allow sysctl path to be configured at build time

[aanderse]

my sysctl isn't located in /sbin - i followed convention seen elsewhere

[troglobit]

Great idea to make this configurable! You'll undoubtedly find more.

The format of these have been a bit up in the air. For internal ones, and those sourced from paths.h for instance, they are usually prefixed with a _PATH, but for those read at configure time I think we should go with FOO_PATH.

Example (which needs updating): modules-load.c use MODPROBE_PATH, which needs an #ifndef like yours in procps.c.

So please go for SYSCTL_PATH instead, and if you'd like to update more plugins to follow, you're very welcome to do so 😃 👍

[aanderse]

So please go for SYSCTL_PATH instead

ah, yeah i see now - thanks

You'll undoubtedly find more.

well... most of the others are different - they have the implicit assumption that PATH contains the executable in question, which is probably the best way to do it

procps.c is different than most other cases because it hardcodes a path (/sbin)
even your modules-load.c example isn't quite the same because it allows you to specify a path at "runtime" (ie. in the configuration file)

in fact... maybe we should just modify procps.c to assume sysctl exists on PATH like the rest... or are there implications to that i haven't considered? 🤔

[troglobit]

You'll undoubtedly find more.
well... most of the others are different - they have the implicit assumption that PATH contains the executable in question, which is probably the best way to do it

Hmm, yeah 🤔

procps.c is different than most other cases because it hardcodes a path (/sbin) even your modules-load.c example isn't quite the same because it allows you to specify a path at "runtime" (ie. in the configuration file)
in fact... maybe we should just modify procps.c to assume sysctl exists on PATH like the rest... or are there implications to that i haven't considered? 🤔

For most users that would probably be sufficient, yes. But I like that with your PR we now will get a way for users to override.

Also, as PID 1 the default PATH is usually _PATH_STDPATH which, unless user override, defaults to "/usr/bin:/bin:/usr/sbin:/sbin"

[aanderse]

out of curiosity what is the difference between sysctl and mount in your mind then? in finit.c there is no way to satisfy requirements other than ensuring mount exists on PATH - no MOUNT_PATH (or i guess _PATH_MOUNT 😅) exists - while procps.c will ignore PATH and only observe compile time options.

maybe i am thinking too hard about a fairly small detail...

[troglobit]

out of curiosity what is the difference between sysctl and mount in your mind then? in finit.c there is no way to satisfy requirements other than ensuring mount exists on PATH - no MOUNT_PATH (or i guess _PATH_MOUNT 😅) exists - while procps.c will ignore PATH and only observe compile time options.

maybe i am thinking too hard about a fairly small detail...

There is no difference really, in my mind. Much of Finit grew organically, sometimes by external contributions, some hard-coded paths, others relied on $PATH. Personally I prefer to be more lax and allow finding sysctl and others in $PATH, but experience tells me people often have varying degrees of both knowledge and adherence to the FHS so we should prepare for both and make the common case simple.

This was a generic answer, maybe not what you were looking for?

I guess what I'd like is to have the following pattern in most/all places:

#ifndef FOO
#define FOO foo
#endif 


some_function()
{
    systemf(FOO "-some %s", args);
}

Which would make it possible to both rely on $PATH in the common case, and override in the specific case. Does that make sense?

[aanderse]

great answer, what i was looking for

in that case... how about we merge this as it stands and in the future if i want i can reference this in a new PR?

thanks

[troglobit]

Yup 💯 just wanted to sync with you first.