lib/other/putenv.c

   1 /*
   2  * (c) copyright 1989 by the Vrije Universiteit, Amsterdam, The Netherlands.
   3  * See the copyright notice in the ACK home directory, in the file "Copyright".
   4  */
   5 /* $Header$ */
   6
   7 #include        <stdlib.h>
   8 #include        <string.h>
   9
  10 #define ENTRY_INC       10
  11 #define rounded(x)      (((x / ENTRY_INC) + 1) * ENTRY_INC)
  12
  13 extern _CONST char ***_penviron;
  14
  15 int
  16 putenv(name)
  17 char *name;
  18 {
  19         register _CONST char **v = *_penviron;
  20         register char *r;
  21         static int size = 0;
  22         /* When size != 0, it contains the number of entries in the
  23          * table (including the final NULL pointer). This means that the
  24          * last non-null entry  is environ[size - 2].
  25          */
  26
  27         if (!name) return 0;
  28         if (*_penviron == NULL) return 1;
  29         if (r = strchr(name, '=')) {
  30                 register _CONST char *p, *q;
  31
  32                 *r = '\0';
  33
  34                 if (v != NULL) {
  35                         while ((p = *v) != NULL) {
  36                                 q = name;
  37                                 while (*q && (*q++ == *p++))
  38                                         /* EMPTY */ ;
  39                                 if (*q || (*p != '=')) {
  40                                         v++;
  41                                 } else {
  42                                         /* The name was already in the
  43                                          * environment.
  44                                          */
  45                                         *r = '=';
  46                                         *v = name;
  47                                         return 0;
  48                                 }
  49                         }
  50                 }
  51                 *r = '=';
  52                 v = *_penviron;
  53         }
  54
  55         if (!size) {
  56                 register _CONST char **p;
  57                 register int i = 0;
  58
  59                 if (v)
  60                         do {
  61                                 i++;
  62                         } while (*v++);
  63                 if (!(v = malloc(rounded(i) * sizeof(char **))))
  64                         return 1;
  65                 size = i;
  66                 p = *_penviron;
  67                 *_penviron = v;
  68                 while (*v++ = *p++);            /* copy the environment */
  69                 v = *_penviron;
  70         } else if (!(size % ENTRY_INC)) {
  71                 if (!(v = realloc(*_penviron, rounded(size) * sizeof(char **))))
  72                         return 1;
  73                 *_penviron = v;
  74         }
  75         v[size - 1] = name;
  76         v[size] = NULL;
  77         size++;
  78         return 0;
  79 }