log_sds log_sdscatvprintf()

in Sources/aliyun-log-c-sdk/log_sds.c [339:374]

• 28 lines of code
• 8 McCabe index (conditional complexity)

log_sds log_sdscatvprintf(log_sds s, const char *fmt, va_list ap) {
    va_list cpy;
    char staticbuf[1024], *buf = staticbuf, *t;
    size_t buflen = strlen(fmt) * 2;

    /* We try to start using a static buffer for speed.
     * If not possible we revert to heap allocation. */
    if (buflen > sizeof(staticbuf)) {
        buf = malloc(buflen);
        if (buf == NULL) return NULL;
    } else {
        buflen = sizeof(staticbuf);
    }

    /* Try with buffers two times bigger every time we fail to
     * fit the string in the current buffer size. */
    while (1) {
        buf[buflen - 2] = '\0';
        va_copy(cpy, ap);
        vsnprintf(buf, buflen, fmt, cpy);
        va_end(cpy);
        if (buf[buflen - 2] != '\0') {
            if (buf != staticbuf) free(buf);
            buflen *= 2;
            buf = malloc(buflen);
            if (buf == NULL) return NULL;
            continue;
        }
        break;
    }

    /* Finally concat the obtained string to the SDS string and return it. */
    t = log_sdscat(s, buf);
    if (buf != staticbuf) free(buf);
    return t;
}