9os

Experimental kernel using plan9 ideas for embedded device
git clone git://git.simple-cc.org/9os
Log | Files | Refs | README | LICENSE

putenv.c (632B)

      1 #include <errno.h>
      2 #include <stdlib.h>
      3 #include <string.h>
      4 
      5 extern char **_environ;
      6 
      7 int
      8 putenv(char *name)
      9 {
     10 	char **p, *s;
     11 	size_t siz, len, cnt;
     12 	static char **lastenv;
     13 
     14 	if ((s = strchr(name, '=')) == NULL) {
     15 		errno = EINVAL;
     16 		return -1;
     17 	}
     18 	len = s - name;
     19 
     20 	for (p = _environ; *p; ++p) {
     21 		if (!strncmp(name, *p, len) && (*p)[len] == '=') {
     22 			*p = name;
     23 			return 0;
     24 		}
     25 	}
     26 
     27 	cnt = p - _environ;
     28 	siz = (cnt + 2) * sizeof(char **);
     29 
     30 	if ((p = realloc(lastenv, siz)) == NULL)
     31 		return -1;
     32 	if (!lastenv)
     33 		memcpy(p, _environ, cnt * sizeof(char **));
     34 	lastenv = _environ = p;
     35 
     36 	p[cnt] = name;
     37 	p[cnt+1] = NULL;
     38 
     39 	return 0;
     40 }