From 77f0f3c11a5b9e2d5bbf20a6e2840c19822bc134 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 24 Feb 2023 20:01:22 -0700
Subject: [PATCH] [wasm-api] Make buffer_copy_contents return zero length on
 mem fail

---
 src/hb-wasm-api-buffer.hh  |  4 ++--
 src/hb-wasm-shape.cc       | 15 ++-------------
 src/wasm-graphite/shape.cc |  2 ++
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/src/hb-wasm-api-buffer.hh b/src/hb-wasm-api-buffer.hh
index 78d44b572..91b3a8720 100644
--- a/src/hb-wasm-api-buffer.hh
+++ b/src/hb-wasm-api-buffer.hh
@@ -109,8 +109,8 @@ HB_WASM_API_COMPOUND (buffer_contents_t, buffer_copy_contents) (HB_WASM_EXEC_ENV
   ret.info = wasm_runtime_module_dup_data (module_inst, (const char *) buffer->info, length * sizeof (buffer->info[0]));
   ret.pos = wasm_runtime_module_dup_data (module_inst, (const char *) buffer->pos, length * sizeof (buffer->pos[0]));
 
-  if (unlikely (buffer->successful && (!ret.info || !ret.pos)))
-    buffer->successful = false;
+  if (!ret.info || !ret.pos)
+    ret.length = 0;
 }
 
 HB_WASM_API (bool_t, buffer_set_contents) (HB_WASM_EXEC_ENV
diff --git a/src/hb-wasm-shape.cc b/src/hb-wasm-shape.cc
index b43a8c9fb..a44ef5e23 100644
--- a/src/hb-wasm-shape.cc
+++ b/src/hb-wasm-shape.cc
@@ -348,21 +348,10 @@ retry:
 
   wasm_runtime_module_free (module_inst, arguments[2].of.i32);
 
-  if (unlikely (buffer->in_error ()))
-  {
-    DEBUG_MSG (WASM, module_inst, "Buffer in error. Memory allocation fail in the wasm?");
-    if (retried)
-      goto fail;
-    buffer->successful = true;
-    retried = true;
-    release_shape_plan (face_data, plan);
-    goto retry;
-  }
-
-  if (unlikely (!ret))
+  if (unlikely (!ret || !results[0].of.i32))
   {
     DEBUG_MSG (WASM, module_inst, "Calling shape() failed: %s",
-	       wasm_runtime_get_exception(module_inst));
+	       wasm_runtime_get_exception (module_inst));
     if (retried)
       goto fail;
     buffer->successful = true;
diff --git a/src/wasm-graphite/shape.cc b/src/wasm-graphite/shape.cc
index 80ef1c500..d4abc735a 100644
--- a/src/wasm-graphite/shape.cc
+++ b/src/wasm-graphite/shape.cc
@@ -75,6 +75,8 @@ shape (void *shape_plan,
   }
 
   buffer_contents_t contents = buffer_copy_contents (buffer);
+  if (!contents.length)
+    return false;
 
   gr_segment *seg = nullptr;
   const gr_slot *is;