wordexp() implementation without fork()

[Brian Inglis]

On 2020-08-05 11:09, Sebastian Huber wrote:
> On 05/08/2020 17:35, Joel Sherrill wrote:
>> Having a single process wordexp() implementation has been on the RTEMS 
>> POSIX wishlist for a while. I haven't been able to find one. The POSIX 
>> method description seems to hint that this implementation strategy is
>> possible and the Linux man page uses the phrase "shell-like expansion".
>>
>> Does anyone know of an implementation that doesn't use fork()? Or an 
>> implementation strategy based around some open source wildcard evaluation?
>>
>> Or is this a POSIX method that is just unimplementable without multiple
>> processes?

> Can't you re-use parts of the shell implementation, e.g. freebsd_wordexpcmd() in
> 
> https://github.com/freebsd/freebsd/blob/master/bin/sh/expand.c#L1507

The main issue seems to be if command substitution is supported, it has to be
executed in a subshell, with the full capabilities of a POSIX shell:

https://pubs.opengroup.org/onlinepubs/9699919799/functions/wordexp.html

See RATIONALE:

"While wordexp() could be implemented entirely as a library routine, it is
expected that most implementations run a shell in a subprocess to do the expansion."

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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