Gentoo Archives: gentoo-dev

From: Ionen Wolkens <ionen@g.o>
To: gentoo-dev@l.g.o
Subject: Re: [gentoo-dev] [PATCH v2 1/1] esed.eclass: new eclass
Date: Sat, 04 Jun 2022 07:00:46
Message-Id: YpsDEnqAN/YUMDSH@eversor
In Reply to: Re: [gentoo-dev] [PATCH v2 1/1] esed.eclass: new eclass by Oskari Pirhonen
1 On Fri, Jun 03, 2022 at 07:15:17PM -0500, Oskari Pirhonen wrote:
2 [snip[
3 > Testing for (in)equality between pre- and post-sed contents is
4 > reasonable enough in most cases. This time, though, it would fail to
5 > detect anything has changed since the pre-sed contents have their NULL's
6 > unintentionally stripped, whereas the post-sed contents have them
7 > intentionally stripped.
8 >
9 > While I personally don't think that running sed on binary files is a
10 > good idea in the first place, it's still relevant since the end result
11 > would be an incorrect answer to the question of "Did sed actually do
12 > anything?".
14 Yeah one of the primary motivation to silence this was elsewhere, I
15 don't think silencing matters for esed and if binary files are being
16 modified may as well use sed(1) directly instead (this is something
17 that'd need to be more intensively verified on bumps than with esed
18 anyway).
20 Use is also very uncommon, although sed is still "handy" when changing
21 just 1 instruction and want to avoid an extra dependency on a proper
22 binary patching method.
24 > On the other hand, saving a set of pre- and post-sed hashes like Ulrich
25 > suggested would give the expected result.
27 If really wanted to solve this yes, although it may make sense to say
28 this eclass is not for binary files. The talk to add bash-only "erepl"
29 makes it rather difficult to preserve nulls (mapfile silently strip \0
30 without even a warning). mapfile -d '' could allow to restore them
31 but ideally want to iterate on lines to do per-line pattern matches.
32 Is it possible to hack away something to preserve? Probably.. but it's
33 going to make this messy and I'm not sure it's worth it.
35 erepl is also worse because they'll be lost in output and not just
36 during comparison.
38 --
39 ionen


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