STDIN behaviour change ( 2.2.44/2.4.5)

[Werner Koch]

Hi!

On Wed, 11 Dec 2024 19:58, Dirk-Willem van Gulik said:

> After an update to 2.4.5 - we’re seeing an odd behaviour change (not sure it is regression) - where GPG seems to wait for an EOF as opposed to the end of message.

I am not sure what you mean by EOF vs. end of message.  How should gpg
distinguish your two use cases - it reads the input and acts upon it.
There might have been changes in the input buffering but that can't
be the problem.

On Unix we use read(2) until it returns 0 to indicate EOF or until we
see an error and the errno is EPIPE.  All other errors will print an
error message.

For reference  the code in 2.2 is:

	  do
	    {
	      n = read (f, buf, size);
	    }
	  while (n == -1 && errno == EINTR);
	  if (n == -1)
	    {			/* error */
	      if (errno != EPIPE)
		{
		  rc = gpg_error_from_syserror ();
		  log_error ("%s: read error: %s\n",
			     a->fname, strerror (errno));
		}
	    }
	  else if (!n)
	    {			/* eof */
	      a->eof_seen = 1;
	      rc = -1;
	    }
	  else
	    {
	      nbytes = n;
	    }

and in 2.4:

        read_more:
          do
            {
              n = read (f, buf + nbytes, size - nbytes);
            }
          while (n == -1 && errno == EINTR);
          if (n > 0)
            {
              nbytes += n;
              if (nbytes < size)
                goto read_more;
            }
          else if (!n) /* eof */
            {
              if (nbytes)
                a->delayed_rc = -1;
              else
                {
                  a->eof_seen = 1;
                  rc = -1;
                }
            }
          else /* error */
            {
              rc = gpg_error_from_syserror ();
              if (gpg_err_code (rc) != GPG_ERR_EPIPE)
                log_error ("%s: read error: %s\n", a->fname, gpg_strerror (rc));
              if (nbytes)
                {
                  a->delayed_rc = rc;
                  rc = 0;
                }
            }

The change in 2.4 (from 2018) is due to
https://dev.gnupg.org/rGbfc11816444512b4ebcc6617d3c3b5988e753de3
which tries to utilize larger buffers.


Shalom-Salam,

   Werner


-- 
The pioneers of a warless world are the youth that
refuse military service.             - A. Einstein
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