From 898fe9fe59b869a8d7517ea9c2921a11a8a298a1 Mon Sep 17 00:00:00 2001
From: Brian Benjamin Maranville <brian.maranville@nist.gov>
Date: Sat, 24 Aug 2024 13:27:04 -0400
Subject: [PATCH 1/2] adding method to read metadata for committed Datatype

---
 src/hdf5_hl.d.ts           |  5 ++++-
 src/hdf5_hl.ts             | 13 +++++++++++--
 src/hdf5_util.cc           | 19 +++++++++++++++++++
 src/hdf5_util_helpers.d.ts |  1 +
 4 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/hdf5_hl.d.ts b/src/hdf5_hl.d.ts
index 22b3852..a8771cb 100644
--- a/src/hdf5_hl.d.ts
+++ b/src/hdf5_hl.d.ts
@@ -51,8 +51,11 @@ export declare class ExternalLink {
     constructor(filename: string, obj_path: string);
 }
 export declare class Datatype {
+    file_id: bigint;
+    path: string;
     type: OBJECT_TYPE;
-    constructor();
+    constructor(file_id: bigint, path: string);
+    get metadata(): Metadata;
 }
 export declare class Reference {
     ref_data: Uint8Array;
diff --git a/src/hdf5_hl.ts b/src/hdf5_hl.ts
index 7833f8e..9e1c4df 100644
--- a/src/hdf5_hl.ts
+++ b/src/hdf5_hl.ts
@@ -524,8 +524,17 @@ export class ExternalLink {
 }
 
 export class Datatype {
+  file_id: bigint;
+  path: string;
   type: OBJECT_TYPE = OBJECT_TYPE.DATATYPE
-  constructor() {}
+  constructor(file_id: bigint, path: string) {
+    this.file_id = file_id;
+    this.path = path;
+  }
+
+  get metadata() {
+    return Module.get_datatype_metadata(this.file_id, this.path);
+  }
 }
 
 export class Reference {
@@ -736,7 +745,7 @@ export class Group extends HasAttrs {
       return new ExternalLink(filename, obj_path);
     }
     else if (type === Module.H5G_TYPE) {
-      return new Datatype()
+      return new Datatype(this.file_id, fullpath);
     }
     // unknown type or object not found
     return null
diff --git a/src/hdf5_util.cc b/src/hdf5_util.cc
index b2aadff..751e04f 100644
--- a/src/hdf5_util.cc
+++ b/src/hdf5_util.cc
@@ -344,6 +344,24 @@ val get_dtype_metadata(hid_t dtype)
     return attr;
 }
 
+val get_datatype_metadata(hid_t loc_id, const std::string& dtype_name_string)
+{
+    hid_t dtype_id;
+    herr_t status;
+    const char *dtype_name = dtype_name_string.c_str();
+
+    dtype_id = H5Topen2(loc_id, dtype_name, H5P_DEFAULT);
+    if (dtype_id < 0)
+    {
+        throw_error("error - name not defined!");
+        return val::null();
+    }
+    val metadata = get_dtype_metadata(dtype_id);
+
+    H5Tclose(dtype_id);
+    return metadata;
+}
+
 val get_abstractDS_metadata(hid_t dspace, hid_t dtype, hid_t dcpl)
 {
     val attr = get_dtype_metadata(dtype);
@@ -1282,6 +1300,7 @@ EMSCRIPTEN_BINDINGS(hdf5)
     function("get_attribute_names", &get_attribute_names);
     function("get_attribute_metadata", &get_attribute_metadata);
     function("get_dataset_metadata", &get_dataset_metadata);
+    function("get_datatype_metadata", &get_datatype_metadata);
     function("get_dataset_filters", &get_dataset_filters);
     function("refresh_dataset", &refresh_dataset);
     function("get_dataset_data", &get_dataset_data);
diff --git a/src/hdf5_util_helpers.d.ts b/src/hdf5_util_helpers.d.ts
index 5857432..2f6e9ba 100644
--- a/src/hdf5_util_helpers.d.ts
+++ b/src/hdf5_util_helpers.d.ts
@@ -98,6 +98,7 @@ export interface H5Module extends EmscriptenModule {
     refresh_dataset(file_id: bigint, path: string): number;
     resize_dataset(file_id: bigint, path: string, new_size: bigint[]): number;
     get_dataset_metadata(file_id: bigint, path: string): Metadata;
+    get_datatype_metadata(file_id: bigint, path: string): Metadata;
     get_dataset_filters(file_id: bigint, path: string): Filter[];
     flush(file_id: bigint): number;
     ccall: typeof ccall;

From 80b48528e588b994167fa879d4a40f5214f13b47 Mon Sep 17 00:00:00 2001
From: Brian Benjamin Maranville <brian.maranville@nist.gov>
Date: Mon, 26 Aug 2024 10:21:13 -0400
Subject: [PATCH 2/2] add metadata check to datatype test

---
 test/datatype_test.mjs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/test/datatype_test.mjs b/test/datatype_test.mjs
index cd90340..7e52344 100644
--- a/test/datatype_test.mjs
+++ b/test/datatype_test.mjs
@@ -7,7 +7,17 @@ async function datatype_test() {
   await h5wasm.ready;
   var f = new h5wasm.File('./test/array.h5', 'r');
 
-  assert.deepEqual(f.get('datatype/value'), new h5wasm.Datatype());
+  const datatype = f.get('datatype/value');
+  assert(datatype instanceof h5wasm.Datatype);
+  assert.deepEqual(datatype.metadata, {
+    signed: false,
+    type: 3,
+    cset: 0,
+    strpad: 1,
+    vlen: false,
+    littleEndian: false,
+    size: 10
+  });
 }
 
 export const tests = [