diplodocus.org Git - nmh/blob - docs/historical/mh-6.8.5/sbr/putenv.c

   1 /* putenv.c - (un) set an envariable */
   2 #ifndef lint
   3 static char ident[] = "@(#)$Id: putenv.c,v 1.6 1992/12/15 00:20:22 jromine Exp $";
   4 #endif  /* lint */
   5
   6 #include "../h/mh.h"
   7 #include <stdio.h>
   8
   9
  10 extern  char **environ;
  11
  12 static nvmatch();
  13
  14 int     m_putenv (name, value)
  15 register char  *name,
  16                *value;
  17 {
  18     register int    i;
  19     register char **ep,
  20                   **nep,
  21                    *cp;
  22
  23     if ((cp = malloc ((unsigned) (strlen (name) + strlen (value) + 2)))
  24             == NULL)
  25         return 1;
  26     (void) sprintf (cp, "%s=%s", name, value);
  27
  28     for (ep = environ, i = 0; *ep; ep++, i++)
  29         if (nvmatch (name, *ep)) {
  30             *ep = cp;
  31             return 0;
  32         }
  33
  34     if ((nep = (char **) malloc ((unsigned) ((i + 2) * sizeof *nep))) == NULL)
  35         return 1;
  36     for (ep = environ, i = 0; *ep; nep[i++] = *ep++)
  37         continue;
  38     nep[i++] = cp;
  39     nep[i] = NULL;
  40     environ = nep;
  41     return 0;
  42 }
  43
  44
  45 int     unputenv (name)
  46 char   *name;
  47 {
  48     char  **ep,
  49           **nep;
  50
  51     for (ep = environ; *ep; ep++)
  52         if (nvmatch (name, *ep))
  53             break;
  54     if (*ep == NULL)
  55         return 1;
  56
  57     for (nep = ep + 1; *nep; nep++)
  58         continue;
  59     *ep = *--nep;
  60     *nep = NULL;
  61     return 0;
  62 }
  63
  64 /* \f */
  65
  66 static nvmatch (s1, s2)
  67 register char  *s1,
  68                *s2;
  69 {
  70     while (*s1 == *s2++)
  71         if (*s1++ == '=')
  72             return 1;
  73
  74     return (*s1 == '\0' && *--s2 == '=');
  75 }