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

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