Add event handler for downloading attachments.

This CL adds event handlers for downloading attachments, and replace
|attachmentToken| with |messageId| in |SaveAttachmentDataMessageData|
since now the controller uses |messageId| to locate the resolver.

Bug: 177188
Change-Id: I9f88c916d5eff997a2b03c91bf646c8dfa6a66e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2337408
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Hui Yingst <nigi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807665}

chrome/browser/resources/pdf/controller.js

@@ -13,6 +13,15 @@ import {PartialPoint, Viewport} from './viewport.js';
 /** @typedef {{type: string, messageId: (string|undefined)}} */
 export let MessageData;
 
+/**
+ * @typedef {{
+ *   type: string,
+ *   dataToSave: Array,
+ *   messageId: string,
+ * }}
+ */
+let SaveAttachmentDataMessageData;
+
 /**
  * @typedef {{
  *   dataToSave: Array,
@@ -103,6 +112,14 @@ export class ContentController {
    */
   save(requestType) {}
 
+  /**
+   * Requests that the attachment at a certain index be saved.
+   * @param {number} index The index of the attachment to be saved.
+   * @return {Promise<{type: string, dataToSave: Array, messageId: string}>}
+   * @abstract
+   */
+  saveAttachment(index) {}
+
   /**
    * Loads PDF document from `data` activates UI.
    * @param {string} fileName
@@ -358,6 +375,14 @@ export class PluginController extends ContentController {
     return resolver.promise;
   }
 
+  /** @override */
+  saveAttachment(index) {
+    return this.postMessageWithReply_({
+      type: 'saveAttachment',
+      attachmentIndex: index,
+    });
+  }
+
   /** @override */
   async load(fileName, data) {
     const url = URL.createObjectURL(new Blob([data]));

chrome/browser/resources/pdf/ink_controller.js

@@ -95,6 +95,9 @@ export class InkController extends ContentController {
     return this.inkHost_.saveDocument();
   }
 
+  /** @override */
+  saveAttachment(index) {}
+
   /** @override */
   undo() {
     this.inkHost_.undo();

chrome/browser/resources/pdf/pdf_viewer.js

@@ -874,6 +874,62 @@ export class PDFViewerElement extends PDFViewerBaseElement {
     this.canSerializeDocument_ = metadata.canSerializeDocument;
   }
 
+  /**
+   * An event handler for when the browser tells the PDF Viewer to perform a
+   * save on the attachment at a certain index. Callers of this function must
+   * be responsible for checking whether the attachment size is valid for
+   * downloading.
+   * @param {!CustomEvent<number>} e The event which contains the index of
+   *     attachment to be downloaded.
+   * @private
+   */
+  async onSaveAttachment_(e) {
+    const index = e.detail;
+    const size = this.attachments_[index].size;
+    assert(size !== -1);
+
+    let dataArray = [];
+    // If the attachment size is 0, skip requesting the backend to fetch the
+    // attachment data.
+    if (size !== 0) {
+      const result = await this.currentController.saveAttachment(index);
+
+      // Cap the PDF attachment size at 100 MB. This cap should be kept in sync
+      // with and is also enforced in pdf/out_of_process_instance.cc.
+      const MAX_FILE_SIZE = 100 * 1000 * 1000;
+      const bufView = new Uint8Array(result.dataToSave);
+      assert(
+          bufView.length <= MAX_FILE_SIZE,
+          `File too large to be saved: ${bufView.length} bytes.`);
+      assert(
+          bufView.length === size,
+          `Received attachment size does not match its expected value: ${
+              size} bytes.`);
+
+      dataArray = [result.dataToSave];
+    }
+
+    const blob = new Blob(dataArray);
+    const fileName = this.attachments_[index].name;
+    chrome.fileSystem.chooseEntry(
+        {type: 'saveFile', suggestedName: fileName}, entry => {
+          if (chrome.runtime.lastError) {
+            if (chrome.runtime.lastError.message !== 'User cancelled') {
+              console.error(
+                  'chrome.fileSystem.chooseEntry failed: ' +
+                  chrome.runtime.lastError.message);
+            }
+            return;
+          }
+          entry.createWriter(writer => {
+            writer.write(blob);
+            // Unblock closing the window now that the user has saved
+            // successfully.
+            chrome.mimeHandlerPrivate.setShowBeforeUnloadDialog(false);
+          });
+        });
+  }
+
   /**
    * An event handler for when the browser tells the PDF Viewer to perform a
    * save.
@@ -1009,7 +1065,7 @@ export class PDFViewerElement extends PDFViewerBaseElement {
         entry => {
           if (chrome.runtime.lastError) {
             if (chrome.runtime.lastError.message !== 'User cancelled') {
-              console.log(
+              console.error(
                   'chrome.fileSystem.chooseEntry failed: ' +
                   chrome.runtime.lastError.message);
             }

pdf/out_of_process_instance.cc

@@ -132,10 +132,9 @@ constexpr char kJSPrintType[] = "print";
 // Save attachment (Page -> Plugin)
 constexpr char kJSSaveAttachmentType[] = "saveAttachment";
 constexpr char kJSAttachmentIndex[] = "attachmentIndex";
-constexpr char kJSAttachmentToken[] = "attachmentToken";
 // Save attachment data (Plugin -> Page)
 constexpr char kJSSaveAttachmentDataType[] = "saveAttachmentData";
-constexpr char kJSAttachmentDataToSave[] = "attachmentDataToSave";
+constexpr char kJSAttachmentDataToSave[] = "dataToSave";
 // Save (Page -> Plugin)
 constexpr char kJSSaveType[] = "save";
 constexpr char kJSToken[] = "token";
@@ -1728,7 +1727,7 @@ void OutOfProcessInstance::HandleResetPrintPreviewModeMessage(
 
 void OutOfProcessInstance::HandleSaveAttachmentMessage(
     const pp::VarDictionary& dict) {
-  if (!dict.Get(pp::Var(kJSAttachmentToken)).is_string() ||
+  if (!dict.Get(pp::Var(kJSMessageId)).is_string() ||
       !dict.Get(pp::Var(kJSAttachmentIndex)).is_int() ||
       dict.Get(pp::Var(kJSAttachmentIndex)).AsInt() < 0) {
     NOTREACHED();
@@ -1739,14 +1738,14 @@ void OutOfProcessInstance::HandleSaveAttachmentMessage(
   const std::vector<DocumentAttachmentInfo>& list =
       engine()->GetDocumentAttachmentInfoList();
   if (static_cast<size_t>(index) >= list.size() || !list[index].is_readable ||
-      list[index].size_bytes == 0) {
+      !IsSaveDataSizeValid(list[index].size_bytes)) {
     NOTREACHED();
     return;
   }
 
   pp::VarDictionary message;
   message.Set(kType, kJSSaveAttachmentDataType);
-  message.Set(kJSAttachmentToken, dict.Get(pp::Var(kJSAttachmentToken)));
+  message.Set(kJSMessageId, dict.Get(pp::Var(kJSMessageId)));
   // This will be overwritten if the save is successful.
   message.Set(kJSAttachmentDataToSave, pp::Var(pp::Var::Null()));