From 51a41ea222eeb852be4f372165d2d9bc9094b2a4 Mon Sep 17 00:00:00 2001
From: Tom Sepez <tsepez@chromium.org>
Date: Tue, 17 Apr 2018 23:46:18 +0000
Subject: Use span<> in GetBits32().

Get bounds checking "for free".

Change-Id: Ic60d63836f6c223e2ee1262649d47da54bb30ecc
Reviewed-on: https://pdfium-review.googlesource.com/30876
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
---
 core/fpdfapi/page/cpdf_sampledfunc.cpp |  4 ++--
 core/fxcrt/fx_extension.cpp            | 12 ++++++------
 core/fxcrt/fx_extension.h              |  4 ++--
 core/fxge/skia/fx_skia_device.cpp      |  2 +-
 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/core/fpdfapi/page/cpdf_sampledfunc.cpp b/core/fpdfapi/page/cpdf_sampledfunc.cpp
index 205ce91eaa..cdedc862bb 100644
--- a/core/fpdfapi/page/cpdf_sampledfunc.cpp
+++ b/core/fpdfapi/page/cpdf_sampledfunc.cpp
@@ -125,8 +125,8 @@ bool CPDF_SampledFunc::v_Call(const float* inputs, float* results) const {
   if (!range_check.IsValid())
     return false;
 
-  const uint8_t* pSampleData = m_pSampleStream->GetData();
-  if (!pSampleData)
+  pdfium::span<const uint8_t> pSampleData = m_pSampleStream->GetSpan();
+  if (pSampleData.empty())
     return false;
 
   for (uint32_t j = 0; j < m_nOutputs; j++, bitpos += m_nBitsPerSample) {
diff --git a/core/fxcrt/fx_extension.cpp b/core/fxcrt/fx_extension.cpp
index 4448a71a9b..83aee86316 100644
--- a/core/fxcrt/fx_extension.cpp
+++ b/core/fxcrt/fx_extension.cpp
@@ -125,9 +125,9 @@ size_t FXSYS_ToUTF16BE(uint32_t unicode, char* buf) {
   return 8;
 }
 
-uint32_t GetBits32(const uint8_t* pData, int bitpos, int nbits) {
+uint32_t GetBits32(pdfium::span<const uint8_t> pData, int bitpos, int nbits) {
   ASSERT(0 < nbits && nbits <= 32);
-  const uint8_t* dataPtr = &pData[bitpos / 8];
+  size_t bytepos = bitpos / 8;
   int bitShift;
   int bitMask;
   int dstShift;
@@ -142,16 +142,16 @@ uint32_t GetBits32(const uint8_t* pData, int bitpos, int nbits) {
     bitMask = (1 << std::min(bitOffset, nbits)) - 1;
     dstShift = nbits - bitOffset;
   }
-  uint32_t result =
-      static_cast<uint32_t>((*dataPtr++ >> bitShift & bitMask) << dstShift);
+  uint32_t result = static_cast<uint32_t>(
+      (pData[bytepos++] >> bitShift & bitMask) << dstShift);
   while (dstShift >= 8) {
     dstShift -= 8;
-    result |= *dataPtr++ << dstShift;
+    result |= pData[bytepos++] << dstShift;
   }
   if (dstShift > 0) {
     bitShift = 8 - dstShift;
     bitMask = (1 << dstShift) - 1;
-    result |= *dataPtr++ >> bitShift & bitMask;
+    result |= pData[bytepos++] >> bitShift & bitMask;
   }
   return result;
 }
diff --git a/core/fxcrt/fx_extension.h b/core/fxcrt/fx_extension.h
index 0f249f89c8..ff96de0f7c 100644
--- a/core/fxcrt/fx_extension.h
+++ b/core/fxcrt/fx_extension.h
@@ -12,6 +12,7 @@
 #include <memory>
 
 #include "core/fxcrt/fx_string.h"
+#include "third_party/base/span.h"
 #include "third_party/icu/source/common/unicode/uchar.h"
 
 #define FX_INVALID_OFFSET static_cast<uint32_t>(-1)
@@ -82,11 +83,10 @@ inline int FXSYS_DecimalCharToInt(const wchar_t c) {
 }
 
 void FXSYS_IntToTwoHexChars(uint8_t c, char* buf);
-
 void FXSYS_IntToFourHexChars(uint16_t c, char* buf);
 
 size_t FXSYS_ToUTF16BE(uint32_t unicode, char* buf);
 
-uint32_t GetBits32(const uint8_t* pData, int bitpos, int nbits);
+uint32_t GetBits32(pdfium::span<const uint8_t> pData, int bitpos, int nbits);
 
 #endif  // CORE_FXCRT_FX_EXTENSION_H_
diff --git a/core/fxge/skia/fx_skia_device.cpp b/core/fxge/skia/fx_skia_device.cpp
index 598dc480c2..6dd19eaed9 100644
--- a/core/fxge/skia/fx_skia_device.cpp
+++ b/core/fxge/skia/fx_skia_device.cpp
@@ -406,7 +406,7 @@ bool AddSamples(const CPDF_SampledFunc* pFunc,
     colorsMin[i] = pFunc->GetRange(i * 2);
     colorsMax[i] = pFunc->GetRange(i * 2 + 1);
   }
-  const uint8_t* pSampleData = pFunc->GetSampleStream()->GetData();
+  pdfium::span<const uint8_t> pSampleData = pFunc->GetSampleStream()->GetSpan();
   for (uint32_t i = 0; i < sampleCount; ++i) {
     float floatColors[3];
     for (uint32_t j = 0; j < 3; ++j) {
-- 
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