- bitorder::read and bitorder::write may fail because of unaligned access #2734.

lib/std/core/bitorder.c3

@@ -90,33 +90,35 @@ bitstruct UInt128LE : uint128 @littleendian
 <*
  @require @is_array_or_slice_of_char(bytes) : "argument must be an array, a pointer to an array or a slice of char"
  @require is_bitorder($Type) : "type must be a bitorder integer"
+ @require $defined(*bytes) ||| $defined(bytes[:$Type.sizeof]) : "Data is too short to contain value"
 *>
 macro read(bytes, $Type)
 {
-	char[] s;
+	char *ptr;
 	$switch $kindof(bytes):
 		$case POINTER:
-			s = (*bytes)[:$Type.sizeof];
+			ptr = bytes;
 		$default:
-			s = bytes[:$Type.sizeof];
+			ptr = bytes[..].ptr;
 	$endswitch
-	return bitcast(*(char[$Type.sizeof]*)s.ptr, $Type).val;
+	return bitcast(@unaligned_load(*(char[$Type.sizeof]*)ptr, 1), $Type).val;
 }
 
 <*
  @require @is_arrayptr_or_slice_of_char(bytes) : "argument must be a pointer to an array or a slice of char"
  @require is_bitorder($Type) : "type must be a bitorder integer"
+ @require $defined(*bytes) ||| $defined(bytes[:$Type.sizeof]) : "Data is not sufficent to hold value"
 *>
 macro write(x, bytes, $Type)
 {
-	char[] s;
+	char *ptr;
 	$switch $kindof(bytes):
 		$case POINTER:
-			s = (*bytes)[:$Type.sizeof];
+			ptr = bytes;
 		$default:
-			s = bytes[:$Type.sizeof];
+			ptr = bytes[..].ptr;
 	$endswitch
-	*($typeof(x)*)s.ptr = bitcast(x, $Type).val;
+	@unaligned_store(*($typeof(x)*)ptr, bitcast(x, $Type).val, 1);
 }
 
 macro bool is_bitorder($Type)

releasenotes.md

@@ -54,6 +54,7 @@
 - Incorrect alignment on typedef and local variable debug info.
 - Assert on optional-returning-function in a comma expression. #2722
 - Creating recursive debug info for functions could cause assertions.
+- bitorder::read and bitorder::write may fail because of unaligned access #2734.
 
 ### Stdlib changes
 - Add `ThreadPool` join function to wait for all threads to finish in the pool without destroying the threads.

test/unit/stdlib/core/bitorder.c3

@@ -1,5 +1,12 @@
 module std::core::bitorder @test;
 
+fn void test_unaligned()
+{
+	usz file_size;
+	char[64] response;
+	bitorder::write(file_size, response[9..], ULongLE);
+}
+
 fn void test_read()
 {
     char[*] bytes = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };