fix!: Memory.get_segment_byte_offset on Passive data sections (#268)

* fix: `Memory.get_segment_byte_offset` on Passive data sections

* feat: Use option instead

Author: spotandjake

src/memory.c

@@ -121,7 +121,12 @@ caml_binaryen_get_memory_segment_byte_offset(value _module, value _name) {
   CAMLparam2(_module, _name);
   BinaryenModuleRef module = BinaryenModuleRef_val(_module);
   char* name = Safe_String_val(_name);
-  CAMLreturn(Val_int(BinaryenGetMemorySegmentByteOffset(module, name)));
+  if (BinaryenGetMemorySegmentPassive(module, name)) {
+    CAMLreturn(Val_none);
+  } else {
+    int offset = BinaryenGetMemorySegmentByteOffset(module, name);
+    CAMLreturn(caml_alloc_some(Val_int(offset)));
+  }
 }
 
 CAMLprim value

src/memory.js

@@ -112,10 +112,10 @@ function caml_binaryen_get_num_memory_segments(wasm_mod) {
 }
 
 //Provides: caml_binaryen_get_memory_segment_byte_offset
-//Requires: caml_jsstring_of_string
+//Requires: caml_jsstring_of_string, to_option
 function caml_binaryen_get_memory_segment_byte_offset(wasm_mod, name) {
   var info = wasm_mod.getMemorySegmentInfo(caml_jsstring_of_string(name));
-  return info.offset;
+  return to_option(info.offset);
 }
 
 //Provides: caml_binaryen_get_memory_segment_passive

src/memory.ml

@@ -71,7 +71,7 @@ let unlimited = -1
 external get_num_segments : Module.t -> int
   = "caml_binaryen_get_num_memory_segments"
 
-external get_segment_byte_offset : Module.t -> string -> int
+external get_segment_byte_offset : Module.t -> string -> int option
   = "caml_binaryen_get_memory_segment_byte_offset"
 
 external get_segment_passive : Module.t -> string -> bool

src/memory.mli

@@ -20,6 +20,6 @@ val is_shared : Module.t -> string -> bool
 val is_64 : Module.t -> string -> bool
 val unlimited : int
 val get_num_segments : Module.t -> int
-val get_segment_byte_offset : Module.t -> string -> int
+val get_segment_byte_offset : Module.t -> string -> int option
 val get_segment_passive : Module.t -> string -> bool
 val get_segment_data : Module.t -> string -> bytes

test/test.ml

@@ -248,6 +248,9 @@ let _ = Memory.set_memory max_memory_wasm_mod 1 2 "memory" [] false false "0"
 let _ = assert (Memory.has_max max_memory_wasm_mod "0" = true)
 let _ = assert (Memory.get_max max_memory_wasm_mod "0" = 2)
 
+(* Memory.get_segment_byte_offset Passive *)
+let _ = assert (Memory.get_segment_byte_offset wasm_mod "world" = None)
+
 let _ =
   assert (
     Bytes.equal