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fix: bound wizard-created Which against its item table (closes #10)

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createObj stored the raw 0-f nibble as Object.Which with no bounds
check, so wizard mode -> C -> / -> f made a wand numbered 15 against a
14-entry table and panicked in fixStick; input below 'a' or '0' went
negative and panicked the same way. C's create_obj() was equally
unchecked, but its consumers were either switches (defined for any
value) or static-array reads past the end (undefined, and survivable in
practice). Since one game is now one process, the Go panic kills the
game outright and leaves the terminal in raw mode.

Reject at the two boundaries a bad Which can enter through. createObj
now refuses an out-of-range choice with a message drawn from C's own
type_name() vocabulary and adds nothing to the pack, a deliberate
divergence recorded in a comment because C had no defined behavior here
to be faithful to. Restore refuses a snapshot describing such an object
(ErrSaveCorrupt) rather than loading a game that would explode later.

Behind those, whichLimit/hasValidWhich back defensive guards at every
dispatch the issue names: the quaffHandler/readHandler/zapHandler
accessors return no handler instead of indexing (for wands that is
exactly what non-MASTER C did, matching no case and still running
o_charges--), the callIt lore lookups, identifyType, armorClass for the
a_class[] reads, initWeapon against the missing init_dam[] row for
WeaponFlame, fixStick's ws_type[] read, and inventoryName and
objectWorth, hoisted so one check each covers the whole family of
per-kind name and appraisal tables.

No in-range input changes behavior and no guard consumes a random
number: the rejection precedes every rnd() call. TestSeedCompatItemTables
stays green untouched.

New game/wizard_test.go covers the exact reproducer, a rejection sweep
over every indexed kind including both negative-input forms, an
acceptance sweep proving valid choices still build the right item, one
no-panic test per guarded family, the fixStick crash site, the
corrupt-save rejection, and a check that whichLimit still agrees with
the table sizes. Each guard was confirmed load-bearing by reverting it
and watching the test panic.

TODO.md records the step; Next Step is deliberately left alone, since
this arrived out of band via an issue.
This commit is contained in:
Jeffrey Paul
2026-08-09 05:09:03 +00:00
parent eb31473ef0
commit 9dbd9d11cb
12 changed files with 660 additions and 13 deletions
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12
game/sticks.go
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@@ -31,7 +31,11 @@ func (g *RogueGame) doZap() {
return
}
if h := g.data.zapHandlers[obj.WandKind()]; h != nil {
// A malformed Which yields no handler, which is exactly what C did in a
// non-MASTER build: its do_zap switch matched no case, fell out, and
// still ran o_charges--. (The MASTER-only "what a bizarre schtick!"
// message for that arm is issue #13, not this bounds fix.)
if h := g.data.zapHandler(obj); h != nil {
if !h(g, obj) {
return // the zap aborted; no charge is used
}
@@ -502,7 +506,11 @@ func (g *RogueGame) boltStrikesHero(start Coord, name string, fromHero bool) boo
// fixStick sets up a new wand or staff (sticks.c fix_stick).
func (g *RogueGame) fixStick(cur *Object) {
if g.Items.WandType[cur.Which] == staffName {
// ws_type[] is indexed by Which; a malformed one is treated as a wand,
// which is the branch the C string compare would take against any
// value that is not literally "staff". The charge switch below already
// funnels everything but WandLight into its default arm.
if cur.hasValidWhich() && g.Items.WandType[cur.Which] == staffName {
cur.Damage = dice("2x3")
} else {
cur.Damage = dice("1x1")