Implement CPDF_HintsTable::SharedObjGroupInfo.

Merge shared objects related data into CPDF_HintsTable::SharedObjGroupInfo.

Change-Id: I53bb7fc42ea6bcd26b3ebf91b8c6aa402108d086
Reviewed-on: https://pdfium-review.googlesource.com/15830
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Art Snake <art-snake@yandex-team.ru>

3 files changed, 58 insertions, 60 deletions

diff --git a/core/fpdfapi/parser/cpdf_hint_tables.cpp b/core/fpdfapi/parser/cpdf_hint_tables.cpp
index fc9a46d68a..f4f87d59e6 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables.cpp
+++ b/core/fpdfapi/parser/cpdf_hint_tables.cpp
@@ -277,60 +277,38 @@ bool CPDF_HintTables::ReadSharedObjHintTable(CFX_BitStream* hStream,
     return false;
   }
 
-  const uint32_t nFirstPageObjNum = m_pLinearized->GetFirstPageObjNum();
-
-  uint32_t dwPrevObjLen = 0;
-  uint32_t dwCurObjLen = 0;
   FX_SAFE_UINT32 required_bits = dwSharedObjTotal;
   required_bits *= dwDeltaGroupLen;
   if (!CanReadFromBitStream(hStream, required_bits))
     return false;
 
-  for (uint32_t i = 0; i < dwSharedObjTotal; ++i) {
-    dwPrevObjLen = dwCurObjLen;
-    FX_SAFE_UINT32 safeObjLen = hStream->GetBits(dwDeltaGroupLen);
-    safeObjLen += dwGroupLeastLen;
-    if (!safeObjLen.IsValid())
-      return false;
-
-    dwCurObjLen = safeObjLen.ValueOrDie();
-    if (i < m_nFirstPageSharedObjs) {
-      m_dwSharedObjNumArray.push_back(nFirstPageObjNum + i);
-      if (i == 0)
-        m_szSharedObjOffsetArray.push_back(m_szFirstPageObjOffset);
-    } else {
+  if (dwSharedObjTotal > 0) {
+    uint32_t dwLastSharedObj = dwSharedObjTotal - 1;
+    if (dwLastSharedObj > m_nFirstPageSharedObjs) {
       FX_SAFE_UINT32 safeObjNum = dwFirstSharedObjNum;
-      safeObjNum += i - m_nFirstPageSharedObjs;
+      safeObjNum += dwLastSharedObj - m_nFirstPageSharedObjs;
       if (!safeObjNum.IsValid())
         return false;
-
-      m_dwSharedObjNumArray.push_back(safeObjNum.ValueOrDie());
-      if (i == m_nFirstPageSharedObjs) {
-        FX_SAFE_FILESIZE safeLoc = szFirstSharedObjLoc;
-        if (!safeLoc.IsValid())
-          return false;
-
-        m_szSharedObjOffsetArray.push_back(safeLoc.ValueOrDie());
-      }
-    }
-
-    if (i != 0 && i != m_nFirstPageSharedObjs) {
-      FX_SAFE_FILESIZE safeLoc = dwPrevObjLen;
-      safeLoc += m_szSharedObjOffsetArray[i - 1];
-      if (!safeLoc.IsValid())
-        return false;
-
-      m_szSharedObjOffsetArray.push_back(safeLoc.ValueOrDie());
     }
   }
 
-  if (dwSharedObjTotal > 0) {
-    FX_SAFE_FILESIZE safeLoc = dwCurObjLen;
-    safeLoc += m_szSharedObjOffsetArray[dwSharedObjTotal - 1];
-    if (!safeLoc.IsValid())
+  m_SharedObjGroupInfos.resize(dwSharedObjTotal);
+  FX_SAFE_FILESIZE prev_shared_group_end_offset = m_szFirstPageObjOffset;
+  for (uint32_t i = 0; i < dwSharedObjTotal; ++i) {
+    if (i == m_nFirstPageSharedObjs)
+      prev_shared_group_end_offset = szFirstSharedObjLoc;
+
+    FX_SAFE_UINT32 safeObjLen = hStream->GetBits(dwDeltaGroupLen);
+    safeObjLen += dwGroupLeastLen;
+    if (!safeObjLen.IsValid())
       return false;
 
-    m_szSharedObjOffsetArray.push_back(safeLoc.ValueOrDie());
+    m_SharedObjGroupInfos[i].m_dwLength = safeObjLen.ValueOrDie();
+    m_SharedObjGroupInfos[i].m_szOffset =
+        prev_shared_group_end_offset.ValueOrDie();
+    prev_shared_group_end_offset += m_SharedObjGroupInfos[i].m_dwLength;
+    if (!prev_shared_group_end_offset.IsValid())
+      return false;
   }
 
   hStream->ByteAlign();
@@ -362,7 +340,7 @@ CPDF_DataAvail::DocAvailStatus CPDF_HintTables::CheckPage(uint32_t index) {
   if (index >= m_pLinearized->GetPageCount())
     return CPDF_DataAvail::DataError;
 
-  uint32_t dwLength = m_PageInfos[index].page_length();
+  const uint32_t dwLength = m_PageInfos[index].page_length();
   if (!dwLength)
     return CPDF_DataAvail::DataError;
 
@@ -372,27 +350,17 @@ CPDF_DataAvail::DocAvailStatus CPDF_HintTables::CheckPage(uint32_t index) {
   }
 
   // Download data of shared objects in the page.
-  const uint32_t nFirstPageObjNum = m_pLinearized->GetFirstPageObjNum();
-
-  uint32_t dwObjNum = 0;
   for (const uint32_t dwIndex : m_PageInfos[index].Identifiers()) {
-    if (dwIndex >= m_dwSharedObjNumArray.size())
+    if (dwIndex >= m_SharedObjGroupInfos.size())
       continue;
+    const SharedObjGroupInfo& shared_group_info =
+        m_SharedObjGroupInfos[dwIndex];
 
-    dwObjNum = m_dwSharedObjNumArray[dwIndex];
-    if (dwObjNum >= static_cast<uint32_t>(nFirstPageObjNum) &&
-        dwObjNum <
-            static_cast<uint32_t>(nFirstPageObjNum) + m_nFirstPageSharedObjs) {
-      continue;
-    }
-
-    dwLength = GetItemLength(dwIndex, m_szSharedObjOffsetArray);
-    // If two objects have the same offset, it should be treated as an error.
-    if (!dwLength)
+    if (!shared_group_info.m_szOffset || !shared_group_info.m_dwLength)
       return CPDF_DataAvail::DataError;
 
     if (!m_pValidator->CheckDataRangeAndRequestIfUnavailable(
-            m_szSharedObjOffsetArray[dwIndex], dwLength)) {
+            shared_group_info.m_szOffset, shared_group_info.m_dwLength)) {
       return CPDF_DataAvail::DataNotAvailable;
     }
   }
diff --git a/core/fpdfapi/parser/cpdf_hint_tables.h b/core/fpdfapi/parser/cpdf_hint_tables.h
index 0db190b189..861f231547 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables.h
+++ b/core/fpdfapi/parser/cpdf_hint_tables.h
@@ -20,6 +20,11 @@ class CPDF_ReadValidator;
 
 class CPDF_HintTables {
  public:
+  struct SharedObjGroupInfo {
+    FX_FILESIZE m_szOffset = 0;
+    uint32_t m_dwLength = 0;
+  };
+
   class PageInfo {
    public:
     PageInfo();
@@ -74,6 +79,9 @@ class CPDF_HintTables {
   bool LoadHintStream(CPDF_Stream* pHintStream);
 
   const std::vector<PageInfo>& PageInfos() const { return m_PageInfos; }
+  const std::vector<SharedObjGroupInfo>& SharedGroupInfos() const {
+    return m_SharedObjGroupInfos;
+  }
 
  protected:
   bool ReadPageHintTable(CFX_BitStream* hStream);
@@ -95,8 +103,7 @@ class CPDF_HintTables {
   FX_FILESIZE m_szFirstPageObjOffset;
 
   std::vector<PageInfo> m_PageInfos;
-  std::vector<uint32_t> m_dwSharedObjNumArray;
-  std::vector<FX_FILESIZE> m_szSharedObjOffsetArray;
+  std::vector<SharedObjGroupInfo> m_SharedObjGroupInfos;
 };
 
 #endif  // CORE_FPDFAPI_PARSER_CPDF_HINT_TABLES_H_
diff --git a/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp b/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp
index 3d98196093..af0e9ff745 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp
@@ -10,6 +10,8 @@
 
 #include "core/fpdfapi/cpdf_modulemgr.h"
 #include "core/fpdfapi/parser/cpdf_data_avail.h"
+#include "core/fpdfapi/parser/cpdf_object.h"
+#include "core/fpdfapi/parser/cpdf_syntax_parser.h"
 #include "core/fxcrt/fx_stream.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -68,7 +70,7 @@ TEST_F(CPDF_HintTablesTest, Load) {
       hint_tables->GetPagePos(2, &page_start, &page_length, &page_obj_num));
 }
 
-TEST_F(CPDF_HintTablesTest, PageInfos) {
+TEST_F(CPDF_HintTablesTest, PageAndGroupInfos) {
   auto data_avail = MakeDataAvailFromFile("feature_linearized_loading.pdf");
   ASSERT_EQ(CPDF_DataAvail::DocAvailStatus::DataAvailable,
             data_avail->IsDocAvail(nullptr));
@@ -95,4 +97,25 @@ TEST_F(CPDF_HintTablesTest, PageInfos) {
   EXPECT_EQ(2u, hint_tables->PageInfos()[1].Identifiers()[0]);
   EXPECT_EQ(5u, hint_tables->PageInfos()[1].Identifiers()[1]);
   EXPECT_EQ(3u, hint_tables->PageInfos()[1].Identifiers()[2]);
+
+  // SharedGroupInfo
+  ASSERT_EQ(6u, hint_tables->SharedGroupInfos().size());
+
+  EXPECT_EQ(777, hint_tables->SharedGroupInfos()[0].m_szOffset);
+  EXPECT_EQ(254u, hint_tables->SharedGroupInfos()[0].m_dwLength);
+
+  EXPECT_EQ(1031, hint_tables->SharedGroupInfos()[1].m_szOffset);
+  EXPECT_EQ(389u, hint_tables->SharedGroupInfos()[1].m_dwLength);
+
+  EXPECT_EQ(1420, hint_tables->SharedGroupInfos()[2].m_szOffset);
+  EXPECT_EQ(726u, hint_tables->SharedGroupInfos()[2].m_dwLength);
+
+  EXPECT_EQ(2146, hint_tables->SharedGroupInfos()[3].m_szOffset);
+  EXPECT_EQ(290u, hint_tables->SharedGroupInfos()[3].m_dwLength);
+
+  EXPECT_EQ(2436, hint_tables->SharedGroupInfos()[4].m_szOffset);
+  EXPECT_EQ(2669u, hint_tables->SharedGroupInfos()[4].m_dwLength);
+
+  EXPECT_EQ(10939, hint_tables->SharedGroupInfos()[5].m_szOffset);
+  EXPECT_EQ(544u, hint_tables->SharedGroupInfos()[5].m_dwLength);
 }