Re: [PATCH v4 03/12] pkt-line: (optionally) libify the packet readers

On Thu, Mar 04, 2021 at 09:17:41AM -0500, Jeff Hostetler wrote:

quoted

In the post-context of this hunk, there is this code:

	if ((options & PACKET_READ_DIE_ON_ERR_PACKET) &&
	    starts_with(buffer, "ERR "))
		die(_("remote error: %s"), buffer + 4);

	*pktlen = len;
	return PACKET_READ_NORMAL;

But here, there is no way to override the DIE_ON_ERR with
READ_NEVER_DIE.

The asymmetry is somewhat annoying (i.e. if "if you do not want to
die upon ERR, don't pass DIE_ON_ERR" could be a valid suggestion to
the callers, then "if you do not want to die upon an unexpected
hung-up, pass GENTLE_ON_EOF" would equally be valid suggestion),
but I'll let it pass.

I agree that there is something odd about all of these flags,
but I don't have the context on all the various caller combinations
to make a better suggestion at this time.  And I certainly don't
want to stir up a bigger mess than I already have. :-)

We did document in the .h that READ_NEVER_DIE excludes ERR packets
when READ_DIE_ON_ERR is set, so I think we're safe from unexpected
surprises.

I think the flag is doing sensible things; it's just that the word
"never" in the name is confusing, since it is "never except this one
time".

Would PACKET_READ_GENTLE_ON_READ_ERROR be a better name, to match
GENTLE_ON_EOF? I was tempted to just call it "ON_ERROR", since it also
include parsing errors, but maybe somebody would think that includes ERR
packets (that is more of a stretch, though, I think).

Likewise, I kind of wonder if callers would really prefer suppressing
the error() calls, too. Saying "error: the remote end hung up
unexpectedly" is not that helpful if the "remote end" we are talking
about is fsmonitor, and not the server side of a fetch.

-Peff