+
+char *strextend(char **x, ...) {
+ va_list ap;
+ size_t f, l;
+ char *r, *p;
+
+ assert(x);
+
+ l = f = *x ? strlen(*x) : 0;
+
+ va_start(ap, x);
+ for (;;) {
+ const char *t;
+ size_t n;
+
+ t = va_arg(ap, const char *);
+ if (!t)
+ break;
+
+ n = strlen(t);
+ if (n > ((size_t) -1) - l) {
+ va_end(ap);
+ return NULL;
+ }
+
+ l += n;
+ }
+ va_end(ap);
+
+ r = realloc(*x, l+1);
+ if (!r)
+ return NULL;
+
+ p = r + f;
+
+ va_start(ap, x);
+ for (;;) {
+ const char *t;
+
+ t = va_arg(ap, const char *);
+ if (!t)
+ break;
+
+ p = stpcpy(p, t);
+ }
+ va_end(ap);
+
+ *p = 0;
+ *x = r;
+
+ return r + l;
+}