authorgravatar for mlugg@mlugg.co.ukMatthew Lugg <mlugg@mlugg.co.uk> 2023-09-20 21:18:50+01:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2023-09-21 14:48:40-07:00
log0182b7242e216ea6eabf465e32b7da60ad32ee2d
treed286e0ce25374525e8106ecbe93de25e325e1b47
parent2da62a710652571cefe81e958e86d9c9ef74c747

TypedValue: do not crash when failing to dereference pointer

All of the logic in `Value.elemValue` is quite questionable, but printing an error is definitely better than crashing. Notably, this should stop us from hitting crashes when dumping AIR.

2 files changed, 26 insertions(+), 16 deletions(-)

src/TypedValue.zig+9-4
......@@ -135,9 +135,10 @@ pub fn print(
135135
136136 var i: u32 = 0;
137137 while (i < max_len) : (i += 1) {
138 const elem_val = payload.ptr.elemValue(mod, i) catch |err| switch (err) {
138 const maybe_elem_val = payload.ptr.maybeElemValue(mod, i) catch |err| switch (err) {
139139 error.OutOfMemory => @panic("OOM"), // TODO: eliminate this panic
140140 };
141 const elem_val = maybe_elem_val orelse return writer.writeAll(".{ (reinterpreted data) }");
141142 if (elem_val.isUndef(mod)) break :str;
142143 buf[i] = std.math.cast(u8, elem_val.toUnsignedInt(mod)) orelse break :str;
143144 }
......@@ -153,9 +154,10 @@ pub fn print(
153154 var i: u32 = 0;
154155 while (i < max_len) : (i += 1) {
155156 if (i != 0) try writer.writeAll(", ");
156 const elem_val = payload.ptr.elemValue(mod, i) catch |err| switch (err) {
157 const maybe_elem_val = payload.ptr.maybeElemValue(mod, i) catch |err| switch (err) {
157158 error.OutOfMemory => @panic("OOM"), // TODO: eliminate this panic
158159 };
160 const elem_val = maybe_elem_val orelse return writer.writeAll("(reinterpreted data) }");
159161 try print(.{
160162 .ty = elem_ty,
161163 .val = elem_val,
......@@ -272,7 +274,8 @@ pub fn print(
272274 const max_len = @min(len, max_string_len);
273275 var buf: [max_string_len]u8 = undefined;
274276 for (buf[0..max_len], 0..) |*c, i| {
275 const elem = try val.elemValue(mod, i);
277 const maybe_elem = try val.maybeElemValue(mod, i);
278 const elem = maybe_elem orelse return writer.writeAll(".{ (reinterpreted data) }");
276279 if (elem.isUndef(mod)) break :str;
277280 c.* = @as(u8, @intCast(elem.toUnsignedInt(mod)));
278281 }
......@@ -283,9 +286,11 @@ pub fn print(
283286 const max_len = @min(len, max_aggregate_items);
284287 for (0..max_len) |i| {
285288 if (i != 0) try writer.writeAll(", ");
289 const maybe_elem = try val.maybeElemValue(mod, i);
290 const elem = maybe_elem orelse return writer.writeAll("(reinterpreted data) }");
286291 try print(.{
287292 .ty = elem_ty,
288 .val = try val.elemValue(mod, i),
293 .val = elem,
289294 }, writer, level - 1, mod);
290295 }
291296 if (len > max_aggregate_items) {
src/value.zig+17-12
......@@ -1520,33 +1520,38 @@ pub const Value = struct {
15201520 /// Asserts the value is a single-item pointer to an array, or an array,
15211521 /// or an unknown-length pointer, and returns the element value at the index.
15221522 pub fn elemValue(val: Value, mod: *Module, index: usize) Allocator.Error!Value {
1523 return (try val.maybeElemValue(mod, index)).?;
1524 }
1525
1526 /// Like `elemValue`, but returns `null` instead of asserting on failure.
1527 pub fn maybeElemValue(val: Value, mod: *Module, index: usize) Allocator.Error!?Value {
15231528 return switch (val.ip_index) {
15241529 .none => switch (val.tag()) {
15251530 .bytes => try mod.intValue(Type.u8, val.castTag(.bytes).?.data[index]),
15261531 .repeated => val.castTag(.repeated).?.data,
15271532 .aggregate => val.castTag(.aggregate).?.data[index],
1528 .slice => val.castTag(.slice).?.data.ptr.elemValue(mod, index),
1529 else => unreachable,
1533 .slice => val.castTag(.slice).?.data.ptr.maybeElemValue(mod, index),
1534 else => null,
15301535 },
15311536 else => switch (mod.intern_pool.indexToKey(val.toIntern())) {
15321537 .undef => |ty| (try mod.intern(.{
15331538 .undef = ty.toType().elemType2(mod).toIntern(),
15341539 })).toValue(),
15351540 .ptr => |ptr| switch (ptr.addr) {
1536 .decl => |decl| mod.declPtr(decl).val.elemValue(mod, index),
1541 .decl => |decl| mod.declPtr(decl).val.maybeElemValue(mod, index),
15371542 .mut_decl => |mut_decl| (try mod.declPtr(mut_decl.decl).internValue(mod))
1538 .toValue().elemValue(mod, index),
1539 .int, .eu_payload => unreachable,
1540 .opt_payload => |base| base.toValue().elemValue(mod, index),
1541 .comptime_field => |field_val| field_val.toValue().elemValue(mod, index),
1542 .elem => |elem| elem.base.toValue().elemValue(mod, index + @as(usize, @intCast(elem.index))),
1543 .toValue().maybeElemValue(mod, index),
1544 .int, .eu_payload => null,
1545 .opt_payload => |base| base.toValue().maybeElemValue(mod, index),
1546 .comptime_field => |field_val| field_val.toValue().maybeElemValue(mod, index),
1547 .elem => |elem| elem.base.toValue().maybeElemValue(mod, index + @as(usize, @intCast(elem.index))),
15431548 .field => |field| if (field.base.toValue().pointerDecl(mod)) |decl_index| {
15441549 const base_decl = mod.declPtr(decl_index);
15451550 const field_val = try base_decl.val.fieldValue(mod, @as(usize, @intCast(field.index)));
1546 return field_val.elemValue(mod, index);
1547 } else unreachable,
1551 return field_val.maybeElemValue(mod, index);
1552 } else null,
15481553 },
1549 .opt => |opt| opt.val.toValue().elemValue(mod, index),
1554 .opt => |opt| opt.val.toValue().maybeElemValue(mod, index),
15501555 .aggregate => |aggregate| {
15511556 const len = mod.intern_pool.aggregateTypeLen(aggregate.ty);
15521557 if (index < len) return switch (aggregate.storage) {
......@@ -1560,7 +1565,7 @@ pub const Value = struct {
15601565 assert(index == len);
15611566 return mod.intern_pool.indexToKey(aggregate.ty).array_type.sentinel.toValue();
15621567 },
1563 else => unreachable,
1568 else => null,
15641569 },
15651570 };
15661571 }