[Toybox] "bad xform" not very helpful

[David Seikel]

On 2022-08-31 18:18:15, enh via Toybox wrote:
>    it does by default. that's what i turned off as a workaround for this bug.

Um how does one using toybox as the foundation for something else
actually call any random toy directly?  Is there a vararg calltoy()
function I missed?

>    On Wed, Aug 31, 2022, 18:15 David Seikel <onefang_toybox at dave.isageek.net>
>    wrote:
> 
>      On 2022-08-31 14:55:24, enh via Toybox wrote:
>      >    On Tue, Aug 16, 2022 at 12:22 PM enh <enh at google.com> wrote:
>      >
>      >      On Tue, Aug 16, 2022 at 10:28 AM enh <enh at google.com> wrote:
>      >
>      >        On Tue, Aug 16, 2022 at 1:43 AM Rob Landley <rob at landley.net>
>      wrote:
>      >
>      >          On 8/15/22 18:50, enh via Toybox wrote:
>      >          > and here's their minimized repro case:
>      >          >
>      >          > echo > /tmp/foo.txt; echo /tmp/foo.txt > /tmp/find.txt
>      >          >
>      >          > cat /tmp/find.txt |
>      prebuilts/build-tools/path/linux-x86/tar czf
>      >          /tmp/out.tar.gz \
>      >          >   --absolute-names \
>      >          >   --transform 's,^/,,' -T -
>      >          >
>      >          > This fails with
>      >          >
>      >          > tar: bad xform
>      >
>      >          Hmmm...
>      >
>      >          $ echo > /tmp/foo.txt; echo /tmp/foo.txt > /tmp/find.txt
>      >          $ cat /tmp/find.txt | PATH=$PWD/sub9:$PATH ./tar czf
>      out.tar.gz \
>      >            --absolute-names --transform 's,^/,,' -T -
>      >          $ tar tvf /tmp/out.tar.gz
>      >          -rw-r--r-- landley/landley   1 2022-08-16 01:53 tmp/foo.txt
>      >
>      >          Working for me? (The sub9 bit was because I stuck toybox sed
>      in the
>      >          $PATH to
>      >          make sure that wasn't it...)
>      >
>      >        repos for me, both with their prebuilt but also with a fresh
>      clone (on
>      >        either macos or linux):
>      >
>      >        /tmp/toybox$ cat /tmp/find.txt | ./toybox tar czf
>      /tmp/out.tar.gz  
>      >        --absolute-names   --transform 's,^/,,' -T -
>      >
>      >        tar: bad xform
>      >
>      >        /tmp/toybox$ 
>      >
>      >         
>      >        a bit of printf debugging shows we're reading nothing back:
>      >
>      >        /tmp/toybox$ cat /tmp/find.txt | strace -f ./toybox tar czf
>      >        /tmp/out.tar.gz   --absolute-names   --transform 's,^/,,' -T -
>      2>
>      >        /tmp/out
>      >
>      >        argv[0]="sed"
>      >
>      >        argv[1]="-e"
>      >
>      >        argv[2]="s,^/,,"
>      >
>      >        pid=1779946
>      >
>      >        stdin="/tmp/foo.txt"
>      >
>      >          len=0 Success
>      >
>      >        total=0 result="(null)"
>      >
>      >        but strace implies we're not actually exec()ing sed at all?
>      >
>      >      and if i `CONFIG_TOYBOX_NORECURSE=y`, it calls sed and works...
>      >
>      >    ...though this might be about to come back and bite me. i'm hearing
>      as-yet
>      >    unconfirmed reports that toybox `tar czf` is a lot slower than gnu
>      tar,
>      >    and -- given that they're using --transform` while they're assuming
>      it's
>      >    tar or gzip, i'm wondering whether it's actually the fact that
>      we're
>      >    forking out to sed for every file?
>      >    i've asked for repro steps or a `perf record` i can look at...
> 
>      That reminds me...
> 
>      I've long thought it would be great if toybox toys could call other
>      toybox toys directly.  So tar wouldn't fork out to sed, we have our own
>      sed, just call it directly.  Then you avoid the fork and other overhead,
>      which will probably speed things up.
> 
>      --
>      A big old stinking pile of genius that no one wants
>      coz there are too many silver coated monkeys in the world.
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-- 
A big old stinking pile of genius that no one wants
coz there are too many silver coated monkeys in the world.