From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Corrupt input while restoring file
Date: Sat, 14 Mar 2015 15:00:47 +0100
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In-Reply-To: <87h9tp3d9e.fsf@fsf.org> (David Thompson's message of "Thu, 12
	Mar 2015 21:19:25 -0400")
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To: David Thompson <dthompson2@worcester.edu>
Cc: guix-devel@gnu.org

David Thompson <dthompson2@worcester.edu> skribis:

> Take this for example:
>
>     guix substitute-binary --substitute /gnu/store/z8kf6hgln4a7xf68pdnlib=
l3vcg5rl15-ruby-2.2.1 /tmp/foobar
>
> This store item is 39.7MiB uncompressed, but Guix tries to read a 162MiB
> file out of it!

Please check the file
/var/guix/substitute-binary/cache/z8kf6hgln4a7xf68pdnlibl3vcg5rl15.  It
should contain the raw narinfo produced by =E2=80=98guix publish=E2=80=99. =
 Is it
correct?

If not, you can remove that file and do a query to repopulate it (like
=E2=80=98guix build ruby -n=E2=80=99, which leads to the daemon invoking =
=E2=80=98guix
substitute-binary --query=E2=80=99.)

The narinfo has a =E2=80=98NarSize=E2=80=99 field, which gets map to what t=
he
=E2=80=98narinfo-size=E2=80=99 procedure in (guix scripts substitute-binary=
) returns.
This is the expected size of the .nar, uncompressed:

  (format (current-error-port) "downloading `~a'~:[~*~; (~,1f MiB installed=
)~]...~%"
          store-path

          ;; Use the Nar size as an estimate of the installed size.
          (narinfo-size narinfo)
          (and=3D> (narinfo-size narinfo)
                 (cute / <> (expt 2. 20))))

(The actual size of the data being downloaded is smaller or equal to the
nar size, due to compression; the installed size is typically greater.)

>      331: 7 [restore-file #<input: r6rs-custom-binary-input-port 16ab820>=
 "/tmp/foobar"]
>      365: 6 [restore "/tmp/foobar"]
>      365: 5 [restore "/tmp/foobar/bin"]
>      333: 4 [restore "/tmp/foobar/bin/irb"]

This suggests that the nar is properly decoded so far.

>      127: 3 [read-string #<input: r6rs-custom-binary-input-port 16ab820>]
>      119: 2 [read-byte-string #<input: r6rs-custom-binary-input-port 16ab=
820>]
>       78: 1 [get-bytevector-n* #<input: r6rs-custom-binary-input-port 16a=
b820> ...]
>     In unknown file:
>        ?: 0 [scm-error misc-error #f "~A" ("foo") #f]

So where does this =E2=80=98error=E2=80=99 call come from?  What does =E2=
=80=98read-contents=E2=80=99
sees for the =E2=80=98irb=E2=80=99 file, namely the =E2=80=98executable?=E2=
=80=99 and =E2=80=98size=E2=80=99 variables?

Thanks,
Ludo=E2=80=99.