BSD 4_1c_2 release

[unix-history] / usr / src / lib / libc / gen / getenv.c

/* @(#)getenv.c 4.1 (Berkeley) 12/21/80 */
/*
*      getenv(name)
*      returns ptr to value associated with name, if any, else NULL
*/
#define NULL    0
extern  char **environ;
char    *nvmatch();

char *
getenv(name)
register char *name;
{
       register char **p = environ;
       register char *v;

       while (*p != NULL)
               if ((v = nvmatch(name, *p++)) != NULL)
                       return(v);
       return(NULL);
}

/*
*      s1 is either name, or name=value
*      s2 is name=value
*      if names match, return value of s2, else NULL
*      used for environment searching: see getenv
*/

static char *
nvmatch(s1, s2)
register char *s1, *s2;
{

       while (*s1 == *s2++)
               if (*s1++ == '=')
                       return(s2);
       if (*s1 == '\0' && *(s2-1) == '=')
               return(s2);
       return(NULL);
}