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>

2 files changed, 4 insertions, 7 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;
         }