RE: [PATCH] fat: Use pointer to d_name[0] in put_user() for compat case

[David Laight <David.Laight@ACULAB.COM>]

From: Helge Deller
> Sent: 13 February 2022 22:10
> 
> The put_user(val,ptr) macro wants a pointer in the second parameter, but in
> fat_ioctl_filldir() the d_name field references a whole "array of chars".
> Usually the compiler automatically converts it and uses a pointer to that
> array, but it's more clean to explicitly give the real pointer to where someting
> is put, which is in this case the first character of the d_name[] array.

That just isn't true.

In C both x->char_array and &x->char_array[0] have the same type
'char *'.

The 'bug' is caused by put_user() trying to do:
	__typeof__(ptr) __ptr = ptr;
where __typeof__ is returning char[n] not char *.

I've tried a few things but can't get __typeof__ to
generate a suitable type for both a simple type and array.

	David

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