Re: [Xen-devel] [PATCH 6/6] firmware/shim: fix build process to use POSIX find options

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 17/01/18 17:32, Roger Pau Monné wrote:
> On Wed, Jan 17, 2018 at 04:24:27PM +0000, Ian Jackson wrote:
>> Roger Pau Monne writes ("[PATCH 6/6] firmware/shim: fix build process to use 
>> POSIX find options"):
>>> The -printf find option is not POSIX compatible, so replace it with
>>> another rune.
>> ...
>>>               cd $(D)/$(d); \
>>> -             find $(XEN_ROOT)/$(d)/ -type d -printf "./%P\n" |  xargs 
>>> mkdir -p);)
>>> +             find $(XEN_ROOT)/$(d)/ -type d -exec sh -c \
>>> +                 "echo {} | sed 's,^$(XEN_ROOT)/$(d)/,,g' | xargs mkdir 
>>> -p" \;);)
>> This is now a pretty nasty shell construct.
>>
>> If you're going to use sed, you could just
>>    find ... -print | sed ... | xargs mkdir -p
> I think I will go with this one...
>
>> Substituting {} into the middle of the shell rune is bad practice in
>> general because it might contain metacharacters or spaces.  In our
>> build system this doesn't matter because that breaks anyway, but it's
>> very poor style (and also it buries the actual data flow path into the
>> middle of a complicated manglement).
>>
>> If you wanted to use -exec and sh, you could do something like this
>>    -exec sh -c 'exec mkdir "${1#$(XEN_ROOT}/$(d)/}"' x {}
>> maybe.
> ... because I cannot really make #2 work, and I'm not sure I fully
> understand it.

Probably because it needs to be 'exec mkdir "$${1 .... so shell sees ${1
when its passed through Make.

~Andrew

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