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[emacs.git] / src / environ.c
blob863f40ccd2a1cf9e1e197f7e9c36b1e6e034f1e3
1 /* Environment-hacking for GNU Emacs subprocess
2 Copyright (C) 1986 Free Software Foundation, Inc.
4 This file is part of GNU Emacs.
6 GNU Emacs 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 1, or (at your option)
9 any later version.
11 GNU Emacs 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.
16 You should have received a copy of the GNU General Public License
17 along with GNU Emacs; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 #include "config.h"
22 #include "lisp.h"
24 #ifdef MAINTAIN_ENVIRONMENT
26 #ifdef VMS
27 you lose -- this is un*x-only
28 #endif
30 /* alist of (name-string . value-string) */
31 Lisp_Object Venvironment_alist;
32 extern char **environ;
34 void
35 set_environment_alist (str, val)
36 register Lisp_Object str, val;
38 register Lisp_Object tem;
40 tem = Fassoc (str, Venvironment_alist);
41 if (NULL (tem))
42 if (NULL (val))
44 else
45 Venvironment_alist = Fcons (Fcons (str, val), Venvironment_alist);
46 else
47 if (NULL (val))
48 Venvironment_alist = Fdelq (tem, Venvironment_alist);
49 else
50 XCONS (tem)->cdr = val;
55 static void
56 initialize_environment_alist ()
58 register unsigned char **e, *s;
59 extern char *index ();
61 for (e = (unsigned char **) environ; *e; e++)
63 s = (unsigned char *) index (*e, '=');
64 if (s)
65 set_environment_alist (make_string (*e, s - *e),
66 build_string (s + 1));
71 unsigned char *
72 getenv_1 (str, ephemeral)
73 register unsigned char *str;
74 int ephemeral; /* if ephmeral, don't need to gc-proof */
76 register Lisp_Object env;
77 int len = strlen (str);
79 for (env = Venvironment_alist; CONSP (env); env = XCONS (env)->cdr)
81 register Lisp_Object car = XCONS (env)->car;
82 register Lisp_Object tem = XCONS (car)->car;
84 if ((len == XSTRING (tem)->size) &&
85 (!bcmp (str, XSTRING (tem)->data, len)))
87 /* Found it in the lisp environment */
88 tem = XCONS (car)->cdr;
89 if (ephemeral)
90 /* Caller promises that gc won't make him lose */
91 return XSTRING (tem)->data;
92 else
94 register unsigned char **e;
95 unsigned char *s;
96 int ll = XSTRING (tem)->size;
98 /* Look for element in the original unix environment */
99 for (e = (unsigned char **) environ; *e; e++)
100 if (!bcmp (str, *e, len) && *(*e + len) == '=')
102 s = *e + len + 1;
103 if (strlen (s) >= ll)
104 /* User hasn't either hasn't munged it or has set it
105 to something shorter -- we don't have to cons */
106 goto copy;
107 else
108 goto cons;
110 cons:
111 /* User has setenv'ed it to a diferent value, and our caller
112 isn't guaranteeing that he won't stash it away somewhere.
113 We can't just return a pointer to the lisp string, as that
114 will be corrupted when gc happens. So, we cons (in such
115 a way that it can't be freed -- though this isn't such a
116 problem since the only callers of getenv (as opposed to
117 those of egetenv) are very early, before the user -could-
118 have frobbed the environment. */
119 s = (unsigned char *) xmalloc (ll + 1);
120 copy:
121 bcopy (XSTRING (tem)->data, s, ll + 1);
122 return (s);
126 return ((unsigned char *) 0);
129 /* unsigned -- stupid delcaration in lisp.h */ char *
130 getenv (str)
131 register unsigned char *str;
133 return ((char *) getenv_1 (str, 0));
136 unsigned char *
137 egetenv (str)
138 register unsigned char *str;
140 return (getenv_1 (str, 1));
144 #if (1 == 1) /* use caller-alloca versions, rather than callee-malloc */
146 size_of_current_environ ()
148 register int size;
149 Lisp_Object tem;
151 tem = Flength (Venvironment_alist);
153 size = (XINT (tem) + 1) * sizeof (unsigned char *);
154 /* + 1 for environment-terminating 0 */
156 for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
158 register Lisp_Object str, val;
160 str = XCONS (XCONS (tem)->car)->car;
161 val = XCONS (XCONS (tem)->car)->cdr;
163 size += (XSTRING (str)->size +
164 XSTRING (val)->size +
165 2); /* 1 for '=', 1 for '\000' */
167 return size;
170 void
171 get_current_environ (memory_block)
172 unsigned char **memory_block;
174 register unsigned char **e, *s;
175 register int len;
176 register Lisp_Object tem;
178 e = memory_block;
180 tem = Flength (Venvironment_alist);
182 s = (unsigned char *) memory_block
183 + (XINT (tem) + 1) * sizeof (unsigned char *);
185 for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
187 register Lisp_Object str, val;
189 str = XCONS (XCONS (tem)->car)->car;
190 val = XCONS (XCONS (tem)->car)->cdr;
192 *e++ = s;
193 len = XSTRING (str)->size;
194 bcopy (XSTRING (str)->data, s, len);
195 s += len;
196 *s++ = '=';
197 len = XSTRING (val)->size;
198 bcopy (XSTRING (val)->data, s, len);
199 s += len;
200 *s++ = '\000';
202 *e = 0;
205 #else
206 /* dead code (this function mallocs, caller frees) superseded by above (which allows caller to use alloca) */
207 unsigned char **
208 current_environ ()
210 unsigned char **env;
211 register unsigned char **e, *s;
212 register int len, env_len;
213 Lisp_Object tem;
214 Lisp_Object str, val;
216 tem = Flength (Venvironment_alist);
218 env_len = (XINT (tem) + 1) * sizeof (char *);
219 /* + 1 for terminating 0 */
221 len = 0;
222 for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
224 str = XCONS (XCONS (tem)->car)->car;
225 val = XCONS (XCONS (tem)->car)->cdr;
227 len += (XSTRING (str)->size +
228 XSTRING (val)->size +
232 e = env = (unsigned char **) xmalloc (env_len + len);
233 s = (unsigned char *) env + env_len;
235 for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
237 str = XCONS (XCONS (tem)->car)->car;
238 val = XCONS (XCONS (tem)->car)->cdr;
240 *e++ = s;
241 len = XSTRING (str)->size;
242 bcopy (XSTRING (str)->data, s, len);
243 s += len;
244 *s++ = '=';
245 len = XSTRING (val)->size;
246 bcopy (XSTRING (val)->data, s, len);
247 s += len;
248 *s++ = '\000';
250 *e = 0;
252 return env;
255 #endif /* dead code */
258 DEFUN ("getenv", Fgetenv, Sgetenv, 1, 2, "sEnvironment variable: \np",
259 "Return the value of environment variable VAR, as a string.\n\
260 When invoked interactively, print the value in the echo area.\n\
261 VAR is a string, the name of the variable,\n\
262 or the symbol t, meaning to return an alist representing the\n\
263 current environment.")
264 (str, interactivep)
265 Lisp_Object str, interactivep;
267 Lisp_Object val;
269 if (str == Qt) /* If arg is t, return whole environment */
270 return (Fcopy_alist (Venvironment_alist));
272 CHECK_STRING (str, 0);
273 val = Fcdr (Fassoc (str, Venvironment_alist));
274 if (!NULL (interactivep))
276 if (NULL (val))
277 message ("%s not defined in environment", XSTRING (str)->data);
278 else
279 message ("\"%s\"", XSTRING (val)->data);
281 return val;
284 DEFUN ("setenv", Fsetenv, Ssetenv, 1, 2,
285 "sEnvironment variable: \nsSet %s to value: ",
286 "Set the value of environment variable VAR to VALUE.\n\
287 Both args must be strings. Returns VALUE.")
288 (str, val)
289 Lisp_Object str;
290 Lisp_Object val;
292 Lisp_Object tem;
294 CHECK_STRING (str, 0);
295 if (!NULL (val))
296 CHECK_STRING (val, 0);
298 set_environment_alist (str, val);
299 return val;
303 syms_of_environ ()
305 staticpro (&Venvironment_alist);
306 defsubr (&Ssetenv);
307 defsubr (&Sgetenv);
310 init_environ ()
312 Venvironment_alist = Qnil;
313 initialize_environment_alist ();
316 #endif /* MAINTAIN_ENVIRONMENT */