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Fix crashes with empty array #936

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Merged
merged 2 commits into from
Aug 8, 2025
Merged

Fix crashes with empty array #936

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b785884
runtime: fix returning an empty array crash
krichprollsch Aug 8, 2025
f463cb1
runtime: handle empty array parameter
krichprollsch Aug 8, 2025
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23 changes: 18 additions & 5 deletions src/runtime/js.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -976,49 +976,57 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
// need this sentinel check to keep the compiler happy
if (ptr.sentinel() == null) {
if (force_u8 or js_value.isUint8Array() or js_value.isUint8ClampedArray()) {
if (byte_len == 0) return &[_]u8{};
const arr_ptr = @as([*]u8, @alignCast(@ptrCast(data)));
return arr_ptr[0..byte_len];
}
}
},
i8 => {
if (js_value.isInt8Array()) {
if (byte_len == 0) return &[_]i8{};
const arr_ptr = @as([*]i8, @alignCast(@ptrCast(data)));
return arr_ptr[0..byte_len];
}
},
u16 => {
if (js_value.isUint16Array()) {
if (byte_len == 0) return &[_]u16{};
const arr_ptr = @as([*]u16, @alignCast(@ptrCast(data)));
return arr_ptr[0 .. byte_len / 2];
}
},
i16 => {
if (js_value.isInt16Array()) {
if (byte_len == 0) return &[_]i16{};
const arr_ptr = @as([*]i16, @alignCast(@ptrCast(data)));
return arr_ptr[0 .. byte_len / 2];
}
},
u32 => {
if (js_value.isUint32Array()) {
if (byte_len == 0) return &[_]u32{};
const arr_ptr = @as([*]u32, @alignCast(@ptrCast(data)));
return arr_ptr[0 .. byte_len / 4];
}
},
i32 => {
if (js_value.isInt32Array()) {
if (byte_len == 0) return &[_]i32{};
const arr_ptr = @as([*]i32, @alignCast(@ptrCast(data)));
return arr_ptr[0 .. byte_len / 4];
}
},
u64 => {
if (js_value.isBigUint64Array()) {
if (byte_len == 0) return &[_]u64{};
const arr_ptr = @as([*]u64, @alignCast(@ptrCast(data)));
return arr_ptr[0 .. byte_len / 8];
}
},
i64 => {
if (js_value.isBigInt64Array()) {
if (byte_len == 0) return &[_]i64{};
const arr_ptr = @as([*]i64, @alignCast(@ptrCast(data)));
return arr_ptr[0 .. byte_len / 8];
}
Expand Down Expand Up @@ -3469,11 +3477,16 @@ fn simpleZigValueToJs(isolate: v8.Isolate, value: anytype, comptime fail: bool)
else => @compileError("Invalid TypeArray type: " ++ @typeName(value_type)),
};

const buffer_len = len * bits / 8;
const backing_store = v8.BackingStore.init(isolate, buffer_len);
const data: [*]u8 = @alignCast(@ptrCast(backing_store.getData()));
@memcpy(data[0..buffer_len], @as([]const u8, @ptrCast(values))[0..buffer_len]);
const array_buffer = v8.ArrayBuffer.initWithBackingStore(isolate, &backing_store.toSharedPtr());
var array_buffer: v8.ArrayBuffer = undefined;
if (len == 0) {
array_buffer = v8.ArrayBuffer.init(isolate, 0);
} else {
const buffer_len = len * bits / 8;
const backing_store = v8.BackingStore.init(isolate, buffer_len);
const data: [*]u8 = @alignCast(@ptrCast(backing_store.getData()));
@memcpy(data[0..buffer_len], @as([]const u8, @ptrCast(values))[0..buffer_len]);
array_buffer = v8.ArrayBuffer.initWithBackingStore(isolate, &backing_store.toSharedPtr());
}

switch (@typeInfo(value_type)) {
.int => |n| switch (n.signedness) {
Expand Down
9 changes: 9 additions & 0 deletions src/runtime/test_primitive_types.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,10 @@ const Primitives = struct {
}
}

pub fn _returnEmptyUint8(_: *const Primitives) Env.TypedArray(u8) {
return .{ .values = &.{} };
}

pub fn _returnUint8(_: *const Primitives) Env.TypedArray(u8) {
return .{ .values = &.{ 10, 20, 250 } };
}
Expand Down Expand Up @@ -277,6 +281,10 @@ test "JS: primitive types" {

// typed arrays
try runner.testCases(&.{
.{ "let empty_arr = new Int8Array([]);", "undefined" },
.{ "p.int8(empty_arr)", "undefined" },
.{ "empty_arr;", "" },

.{ "let arr_i8 = new Int8Array([-10, -20, -30]);", "undefined" },
.{ "p.int8(arr_i8)", "undefined" },
.{ "arr_i8;", "-13,-23,-33" },
Expand Down Expand Up @@ -325,6 +333,7 @@ test "JS: primitive types" {
.{ "try { p.intu64(arr_i64) } catch(e) { e instanceof TypeError; }", "true" },
.{ "try { p.intu64(arr_u32) } catch(e) { e instanceof TypeError; }", "true" },

.{ "p.returnEmptyUint8()", "" },
.{ "p.returnUint8()", "10,20,250" },
.{ "p.returnInt8()", "10,-20,-120" },
.{ "p.returnUint16()", "10,200,2050" },
Expand Down