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
  14 extern char **environ;
  15
  16 /*
  17  * prototypes
  18  */
  19 int m_putenv (char *, char *);
  20 int unputenv (char *);
  21 static int nvmatch (char *, char *);
  22
  23
  24 int
  25 m_putenv (char *name, char *value)
  26 {
  27     register int i;
  28     register char **ep, **nep, *cp;
  29
  30     if (!(cp = malloc ((size_t) (strlen (name) + strlen (value) + 2))))
  31         return 1;
  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     if (!(nep = (char **) malloc ((size_t) ((i + 2) * sizeof(*nep)))))
  42         return 1;
  43
  44     for (ep = environ, i = 0; *ep; nep[i++] = *ep++)
  45         continue;
  46     nep[i++] = cp;
  47     nep[i] = NULL;
  48     environ = nep;
  49     return 0;
  50 }
  51
  52
  53 int
  54 unputenv (char *name)
  55 {
  56     char **ep, **nep;
  57
  58     for (ep = environ; *ep; ep++)
  59         if (nvmatch (name, *ep))
  60             break;
  61     if (*ep == NULL)
  62         return 1;
  63
  64     for (nep = ep + 1; *nep; nep++)
  65         continue;
  66     *ep = *--nep;
  67     *nep = NULL;
  68     return 0;
  69 }
  70
  71
  72 static int
  73 nvmatch (char *s1, char *s2)
  74 {
  75     while (*s1 == *s2++)
  76         if (*s1++ == '=')
  77             return 1;
  78
  79     return (*s1 == '\0' && *--s2 == '=');
  80 }