fix: bound wizard-created Which against its item table (closes #10)
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 outside 0-f overshoots much further rather than going negative: readchar returns a byte, so the int(ch-'a') + 10 branch is byte arithmetic and wraps, giving 234 for 'A' and 202 for '!', 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. A decoded snapshot is also the only source of a genuinely negative Which, Which being a plain int off the wire, so it is what the Which >= 0 arm of hasValidWhich defends against. 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. identifyType's bound is defensive rather than live: readHandlers registers readIdentify only for the identify scrolls, all of which sit inside the shorter idType table. 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 the wrapped values from input outside 0-f, 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 over both the wrapped values and a negative Which, and a check that whichLimit still agrees with the table sizes. Each guard was confirmed load-bearing by reverting it and watching the test fail. 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:
426
game/wizard_test.go
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426
game/wizard_test.go
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@@ -0,0 +1,426 @@
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//nolint:testpackage // white-box tests reach unexported state (approved 2026-07-07)
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package game
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import (
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"encoding/gob"
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"errors"
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"os"
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"path/filepath"
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"testing"
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)
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// mustNotPanic runs fn and turns a panic into an ordinary test failure.
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// The bug these tests cover (issue #10) panicked out of an array index,
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// and an unrecovered panic would take the whole test binary down instead
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// of reporting which dispatch regressed.
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func mustNotPanic(t *testing.T, what string, fn func()) {
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t.Helper()
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defer func() {
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if r := recover(); r != nil {
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t.Errorf("%s panicked: %v", what, r)
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}
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}()
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fn()
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}
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// TestCreateObjWandFReproducer is the exact reported crash: wizard mode,
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// C, '/' for a wand, 'f' for which. 'f' is nibble 15 and there are only
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// NumWandTypes (14) wands, so fixStick used to index two past the end of
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// ws_type[] and panic.
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func TestCreateObjWandFReproducer(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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g.Wizard = true
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before := len(g.Player.Pack)
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setInput(t, g, '/', 'f')
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mustNotPanic(t, "createObj with wand 'f'", g.createObj)
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if len(g.Player.Pack) != before {
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t.Errorf("out-of-range wand was added to the pack: %d items, want %d",
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len(g.Player.Pack), before)
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}
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}
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// TestCreateObjRejectsOutOfRangeWhich sweeps the rejection across every
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// kind whose Which is a table index, including input outside '0'-'f'.
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// isDigit is false for such input, so it takes the letter branch, where
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// ch-'a' is byte arithmetic and wraps rather than going negative: 'A'
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// (65) gives int(224)+10 == 234 and '!' (33) gives int(192)+10 == 202.
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// Those far-past-the-end values, not negative ones, are what the guard
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// has to catch on the keyboard path.
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func TestCreateObjRejectsOutOfRangeWhich(t *testing.T) {
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t.Parallel()
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cases := []struct {
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name string
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typ byte
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which byte
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}{
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{"wand f is past NumWandTypes", Stick, 'f'},
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{"potion f is past NumPotionTypes", Potion, 'f'},
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{"ring f is past NumRingTypes", Ring, 'f'},
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// NumScrollTypes is 18, past the 'f' the prompt tops out at, so a
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// scroll can only be driven out of range by input that wraps.
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{"scroll 'A' wraps to 234", Scroll, 'A'},
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{"armor 9 is past NumArmorTypes", Armor, '9'},
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{"weapon 9 is the flame pseudo-weapon", Weapon, '9'},
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{"wand 'A' wraps to 234", Stick, 'A'},
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{"wand '!' wraps to 202", Stick, '!'},
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{"armor 'A' wraps to 234", Armor, 'A'},
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{"weapon '!' wraps to 202", Weapon, '!'},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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g.Wizard = true
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before := len(g.Player.Pack)
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setInput(t, g, tc.typ, tc.which)
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mustNotPanic(t, tc.name, g.createObj)
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if len(g.Player.Pack) != before {
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t.Errorf("pack grew to %d items, want %d: a rejected item was created",
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len(g.Player.Pack), before)
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}
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})
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}
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}
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// TestCreateObjAcceptsValidWhich pins the other half of the contract: the
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// bounds check must not touch any in-range choice.
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func TestCreateObjAcceptsValidWhich(t *testing.T) {
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t.Parallel()
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cases := []struct {
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name string
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typ byte
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which byte
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kind ObjectKind
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want int
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}{
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{"wand of light", Stick, '0', KindWand, int(WandLight)},
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{"potion 0", Potion, '0', KindPotion, int(PotionConfusion)},
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{"scroll 9", Scroll, '9', KindScroll, int(ScrollIdentifyRingOrStick)},
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{"ring d, the last ring", Ring, 'd', KindRing, int(NumRingTypes) - 1},
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{"armor 7, the last armor", Armor, '7', KindArmor, int(NumArmorTypes) - 1},
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{"weapon 8, the last real weapon", Weapon, '8', KindWeapon, int(WeaponSpear)},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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g.Wizard = true
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before := make(map[*Object]bool, len(g.Player.Pack))
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for _, o := range g.Player.Pack {
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before[o] = true
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}
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// The armor and weapon arms read one more character for the
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// blessing prompt; 'n' means neither cursed nor blessed.
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setInput(t, g, tc.typ, tc.which, 'n')
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g.createObj()
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if len(g.Player.Pack) != len(before)+1 {
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t.Fatalf("pack has %d items, want %d: valid item not created",
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len(g.Player.Pack), len(before)+1)
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}
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// addPack files the new item in kind order, so find it by
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// identity rather than assuming it landed at the end.
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var made *Object
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for _, o := range g.Player.Pack {
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if !before[o] {
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made = o
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}
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}
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if made.Kind != tc.kind || made.Which != tc.want {
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t.Errorf("created %v which %d, want %v which %d",
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made.Kind, made.Which, tc.kind, tc.want)
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}
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})
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}
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}
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// TestCreateObjKeepsRNGSequence proves the guard costs no RNG draws: a
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// rejected creation must leave the generator exactly where it was, or
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// every later roll in the game would shift.
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func TestCreateObjKeepsRNGSequence(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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g.Wizard = true
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before := g.Rng.Seed
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setInput(t, g, Stick, 'f')
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g.createObj()
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if g.Rng.Seed != before {
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t.Errorf("rejected creation consumed RNG: seed %d, want %d",
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g.Rng.Seed, before)
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}
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}
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// malformed builds an object of the given kind whose Which sits one past
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// the end of that kind's table — the state the wizard bug used to leave
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// behind, and the state a corrupt save file could still describe.
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func malformed(kind ObjectKind) *Object {
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obj := newObject()
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obj.Kind = kind
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obj.Which = whichLimit(kind)
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obj.Count = 1
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return obj
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}
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// TestZapMalformedWandDoesNotPanic covers the sticks.go dispatch. C's
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// non-MASTER do_zap matched no case and still ran o_charges--, so the
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// charge must be spent even though nothing happens.
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func TestZapMalformedWandDoesNotPanic(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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wand := malformed(KindWand)
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wand.Charges = 3
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ch := give(g, wand)
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setInput(t, g, ch)
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mustNotPanic(t, "doZap on a malformed wand", g.doZap)
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if wand.Charges != 2 {
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t.Errorf("charges = %d after zapping, want 2", wand.Charges)
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}
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}
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// TestQuaffMalformedPotionDoesNotPanic covers the potions.go dispatch and
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// the callIt lookup that follows it.
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func TestQuaffMalformedPotionDoesNotPanic(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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before := len(g.Player.Pack)
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ch := give(g, malformed(KindPotion))
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setInput(t, g, ch)
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mustNotPanic(t, "quaff of a malformed potion", g.quaff)
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if len(g.Player.Pack) != before {
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t.Errorf("pack has %d items, want %d: the potion was not consumed",
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len(g.Player.Pack), before)
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}
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}
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// TestReadMalformedScrollDoesNotPanic covers the scrolls.go dispatch and
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// its callIt lookup.
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func TestReadMalformedScrollDoesNotPanic(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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before := len(g.Player.Pack)
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ch := give(g, malformed(KindScroll))
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setInput(t, g, ch)
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mustNotPanic(t, "readScroll of a malformed scroll", g.readScroll)
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if len(g.Player.Pack) != before {
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t.Errorf("pack has %d items, want %d: the scroll was not consumed",
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len(g.Player.Pack), before)
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}
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}
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// TestMalformedArmorDoesNotPanic covers the a_class[] reads: pricing at
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// death, the identified-armor name, and the detect-magic test.
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func TestMalformedArmorDoesNotPanic(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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armor := malformed(KindArmor)
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armor.Flags.Set(Known)
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mustNotPanic(t, "naming a malformed suit of armor", func() {
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if got := g.inventoryName(armor, false); got != armor.Kind.String() {
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t.Errorf("inventoryName = %q, want %q", got, armor.Kind.String())
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}
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})
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mustNotPanic(t, "isMagic on a malformed suit of armor", func() {
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g.isMagic(armor)
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})
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mustNotPanic(t, "appraising a malformed suit of armor", func() {
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if worth := g.objectWorth(armor); worth != 0 {
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t.Errorf("objectWorth = %d, want 0", worth)
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}
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})
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if got := g.data.armorClass(armor.Which); got != 0 {
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t.Errorf("armorClass(%d) = %d, want 0", armor.Which, got)
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}
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}
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// TestMalformedWeaponDoesNotPanic covers the init_dam[] read. WeaponFlame
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// is the first kind with no table row, so initWeapon must leave the
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// object alone rather than index past the end.
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func TestMalformedWeaponDoesNotPanic(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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weap := newObject()
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mustNotPanic(t, "initWeapon with the flame pseudo-weapon", func() {
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g.initWeapon(weap, WeaponFlame)
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})
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mustNotPanic(t, "initWeapon with a negative weapon kind", func() {
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g.initWeapon(weap, WeaponKind(-1))
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})
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if weap.Kind != KindNone {
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t.Errorf("weapon was initialized from a missing table row: kind %v",
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weap.Kind)
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}
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}
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// TestFixStickMalformedWhichDoesNotPanic covers the ws_type[] read that
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// the reported reproducer actually crashed on.
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func TestFixStickMalformedWhichDoesNotPanic(t *testing.T) {
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t.Parallel()
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g := mkGameInput(t)
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wand := malformed(KindWand)
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mustNotPanic(t, "fixStick on a malformed wand", func() {
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g.fixStick(wand)
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})
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if wand.Damage.String() != "1x1" {
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t.Errorf("damage = %q, want the wand damage %q",
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wand.Damage.String(), "1x1")
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}
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}
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// TestRestoreRejectsOutOfRangeWhich is the save-file half of the fix: a
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// malformed object must not be able to sneak past the keyboard guard by
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// arriving in a snapshot.
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//
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// A decoded save is also the only place a *negative* Which can come
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// from. On the keyboard path createObj's ch-'a' is byte arithmetic and
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// wraps, so 'A' and '!' land at 234 and 202; Which is a plain int in the
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// gob stream, so a tampered file can carry any value at all. Both shapes
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// are covered here, and the negative case is what exercises the
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// Which >= 0 arm of hasValidWhich.
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func TestRestoreRejectsOutOfRangeWhich(t *testing.T) {
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t.Parallel()
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cases := []struct {
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name string
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which int
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}{
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{"one past the wand table", int(NumWandTypes)},
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{"the value 'A' wraps to on the keyboard path", 234},
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{"the value '!' wraps to on the keyboard path", 202},
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{"negative, reachable only from a tampered file", -1},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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g := mkGame(t, 11)
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st := g.snapshot()
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if len(st.Player.Body.Pack) == 0 {
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t.Fatal("starting pack is empty; nothing to corrupt")
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}
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st.Player.Body.Pack[0].Kind = KindWand
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st.Player.Body.Pack[0].Which = tc.which
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path := filepath.Join(t.TempDir(), "rogue.save")
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writeSnapshot(t, path, st)
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_, restoreErr := Restore(path, Params{Term: &testTerm{}})
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if !errors.Is(restoreErr, ErrSaveCorrupt) {
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t.Errorf("Restore error = %v, want ErrSaveCorrupt", restoreErr)
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}
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_, statErr := os.Stat(path)
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if statErr != nil {
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t.Error("a rejected save file was deleted; it should be left alone")
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}
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})
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}
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}
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// writeSnapshot gob-encodes a snapshot to path the way saveFile does.
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func writeSnapshot(t *testing.T, path string, st *SaveState) {
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t.Helper()
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f, err := os.Create(path) //nolint:gosec // G304: test temp path
|
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if err != nil {
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t.Fatal(err)
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}
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encErr := gob.NewEncoder(f).Encode(st)
|
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if encErr != nil {
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t.Fatal(encErr)
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}
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closeErr := f.Close()
|
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if closeErr != nil {
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t.Fatal(closeErr)
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}
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}
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// TestWhichLimitCoversEveryIndexedTable pins the bounds table itself
|
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// against the per-kind arrays it has to agree with.
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func TestWhichLimitCoversEveryIndexedTable(t *testing.T) {
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t.Parallel()
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|
||||
// len() of an array field is a compile-time constant, so the zero
|
||||
// value is enough to read the table sizes off.
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var it ItemLore
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cases := []struct {
|
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kind ObjectKind
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size int
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}{
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{KindPotion, len(it.Potions)},
|
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{KindScroll, len(it.Scrolls)},
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{KindRing, len(it.Rings)},
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{KindWand, len(it.Sticks)},
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{KindArmor, len(it.Armors)},
|
||||
{KindWeapon, len(it.Weapons)},
|
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}
|
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|
||||
for _, tc := range cases {
|
||||
if got := whichLimit(tc.kind); got != tc.size {
|
||||
t.Errorf("whichLimit(%v) = %d, want the table size %d",
|
||||
tc.kind, got, tc.size)
|
||||
}
|
||||
}
|
||||
|
||||
// Kinds whose Which is not a table index accept anything, as in C.
|
||||
for _, kind := range []ObjectKind{KindFood, KindAmulet, KindGold, KindNone} {
|
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obj := &Object{Kind: kind, Which: 99}
|
||||
if !obj.hasValidWhich() {
|
||||
t.Errorf("%v should not be bounds-checked on Which", kind)
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user