[LEDE-DEV] [RFC 1/1] base-files/etc/rc.common: allow services to overwrite PROCD functions

[Felix Fietkau]

On 2017-11-20 14:25, Zefir Kurtisi wrote:
> On 11/20/2017 01:27 PM, Felix Fietkau wrote:
>> On 2017-11-20 11:20, Zefir Kurtisi wrote:
>>> PROCD services can't overwrite those functions defined in the
>>> USE_PROCD body (like stop()), since the initfile is sourced
>>> before.
>>>
>>> This change moves the sourcing below and with that allows
>>> PROCD init scripts to overwrite them.
>>>
>>> Signed-off-by: Zefir Kurtisi <zefir.kurtisi at neratec.com>
>> This seems broken to me. USE_PROCD is defined by the init script, so you
>> can't test for it before the script has been sourced.
>> 
>> - Felix
>> 
> This was my initial assumption, but in fact it works as expected (for PROCD and
> legacy services). Running 'INIT_TRACE=y /etc/init.d/log shows that USE_PROCD is
> set correctly during execution.
> 
> Why it does I don't understand, since when
> * /etc/init.d/log starts with '#!/bin/sh /etc/rc.common'
> * in /etc/rc.common, the initscript is sourced again
> 
> ... I expected this to be a circular dependency, but what it does is:
> 1. interpreting all the variables set in initscript (including USE_PROCD=1)
> 2. interpreting all the variables set in rc.common
>    (starting with [ -n "$USE_PROCD" ])
> 3. executing the functions
> 
> Could not find enough information about how shebanging a shell-script is executed.
> 
> Does somebody know and could please clarify?
I just did an experiment and your claimed step 1 does not happen in my
test. rc.common gets interpreted first, and USE_PROCD is unset where it
would be needed.

- Felix