From db8e51e01b972aaf6d32309ef5aa381964950af4 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 22 Feb 2023 13:33:34 -0700
Subject: [PATCH] [wasm] More boilerplate

---
 src/hb-wasm-shape.cc | 69 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 67 insertions(+), 2 deletions(-)

diff --git a/src/hb-wasm-shape.cc b/src/hb-wasm-shape.cc
index 4e87dbd3a..e3cc7aa24 100644
--- a/src/hb-wasm-shape.cc
+++ b/src/hb-wasm-shape.cc
@@ -56,38 +56,59 @@ get_wasm_store ()
 struct hb_wasm_face_data_t {
   hb_blob_t *blob;
   wasm_module_t *mod;
+  unsigned shape_func_idx;
 };
 
 hb_wasm_face_data_t *
 _hb_wasm_shaper_face_data_create (hb_face_t *face)
 {
+  wasm_store_t *wasm_store = nullptr;
   hb_blob_t *wasm_blob = nullptr;
   own wasm_module_t *wasm_module = nullptr;
   hb_wasm_face_data_t *data = nullptr;
+  wasm_exporttype_vec_t exports = {};
+  unsigned shape_func_idx = (unsigned) -1;
 
   wasm_blob = hb_face_reference_table (face, HB_WASM_TAG_WASM);
   unsigned length = hb_blob_get_length (wasm_blob);
   if (!length)
     goto fail;
 
+  wasm_store = get_wasm_store (); // Do before others to initialize
+
   wasm_byte_vec_t binary;
   wasm_byte_vec_new_uninitialized (&binary, length);
   memcpy (binary.data, hb_blob_get_data (wasm_blob, nullptr), length);
-  wasm_module = wasm_module_new (get_wasm_store (), &binary);
+  wasm_module = wasm_module_new (wasm_store, &binary);
   if (!wasm_module)
     goto fail;
   wasm_byte_vec_delete(&binary);
 
+  wasm_module_exports (wasm_module, &exports);
+  for (unsigned i = 0; i < exports.size; i++)
+  {
+    auto *name = wasm_exporttype_name(exports.data[i]);
+    if (0 == memcmp ("shape", name->data, name->size))
+    {
+      shape_func_idx = i;
+      break;
+    }
+  }
+  if (shape_func_idx == (unsigned) -1)
+    goto fail;
+
   data = (hb_wasm_face_data_t *) hb_calloc (1, sizeof (hb_wasm_face_data_t));
   if (unlikely (!data))
     goto fail;
 
   data->blob = wasm_blob;
   data->mod = wasm_module;
+  data->shape_func_idx = shape_func_idx;
 
   return data;
 
 fail:
+  wasm_exporttype_vec_delete (&exports);
   if (wasm_module)
     wasm_module_delete (wasm_module);
   hb_blob_destroy (wasm_blob);
@@ -133,7 +154,51 @@ _hb_wasm_shape (hb_shape_plan_t    *shape_plan,
 		const hb_feature_t *features,
 		unsigned int        num_features)
 {
-  return false;
+  bool ret = true;
+  const hb_wasm_face_data_t *face_data = font->face->data.wasm;
+  own wasm_instance_t *instance = nullptr;
+  const wasm_func_t *run_func = nullptr;
+  wasm_trap_t *trap = nullptr;
+  own wasm_extern_vec_t exports = {};
+
+  wasm_val_t as[1] = { WASM_I32_VAL(6) };
+  wasm_val_t rs[1] = { WASM_INIT_VAL };
+  wasm_val_vec_t args = WASM_ARRAY_VEC (as);
+  wasm_val_vec_t results = WASM_ARRAY_VEC (rs);
+
+  instance = wasm_instance_new (get_wasm_store (), face_data->mod, nullptr/*imports*/, nullptr);
+  if (!instance)
+    goto fail;
+
+  wasm_instance_exports (instance, &exports);
+  if (exports.size == 0)
+    goto fail;
+
+  run_func = wasm_extern_as_func (exports.data[face_data->shape_func_idx]);
+  if (!run_func)
+    goto fail;
+
+  trap = wasm_func_call (run_func, &args, &results);
+  if (trap)
+  {
+    goto fail;
+  }
+
+  ret = bool (rs[0].of.i32);
+
+  if (0)
+  {
+fail:
+    ret = false;
+  }
+
+  wasm_extern_vec_delete (&exports);
+  if (instance)
+    wasm_instance_delete(instance);
+  if (trap)
+    wasm_trap_delete (trap);
+
+  return ret;
 }
 
 #endif