+bool tal_append_vfmt(char **baseptr, const char *fmt, va_list ap)
+{
+ if (!fmt && taken(fmt))
+ return false;
+
+ return do_vfmt(baseptr, strlen(*baseptr), fmt, ap);
+}
+
+bool tal_append_fmt(char **baseptr, const char *fmt, ...)
+{
+ va_list ap;
+ bool ret;
+
+ va_start(ap, fmt);
+ ret = tal_append_vfmt(baseptr, fmt, ap);
+ va_end(ap);
+
+ return ret;
+}
+
+char *tal_strcat(const tal_t *ctx, const char *s1, const char *s2)
+{
+ size_t len1, len2;
+ char *ret;
+
+ if (unlikely(!s2) && taken(s2)) {
+ if (taken(s1))
+ tal_free(s1);
+ return NULL;
+ }
+ /* We have to let through NULL for take(). */
+ len1 = s1 ? strlen(s1) : 0;
+ len2 = strlen(s2);
+
+ /* We use tal_dup_ here to avoid attaching a length property. */
+ ret = tal_dup_(ctx, s1, 1, len1, len2 + 1, false,
+ TAL_LABEL(char, "[]"));
+ if (likely(ret))
+ memcpy(ret + len1, s2, len2 + 1);
+
+ if (taken(s2))
+ tal_free(s2);
+ return ret;
+}
+