue = g_new (wchar_t, len);
508
509 if (ExpandEnvironmentStringsW (tem, wvalue, len) != len)
510 {
511 g_free (wvalue);
512 wvalue = tem;
513 }
514 else
515 g_free (tem);
516 }
517 }
518
519 value = g_utf16_to_utf8 (wvalue, -1, NULL, NULL, NULL);
520
521 g_free (wname);
522 g_free (wvalue);
523
524 quark = g_quark_from_string (value);
525 g_free (value);
526
527 return g_quark_to_string (quark);
528 }
529
530 gboolean
531 g_setenv (const gchar *variable,
532 const gchar *value,
533 gboolean overwrite)
534 {
535 gboolean retval;
536 wchar_t *wname, *wvalue, *wassignment;
537 gchar *tem;
538
539 g_return_val_if_fail (variable != NULL, FALSE);
540 g_return_val_if_fail (strchr (variable, '=') == NULL, FALSE);
541 g_return_val_if_fail (value != NULL, FALSE);
542 g_return_val_if_fail (g_utf8_validate (variable, -1, NULL), FALSE);
543 g_return_val_if_fail (g_utf8_validate (value, -1, NULL), FALSE);
544
545 if (!overwrite && g_getenv (variable) != NULL)
546 return TRUE;
547
548 /* We want to (if possible) set both the environment variable copy
549 * kept by the C runtime and the one kept by the system.
550 *
551 * We can't use only the C runtime's putenv or _wputenv() as that
552 * won't work for arbitrary Unicode strings in a "non-Unicode" app
553 * (with main() and not wmain()). In a "main()" app the C runtime
554 * initializes the C runtime's environment table by converting the
555 * real (wide char) environment variables to system codepage, thus
556 * breaking those that aren't representable in the system codepage.
557 *
558 * As the C runtime's putenv() will also set the system copy, we do
559 * the putenv() first, then call SetEnvironmentValueW ourselves.
560 */
561
562 wname = g_utf8_to_utf16 (variable, -1, NULL, NULL, NULL);
563 wvalue = g_utf8_to_utf16 (value, -1, NULL, NULL, NULL);
564 tem = g_strconcat (variable, "=", value, NULL);
565 wassignment = g_utf8_to_utf16 (tem, -1, NULL, NULL, NULL);
566
567 g_free (tem);
568 _wputenv (wassignment);
569 g_free (wassignment);
570
571 retval = (SetEnvironmentVariableW (wname, wvalue) != 0);
572
573 g_free (wname);
574 g_free (wvalue);
575
576 return retval;
577 }
578
579 void
580 g_unsetenv (const gchar *variable)
581 {
582 wchar_t *wname, *wassignment;
583 gchar *tem;
584
585 g_return_if_fail (variable != NULL);
586 g_return_if_fail (strchr (variable, '=') == NULL);
587 g_return_if_fail (g_utf8_validate (variable, -1, NULL));
588
589 wname = g_utf8_to_utf16 (variable, -1, NULL, NULL, NULL);
590 tem = g_strconcat (variable, "=", NULL);
591 wassignment = g_utf8_to_utf16 (tem, -1, NULL, NULL, NULL);
592
593 g_free (tem);
594 _wputenv (wassignment);
595 g_free (wassignment);
596
597 SetEnvironmentVariableW (wname, NULL);
598
599 g_free (wname);
600 }
601
602 gchar **
603 g_listenv (void)
604 {
605 gchar **result, *eq;
606 gint len = 0, j;
607 wchar_t *p, *q;
608
609 p = (wchar_t *) GetEnvironmentStringsW ();
610 if (p != NULL)
611 {
612 q = p;
613 while (*q)
614 {
615 q += wcslen (q) + 1;
616 len++;
617 }
618 }
619 result = g_new0 (gchar *, len + 1);
620
621 j = 0;
622 q = p;
623 while (*q)
624 {
625 result[j] = g_utf16_to_utf8 (q, -1, NULL, NULL, NULL);
626 if (result[j] != NULL)
627 {
628 eq = strchr (result[j], '=');
629 if (eq && eq > result[j])
630 {
631 *eq = '\0';
632 j++;
633 }
634 else
635 g_free (result[j]);
636 }
637 q += wcslen (q) + 1;
638 }
639 result[j] = NULL;
640 FreeEnvironmentStringsW (p);
641
642 return result;
643 }
644
645 gchar **
646 g_get_environ (void)
647 {
648 gunichar2 *strings;
649 gchar **result;
650 gint i, n;
651
652 strings = GetEnvironmentStringsW ();
653 for (n = 0, i = 0; strings[n]; i++)
654 n += wcslen (strings + n) + 1;
655
656 result = g_new (char *, i + 1);
657 for (n = 0, i = 0; strings[n]; i++)
658 {
659 result[i] = g_utf16_to_utf8 (strings + n, -1, NULL, NULL, NULL);
660 n += wcslen (strings + n) + 1;
661 }
662 FreeEnvironmentStringsW (strings);
663 result[i] = NULL;
664
665 return result;
666 }
667
668 #endif /* G_OS_WIN32 */
669
670 #ifdef G_OS_WIN32
671
672 /* Binary compatibility versions. Not for newly compiled code. */
673
674 _GLIB_EXTERN const gchar *g_getenv_utf8 (const gchar *variable);
675 _GLIB_EXTERN gboolean g_setenv_utf8 (const gchar *variable,
676 const gchar *value,
677 gboolean overwrite);
678 _GLIB_EXTERN void g_unsetenv_utf8 (const gchar *variable);
679
680 const gchar *
681 g_getenv_utf8 (const gchar *variable)
682 {
683 return g_getenv (variable);
684 }
685
686 gboolean
687 g_setenv_utf8 (const gchar *variable,
688 const gchar *value,
689 gboolean overwrite)
690 {
691 return g_setenv (variable, value, overwrite);
692 }
693
694 void
695 g_unsetenv_utf8 (const gchar *variable)
696 {
697 g_unsetenv (variable);
698 }
699
700 #endif
701
702 /* Epilogue {{{1 */
703 /* vim: set foldmethod=marker: */