CHANNEL_STATE_MAX has wrong value

[ksedgwic]

enum channel_state {
    DUALOPEND_OPEN_INIT = 1,
    CHANNELD_AWAITING_LOCKIN,
    CHANNELD_NORMAL,
        ...
    DUALOPEND_OPEN_COMMITTED,
    DUALOPEND_AWAITING_LOCKIN,
    CHANNELD_AWAITING_SPLICE,
    DUALOPEND_OPEN_COMMIT_READY,
};
#define CHANNEL_STATE_MAX CHANNELD_AWAITING_SPLICE

I think it should be set to DUALOPEND_OPEN_COMMIT_READY instead. Looks like a likely merge conflict.

All uses of CHANNEL_STATE_MAX should be carefully considered as well ...

thumbs up from @niftynei in #core-lightning-dev-chat:
https://discord.com/channels/899980449231814676/899989708065632276/1392940900493295746

[ksedgwic]

Give the memory layout of the billboard I think writing past the permanent array would inadvertently assign to transient instead?:

struct billboard {
	/* Status information to display on listpeers */
	const char *permanent[CHANNEL_STATE_MAX+1];
	const char *transient;
};

[ddustin]

This same issue happened when I added CHANNELD_AWAITING_SPLICE and it was very difficult to notice from the resulting behavior.

It would be nice to get this into a compile or assert or something that would directly fail CI 👀.

[ddustin]

Here is a PR that updates the max state and adds a regression test: #8420

[ksedgwic]

Does ARRAY_SIZE() work? I think it is a compile-time constant ...

bah, nm, it is an enum

[ksedgwic]

We could add a sentinel as the explicit last state so we wouldn't have to update the CHANNEL_STATE_MAX expr every time ...

	CHANNELD_AWAITING_SPLICE,
	DUALOPEND_OPEN_COMMIT_READY,

	/* Always keep this one last */
	CHANNEL_STATE_LIMIT
};
#define CHANNEL_STATE_MAX  (CHANNEL_STATE_LIMIT - 1)