Re: Improving psql's \password command

"Bossart, Nathan" <bossartn(at)amazon(dot)com> writes:
> Here is an attempt at adding control-C support for \password. With
> this patch, we pass sigint_interrupt_jmp and sigint_interrupt_enabled
> all the way down to pg_get_line_append(), which is admittedly a bit
> more complicated than I think would be ideal. I see a couple of other
> calls to simple_prompt() (e.g., \prompt and \connect), and I think the
> same infrastructure could be used for those as well. I'll send some
> follow-up patches for those if this approach seems reasonable.

Hm. It's not as bad as I thought it might be, but I still dislike
importing <setjmp.h> into common/string.h --- that seems like a mighty
ugly dependency to have there. I guess one idea to avoid that is to
declare SigintInterruptContext.jmpbuf as "void *". Alternatively we
could push those function declarations into some specialized header.

Some other random observations (not a full review):

* API spec for SigintInterruptContext needs to be a bit more detailed.
Maybe "... via an existing SIGINT signal handler that will longjmp to
the specified place, but only when *enabled is true".

* I don't believe that this bit is necessary, or if it is,
the comment fails to justify it:

- initStringInfo(&buf);
+ /* make sure buf is palloc'd so we don't lose changes after a longjmp */
+ buf = makeStringInfo();

* You're failing to re-enable sigint_ctx->enabled when looping
around for another fgets call.

* Personally I'd write those assignments like

*(sigint_ctx->enabled) = true;

as that seems clearer.

regards, tom lane