src/environ.c

   1 /* Environment-hacking for GNU Emacs subprocess
   2    Copyright (C) 1986 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   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.
  10
  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.
  15
  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.  */
  19
  20
  21 #include "config.h"
  22 #include "lisp.h"
  23
  24 #ifdef MAINTAIN_ENVIRONMENT
  25
  26 #ifdef VMS
  27 you lose -- this is un*x-only
  28 #endif
  29
  30 /* alist of (name-string . value-string) */
  31 Lisp_Object Venvironment_alist;
  32 extern char **environ;
  33
  34 void
  35 set_environment_alist (str, val)
  36      register Lisp_Object str, val;
  37 {
  38   register Lisp_Object tem;
  39
  40   tem = Fassoc (str, Venvironment_alist);
  41   if (NULL (tem))
  42     if (NULL (val))
  43       ;
  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;
  51 }
  52
  53
  54
  55 static void
  56 initialize_environment_alist ()
  57 {
  58   register unsigned char **e, *s;
  59   extern char *index ();
  60
  61   for (e = (unsigned char **) environ; *e; e++)
  62     {
  63       s = (unsigned char *) index (*e, '=');
  64       if (s)
  65         set_environment_alist (make_string (*e, s - *e),
  66                                build_string (s + 1));
  67     }
  68 }
  69
  70 \f
  71 unsigned char *
  72 getenv_1 (str, ephemeral)
  73      register unsigned char *str;
  74      int ephemeral;             /* if ephmeral, don't need to gc-proof */
  75 {
  76   register Lisp_Object env;
  77   int len = strlen (str);
  78
  79   for (env = Venvironment_alist; CONSP (env); env = XCONS (env)->cdr)
  80     {
  81       register Lisp_Object car = XCONS (env)->car;
  82       register Lisp_Object tem = XCONS (car)->car;
  83
  84       if ((len == XSTRING (tem)->size) &&
  85           (!bcmp (str, XSTRING (tem)->data, len)))
  86         {
  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
  93             {
  94               register unsigned char **e;
  95               unsigned char *s;
  96               int ll = XSTRING (tem)->size;
  97
  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) == '=')
 101                   {
 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;
 109                   };
 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);
 123             }
 124         }
 125     }
 126   return ((unsigned char *) 0);
 127 }
 128
 129 /* unsigned  -- stupid delcaration in lisp.h */ char *
 130 getenv (str)
 131      register unsigned char *str;
 132 {
 133   return ((char *) getenv_1 (str, 0));
 134 }
 135
 136 unsigned char *
 137 egetenv (str)
 138      register unsigned char *str;
 139 {
 140   return (getenv_1 (str, 1));
 141 }
 142 \f
 143
 144 #if (1 == 1) /* use caller-alloca versions, rather than callee-malloc */
 145 int
 146 size_of_current_environ ()
 147 {
 148   register int size;
 149   Lisp_Object tem;
 150
 151   tem = Flength (Venvironment_alist);
 152
 153   size = (XINT (tem) + 1) * sizeof (unsigned char *);
 154   /* + 1 for environment-terminating 0 */
 155
 156   for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
 157     {
 158       register Lisp_Object str, val;
 159
 160       str = XCONS (XCONS (tem)->car)->car;
 161       val = XCONS (XCONS (tem)->car)->cdr;
 162
 163       size += (XSTRING (str)->size +
 164                XSTRING (val)->size +
 165                2);      /* 1 for '=', 1 for '\000' */
 166     }
 167   return size;
 168 }
 169
 170 void
 171 get_current_environ (memory_block)
 172      unsigned char **memory_block;
 173 {
 174   register unsigned char **e, *s;
 175   register int len;
 176   register Lisp_Object tem;
 177
 178   e = memory_block;
 179
 180   tem = Flength (Venvironment_alist);
 181
 182   s = (unsigned char *) memory_block
 183                 + (XINT (tem) + 1) * sizeof (unsigned char *);
 184
 185   for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
 186     {
 187       register Lisp_Object str, val;
 188
 189       str = XCONS (XCONS (tem)->car)->car;
 190       val = XCONS (XCONS (tem)->car)->cdr;
 191
 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';
 201     }
 202   *e = 0;
 203 }
 204
 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 ()
 209 {
 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;
 215
 216   tem = Flength (Venvironment_alist);
 217
 218   env_len = (XINT (tem) + 1) * sizeof (char *);
 219   /* + 1 for terminating 0 */
 220
 221   len = 0;
 222   for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
 223     {
 224       str = XCONS (XCONS (tem)->car)->car;
 225       val = XCONS (XCONS (tem)->car)->cdr;
 226
 227       len += (XSTRING (str)->size +
 228               XSTRING (val)->size +
 229               2);
 230     }
 231
 232   e = env = (unsigned char **) xmalloc (env_len + len);
 233   s = (unsigned char *) env + env_len;
 234
 235   for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
 236     {
 237       str = XCONS (XCONS (tem)->car)->car;
 238       val = XCONS (XCONS (tem)->car)->cdr;
 239
 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';
 249     }
 250   *e = 0;
 251
 252   return env;
 253 }
 254
 255 #endif /* dead code */
 256
 257 \f
 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;
 266 {
 267   Lisp_Object val;
 268
 269   if (str == Qt)                /* If arg is t, return whole environment */
 270     return (Fcopy_alist (Venvironment_alist));
 271
 272   CHECK_STRING (str, 0);
 273   val = Fcdr (Fassoc (str, Venvironment_alist));
 274   if (!NULL (interactivep))
 275     {
 276       if (NULL (val))
 277         message ("%s not defined in environment", XSTRING (str)->data);
 278       else
 279         message ("\"%s\"", XSTRING (val)->data);
 280     }
 281   return val;
 282 }
 283
 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;
 291 {
 292   Lisp_Object tem;
 293
 294   CHECK_STRING (str, 0);
 295   if (!NULL (val))
 296     CHECK_STRING (val, 0);
 297
 298   set_environment_alist (str, val);
 299   return val;
 300 }
 301 \f
 302
 303 syms_of_environ ()
 304 {
 305   staticpro (&Venvironment_alist);
 306   defsubr (&Ssetenv);
 307   defsubr (&Sgetenv);
 308 }
 309
 310 init_environ ()
 311 {
 312   Venvironment_alist = Qnil;
 313   initialize_environment_alist ();
 314 }
 315
 316 #endif /* MAINTAIN_ENVIRONMENT */