commit 0182b7242e216ea6eabf465e32b7da60ad32ee2d (tree)
parent 2da62a710652571cefe81e958e86d9c9ef74c747
Author: mlugg <mlugg@mlugg.co.uk>
Date: Wed, 20 Sep 2023 21:18:50 +0100
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.
Diffstat:
2 files changed, 26 insertions(+), 16 deletions(-)
diff --git a/src/TypedValue.zig b/src/TypedValue.zig
@@ -135,9 +135,10 @@ pub fn print(
var i: u32 = 0;
while (i < max_len) : (i += 1) {
- const elem_val = payload.ptr.elemValue(mod, i) catch |err| switch (err) {
+ const maybe_elem_val = payload.ptr.maybeElemValue(mod, i) catch |err| switch (err) {
error.OutOfMemory => @panic("OOM"), // TODO: eliminate this panic
};
+ const elem_val = maybe_elem_val orelse return writer.writeAll(".{ (reinterpreted data) }");
if (elem_val.isUndef(mod)) break :str;
buf[i] = std.math.cast(u8, elem_val.toUnsignedInt(mod)) orelse break :str;
}
@@ -153,9 +154,10 @@ pub fn print(
var i: u32 = 0;
while (i < max_len) : (i += 1) {
if (i != 0) try writer.writeAll(", ");
- const elem_val = payload.ptr.elemValue(mod, i) catch |err| switch (err) {
+ const maybe_elem_val = payload.ptr.maybeElemValue(mod, i) catch |err| switch (err) {
error.OutOfMemory => @panic("OOM"), // TODO: eliminate this panic
};
+ const elem_val = maybe_elem_val orelse return writer.writeAll("(reinterpreted data) }");
try print(.{
.ty = elem_ty,
.val = elem_val,
@@ -272,7 +274,8 @@ pub fn print(
const max_len = @min(len, max_string_len);
var buf: [max_string_len]u8 = undefined;
for (buf[0..max_len], 0..) |*c, i| {
- const elem = try val.elemValue(mod, i);
+ const maybe_elem = try val.maybeElemValue(mod, i);
+ const elem = maybe_elem orelse return writer.writeAll(".{ (reinterpreted data) }");
if (elem.isUndef(mod)) break :str;
c.* = @as(u8, @intCast(elem.toUnsignedInt(mod)));
}
@@ -283,9 +286,11 @@ pub fn print(
const max_len = @min(len, max_aggregate_items);
for (0..max_len) |i| {
if (i != 0) try writer.writeAll(", ");
+ const maybe_elem = try val.maybeElemValue(mod, i);
+ const elem = maybe_elem orelse return writer.writeAll("(reinterpreted data) }");
try print(.{
.ty = elem_ty,
- .val = try val.elemValue(mod, i),
+ .val = elem,
}, writer, level - 1, mod);
}
if (len > max_aggregate_items) {
diff --git a/src/value.zig b/src/value.zig
@@ -1520,33 +1520,38 @@ pub const Value = struct {
/// Asserts the value is a single-item pointer to an array, or an array,
/// or an unknown-length pointer, and returns the element value at the index.
pub fn elemValue(val: Value, mod: *Module, index: usize) Allocator.Error!Value {
+ return (try val.maybeElemValue(mod, index)).?;
+ }
+
+ /// Like `elemValue`, but returns `null` instead of asserting on failure.
+ pub fn maybeElemValue(val: Value, mod: *Module, index: usize) Allocator.Error!?Value {
return switch (val.ip_index) {
.none => switch (val.tag()) {
.bytes => try mod.intValue(Type.u8, val.castTag(.bytes).?.data[index]),
.repeated => val.castTag(.repeated).?.data,
.aggregate => val.castTag(.aggregate).?.data[index],
- .slice => val.castTag(.slice).?.data.ptr.elemValue(mod, index),
- else => unreachable,
+ .slice => val.castTag(.slice).?.data.ptr.maybeElemValue(mod, index),
+ else => null,
},
else => switch (mod.intern_pool.indexToKey(val.toIntern())) {
.undef => |ty| (try mod.intern(.{
.undef = ty.toType().elemType2(mod).toIntern(),
})).toValue(),
.ptr => |ptr| switch (ptr.addr) {
- .decl => |decl| mod.declPtr(decl).val.elemValue(mod, index),
+ .decl => |decl| mod.declPtr(decl).val.maybeElemValue(mod, index),
.mut_decl => |mut_decl| (try mod.declPtr(mut_decl.decl).internValue(mod))
- .toValue().elemValue(mod, index),
- .int, .eu_payload => unreachable,
- .opt_payload => |base| base.toValue().elemValue(mod, index),
- .comptime_field => |field_val| field_val.toValue().elemValue(mod, index),
- .elem => |elem| elem.base.toValue().elemValue(mod, index + @as(usize, @intCast(elem.index))),
+ .toValue().maybeElemValue(mod, index),
+ .int, .eu_payload => null,
+ .opt_payload => |base| base.toValue().maybeElemValue(mod, index),
+ .comptime_field => |field_val| field_val.toValue().maybeElemValue(mod, index),
+ .elem => |elem| elem.base.toValue().maybeElemValue(mod, index + @as(usize, @intCast(elem.index))),
.field => |field| if (field.base.toValue().pointerDecl(mod)) |decl_index| {
const base_decl = mod.declPtr(decl_index);
const field_val = try base_decl.val.fieldValue(mod, @as(usize, @intCast(field.index)));
- return field_val.elemValue(mod, index);
- } else unreachable,
+ return field_val.maybeElemValue(mod, index);
+ } else null,
},
- .opt => |opt| opt.val.toValue().elemValue(mod, index),
+ .opt => |opt| opt.val.toValue().maybeElemValue(mod, index),
.aggregate => |aggregate| {
const len = mod.intern_pool.aggregateTypeLen(aggregate.ty);
if (index < len) return switch (aggregate.storage) {
@@ -1560,7 +1565,7 @@ pub const Value = struct {
assert(index == len);
return mod.intern_pool.indexToKey(aggregate.ty).array_type.sentinel.toValue();
},
- else => unreachable,
+ else => null,
},
};
}
