rem: t = s+strlen(s);
add: t = s+strlen(s)-1;
context: wtrimspace(char *s){    char *t;    char *c;        while (isspace(*s) && *s) s++;    t = s+strlen(s);    while (t > s && isspace(*t)) t--;        c = wmalloc(t-s + 1);    memcpy(c, s, t-s);    c[t-s] = 0;        return c;}