In D59034#1354663, @kib wrote:

Why passing struct sendile_args to kern_sendfile()? This is not how all other kern_* wrappers are done, and IMO is worse than flattening the args. You have to explicitly initialize the literal anyway, which makes it equivalent to list the function's argument in the call.

• freebsd32_copyin_hdtr: take a void *, fix trailer count
• make copyinuio_t take a void * (but don't update the functions yet)

Merging the implementations will avoid future instances of oversights like the one fixed in 4b17776d9afd0009ac8547126c59c97eda0f3fc9 as well as avoiding a third copy of this code from freebsd64 when it lands.

Please name the file following the exiting convention (patch-backport-4bed796a5fea) and produce with --no-prefix.

Seems reasonable to me.

Correct feature introduction to 16.0. Bump doc date.

Put the common case inside the switch statement

Actually describe this test

Improve test description

Move global struct uexterror and constructor to its own file

Switch to rwlock, hoist free outside the locked region.

Fix some whitespace

Move to its own file, document, update copyrights

Make "sys/" prefix depend on category source. Move test to D58237

Move test here from D58238

When an unsupported or broken format is encoutered emite a warning like "<unsupported-format>".

Emit errors in formatted text for unsupported or invalid formats.

Update for UEXTERROR returning void.

Add docs. Make uexterr_set return void.

Use UEXTERROR().

Add UEXTERROR() analog to EXTERROR(). It differs in that it just wraps uexterr_set and thus it gets a different name.

Look up kern.exterr.categories mib once on the first error

Reserve 4 bits for sources (up from 2)

I don't think performance of this path matters at all because users have to go out of their way to enable this code path with EXTERROR_VERBOSE.

Drop used of __unreachable()

Add helper in libc. Tag categories as user space.

Having just hit submit... I wonder if we want to spend the available bit in EXTERR_CAT_SRC_MASK on in-tree vs out of tree or maybe just make pre-pending sys/ a legacy category source thing.

I think I want to refactor cat_to_filename() to take a buffer and to handle the selective prepending of sys/, perhaps bumping the uexterr_gettext ABI. It's fine for in-tree code, but definitely wrong for out of tree modules.

This addresses an issue I realized during Kirk's talk at BSDCan. In the existing model, it's quite hard to support third-party modules and even in-tree modules for downstreams would require reserving a portion of the identifier space. This approach adds cost to the EXTERROR_VERBOSE reporting path, but significantly decouples the kernel and libc. I'm not sure I'd want to go as far moving entirely to dynamic, but it's probably not a problem in practice.

Address feedback

Expand __uint64ptr_t to spares

The big thing that needs to be dealt with for this to make sense is to have a way to specify the filename that isn't a table embedded in libc. A first cut could be a special index that means no-file and perhaps using -1 as the line, but without that, we can't scale beyond files in the base system. (This also poses a problem for out of tree kernel modules.) We might also want macros like the kernel, but I'm less sure of that.