From: Phillip Wood <phillip.wood123@gmail.com>
To: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org
Cc: Johannes Schindelin <johannes.schindelin@gmx.de>,
Taylor Blau <me@ttaylorr.com>
Subject: Re: [PATCH] range-diff: support reading mbox files
Date: Thu, 17 Nov 2022 10:26:07 +0000 [thread overview]
Message-ID: <50d8767b-cb8c-74c5-b280-43472fa074a2@dunelm.org.uk> (raw)
In-Reply-To: <dfe0190c-1d2e-804a-5312-877b7b2f5822@dunelm.org.uk>
Hi Dscho
Having slept on it I think I misunderstood what was happening in the
diff parsing yesterday
On 16/11/2022 14:40, Phillip Wood wrote:
>> + } else if (state == MBOX_IN_DIFF) {
>> + switch (line[0]) {
>> + case '\0':
>> + continue; /* ignore empty lines after diff */
>> + case '+':
>> + case '-':
>> + case ' ':
>> + if (!old_count && !new_count)
>> + break;
>
> This shouldn't happen in a well formed diff. Below we happily accept bad
> counts, is there a reason to reject them here?
I think this might be picking up the "--" at the end of the patch as we
don't want to break here at the end of a hunk. If so then a comment
would be helpful.
>> + if (old_count && line[0] != '+')
>> + old_count--;
>> + if (new_count && line[0] != '-')
>> + new_count--;
>
> The diff is malformed if old_count == 0 and we see '-' or ' ' or
> new_count == 0 and we see '+' or ' '. The code is careful not to
> decrement the count in that case so I think it is harmless to accept
> diffs with bad line counts in the hunk header.
>> + /* fallthrough */
>> + case '\\':
>> + strbuf_addstr(&buf, line);
>> + strbuf_addch(&buf, '\n');
>> + util->diffsize++;
>
> I think this might be a better place to break if old_count and new_count
> are both zero.
It would be the right place to break at the end of each hunk, but I
don't think we want to do that.
>> + continue;
>> + case '@':
>> + if (parse_hunk_header(line, &old_count,
>> + &new_count, &p))
>> + break;
>> +
>> + strbuf_addstr(&buf, "@@");
>> + if (current_filename && *p)
>> + strbuf_addf(&buf, " %s:",
>> + current_filename);
>> + strbuf_addstr(&buf, p);
>> + strbuf_addch(&buf, '\n');
>> + util->diffsize++;
>> + continue;
>> + }
>
> This is effectively the `default:` clause as it is executed when we
> don't handle the line above. We ignore the contents of this line which
> makes me wonder what happens if it is the start of another diff.
We'll pick that up earlier with "if (starts_with(line, "diff --git"))"
We only get here at the end of a patch (assuming it has the "--" line
from format-patch)
Best Wishes
Phillip
> Do we
> have tests that alter more than one file in a single commit?
>
> I think this is a useful addition, it could perhaps benefit from more
> tests though. Having tests for bad input, "\r\n" line endings and
> getting the author from a From: header as well as an in-body From: line
> would give a bit more reassurance about how robust the parser is.
>
> Best Wishes
>
> Phillip
next prev parent reply other threads:[~2022-11-17 10:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-15 18:20 [PATCH] range-diff: support reading mbox files Johannes Schindelin via GitGitGadget
2022-11-16 2:09 ` Taylor Blau
2022-11-16 14:40 ` Phillip Wood
2022-11-17 10:26 ` Phillip Wood [this message]
2022-11-18 12:53 ` Johannes Schindelin
2022-11-18 13:16 ` Johannes Schindelin
2022-11-17 18:24 ` Ævar Arnfjörð Bjarmason
2022-11-18 11:39 ` Johannes Schindelin
2022-11-19 23:11 ` [PATCH v2] " Johannes Schindelin via GitGitGadget
2022-11-21 10:08 ` Phillip Wood
2022-11-22 7:40 ` Johannes Schindelin
2022-11-22 14:20 ` Phillip Wood
2022-11-22 9:08 ` [PATCH v3] " Johannes Schindelin via GitGitGadget
2022-11-22 14:23 ` Phillip Wood
2022-11-22 23:58 ` Junio C Hamano
2023-03-03 22:02 ` Junio C Hamano
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