entered into RCS

1 files changed, 338 insertions, 0 deletions

diff --git a/lib-src/env.c b/lib-src/env.c
new file mode 100644
index 00000000000..853cb5bfb22
--- /dev/null
+++ b/lib-src/env.c
@@ -0,0 +1,338 @@
+/* env - manipulate environment and execute a program in that environment
+   Copyright (C) 1986 Free Software Foundation, Inc.
+
+   This program 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 2, or (at your option)
+   any later version.
+
+   This program 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 this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* Mly 861126 */
+
+/* If first argument is "-", then a new environment is constructed
+   from scratch; otherwise the environment is inherited from the parent
+   process, except as modified by other options.
+
+   So, "env - foo" will invoke the "foo" program in a null environment,
+   whereas "env foo" would invoke "foo" in the same environment as that
+   passed to "env" itself.
+
+   Subsequent arguments are interpreted as follows:
+
+   * "variable=value" (i.e., an arg containing a "=" character)
+     means to set the specified environment variable to that value.
+     `value' may be of zero length ("variable=").  Note that setting
+     a variable to a zero-length value is different from unsetting it.
+
+   * "-u variable" or "-unset variable"
+     means to unset that variable.
+     If that variable isn't set, does nothing.
+
+   * "-s variable value" or "-set variable value"
+     same as "variable=value".
+
+   * "-" or "--"
+     are used to indicate that the following argument is the program
+     to invoke.  This is only necessary when the program's name
+     begins with "-" or contains a "=".
+
+   * anything else
+     The first remaining argument specifies a program to invoke
+     (it is searched for according to the specification of the PATH
+     environment variable) and any arguments following that are
+     passed as arguments to that program.
+
+     If no program-name is specified following the environment
+     specifications, the resulting environment is printed.
+     This is like specifying a program-name of "printenv".
+
+   Examples:
+     If the environment passed to "env" is
+     { USER=rms EDITOR=emacs PATH=.:/gnubin:/hacks }
+
+     * "env DISPLAY=gnu:0 nemacs"
+        calls "nemacs" in the envionment
+	{ USER=rms EDITOR=emacs PATH=.:/gnubin:/hacks DISPLAY=gnu:0 }
+
+     * "env - USER=foo /hacks/hack bar baz"
+       calls the "hack" program on arguments "bar" and "baz"
+       in an environment in which the only variable is "USER".
+       Note that the "-" option clears out the PATH variable,
+       so one should be careful to specify in which directory
+       to find the program to call.
+
+     * "env -u EDITOR USER=foo PATH=/energy -- e=mc2 bar baz"
+       The program "/energy/e=mc2" is called with environment
+       { USER=foo PATH=/energy }
+*/
+
+#ifdef EMACS
+#define NO_SHORTNAMES
+#include "../src/config.h"
+#endif /* EMACS */
+
+#include <stdio.h>
+
+extern int execvp ();
+
+char *xmalloc (), *xrealloc ();
+char *concat ();
+
+extern char **environ;
+
+char **nenv;
+int nenv_size;
+
+char *progname;
+void setenv ();
+void fatal ();
+char *myindex ();
+
+main (argc, argv, envp)
+     register int argc;
+     register char **argv;
+     char **envp;
+{
+  register char *tem;
+
+  progname = argv[0];
+  argc--;
+  argv++;
+
+  nenv_size = 100;
+  nenv = (char **) xmalloc (nenv_size * sizeof (char *));
+  *nenv = (char *) 0;
+
+  /* "-" flag means to not inherit parent's environment */
+  if (argc && !strcmp (*argv, "-"))
+    {
+      argc--;
+      argv++;
+    }
+  else
+    /* Else pass on existing env vars. */
+    for (; *envp; envp++)
+      {
+	tem = myindex (*envp, '=');
+	if (tem)
+	  {
+	    *tem = '\000';
+	    setenv (*envp, tem + 1);
+	  }
+      }
+
+  while (argc > 0)
+    {
+      tem = myindex (*argv, '=');
+      if (tem)
+	/* If arg contains a "=" it specifies to set a variable */
+	{
+	  *tem = '\000';
+	  setenv (*argv, tem + 1);
+	  argc--;
+	  argv++;
+	  continue;
+	}
+
+      if (**argv != '-')
+	/* Remaining args are program name and args to pass it */
+	break;
+
+      if (argc < 2)
+	fatal ("no argument for `%s' option", *argv);
+      if (!strcmp (*argv, "-u")
+	  || !strcmp (*argv, "-unset"))
+	/* Unset a variable */
+	{
+	  argc--;
+	  argv++;
+	  setenv (*argv, (char *) 0);
+	  argc--;
+	  argv++;
+	}
+      else if (!strcmp (*argv, "-s") ||
+	       !strcmp (*argv, "-set"))
+	/* Set a variable */
+	{
+	  argc--;
+	  argv++;
+	  tem = *argv;
+	  if (argc < 2)
+	    fatal ("no value specified for variable \"%s\"", tem);
+	  argc--;
+	  argv++;
+	  setenv (tem, *argv);
+	  argc--;
+	  argv++;
+	}
+      else if (!strcmp (*argv, "-") || !strcmp (*argv, "--"))
+	{
+	  argc--;
+	  argv++;
+	  break;
+	}
+      else
+	{
+	  fatal ("unrecognized option `%s'", *argv);
+	}
+    }
+
+  /* If no program specified print the environment and exit */
+  if (argc <= 0)
+    {
+      while (*nenv)
+	printf ("%s\n", *nenv++);
+      exit (0);
+    }
+  else
+    {
+      extern int errno, sys_nerr;
+      extern char *sys_errlist[];
+
+      environ = nenv;
+      (void) execvp (*argv, argv);
+
+      fprintf (stderr, "%s: cannot execute `%s'", progname, *argv);
+      if (errno < sys_nerr)
+	fprintf (stderr, ": %s\n", sys_errlist[errno]);
+      else
+	putc ('\n', stderr);
+      exit (errno != 0 ? errno : 1);
+    }
+}
+
+void
+setenv (var, val)
+     register char *var, *val;
+{
+  register char **e;
+  int len = strlen (var);
+
+  {
+    register char *tem = myindex (var, '=');
+    if (tem)
+      fatal ("environment variable names can not contain `=': %s", var);
+    else if (*var == '\000')
+      fatal ("zero-length environment variable name specified");
+  }
+
+  for (e = nenv; *e; e++)
+    if (!strncmp (var, *e, len) && (*e)[len] == '=')
+      {
+	if (val)
+	  goto set;
+	else
+	  do
+	    {
+	      *e = *(e + 1);
+	  } while (*e++);
+	return;
+      }
+
+  if (!val)
+    return;			/* Nothing to unset */
+
+  len = e - nenv;
+  if (len + 1 >= nenv_size)
+    {
+      nenv_size += 100;
+      nenv = (char **) xrealloc (nenv, nenv_size * sizeof (char *));
+      e = nenv + len;
+    }
+
+set:
+  val = concat (var, "=", val);
+  if (*e)
+    free (*e);
+  else
+    *(e + 1) = (char *) 0;
+  *e = val;
+  return;
+}
+
+void
+fatal (msg, arg1, arg2)
+     char *msg, *arg1, *arg2;
+{
+  fprintf (stderr, "%s: ", progname);
+  fprintf (stderr, msg, arg1, arg2);
+  putc ('\n', stderr);
+  exit (1);
+}
+
+
+extern char *malloc (), *realloc ();
+
+void
+memory_fatal ()
+{
+  fatal ("virtual memory exhausted");
+}
+
+char *
+xmalloc (size)
+     int size;
+{
+  register char *value;
+  value = (char *) malloc (size);
+  if (!value)
+    memory_fatal ();
+  return (value);
+}
+
+char *
+xrealloc (ptr, size)
+     char *ptr;
+     int size;
+{
+  register char *value;
+  value = (char *) realloc (ptr, size);
+  if (!value)
+    memory_fatal ();
+  return (value);
+}
+
+/* Return a newly-allocated string whose contents concatenate
+   those of S1, S2, S3.  */
+
+char *
+concat (s1, s2, s3)
+     char *s1, *s2, *s3;
+{
+  int len1 = strlen (s1), len2 = strlen (s2), len3 = strlen (s3);
+  char *result = (char *) xmalloc (len1 + len2 + len3 + 1);
+
+  strcpy (result, s1);
+  strcpy (result + len1, s2);
+  strcpy (result + len1 + len2, s3);
+  result[len1 + len2 + len3] = 0;
+
+  return result;
+}
+
+/* Return a pointer to the first occurrence in STR of C,
+   or 0 if C does not occur.  */
+
+char *
+myindex (str, c)
+     char *str;
+     char c;
+{
+  char *s = str;
+
+  while (*s)
+    {
+      if (*s == c)
+	return s;
+      s++;
+    }
+  return 0;
+}