entered into RCS

src/environ.c

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+/* Environment-hacking for GNU Emacs subprocess
+   Copyright (C) 1986 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 1, or (at your option)
+any later version.
+
+GNU Emacs 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+
+#include "config.h"
+#include "lisp.h"
+
+#ifdef MAINTAIN_ENVIRONMENT
+
+#ifdef VMS
+you lose -- this is un*x-only
+#endif
+
+/* alist of (name-string . value-string) */
+Lisp_Object Venvironment_alist;
+extern char **environ;
+
+void
+set_environment_alist (str, val)
+     register Lisp_Object str, val;
+{
+  register Lisp_Object tem;
+
+  tem = Fassoc (str, Venvironment_alist);
+  if (NULL (tem))
+    if (NULL (val))
+      ;
+    else
+      Venvironment_alist = Fcons (Fcons (str, val), Venvironment_alist);
+  else
+    if (NULL (val))
+      Venvironment_alist = Fdelq (tem, Venvironment_alist);
+    else
+      XCONS (tem)->cdr = val;
+}
+
+
+
+static void
+initialize_environment_alist ()
+{
+  register unsigned char **e, *s;
+  extern char *index ();
+
+  for (e = (unsigned char **) environ; *e; e++)
+    {
+      s = (unsigned char *) index (*e, '=');
+      if (s)
+	set_environment_alist (make_string (*e, s - *e),
+			       build_string (s + 1));
+    }
+}
+
+
+unsigned char *
+getenv_1 (str, ephemeral)
+     register unsigned char *str;
+     int ephemeral;		/* if ephmeral, don't need to gc-proof */
+{
+  register Lisp_Object env;
+  int len = strlen (str);
+
+  for (env = Venvironment_alist; CONSP (env); env = XCONS (env)->cdr)
+    {
+      register Lisp_Object car = XCONS (env)->car;
+      register Lisp_Object tem = XCONS (car)->car;
+
+      if ((len == XSTRING (tem)->size) &&
+	  (!bcmp (str, XSTRING (tem)->data, len)))
+	{
+	  /* Found it in the lisp environment */
+	  tem = XCONS (car)->cdr;
+	  if (ephemeral)
+	    /* Caller promises that gc won't make him lose */
+	    return XSTRING (tem)->data;
+	  else
+	    {
+	      register unsigned char **e;
+	      unsigned char *s;
+	      int ll = XSTRING (tem)->size;
+
+	      /* Look for element in the original unix environment */
+	      for (e = (unsigned char **) environ; *e; e++)
+		if (!bcmp (str, *e, len) && *(*e + len) == '=')
+		  {
+		    s = *e + len + 1;
+		    if (strlen (s) >= ll)
+		      /* User hasn't either hasn't munged it or has set it
+			 to something shorter -- we don't have to cons */
+		      goto copy;
+		    else
+		      goto cons;
+		  };
+	    cons:
+	      /* User has setenv'ed it to a diferent value, and our caller
+		 isn't guaranteeing that he won't stash it away somewhere.
+		 We can't just return a pointer to the lisp string, as that
+		 will be corrupted when gc happens.  So, we cons (in such
+		 a way that it can't be freed -- though this isn't such a
+		 problem since the only callers of getenv (as opposed to
+		 those of egetenv) are very early, before the user -could-
+		 have frobbed the environment. */
+	      s = (unsigned char *) xmalloc (ll + 1);
+	    copy:
+	      bcopy (XSTRING (tem)->data, s, ll + 1);
+	      return (s);
+	    }
+	}
+    }
+  return ((unsigned char *) 0);
+}
+
+/* unsigned  -- stupid delcaration in lisp.h */ char *
+getenv (str)
+     register unsigned char *str;
+{
+  return ((char *) getenv_1 (str, 0));
+}
+
+unsigned char *
+egetenv (str)
+     register unsigned char *str;
+{
+  return (getenv_1 (str, 1));
+}
+
+
+#if (1 == 1) /* use caller-alloca versions, rather than callee-malloc */
+int
+size_of_current_environ ()
+{
+  register int size;
+  Lisp_Object tem;
+
+  tem = Flength (Venvironment_alist);
+  
+  size = (XINT (tem) + 1) * sizeof (unsigned char *);
+  /* + 1 for environment-terminating 0 */
+
+  for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
+    {
+      register Lisp_Object str, val;
+
+      str = XCONS (XCONS (tem)->car)->car;
+      val = XCONS (XCONS (tem)->car)->cdr;
+
+      size += (XSTRING (str)->size +
+	       XSTRING (val)->size +
+	       2);	/* 1 for '=', 1 for '\000' */
+    }
+  return size;
+}
+
+void
+get_current_environ (memory_block)
+     unsigned char **memory_block;
+{
+  register unsigned char **e, *s;
+  register int len;
+  register Lisp_Object tem;
+
+  e = memory_block;
+
+  tem = Flength (Venvironment_alist);
+  
+  s = (unsigned char *) memory_block
+		+ (XINT (tem) + 1) * sizeof (unsigned char *);
+
+  for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
+    {
+      register Lisp_Object str, val;
+
+      str = XCONS (XCONS (tem)->car)->car;
+      val = XCONS (XCONS (tem)->car)->cdr;
+
+      *e++ = s;
+      len = XSTRING (str)->size;
+      bcopy (XSTRING (str)->data, s, len);
+      s += len;
+      *s++ = '=';
+      len = XSTRING (val)->size;
+      bcopy (XSTRING (val)->data, s, len);
+      s += len;
+      *s++ = '\000';
+    }
+  *e = 0;
+}
+
+#else
+/* dead code (this function mallocs, caller frees) superseded by above (which allows caller to use alloca) */
+unsigned char **
+current_environ ()
+{
+  unsigned char **env;
+  register unsigned char **e, *s;
+  register int len, env_len;
+  Lisp_Object tem;
+  Lisp_Object str, val;
+
+  tem = Flength (Venvironment_alist);
+
+  env_len = (XINT (tem) + 1) * sizeof (char *);
+  /* + 1 for terminating 0 */
+
+  len = 0;
+  for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
+    {
+      str = XCONS (XCONS (tem)->car)->car;
+      val = XCONS (XCONS (tem)->car)->cdr;
+
+      len += (XSTRING (str)->size +
+	      XSTRING (val)->size +
+	      2);
+    }
+
+  e = env = (unsigned char **) xmalloc (env_len + len);
+  s = (unsigned char *) env + env_len;
+
+  for (tem = Venvironment_alist; !NULL (tem); tem = XCONS (tem)->cdr)
+    {
+      str = XCONS (XCONS (tem)->car)->car;
+      val = XCONS (XCONS (tem)->car)->cdr;
+
+      *e++ = s;
+      len = XSTRING (str)->size;
+      bcopy (XSTRING (str)->data, s, len);
+      s += len;
+      *s++ = '=';
+      len = XSTRING (val)->size;
+      bcopy (XSTRING (val)->data, s, len);
+      s += len;
+      *s++ = '\000';
+    }
+  *e = 0;
+
+  return env;
+}
+
+#endif /* dead code */
+
+
+DEFUN ("getenv", Fgetenv, Sgetenv, 1, 2, "sEnvironment variable: \np",
+  "Return the value of environment variable VAR, as a string.\n\
+When invoked interactively, print the value in the echo area.\n\
+VAR is a string, the name of the variable,\n\
+ or the symbol t, meaning to return an alist representing the\n\
+ current environment.")
+  (str, interactivep)
+     Lisp_Object str, interactivep;
+{
+  Lisp_Object val;
+  
+  if (str == Qt)		/* If arg is t, return whole environment */
+    return (Fcopy_alist (Venvironment_alist));
+
+  CHECK_STRING (str, 0);
+  val = Fcdr (Fassoc (str, Venvironment_alist));
+  if (!NULL (interactivep))
+    {
+      if (NULL (val))
+	message ("%s not defined in environment", XSTRING (str)->data);
+      else
+	message ("\"%s\"", XSTRING (val)->data);
+    }
+  return val;
+}
+
+DEFUN ("setenv", Fsetenv, Ssetenv, 1, 2,
+  "sEnvironment variable: \nsSet %s to value: ",
+  "Set the value of environment variable VAR to VALUE.\n\
+Both args must be strings.  Returns VALUE.")
+  (str, val)
+     Lisp_Object str;
+     Lisp_Object val;
+{
+  Lisp_Object tem;
+
+  CHECK_STRING (str, 0);
+  if (!NULL (val))
+    CHECK_STRING (val, 0);
+
+  set_environment_alist (str, val);
+  return val;
+}
+
+
+syms_of_environ ()
+{
+  staticpro (&Venvironment_alist);
+  defsubr (&Ssetenv);
+  defsubr (&Sgetenv);
+}
+
+init_environ ()
+{
+  Venvironment_alist = Qnil;
+  initialize_environment_alist ();
+}
+
+#endif /* MAINTAIN_ENVIRONMENT */