Joseph Ferano
2e203f64b8
The INSERTIONSORT crash, all three rulings (FIX.org 2026-09-20): - (bytes s) allocates a writable copy through the allocator surface — context or (bytes s a), StorageExhausted with retry, a registry note in dev builds (flan_bytes_dup, lowered like vec-new). (bytes-view s) is the old zero-cost reinterpret, renamed, read-only by convention; every in-repo reader swept over to it. (string b) unchanged. - String constants were already read-only on both backends at -O0; now pinned — bytes-copy.flan rows on LLVM/-O0/--x86, and dies_segv rows asserting the write-through-view trap on both backends. - A dev build installs a SIGSEGV/SIGBUS handler by the same dev-only constructor slot that arms the registry: one line naming the address and the innermost frame, then the trap-hook park — stopped, not dead, the daemon serving. No agent: message and re-raise. Release builds untouched. Pinned by trap_park over dev-segv.flan.
104 lines
4.5 KiB
Plaintext
104 lines
4.5 KiB
Plaintext
;;;; slurp and barf — NEXT.md decisions 2 and 5.
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;;;;
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;;;; slurp reads a whole file and answers a (Vec u8). It allocates, which is
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;;;; why it waited for Vec, and it follows spec-memory.md's rule to the letter:
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;;;; no allocating operation returns an error, so there is no Result here and
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;;;; no out-parameter anywhere.
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;;;;
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;;;; Failure signals a condition under a restart, which is the pattern
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;;;; StorageExhausted set this session. Two restarts, and they are the pair
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;;;; Common Lisp establishes for a file-error:
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;;;;
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;;;; retry the file may be there now
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;;;; use-value [p string] try this other path instead
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;;;;
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;;;; use-value is a *typed* restart — the second thing this session bought —
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;;;; and it is the first one the compiler itself emits. Its parameter is the
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;;;; path slot the attempt reads, so the clause body is empty: the invoker's
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;;;; argument lands in the slot, the clause falls through, and the loop
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;;;; re-attempts against the new path.
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;; Handlers cannot see the locals of the function that established them, so the
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;; observations are globals — the same shape exhausted.flan uses.
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(defvar seen i64)
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(defvar last-reason i32)
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(defvar last-op i32)
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(defvar last-path string)
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(defn main [] i32
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;; ── The happy path ────────────────────────────────────────────────
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(let [v (slurp "programs/assets/a.txt")]
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(println (len v)) ; 13
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(print (string (as-slice v))) ; hello from a
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(free v))
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;; Byte-exact, the same as an embed: nothing here decodes anything.
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(let [v (slurp "programs/assets/raw.bin")]
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(println (len v)) ; 4
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(println (at v 0)) ; 0
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(println (at v 2)) ; 255
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(free v))
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;; ── use-value: a missing file, answered with another path ─────────
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;; The textbook case. The handler does not know what slurp was going to do
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;; with the bytes and does not have to: it names a file that is there and
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;; the read resumes as if that had been asked for all along.
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(handler-bind
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[(FileError [c]
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(set seen (+ seen 1))
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(set last-reason (.reason c))
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(set last-op (.op c))
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(set last-path (.path c))
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(invoke-restart 'use-value "programs/assets/b.bin"))]
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(let [v (slurp "programs/assets/does-not-exist")]
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(println (len v)) ; 3
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(println (string (as-slice v))) ; BBB
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(free v)))
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(println seen) ; 1
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(println (= last-reason file-missing)) ; true
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(println (= last-op file-op-read)) ; true
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;; The condition carries the path that actually failed, not the one that
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;; eventually worked — the handler is told what it is answering about.
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(println last-path) ; programs/assets/does-not-exist
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;; ── barf, and reading back what it wrote ──────────────────────────
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(barf "slurp-out.txt" (bytes-view "round trip\n"))
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(let [v (slurp "slurp-out.txt")]
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(println (len v)) ; 11
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(print (string (as-slice v))) ; round trip
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(free v))
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;; barf's own failure signals the same condition with op = write. A directory
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;; that does not exist is the reachable case on every platform.
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(set seen 0)
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(handler-bind
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[(FileError [c]
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(set seen (+ seen 1))
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(set last-op (.op c))
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(invoke-restart 'use-value "slurp-out.txt"))]
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(barf "no-such-dir/x.txt" (bytes-view "second\n")))
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(println seen) ; 1
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(println (= last-op file-op-write)) ; true
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(let [v (slurp "slurp-out.txt")]
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(print (string (as-slice v))) ; second
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(free v))
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;; ── retry: the file was not there, so the handler makes it ────────
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;; The other restart, and the one use-value cannot stand in for: here the
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;; path is right and the world is wrong. The handler fixes the world and
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;; re-attempts the *same* request, which is exactly what retry means for a
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;; failed allocation too.
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(set seen 0)
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(handler-bind
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[(FileError [c]
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(set seen (+ seen 1))
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(set last-reason (.reason c))
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(barf "slurp-made.txt" (bytes-view "made by the handler\n"))
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(invoke-restart 'retry))]
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(let [v (slurp "slurp-made.txt")]
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(print (string (as-slice v))) ; made by the handler
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(free v)))
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(println seen) ; 1
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(println (= last-reason file-missing)) ; true
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0)
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