Re: Re: [PATCH 0/9] Introduce esplit.eclass and port to it

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On Fri, Jul 10, 2026 at 11:09:51PM -0000, Duncan wrote:
> Sam James posted on Thu,  9 Jul 2026 22:22:09 +0100 as excerpted:
>=20
> > Introduce a new eclass (esplit.eclass) and port ebuilds to it. This is
> > needed to unblock a Portage release with sandboxing for the 'depend'
> > phase enabled, because the uses of a heredoc replaced here always
> > require a temporary file with < EAPI 9 (and with >=3D EAPI 9, they do b=
ut
> > for large inputs only).
>=20
> Just to ask, since "with >=3D EAPI 9" has unlimited scope that could be w=
ith=20
> us for awhile and the vagueness of "large" accordingly disturbs me...
>=20
> Is it possible to better define "large" in "large inputs only"?
>=20
> Are we talking "large" in terms of lines, characters, ...?  Is it on the=
=20
> order of 1K lines/characters?  Just 10 (hopefully lines in that case)?=20
> 100K?  GiB size?

As I understand it (no expert), either the value of fnctl's
F_GETPIPE_SZ determined at runtime if possible (e.g. on Linux) or
PIPE_BUF at build time in bytes, which values vary depending on the
operating system.

On linux, this seems to be 64kiB minus 1 -- you can check with e.g.:

$ strace bash -c "read <<<\$(printf '%*s' 65535 '')" 2>&1 | grep /tmp
<no output, aka no tmp file used>

And then we do +1...

$ strace bash -c "read <<<\$(printf '%*s' 65536 '')" 2>&1 | grep /tmp
newfstatat(AT_FDCWD, "/tmp" [...]

(note that can test the EAPI=3D8 behaviour by setting BASH_COMPAT=3D5.0,
it should make both cases report /tmp usage)

In global scope we don't (and shouldn't) operate on anything overly
large -- typically it's only version strings, a package name or such.
Things like large crate lists are worse but they wouldn't reach
64kiB still, if they do we really should re-arrange to avoid that not
just because of this.

Albeit I read MacOS may go as low as 512 bytes, so I dunno how that may
work out on prefix -- but not sure how/if the same type of sandboxing
is used there.

>=20
> And should such justification be in the eclass (in-eclass documentation,=
=20
> or possibly just in the git commit comment) itself or is the series cover-
> letter alone discoverable enough in terms of people "archaeologically"=20
> looking for the reason it was introduced, a decade or whatever from now?
>=20
> --=20
> Duncan - List replies preferred.   No HTML msgs.
> "Every nonfree program has a lord, a master --
> and if you use the program, he is your master."  Richard Stallman
>=20
>=20

--=20
ionen

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