diplodocus.org Git - nmh/blob - sbr/putenv.c

   1
   2 /*
   3  * putenv.c -- (un)set an envariable
   4  *
   5  * $Id$
   6  *
   7  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   8  * COPYRIGHT file in the root directory of the nmh distribution for
   9  * complete copyright information.
  10  */
  11
  12 #include <h/mh.h>
  13 #include <h/utils.h>
  14
  15 extern char **environ;
  16
  17 /*
  18  * prototypes
  19  */
  20 int m_putenv (char *, char *);
  21 int unputenv (char *);
  22 static int nvmatch (char *, char *);
  23
  24
  25 int
  26 m_putenv (char *name, char *value)
  27 {
  28     register int i;
  29     register char **ep, **nep, *cp;
  30
  31     cp = mh_xmalloc ((size_t) (strlen (name) + strlen (value) + 2));
  32
  33     sprintf (cp, "%s=%s", name, value);
  34
  35     for (ep = environ, i = 0; *ep; ep++, i++)
  36         if (nvmatch (name, *ep)) {
  37             *ep = cp;
  38             return 0;
  39         }
  40
  41     nep = (char **) mh_xmalloc ((size_t) ((i + 2) * sizeof(*nep)));
  42
  43     for (ep = environ, i = 0; *ep; nep[i++] = *ep++)
  44         continue;
  45     nep[i++] = cp;
  46     nep[i] = NULL;
  47     environ = nep;
  48     return 0;
  49 }
  50
  51
  52 int
  53 unputenv (char *name)
  54 {
  55     char **ep, **nep;
  56
  57     for (ep = environ; *ep; ep++)
  58         if (nvmatch (name, *ep))
  59             break;
  60     if (*ep == NULL)
  61         return 1;
  62
  63     for (nep = ep + 1; *nep; nep++)
  64         continue;
  65     *ep = *--nep;
  66     *nep = NULL;
  67     return 0;
  68 }
  69
  70
  71 static int
  72 nvmatch (char *s1, char *s2)
  73 {
  74     while (*s1 == *s2++)
  75         if (*s1++ == '=')
  76             return 1;
  77
  78     return (*s1 == '\0' && *--s2 == '=');
  79 }