General simplification

[KlzXS]

get_output():

• The function now uses UTIL_SH_EXEC to execute the command.
• The command writes directly to a tmp file where applicable.
• Got rid of parameter multi as it's no longer needed.
• A bad use case is now blocked.
• Got rid of cmd and fd as they are no longer needed. Correct me if I'm wrong, but fd wasn't ever used and there is a path to call free(cmd) while it's NULL (multi == FALSE and pipe() failing).
• The comment above wasn't accurate, now it is.
• g_buf is now clobbered only in some cases. Not that it would matter much, I imagine.

@jarun I still need to look into using UTIL_SH_EXEC for running GUI apps as plugins as you suggested, but I thought I should share this regardless.

I only tried the simple case of setting NNN_HELP and opening the help screen. I might do more extensive testing later, or if someone wants to give it a shot as well that would be great.

[jarun]

I see the following issue with nnn -i (to show file info):

Constant message in the info bar: Usage: file [-bcCdEhikLlNnprsSvzZ0] [--apple] [--extension] [--mime-encoding]

[jarun]

I think all internal flows that invoke get_output() are failing e.g. listing a zip file results in:

atool: no command specified
Try `atool --help' for more information.

[jarun]

Thanks @KlzXS!

[jarun]

@KlzXS I reverted this change and the changes I made on top of it. It appears concatenating the arguments don't work when the filename has spaces in it due to the usual shell quirks.

[jarun]

Please re-raise if you find a way around it.

[KlzXS]

I guess it's best to forego using UTIL_SH_EXEC and go the good old way it was while using the rest of the simplification.

I also had thoughts of implementing a new variant of spawn() that would allow us to pass in file descriptors to be mapped to stdin, stdout and stderr. I think a few places in the code might benefit from that. Say we pipe the output directly into nnn instead of writing to a file and reading from it. What do you think?

[jarun]

I guess it's best to forego using UTIL_SH_EXEC and go the good old way it was while using the rest of the simplification.

I agree!

I also had thoughts of implementing a new variant of spawn() that would...

We had problems and breaks with such experiments earlier. I think spawn() is good for now.

[KlzXS]

I think spawn() is good for now.

Sure. I'll do it the old way. I might submit my experiment at a later date. Might.

[jarun]

👍

[N-R-K]

I also had thoughts of implementing a new variant of spawn() that would allow us to pass in file descriptors to be mapped to stdin, stdout and stderr. I think a few places in the code might benefit from that. Say we pipe the output directly into nnn instead of writing to a file and reading from it. What do you think?

@KlzXS You may want to take a look at posix_spawn - it's much faster than fork + dup + exec and I think it should be capable of doing what you want. You can take a look at nsxiv for some reference (the error handling is quite ugly, but otherwise it works quite well): util.c#L251-L294