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module: perform type checking of object IDs to avoid subtle bugs

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2024-12-24 17:00:39 -07:00
parent a28b9798a8
commit 15c3f772ef
1 changed files with 7 additions and 3 deletions
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10
src/module.zig
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@ -309,7 +309,8 @@ pub fn Objects(options: ObjectsOptions, comptime T: type) type {
}; };
} }
// TODO: this doesn't type check currently, but it should (verify id is from this pool of objects.) /// Validates the given object is from this list (type check) and alive (not a use after delete
/// situation.)
fn validateAndUnpack(objs: *const @This(), id: ObjectID, comptime fn_name: []const u8) PackedID { fn validateAndUnpack(objs: *const @This(), id: ObjectID, comptime fn_name: []const u8) PackedID {
const dead = &objs.internal.dead; const dead = &objs.internal.dead;
const generation = &objs.internal.generation; const generation = &objs.internal.generation;
@ -317,11 +318,14 @@ pub fn Objects(options: ObjectsOptions, comptime T: type) type {
// TODO(object): decide whether to disable safety checks like this in some conditions, // TODO(object): decide whether to disable safety checks like this in some conditions,
// e.g. in release builds // e.g. in release builds
const unpacked: PackedID = @bitCast(id); const unpacked: PackedID = @bitCast(id);
if (unpacked.type_id != objs.internal.type_id) {
@panic("mach: " ++ fn_name ++ "() called with object not from this list");
}
if (unpacked.generation != generation.items[unpacked.index]) { if (unpacked.generation != generation.items[unpacked.index]) {
@panic("mach: " ++ fn_name ++ "() called on a dead object (use after delete)"); @panic("mach: " ++ fn_name ++ "() called with a dead object (use after delete, recycled slot)");
} }
if (dead.isSet(unpacked.index)) { if (dead.isSet(unpacked.index)) {
@panic("mach: " ++ fn_name ++ "() called on a dead object"); @panic("mach: " ++ fn_name ++ "() called with a dead object (use after delete)");
} }
return unpacked; return unpacked;
} }