Add IndexInBounds() convenience routine.

Avoid writing |Type| in CollectionSize<Type>() so that index
type can change without rewriting conditions.

Change-Id: I40c94ca39148b379908760ba9b861114b88af7bb
Reviewed-on: https://pdfium-review.googlesource.com/3056
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

4 files changed, 8 insertions, 13 deletions

diff --git a/core/fpdfapi/font/cpdf_font.cpp b/core/fpdfapi/font/cpdf_font.cpp
index 7988ec7124..f0b5ac16b7 100644
--- a/core/fpdfapi/font/cpdf_font.cpp
+++ b/core/fpdfapi/font/cpdf_font.cpp
@@ -458,10 +458,9 @@ uint32_t CPDF_Font::FallbackFontFromCharcode(uint32_t charcode) {
 }
 
 int CPDF_Font::FallbackGlyphFromCharcode(int fallbackFont, uint32_t charcode) {
-  if (fallbackFont < 0 ||
-      fallbackFont >= pdfium::CollectionSize<int>(m_FontFallbacks)) {
+  if (!pdfium::IndexInBounds(m_FontFallbacks, fallbackFont))
     return -1;
-  }
+
   int glyph =
       FXFT_Get_Char_Index(m_FontFallbacks[fallbackFont]->GetFace(), charcode);
   if (glyph == 0 || glyph == 0xffff)
diff --git a/core/fpdfapi/font/ttgsubtable.cpp b/core/fpdfapi/font/ttgsubtable.cpp
index 946ccd7abe..4fae5d41d2 100644
--- a/core/fpdfapi/font/ttgsubtable.cpp
+++ b/core/fpdfapi/font/ttgsubtable.cpp
@@ -127,9 +127,8 @@ bool CFX_CTTGSUBTable::GetVerticalGlyphSub(uint32_t glyphnum,
                                            uint32_t* vglyphnum,
                                            TFeature* Feature) {
   for (int index : Feature->LookupListIndices) {
-    if (index < 0 || index >= pdfium::CollectionSize<int>(LookupList.Lookups))
+    if (!pdfium::IndexInBounds(LookupList.Lookups, index))
       continue;
-
     if (LookupList.Lookups[index].LookupType == 1 &&
         GetVerticalGlyphSub2(glyphnum, vglyphnum, &LookupList.Lookups[index])) {
       return true;
@@ -154,8 +153,7 @@ bool CFX_CTTGSUBTable::GetVerticalGlyphSub2(uint32_t glyphnum,
       case 2: {
         auto* tbl2 = static_cast<TSingleSubstFormat2*>(subTable.get());
         int index = GetCoverageIndex(tbl2->Coverage.get(), glyphnum);
-        if (index >= 0 &&
-            index < pdfium::CollectionSize<int>(tbl2->Substitutes)) {
+        if (pdfium::IndexInBounds(tbl2->Substitutes, index)) {
           *vglyphnum = tbl2->Substitutes[index];
           return true;
         }
diff --git a/core/fpdfapi/page/cpdf_pageobjectlist.cpp b/core/fpdfapi/page/cpdf_pageobjectlist.cpp
index 02b590e413..5c30fe9877 100644
--- a/core/fpdfapi/page/cpdf_pageobjectlist.cpp
+++ b/core/fpdfapi/page/cpdf_pageobjectlist.cpp
@@ -10,7 +10,5 @@
 #include "third_party/base/stl_util.h"
 
 CPDF_PageObject* CPDF_PageObjectList::GetPageObjectByIndex(int index) {
-  if (index < 0 || index >= pdfium::CollectionSize<int>(*this))
-    return nullptr;
-  return (*this)[index].get();
+  return pdfium::IndexInBounds(*this, index) ? (*this)[index].get() : nullptr;
 }
diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index ed88a4f82a..8ff9e66506 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -477,10 +477,10 @@ bool CPDF_Document::IsPageLoaded(int iPage) const {
 }
 
 CPDF_Dictionary* CPDF_Document::GetPage(int iPage) {
-  if (iPage < 0 || iPage >= pdfium::CollectionSize<int>(m_PageList))
+  if (!pdfium::IndexInBounds(m_PageList, iPage))
     return nullptr;
 
-  if (m_bLinearized && (iPage == m_iFirstPageNo)) {
+  if (m_bLinearized && iPage == m_iFirstPageNo) {
     if (CPDF_Dictionary* pDict =
             ToDictionary(GetOrParseIndirectObject(m_dwFirstPageObjNum))) {
       return pDict;
@@ -586,7 +586,7 @@ int CPDF_Document::GetPageIndex(uint32_t objnum) {
   int found_index = FindPageIndex(pPages, &skip_count, objnum, &start_index);
 
   // Corrupt page tree may yield out-of-range results.
-  if (found_index < 0 || found_index >= pdfium::CollectionSize<int>(m_PageList))
+  if (!pdfium::IndexInBounds(m_PageList, found_index))
     return -1;
 
   m_PageList[found_index] = objnum;