Function strbuf_append_fmt_retry

deps/lua/src/strbuf.c:221–248

strbuf_append_fmt_retry() can be used when the there is no known * upper bound for the output string. */

/* strbuf_append_fmt_retry() can be used when the there is no known
 * upper bound for the output string. */
void strbuf_append_fmt_retry(strbuf_t *s, const char *fmt, ...)
{
    va_list arg;
    int fmt_len, try;
    int empty_len;

    /* If the first attempt to append fails, resize the buffer appropriately
     * and try again */
    for (try = 0; ; try++) {
        va_start(arg, fmt);
        /* Append the new formatted string */
        /* fmt_len is the length of the string required, excluding the
         * trailing NULL */
        empty_len = strbuf_empty_length(s);
        /* Add 1 since there is also space to store the terminating NULL. */
        fmt_len = vsnprintf(s->buf + s->length, empty_len + 1, fmt, arg);
        va_end(arg);

        if (fmt_len <= empty_len)
            break;  /* SUCCESS */
        if (try > 0)
            die("BUG: length of formatted string changed");

        strbuf_resize(s, s->length + fmt_len);
    }

    s->length += fmt_len;
}

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