[Toybox] "bad xform" not very helpful

[enh]

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...


> let me know if you've already fixed this on your branch and that's why you
> can't repro, otherwise i'll keep looking after my meeting...
>
> > However, if the file names are fed via the -T /tmp/find.txt, it works:
>>
>> Hmmm... the child process shouldn't have access to the parent's stdin, we
>> replaced it with a pipe? There was a potential bug in that area, but
>> commit
>> dc8b46d5ddab should have fixed it last month and I don't _think_ it would
>> have
>> applied here anyway...
>>
>> > echo > /tmp/foo.txt; echo /tmp/foo.txt > /tmp/find.txt
>> >
>> > prebuilts/build-tools/path/linux-x86/tar czf /tmp/out.tar.gz \
>> >   --absolute-names \
>> >   --transform 's,^/,,' -T /tmp/find.txt
>> >
>> > (the "prebuilts/build-tools/path/linux-x86/" stuff is just a directory
>> full of
>> > symlinks to toybox.)
>>
>> Multiplexer instead of standalone build shouldn't make a difference if
>> you've
>> disabled command recursion. (Modulo you're calling tar out a specific
>> path but
>> it then grabs sed out of the $PATH, but I haven't yet implemented the
>> extra
>> argument processing that would specifically require toybox sed...)
>>
>> (The extra error message is a little tricker than my first guess because
>> you can
>> have multiple --xform things which turn into a list of -e entries to
>> sed...
>> Possibly instead of error_exit() I should error_msg(), dump the sed
>> command line
>> on a second line, and then xexit()...)
>>
>> Rob
>>
>
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