Revert "Do not merge content streams to parse them."

This reverts commit 9d3fb11a985a8f2aefbf361c0030c7bce2248b8e.

Reason for revert: Break rendering of http://www.flbb.lu/bio_files/BIO_25_2005.pdf

Original change's description:
> Do not merge content streams to parse them.
>
> Removed the PrepareContent() step in CPDF_ContentParser, as its goal
> was to merge these streams.
>
> In Parse(), now loop through the m_StreamArray and parse each stream
> separately.
>
> Bug: pdfium:1051
> Change-Id: Id07f3efe766828081c8cf8601bf69c4f37e20e13
> Reviewed-on: https://pdfium-review.googlesource.com/33595
> Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
> Reviewed-by: Ryan Harrison <rharrison@chromium.org>

TBR=thestig@chromium.org,hnakashima@chromium.org,rharrison@chromium.org

Change-Id: I8186b2dac8538ca477302bb91e22dcc54124461a
Bug: pdfium:1051
Reviewed-on: https://pdfium-review.googlesource.com/33991
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

2 files changed, 52 insertions, 25 deletions

diff --git a/core/fpdfapi/page/cpdf_contentparser.cpp b/core/fpdfapi/page/cpdf_contentparser.cpp
index 471e707322..29b5f122bd 100644
--- a/core/fpdfapi/page/cpdf_contentparser.cpp
+++ b/core/fpdfapi/page/cpdf_contentparser.cpp
@@ -16,6 +16,7 @@
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
+#include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/pauseindicator_iface.h"
 #include "third_party/base/ptr_util.h"
 
@@ -37,11 +38,9 @@ CPDF_ContentParser::CPDF_ContentParser(CPDF_Page* pPage)
 
   CPDF_Stream* pStream = pContent->AsStream();
   if (pStream) {
-    RetainPtr<CPDF_StreamAcc> pSingleStream =
-        pdfium::MakeRetain<CPDF_StreamAcc>(pStream);
-    pSingleStream->LoadAllDataFiltered();
-    m_StreamArray.push_back(pSingleStream);
-    m_CurrentStage = Stage::kParse;
+    m_pSingleStream = pdfium::MakeRetain<CPDF_StreamAcc>(pStream);
+    m_pSingleStream->LoadAllDataFiltered();
+    m_CurrentStage = Stage::kPrepareContent;
     return;
   }
 
@@ -107,10 +106,10 @@ CPDF_ContentParser::CPDF_ContentParser(CPDF_Form* pForm,
     pState->SetFillAlpha(1.0f);
     pState->SetSoftMask(nullptr);
   }
-  RetainPtr<CPDF_StreamAcc> pSingleStream =
-      pdfium::MakeRetain<CPDF_StreamAcc>(pForm->GetStream());
-  pSingleStream->LoadAllDataFiltered();
-  m_StreamArray.push_back(pSingleStream);
+  m_pSingleStream = pdfium::MakeRetain<CPDF_StreamAcc>(pForm->GetStream());
+  m_pSingleStream->LoadAllDataFiltered();
+  m_pData.Reset(m_pSingleStream->GetData());
+  m_Size = m_pSingleStream->GetSize();
 }
 
 CPDF_ContentParser::~CPDF_ContentParser() {}
@@ -125,6 +124,9 @@ bool CPDF_ContentParser::Continue(PauseIndicatorIface* pPause) {
       return true;
   }
 
+  if (m_CurrentStage == Stage::kPrepareContent)
+    m_CurrentStage = PrepareContent();
+
   while (m_CurrentStage == Stage::kParse) {
     m_CurrentStage = Parse();
     if (pPause && pPause->NeedToPauseNow())
@@ -148,12 +150,40 @@ CPDF_ContentParser::Stage CPDF_ContentParser::GetContent() {
   m_StreamArray[m_CurrentOffset]->LoadAllDataFiltered();
   m_CurrentOffset++;
 
-  if (m_CurrentOffset >= m_nStreams) {
-    m_CurrentOffset = 0;
+  return m_CurrentOffset == m_nStreams ? Stage::kPrepareContent
+                                       : Stage::kGetContent;
+}
+
+CPDF_ContentParser::Stage CPDF_ContentParser::PrepareContent() {
+  m_CurrentOffset = 0;
+
+  if (m_StreamArray.empty()) {
+    m_pData.Reset(m_pSingleStream->GetData());
+    m_Size = m_pSingleStream->GetSize();
     return Stage::kParse;
   }
 
-  return Stage::kGetContent;
+  FX_SAFE_UINT32 safeSize = 0;
+  for (const auto& stream : m_StreamArray) {
+    safeSize += stream->GetSize();
+    safeSize += 1;
+  }
+  if (!safeSize.IsValid())
+    return Stage::kComplete;
+
+  m_Size = safeSize.ValueOrDie();
+  m_pData.Reset(
+      std::unique_ptr<uint8_t, FxFreeDeleter>(FX_Alloc(uint8_t, m_Size)));
+
+  uint32_t pos = 0;
+  for (const auto& stream : m_StreamArray) {
+    memcpy(m_pData.Get() + pos, stream->GetData(), stream->GetSize());
+    pos += stream->GetSize();
+    m_pData.Get()[pos++] = ' ';
+  }
+  m_StreamArray.clear();
+
+  return Stage::kParse;
 }
 
 CPDF_ContentParser::Stage CPDF_ContentParser::Parse() {
@@ -166,19 +196,12 @@ CPDF_ContentParser::Stage CPDF_ContentParser::Parse() {
         nullptr, m_parsedSet.get());
     m_pParser->GetCurStates()->m_ColorState.SetDefault();
   }
+  if (m_CurrentOffset >= m_Size)
+    return Stage::kCheckClip;
 
-  m_CurrentOffset += m_pParser->Parse(
-      m_StreamArray[m_CurrentStream]->GetData() + m_CurrentOffset,
-      m_StreamArray[m_CurrentStream]->GetSize() - m_CurrentOffset,
-      PARSE_STEP_LIMIT);
-
-  if (m_CurrentOffset >= m_StreamArray[m_CurrentStream]->GetSize()) {
-    m_CurrentOffset = 0;
-    ++m_CurrentStream;
-    if (m_CurrentStream >= m_nStreams)
-      return Stage::kCheckClip;
-  }
-
+  m_CurrentOffset +=
+      m_pParser->Parse(m_pData.Get() + m_CurrentOffset,
+                       m_Size - m_CurrentOffset, PARSE_STEP_LIMIT);
   return Stage::kParse;
 }
 
diff --git a/core/fpdfapi/page/cpdf_contentparser.h b/core/fpdfapi/page/cpdf_contentparser.h
index 92a3e06890..f9b491defa 100644
--- a/core/fpdfapi/page/cpdf_contentparser.h
+++ b/core/fpdfapi/page/cpdf_contentparser.h
@@ -42,22 +42,26 @@ class CPDF_ContentParser {
  private:
   enum class Stage : uint8_t {
     kGetContent = 1,
+    kPrepareContent,
     kParse,
     kCheckClip,
     kComplete,
   };
 
   Stage GetContent();
+  Stage PrepareContent();
   Stage Parse();
   Stage CheckClip();
 
   Stage m_CurrentStage;
   UnownedPtr<CPDF_PageObjectHolder> const m_pObjectHolder;
   UnownedPtr<CPDF_Type3Char> m_pType3Char;  // Only used when parsing forms.
+  RetainPtr<CPDF_StreamAcc> m_pSingleStream;
   std::vector<RetainPtr<CPDF_StreamAcc>> m_StreamArray;
+  MaybeOwned<uint8_t, FxFreeDeleter> m_pData;
   uint32_t m_nStreams = 0;
+  uint32_t m_Size = 0;
   uint32_t m_CurrentOffset = 0;
-  uint32_t m_CurrentStream = 0;
 
   // Only used when parsing pages.
   std::unique_ptr<std::set<const uint8_t*>> m_parsedSet;