Remove potential out of bounds call to GetAt()

Since m_pos is passed into GetAt() on the underlying string in
getCurrentChar(), the value of it needs to confirmed to be valid after
decrementing. Some types were changed to reflect the values being
stored.

BUG=chromium:752480

Change-Id: Ib6d6f52326defd31785e70a17049a08b64dbe069
Reviewed-on: https://pdfium-review.googlesource.com/10652
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/fxbarcode/datamatrix/BC_EncoderContext.cpp b/fxbarcode/datamatrix/BC_EncoderContext.cpp
index 40855fcbd8..404c07d980 100644
--- a/fxbarcode/datamatrix/BC_EncoderContext.cpp
+++ b/fxbarcode/datamatrix/BC_EncoderContext.cpp
@@ -34,9 +34,9 @@ CBC_EncoderContext::CBC_EncoderContext(const CFX_WideString& msg,
   CFX_ByteString dststr;
   CBC_UtilCodingConvert::UnicodeToUTF8(msg, dststr);
   CFX_WideString sb;
-  int32_t c = dststr.GetLength();
-  for (int32_t i = 0; i < c; i++) {
-    wchar_t ch = (wchar_t)(dststr.GetAt(i) & 0xff);
+  FX_STRSIZE c = dststr.GetLength();
+  for (FX_STRSIZE i = 0; i < c; i++) {
+    wchar_t ch = static_cast<wchar_t>(dststr.GetAt(i) & 0xff);
     if (ch == '?' && dststr.GetAt(i) != '?') {
       e = BCExceptionCharactersOutsideISO88591Encoding;
     }
@@ -73,7 +73,7 @@ void CBC_EncoderContext::writeCodewords(const CFX_WideString& codewords) {
 void CBC_EncoderContext::writeCodeword(wchar_t codeword) {
   m_codewords += codeword;
 }
-int32_t CBC_EncoderContext::getCodewordCount() {
+FX_STRSIZE CBC_EncoderContext::getCodewordCount() {
   return m_codewords.GetLength();
 }
 void CBC_EncoderContext::signalEncoderChange(int32_t encoding) {
@@ -85,7 +85,7 @@ void CBC_EncoderContext::resetEncoderSignal() {
 bool CBC_EncoderContext::hasMoreCharacters() {
   return m_pos < getTotalMessageCharCount();
 }
-int32_t CBC_EncoderContext::getRemainingCharacters() {
+FX_STRSIZE CBC_EncoderContext::getRemainingCharacters() {
   return getTotalMessageCharCount() - m_pos;
 }
 void CBC_EncoderContext::updateSymbolInfo(int32_t& e) {
@@ -103,6 +103,6 @@ void CBC_EncoderContext::resetSymbolInfo() {
   m_allowRectangular = true;
 }
 
-int32_t CBC_EncoderContext::getTotalMessageCharCount() {
+FX_STRSIZE CBC_EncoderContext::getTotalMessageCharCount() {
   return m_msg.GetLength() - m_skipAtEnd;
 }