Add runtime detection of V8 memory cage #3384

When using the V8 memory cage, Buffers cannot be wrapped and then
later freed via a callback. When the cage is detected via a throw,
instead fall back to copying Buffer contents to V8 memory.

This approach will be used by Electron 21+ and you should expect
reduced performance and increased memory consumption/fragmentation.

docs/changelog.md

@@ -9,6 +9,9 @@ Requires libvips v8.13.3
 * Add experimental support for JPEG-XL images. Requires libvips compiled with libjxl.
   [#2731](https://github.com/lovell/sharp/issues/2731)
 
+* Add runtime detection of V8 memory cage, ensures compatibility with Electron 21 onwards.
+  [#3384](https://github.com/lovell/sharp/issues/3384)
+
 * Expose `interFrameMaxError` and `interPaletteMaxError` GIF optimisation properties.
   [#3401](https://github.com/lovell/sharp/issues/3401)
 

src/common.cc

@@ -76,6 +76,14 @@ namespace sharp {
     }
     return vector;
   }
+  Napi::Buffer<char> NewOrCopyBuffer(Napi::Env env, char* data, size_t len) {
+    try {
+      return Napi::Buffer<char>::New(env, data, len, FreeCallback);
+    } catch (Napi::Error const &err) {}
+    Napi::Buffer<char> buf = Napi::Buffer<char>::Copy(env, data, len);
+    FreeCallback(nullptr, data);
+    return buf;
+  }
 
   // Create an InputDescriptor instance from a Napi::Object describing an input image
   InputDescriptor* CreateInputDescriptor(Napi::Object input) {

src/common.h

@@ -133,6 +133,7 @@ namespace sharp {
     return static_cast<T>(
       vips_enum_from_nick(nullptr, type, AttrAsStr(obj, attr).data()));
   }
+  Napi::Buffer<char> NewOrCopyBuffer(Napi::Env env, char* data, size_t len);
 
   // Create an InputDescriptor instance from a Napi::Object describing an input image
   InputDescriptor* CreateInputDescriptor(Napi::Object input);

src/metadata.cc

@@ -235,20 +235,20 @@ class MetadataWorker : public Napi::AsyncWorker {
         info.Set("orientation", baton->orientation);
       }
       if (baton->exifLength > 0) {
-        info.Set("exif", Napi::Buffer<char>::New(env, baton->exif, baton->exifLength, sharp::FreeCallback));
+        info.Set("exif", sharp::NewOrCopyBuffer(env, baton->exif, baton->exifLength));
       }
       if (baton->iccLength > 0) {
-        info.Set("icc", Napi::Buffer<char>::New(env, baton->icc, baton->iccLength, sharp::FreeCallback));
+        info.Set("icc", sharp::NewOrCopyBuffer(env, baton->icc, baton->iccLength));
       }
       if (baton->iptcLength > 0) {
-        info.Set("iptc", Napi::Buffer<char>::New(env, baton->iptc, baton->iptcLength, sharp::FreeCallback));
+        info.Set("iptc", sharp::NewOrCopyBuffer(env, baton->iptc, baton->iptcLength));
       }
       if (baton->xmpLength > 0) {
-        info.Set("xmp", Napi::Buffer<char>::New(env, baton->xmp, baton->xmpLength, sharp::FreeCallback));
+        info.Set("xmp", sharp::NewOrCopyBuffer(env, baton->xmp, baton->xmpLength));
       }
       if (baton->tifftagPhotoshopLength > 0) {
         info.Set("tifftagPhotoshop",
-          Napi::Buffer<char>::New(env, baton->tifftagPhotoshop, baton->tifftagPhotoshopLength, sharp::FreeCallback));
+          sharp::NewOrCopyBuffer(env, baton->tifftagPhotoshop, baton->tifftagPhotoshopLength));
       }
       Callback().MakeCallback(Receiver().Value(), { env.Null(), info });
     } else {

src/pipeline.cc

@@ -1206,8 +1206,8 @@ class PipelineWorker : public Napi::AsyncWorker {
         // Add buffer size to info
         info.Set("size", static_cast<uint32_t>(baton->bufferOutLength));
         // Pass ownership of output data to Buffer instance
-        Napi::Buffer<char> data = Napi::Buffer<char>::New(env, static_cast<char*>(baton->bufferOut),
+        Napi::Buffer<char> data = sharp::NewOrCopyBuffer(env, static_cast<char*>(baton->bufferOut),
-          baton->bufferOutLength, sharp::FreeCallback);
+          baton->bufferOutLength);
         Callback().MakeCallback(Receiver().Value(), { env.Null(), data, info });
       } else {
         // Add file size to info