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jolt.ffi: read-array/write-array for binary-faithful buffer I/O

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read-bytes/write-bytes go through UTF-8 (with a latin1 fallback), which mangles
arbitrary binary — gzip payloads, TLS records, any non-text body. An HTTP client
moving bytes between jolt byte-arrays and foreign socket/zlib/OpenSSL buffers
needs byte-exact transfer. read-array returns a fresh byte-array of n bytes from
foreign memory; write-array copies a byte-array's bytes into a pointer. Test
covers a round-trip preserving high bytes (200, 255).
This commit is contained in:
Yogthos 2026-06-22 13:11:08 -04:00
parent 8c6623503f
commit c5e1e0544a
2 changed files with 30 additions and 0 deletions
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13
test/chez/ffi-binding-test.ss
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@ -39,6 +39,19 @@
(let [v (jolt.ffi/read p :int)] (jolt.ffi/free p) v))"))))
(ok "sizeof :pointer is a word" (let ((n (jnum->exact (ev "(jolt.ffi/sizeof :pointer)")))) (or (= n 8) (= n 4))))
;; byte-array buffer I/O: write a byte-array into foreign memory and read it back
;; byte-exact (high bytes preserved, no UTF-8 mangling).
(ok "byte-array roundtrip (binary-faithful)"
(jolt-truthy?
(ev "(let [src (byte-array [0 65 200 255 10])
p (jolt.ffi/alloc 5)]
(jolt.ffi/write-array p src)
(let [back (jolt.ffi/read-array p 5)]
(jolt.ffi/free p)
(and (= 5 (alength back))
(= 0 (aget back 0)) (= 65 (aget back 1))
(= 200 (aget back 2)) (= 255 (aget back 3)) (= 10 (aget back 4)))))")))
;; a :blocking foreign call is collect-safe: a thread parked in it must not pin
;; the stop-the-world collector. (collect) here would throw "cannot collect when
;; multiple threads are active" if usleep weren't emitted __collect_safe.