sizeof jail parameter value strings

[Fabian Freyer]

Hello lists,

From jail(3):

>     The jail_getv() function takes a null-terminated list of name and value
>     strings, and passes it to jail_get(2).  It is the caller's responsibility
>     to ensure that the value strings point to buffers large enough to hold
>     the string representation of the returned parameters.

What exactly does “large enough” mean here? Is there a way to query the size of
the corresponding kernel buffers at runtime? Is there a maximum length à la
MAX_JAIL_PARAM_LEN that the string representations of the returned parameters
are guaranteed to be shorter than?

I’m currently implementing a rust wrapper[1] around the jail(2) interface, and am
not sure how large buffers for the string parameters I’m querying with jail_get
jail_set have to be.

Fabian

(I’m not on the freebsd-jail mailing list, so I’d appreciate being kept in the CC)

[1] https://github.com/fubarnetes/libjail-rs
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