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Take libakerror 2.0.1, and guard the exit status it fixes

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2.0.0 makes the error pool and the status registry thread safe, and it is an ABI
break carrying the soname to libakerror.so.2. The break is a quiet one:
__akerr_last_ignored became thread-local and akerr_next_error() now returns a
context that already holds a reference, so objects compiled against a 1.x header
and linked against 2.x count every reference twice and never give a slot back.
Nothing about that fails to link, which is exactly what a guard is for --
include/akbasic/error.h feature-tests AKERR_THREAD_SAFE instead of
AKERR_FIRST_CONSUMER_STATUS, which 2.0.0 also still defines and which therefore
no longer distinguishes anything.

2.0.1 is the release this band needed most. The default unhandled-error handler
ended in exit(errctx->status), and a process exit status is one byte:
AKBASIC_ERR_BASE is 512, and 512 truncates to 0, so an unhandled
AKBASIC_ERR_SYNTAX reported success to anything watching $?. Every other code in
the band came out as some unrelated error's number. akerr_exit() substitutes 125
for anything a byte cannot carry, and a probe raising AKBASIC_ERR_DEVICE through
FINISH_NORETURN now exits 125 rather than 7.

It was latent here rather than live -- src/main.c handles the context and returns
EXIT_FAILURE, and every test with a top-level ATTEMPT carries a HANDLE_DEFAULT --
but "no caller relies on it today" is not a property a header can keep true.
tests/version_check.c asserts the mapping and fails if AKBASIC_ERR_BASE ever
stops truncating to zero, because that is the day this stops being about our base.

Chapter 10 gains a threading section: libakerror is safe from any thread now, and
this interpreter is not and has no lock anywhere in it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Andrew Kesterson
2026-08-01 08:00:24 -04:00
parent 16b38c1138
commit 8077806598
7 changed files with 123 additions and 23 deletions
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23
tests/version_check.c
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@@ -49,10 +49,29 @@ int main(void)
/*
* libakerror publishes no version macro at all, so there is nothing to
* compare. Its floor is the #error on AKERR_FIRST_CONSUMER_STATUS that
* akbasic/error.h carries -- if this file compiled, that guard passed.
* compare. Its floor is the two #errors akbasic/error.h carries -- if this
* file compiled, both guards passed. What is asserted here is the *value* of
* what they test, because a guard that only checks a macro is defined passes
* against a header that defines it to something else entirely.
*/
TEST_REQUIRE_INT(AKERR_FIRST_CONSUMER_STATUS, 256);
TEST_REQUIRE_INT(AKERR_THREAD_SAFE, 1);
/*
* The one that matters most to this band. AKBASIC_ERR_BASE is 512, and a
* process exit status is one byte: 512 truncates to 0, so before libakerror
* 2.0.1 an unhandled AKBASIC_ERR_SYNTAX exited *success*. akerr_exit()
* substitutes 125 for anything a byte cannot carry.
*
* Asserted as a number rather than trusted as a macro because this is the
* value a supervisor watching $? actually sees, and 125 is chosen to sit
* clear of the 1-124 range a program is likely to use for itself.
*/
TEST_REQUIRE_INT(AKERR_EXIT_STATUS_UNREPRESENTABLE, 125);
TEST_REQUIRE((AKBASIC_ERR_BASE & 0xff) == 0,
"AKBASIC_ERR_BASE %d no longer truncates to zero -- if the band moved, "
"the exit-status hazard this guards moved with it",
AKBASIC_ERR_BASE);
return akbasic_test_failures;
}