Add back-end support for PDF attachments in PDFEngine.

1. Create a new struct DocumentAttachmentInfo, which contains basic
   information about a PDF attachment, including the attachment's name,
   size, creation date and last modified date.

2. Implement a method GetDocumentAttachmentInfoList() in PDFEngine,
   which returns a list of DocumentAttachmentInfo structure(s)
   associated with a PDF document.

3. Add 2 unit tests for the new method. To test on PDFs with
   attachments, this CL uploads a test PDF embedded_attachments.pdf,
   which contains 3 attachments: 1.txt, attached.pdf and 附錄.txt.
   These 3 attachments can cover the tests on different file types and
   names, and tests on attachments with no creation dates or last
   modified dates.

Bug: 177188
Change-Id: If6eaa61f64407af9c848fe2b3b814aa83fc23495
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2202510
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Commit-Queue: Hui Yingst <nigi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773244}

pdf/BUILD.gn

@@ -49,6 +49,8 @@ if (enable_pdf) {
       "accessibility.cc",
       "accessibility.h",
       "chunk_stream.h",
+      "document_attachment_info.cc",
+      "document_attachment_info.h",
       "document_layout.cc",
       "document_layout.h",
       "document_loader.h",

pdf/document_attachment_info.cc

@@ -0,0 +1,16 @@
+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "pdf/document_attachment_info.h"
+
+namespace chrome_pdf {
+
+DocumentAttachmentInfo::DocumentAttachmentInfo() = default;
+
+DocumentAttachmentInfo::DocumentAttachmentInfo(
+    const DocumentAttachmentInfo& other) = default;
+
+DocumentAttachmentInfo::~DocumentAttachmentInfo() = default;
+
+}  // namespace chrome_pdf

pdf/document_attachment_info.h

@@ -0,0 +1,36 @@
+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PDF_DOCUMENT_ATTACHMENT_INFO_H_
+#define PDF_DOCUMENT_ATTACHMENT_INFO_H_
+
+#include "base/strings/string16.h"
+
+namespace chrome_pdf {
+
+struct DocumentAttachmentInfo {
+  DocumentAttachmentInfo();
+
+  DocumentAttachmentInfo(const DocumentAttachmentInfo& other);
+
+  ~DocumentAttachmentInfo();
+
+  // The attachment's name.
+  base::string16 name;
+
+  // The attachment's size in bytes.
+  uint32_t size_bytes = 0;
+
+  // The creation date of the attachment. It stores the arbitrary string saved
+  // in field "CreationDate".
+  base::string16 creation_date;
+
+  // Last modified date of the attachment. It stores the arbitrary string saved
+  // in field "ModDate".
+  base::string16 modified_date;
+};
+
+}  // namespace chrome_pdf
+
+#endif  // PDF_DOCUMENT_ATTACHMENT_INFO_H_

pdf/pdf_engine.h

@@ -56,6 +56,7 @@ class VarDictionary;
 
 namespace chrome_pdf {
 
+struct DocumentAttachmentInfo;
 struct DocumentMetadata;
 
 // Do one time initialization of the SDK.
@@ -371,6 +372,9 @@ class PDFEngine {
   // Checks the permissions associated with this document.
   virtual bool HasPermission(DocumentPermission permission) const = 0;
   virtual void SelectAll() = 0;
+  // Gets the list of DocumentAttachmentInfo from the document.
+  virtual const std::vector<DocumentAttachmentInfo>&
+  GetDocumentAttachmentInfoList() const = 0;
   // Gets metadata about the document.
   virtual const DocumentMetadata& GetDocumentMetadata() const = 0;
   // Gets the number of pages in the document.

pdf/pdfium/pdfium_engine.cc

@@ -351,6 +351,19 @@ void SetLinkUnderCursor(pp::Instance* instance,
   pp::PDF::SetLinkUnderCursor(instance, link_under_cursor.c_str());
 }
 
+base::string16 GetAttachmentAttribute(FPDF_ATTACHMENT attachment,
+                                      FPDF_BYTESTRING field) {
+  return CallPDFiumWideStringBufferApi(
+      base::BindRepeating(&FPDFAttachment_GetStringValue, attachment, field),
+      /*check_expected_size=*/true);
+}
+
+base::string16 GetAttachmentName(FPDF_ATTACHMENT attachment) {
+  return CallPDFiumWideStringBufferApi(
+      base::BindRepeating(&FPDFAttachment_GetName, attachment),
+      /*check_expected_size=*/true);
+}
+
 }  // namespace
 
 void InitializeSDK(bool enable_v8) {
@@ -732,6 +745,8 @@ void PDFiumEngine::FinishLoadingDocument() {
   if (need_update)
     LoadPageInfo();
 
+  LoadDocumentAttachmentInfoList();
+
   LoadDocumentMetadata();
 
   if (called_do_document_action_)
@@ -2106,6 +2121,12 @@ void PDFiumEngine::SelectAll() {
   }
 }
 
+const std::vector<DocumentAttachmentInfo>&
+PDFiumEngine::GetDocumentAttachmentInfoList() const {
+  DCHECK(document_loaded_);
+  return doc_attachment_info_list_;
+}
+
 const DocumentMetadata& PDFiumEngine::GetDocumentMetadata() const {
   DCHECK(document_loaded_);
   return doc_metadata_;
@@ -3753,6 +3774,28 @@ void PDFiumEngine::GetSelection(uint32_t* selection_start_page_index,
   }
 }
 
+void PDFiumEngine::LoadDocumentAttachmentInfoList() {
+  DCHECK(document_loaded_);
+
+  int attachment_count = FPDFDoc_GetAttachmentCount(doc());
+  if (attachment_count <= 0)
+    return;
+
+  doc_attachment_info_list_.resize(attachment_count);
+  for (int i = 0; i < attachment_count; ++i) {
+    FPDF_ATTACHMENT attachment = FPDFDoc_GetAttachment(doc(), i);
+    DCHECK(attachment);
+
+    doc_attachment_info_list_[i].name = GetAttachmentName(attachment);
+    doc_attachment_info_list_[i].size_bytes =
+        FPDFAttachment_GetFile(attachment, /*buffer=*/nullptr, /*buflen=*/0);
+    doc_attachment_info_list_[i].creation_date =
+        GetAttachmentAttribute(attachment, "CreationDate");
+    doc_attachment_info_list_[i].modified_date =
+        GetAttachmentAttribute(attachment, "ModDate");
+  }
+}
+
 void PDFiumEngine::LoadDocumentMetadata() {
   DCHECK(document_loaded_);
 

pdf/pdfium/pdfium_engine.h

@@ -17,6 +17,7 @@
 #include "base/optional.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
+#include "pdf/document_attachment_info.h"
 #include "pdf/document_layout.h"
 #include "pdf/document_loader.h"
 #include "pdf/document_metadata.h"
@@ -113,6 +114,8 @@ class PDFiumEngine : public PDFEngine,
   std::string GetLinkAtPosition(const pp::Point& point) override;
   bool HasPermission(DocumentPermission permission) const override;
   void SelectAll() override;
+  const std::vector<DocumentAttachmentInfo>& GetDocumentAttachmentInfoList()
+      const override;
   const DocumentMetadata& GetDocumentMetadata() const override;
   int GetNumberOfPages() override;
   pp::VarArray GetBookmarks() override;
@@ -586,6 +589,10 @@ class PDFiumEngine : public PDFEngine,
 
   void OnFocusedAnnotationUpdated(FPDF_ANNOTATION annot, int page_index);
 
+  // Read the attachments' information inside the PDF document, and set
+  // |doc_attachment_info_list_|. To be called after the document is loaded.
+  void LoadDocumentAttachmentInfoList();
+
   // Fetches and populates the fields of |doc_metadata_|. To be called after the
   // document is loaded.
   void LoadDocumentMetadata();
@@ -796,6 +803,9 @@ class PDFiumEngine : public PDFEngine,
   // Shadow matrix for generating the page shadow bitmap.
   std::unique_ptr<draw_utils::ShadowMatrix> page_shadow_;
 
+  // A list of information of document attachments.
+  std::vector<DocumentAttachmentInfo> doc_attachment_info_list_;
+
   // Stores parsed document metadata.
   DocumentMetadata doc_metadata_;
 

pdf/pdfium/pdfium_engine_unittest.cc

@@ -4,8 +4,10 @@
 
 #include "pdf/pdfium/pdfium_engine.h"
 
+#include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/test/task_environment.h"
+#include "pdf/document_attachment_info.h"
 #include "pdf/document_layout.h"
 #include "pdf/document_metadata.h"
 #include "pdf/pdf_features.h"
@@ -183,6 +185,53 @@ TEST_F(PDFiumEngineTest, ApplyDocumentLayoutAvoidsInfiniteLoop) {
   CompareSize({343, 1463}, engine->ApplyDocumentLayout(options));
 }
 
+TEST_F(PDFiumEngineTest, GetDocumentAttachmentInfo) {
+  NiceMock<MockTestClient> client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("embedded_attachments.pdf"));
+  ASSERT_TRUE(engine);
+
+  const std::vector<DocumentAttachmentInfo>& attachments =
+      engine->GetDocumentAttachmentInfoList();
+  ASSERT_EQ(3u, attachments.size());
+
+  {
+    const DocumentAttachmentInfo& attachment = attachments[0];
+    EXPECT_EQ("1.txt", base::UTF16ToUTF8(attachment.name));
+    EXPECT_EQ(4u, attachment.size_bytes);
+    EXPECT_EQ("D:20170712214438-07'00'",
+              base::UTF16ToUTF8(attachment.creation_date));
+    EXPECT_EQ("D:20160115091400", base::UTF16ToUTF8(attachment.modified_date));
+  }
+
+  {
+    const DocumentAttachmentInfo& attachment = attachments[1];
+    EXPECT_EQ("attached.pdf", base::UTF16ToUTF8(attachment.name));
+    EXPECT_EQ(5869u, attachment.size_bytes);
+    EXPECT_EQ("D:20170712214443-07'00'",
+              base::UTF16ToUTF8(attachment.creation_date));
+    EXPECT_EQ("D:20170712214410", base::UTF16ToUTF8(attachment.modified_date));
+  }
+
+  {
+    // Test attachments with no creation date or last modified date.
+    const DocumentAttachmentInfo& attachment = attachments[2];
+    EXPECT_EQ("附錄.txt", base::UTF16ToUTF8(attachment.name));
+    EXPECT_EQ(5u, attachment.size_bytes);
+    EXPECT_THAT(attachment.creation_date, IsEmpty());
+    EXPECT_THAT(attachment.modified_date, IsEmpty());
+  }
+}
+
+TEST_F(PDFiumEngineTest, NoDocumentAttachmentInfo) {
+  NiceMock<MockTestClient> client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("hello_world2.pdf"));
+  ASSERT_TRUE(engine);
+
+  EXPECT_EQ(0u, engine->GetDocumentAttachmentInfoList().size());
+}
+
 TEST_F(PDFiumEngineTest, GetDocumentMetadata) {
   NiceMock<MockTestClient> client;
   std::unique_ptr<PDFiumEngine> engine =