Re: [PATCH] revision: parse integer arguments to --max-count, --skip, etc., more carefully

From: Jeff King <peff@peff.net>
Date: Dec 12, 2023, 01:30 UTC
Message-ID: <20231212013045.GE376323@coredump.intra.peff.net>
In-Reply-To: <xmqq5y181fx0.fsf_-_@gitster.g>

On Sat, Dec 09, 2023 at 07:35:23AM +0900, Junio C Hamano wrote:

Show 16 quoted lines

> The "rev-list" and other commands in the "log" family, being the
> oldest part of the system, use their own custom argument parsers,
> and integer values of some options are parsed with atoi(), which
> allows a non-digit after the number (e.g., "1q") to be silently
> ignored.  As a natural consequence, an argument that does not begin
> with a digit (e.g., "q") silently becomes zero, too.
> 
> Switch to use strtol_i() and parse_timestamp() appropriately to
> catch bogus input.
> 
> Note that one may naïvely expect that --max-count, --skip, etc., to
> only take non-negative values, but we must allow them to also take
> negative values, as an escape hatch to countermand a limit set by an
> earlier option on the command line; the underlying variables are
> initialized to (-1) and "--max-count=-1", for example, is a
> legitimate way to reinitialize the limit.

This all looks pretty reasonable to me.

I couldn't help but think, though, that surely we have some helpers for this already? But the closest seems to be git_parse_int(), which also allows unit factors. I'm not sure if allowing "-n 1k" would be a feature or a bug. ;)

I guess "strtol_i()" maybe is that helper already, though I did not even know it existed. Looks like it goes back to 2007, and is seldom used. I wonder if there are more spots that could benefit.

I don't think there is any such helper for timestamps, but the checks in your parser look good (strtol_i() checks for overflow as we cast to int, but I don't think we need to do the same here since timestamp_t and parse_timestamp() should be matched).

-Peff