4 files changed, 88 insertions, 4 deletions

diff --git a/ext/web/09_file.js b/ext/web/09_file.js
index 43d9ffcb3..64cdb7b8a 100644
--- a/ext/web/09_file.js
+++ b/ext/web/09_file.js
@@ -167,11 +167,12 @@
     return bag;
   }
 
+  const _type = Symbol("Type");
   const _size = Symbol("Size");
   const _parts = Symbol("Parts");
 
   class Blob {
-    #type = "";
+    [_type] = "";
     [_size] = 0;
     [_parts];
 
@@ -199,7 +200,7 @@
 
       this[_parts] = parts;
       this[_size] = size;
-      this.#type = normalizeType(options.type);
+      this[_type] = normalizeType(options.type);
     }
 
     /** @returns {number} */
@@ -211,7 +212,7 @@
     /** @returns {string} */
     get type() {
       webidl.assertBranded(this, Blob);
-      return this.#type;
+      return this[_type];
     }
 
     /**
@@ -561,7 +562,44 @@
     }
   }
 
+  /**
+   * Construct a new Blob object from an object URL.
+   *
+   * This new object will not duplicate data in memory with the original Blob
+   * object from which this URL was created or with other Blob objects created
+   * from the same URL, but they will be different objects.
+   *
+   * The object returned from this function will not be a File object, even if
+   * the original object from which the object URL was constructed was one. This
+   * means that the `name` and `lastModified` properties are lost.
+   *
+   * @param {string} url
+   * @returns {Blob | null}
+   */
+  function blobFromObjectUrl(url) {
+    const blobData = core.opSync("op_blob_from_object_url", url);
+    if (blobData === null) {
+      return null;
+    }
+
+    /** @type {BlobReference[]} */
+    const parts = [];
+    let totalSize = 0;
+
+    for (const { uuid, size } of blobData.parts) {
+      ArrayPrototypePush(parts, new BlobReference(uuid, size));
+      totalSize += size;
+    }
+
+    const blob = webidl.createBranded(Blob);
+    blob[_type] = blobData.media_type;
+    blob[_size] = totalSize;
+    blob[_parts] = parts;
+    return blob;
+  }
+
   window.__bootstrap.file = {
+    blobFromObjectUrl,
     getParts,
     Blob,
     File,
diff --git a/ext/web/blob.rs b/ext/web/blob.rs
index 2179de4a6..37e93c853 100644
--- a/ext/web/blob.rs
+++ b/ext/web/blob.rs
@@ -3,7 +3,7 @@ use deno_core::error::type_error;
 use deno_core::parking_lot::Mutex;
 use deno_core::url::Url;
 use deno_core::ZeroCopyBuf;
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt::Debug;
@@ -260,3 +260,46 @@ pub fn op_blob_revoke_object_url(
   blob_store.remove_object_url(&url);
   Ok(())
 }
+
+#[derive(Serialize)]
+pub struct ReturnBlob {
+  pub media_type: String,
+  pub parts: Vec<ReturnBlobPart>,
+}
+
+#[derive(Serialize)]
+pub struct ReturnBlobPart {
+  pub uuid: Uuid,
+  pub size: usize,
+}
+
+pub fn op_blob_from_object_url(
+  state: &mut deno_core::OpState,
+  url: String,
+  _: (),
+) -> Result<Option<ReturnBlob>, AnyError> {
+  let url = Url::parse(&url)?;
+  if url.scheme() != "blob" {
+    return Ok(None);
+  }
+
+  let blob_store = state.try_borrow::<BlobStore>().ok_or_else(|| {
+    type_error("Blob URLs are not supported in this context.")
+  })?;
+  if let Some(blob) = blob_store.get_object_url(url)? {
+    let parts = blob
+      .parts
+      .iter()
+      .map(|part| ReturnBlobPart {
+        uuid: blob_store.insert_part(part.clone()),
+        size: part.size(),
+      })
+      .collect();
+    Ok(Some(ReturnBlob {
+      media_type: blob.media_type.clone(),
+      parts,
+    }))
+  } else {
+    Ok(None)
+  }
+}
diff --git a/ext/web/internal.d.ts b/ext/web/internal.d.ts
index 6e72c1a80..94fc9c196 100644
--- a/ext/web/internal.d.ts
+++ b/ext/web/internal.d.ts
@@ -73,6 +73,7 @@ declare namespace globalThis {
     };
 
     declare var file: {
+      blobFromObjectUrl(url: string): Blob | null;
       getParts(blob: Blob): string[];
       Blob: typeof Blob;
       File: typeof File;
diff --git a/ext/web/lib.rs b/ext/web/lib.rs
index 87ae46f2f..5f8ab1625 100644
--- a/ext/web/lib.rs
+++ b/ext/web/lib.rs
@@ -29,6 +29,7 @@ use std::usize;
 
 use crate::blob::op_blob_create_object_url;
 use crate::blob::op_blob_create_part;
+use crate::blob::op_blob_from_object_url;
 use crate::blob::op_blob_read_part;
 use crate::blob::op_blob_remove_part;
 use crate::blob::op_blob_revoke_object_url;
@@ -88,6 +89,7 @@ pub fn init(blob_store: BlobStore, maybe_location: Option<Url>) -> Extension {
         "op_blob_revoke_object_url",
         op_sync(op_blob_revoke_object_url),
       ),
+      ("op_blob_from_object_url", op_sync(op_blob_from_object_url)),
       (
         "op_message_port_create_entangled",
         op_sync(op_message_port_create_entangled),