proof/FINDINGS.md's Isabelle/HOL word-source sweep (§1) found the two
defects severe enough to actively corrupt the live Tripod multi-VM fleet:
file-scope C statics standing in for state that belongs on struct VM.
- vocabulary_words.c (highest severity in the sweep): forth_vocab/
context_vocab/current_vocab, context_var_addr/current_var_addr, the
ctx_fc/forth_fc first-char search index, and the `initialized` guard
were all process-wide statics. Only the first VM to touch any
vocabulary word ever ran setup; every VM after that silently shared
VM #1's dictionary-chain pointers and reused VM #1's byte-offset
addresses as if valid in its own vm->memory. One VM's VOCABULARY/
DEFINITIONS/FORTH silently changed where every other VM looked up and
defined words.
- control_words.c: cf_stack/cf_sp/cf_last_mode (IF/THEN/BEGIN/DO/CASE
compile-time nesting) and the LEAVE/ENDOF patch-site bookkeeping
(leave_addrs/leave_sp/leave_mark_*, endof_addrs/endof_sp/endof_mark_*)
were also process-wide statics. Two VMs compiling colon definitions at
overlapping times would corrupt each other's nesting state.
Both moved onto struct VM, following the existing hold_addr/hold_pos
precedent in include/vm.h ("lives in each VM's own memory... so child
VMs never alias Hera's buffer"):
- New VocabularyState struct (vm->vocab): chain heads, VM-cell addresses,
first-char index, initialized flag.
- New ControlFlowState struct (vm->cf): cf_stack/cf_sp/cf_last_mode plus
the LEAVE/ENDOF patch-site stacks. cf_tag_t/cf_item_t/CF_STACK_MAX
moved from control_words.c into include/vm.h since they're now part of
the struct VM field's type.
- Sentinel fields (-1/-999, meaning "empty") explicitly initialized in
both vm_init_with_host() implementations (hosted src/vm_bootstrap.c and
kernel src/starkernel/vm/vm_bootstrap.c) alongside the existing
dsp/rsp = -1 initialization, since the preceding zero-init leaves them
at 0 rather than their empty sentinel.
Every word function in both files already took VM *vm, so no call sites
outside these two files needed to change; cf_push_item/cf_pop_item/
cf_peek_item gained a VM* parameter to reach vm->cf.
Verified: hosted (amd64) and kernel (amd64, __STARKERNEL__) both build
clean with -Wall -Werror after a full clean rebuild (struct VM's layout
changed size, and this Makefile has no header-dependency tracking, so a
stale incremental build would have linked mismatched object layouts).
Hosted POST suite 1012/1012 passing (0 regressions). Manually exercised
VOCABULARY/DEFINITIONS/FORTH/ORDER, and IF/ELSE, DO/LOOP/LEAVE,
BEGIN/WHILE/REPEAT, and CASE/OF/ENDOF/ENDCASE (including nested DO with
I/J) in the REPL -- all correct and unchanged from pre-refactor behavior.
Note: a pre-existing CASE/ENDCASE default-clause bug (the code after the
last OF...ENDOF pair does not correctly become the "default" value once
DROP runs) was found while testing this refactor and confirmed present
on unmodified master too -- not touched here, out of scope for this pass.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014Qf6YcnHgaEtEygq3knx19
proof/FINDINGS.md's Isabelle/HOL word-source sweep (§4) flagged five real
defects; this fixes all five and records resolution in that doc:
- EXECUTE (system_words.c): cast a popped cell straight to a DictEntry*
and called through it with only a null check. Now validates via a new
shared vm_dict_entry_ok(), promoted out of starforth_words.c's
ENTROPY@/ENTROPY! guard (dictionary_management.c) so EXECUTE gets the
same live-entry check.
- ? and DUMP (format_words.c): dereferenced the popped cell as a raw host
pointer, bypassing vm_addr_ok entirely (out-of-VM-bounds read). Both now
go through VM_ADDR/vm_addr_ok/vm_load_cell/vm_ptr like every other
memory word (@, `,`, editor_words.c).
- TYPE (io_words.c): bounds check computed addr+count in signed 64-bit
arithmetic, which can overflow and bypass the check on large operands.
Replaced with vm_addr_ok(), which is written to avoid that overflow.
- DECIMAL/HEX/OCTAL (format_words.c): wrote only the BASE memory cell,
never vm->base, the host-mirror field number-output words actually read
via current_base() -- so these words silently affected number parsing
but never printing. Now call the existing vm_set_base() (previously
only used at boot init), which updates both. vm_get_base/vm_set_base
promoted to public declarations in include/vm.h.
- ALIGN vs ALLOT/,/C,/2, (dictionary_words.c): disagreed on dictionary
growth ceiling (2MB vs 5MB). Investigated which was correct rather than
blindly widening: vm_get_block_addr() maps block N to
vm->memory + N*BLOCK_SIZE across the full 5MB arena, and
USER_BLOCKS_START (block 2048) lines up exactly with
DICTIONARY_MEMORY_SIZE -- so ALLOT/,/C,/2, letting `here` grow past 2MB
could silently corrupt live block/user data sharing that memory.
Tightened ALLOT/,/C,/2, to DICTIONARY_MEMORY_SIZE to match ALIGN.
Verified: hosted (amd64) and kernel (amd64, __STARKERNEL__) both build
clean with -Wall -Werror; hosted POST suite 1012/1012 passing (0
regressions); manually exercised EXECUTE, ?/DUMP, TYPE, HEX/DECIMAL/OCTAL,
and large-ALLOT rejection in the REPL.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014Qf6YcnHgaEtEygq3knx19
Aggregates the sweep's cross-cutting architectural findings (file-scope
statics standing in for per-VM state, missing overflow guards, duplicate
word registration/shadowing) and gives an executive-summary coverage
index across all 34 src/word_source/*.c files, per Bob's original framing
for this initiative.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude