[vim/vim] xxd enters infinite loop with some inputs (#5272)

aslvim

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Nov 27, 2019, 12:25:07 AM11/27/19

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xxd -r hits an infinite loop for some inputs:

for example, echo -en '41414141\n\n' | xxd -r will run forever, spinning.

Environment:

xxd V1.10 27oct98 by Juergen Weigert
VIM - Vi IMproved 8.1 (2018 May 18, compiled Nov 7 2019 22:30:47)

x86_64 Arch Linux

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Antonio Giovanni Colombo

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Nov 27, 2019, 2:42:17 AM11/27/19

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You should add the "-p" option to your command (as documented in the xxd man page):

$ echo -en '41414141\n\n' | xxd -r -p
AAAA$

Antonio

On Wed, Nov 27, 2019 at 6:25 AM aslvim <vim-dev...@256bit.org> wrote:

xxd -r hits an infinite loop for some inputs:

for example, echo -en '41414141\n\n' | xxd -r will run forever, spinning.

Environment:

xxd V1.10 27oct98 by Juergen Weigert
VIM - Vi IMproved 8.1 (2018 May 18, compiled Nov 7 2019 22:30:47)

x86_64 Arch Linux

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/||\ | Antonio Colombo

/ || \ | azc...@gmail.com

/ () \ | ant...@geekcorp.com
(___||___) | az...@yahoo.com

vim-dev ML

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Nov 27, 2019, 2:42:18 AM11/27/19

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You should add the "-p" option to your command (as documented in the xxd
man page):

$ echo -en '41414141\n\n' | xxd -r -p
AAAA$

Antonio

On Wed, Nov 27, 2019 at 6:25 AM aslvim <vim-dev...@256bit.org> wrote:

> xxd -r hits an infinite loop for some inputs:
>
> for example, echo -en '41414141\n\n' | xxd -r will run forever, spinning.
>

> *Environment:*

>
> xxd V1.10 27oct98 by Juergen Weigert
> VIM - Vi IMproved 8.1 (2018 May 18, compiled Nov 7 2019 22:30:47)
>
> x86_64 Arch Linux
>

--
/||\ | Antonio Colombo
/ || \ | azc...@gmail.com
/ () \ | ant...@geekcorp.com
(___||___) | az...@yahoo.com

DungSaga

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Oct 18, 2021, 7:52:12 AM10/18/21

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your input (41414141\n\n) means "go to offset 0x41414141". In this case, xxd is using standard input and output, and xxd cannot go directly to that offset. So, xxd writes zero bytes until it reach that offset.
This process will take a while, but it's not forever.
You can see this process in real time with a command like this: echo -en '41414141\n\n' | xxd -r | xxd -g1.

If you want to write 41414141 as 4 bytes, you should use xxd -r -p.

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Christian Brabandt

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Oct 18, 2021, 10:33:43 AM10/18/21

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I suppose this can be closed then.

Christian Brabandt

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Oct 18, 2021, 10:33:45 AM10/18/21

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Closed #5272.

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