Debug: growing message format buffer

void

debug(const char *msg, ...)

{

#define MAX_DEBUG_BUFSIZE       65536

  va_list args;

  char buf[1024];

  static uint bufsize = 4096;

  static char *buf = NULL;

  if (!buf)

    buf = mb_alloc(&root_pool, bufsize);

  va_start(args, msg);

  if (dbgf)

    {

      if (bvsnprintf(buf, sizeof(buf), msg, args) < 0)

	bsprintf(buf + sizeof(buf) - 100, " ... <too long>\n");

      while (bvsnprintf(buf, bufsize, msg, args) < 0)

        if (bufsize >= MAX_DEBUG_BUFSIZE)

          bug("Extremely long debug output, split it.");

        else

          buf = mb_realloc(buf, (bufsize *= 2));

      fputs(buf, dbgf);

    }

  va_end(args);