Convert FX_STRSIZE int->size_t

Change the underlying type for FX_STRSIZE to size_t from int. This
will make the value unsigned and thus all values in the range of the
type will be valid. This allows for the final remove of negative
length strings, but also introduces a some casting and functional 
errors, since many parts of the code base assume that FX_STRSIZE is 
int or another signed type. This also CL fixes these errors.

BUG=pdfium:828

Change-Id: I231dca59e96fc9330cbb099eecbdfc41fcf86f5b
Reviewed-on: https://pdfium-review.googlesource.com/11830
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

3 files changed, 19 insertions, 13 deletions

diff --git a/fxbarcode/datamatrix/BC_ErrorCorrection.cpp b/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
index 2e84df5c59..c45eadcf9a 100644
--- a/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
+++ b/fxbarcode/datamatrix/BC_ErrorCorrection.cpp
@@ -122,7 +122,8 @@ CBC_ErrorCorrection::~CBC_ErrorCorrection() {}
 CFX_WideString CBC_ErrorCorrection::encodeECC200(CFX_WideString codewords,
                                                  CBC_SymbolInfo* symbolInfo,
                                                  int32_t& e) {
-  if (codewords.GetLength() != symbolInfo->dataCapacity()) {
+  if (pdfium::base::checked_cast<int32_t>(codewords.GetLength()) !=
+      symbolInfo->dataCapacity()) {
     e = BCExceptionIllegalArgument;
     return CFX_WideString();
   }
diff --git a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
index d2f40dd060..b8c63946db 100644
--- a/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
+++ b/fxbarcode/datamatrix/BC_HighLevelEncoder.cpp
@@ -118,18 +118,20 @@ CFX_WideString CBC_HighLevelEncoder::encodeHighLevel(CFX_WideString msg,
     }
   }
   CFX_WideString codewords = context.m_codewords;
-  if (codewords.GetLength() < capacity) {
+  if (pdfium::base::checked_cast<int32_t>(codewords.GetLength()) < capacity) {
     codewords += PAD;
   }
-  while (codewords.GetLength() < capacity) {
-    codewords += (randomize253State(PAD, codewords.GetLength() + 1));
+  while (pdfium::base::checked_cast<int32_t>(codewords.GetLength()) <
+         capacity) {
+    codewords += (randomize253State(
+        PAD, pdfium::base::checked_cast<int32_t>(codewords.GetLength()) + 1));
   }
   return codewords;
 }
 int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
                                             int32_t startpos,
                                             int32_t currentMode) {
-  if (startpos >= msg.GetLength()) {
+  if (startpos >= pdfium::base::checked_cast<int32_t>(msg.GetLength())) {
     return currentMode;
   }
   std::vector<float> charCounts;
@@ -151,7 +153,8 @@ int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
   }
   int32_t charsProcessed = 0;
   while (true) {
-    if ((startpos + charsProcessed) == msg.GetLength()) {
+    if ((startpos + charsProcessed) ==
+        pdfium::base::checked_cast<int32_t>(msg.GetLength())) {
       int32_t min = std::numeric_limits<int32_t>::max();
       std::vector<uint8_t> mins(6);
       std::vector<int32_t> intCharCounts(6);
@@ -252,7 +255,9 @@ int32_t CBC_HighLevelEncoder::lookAheadTest(CFX_WideString msg,
         }
         if (intCharCounts[C40_ENCODATION] == intCharCounts[X12_ENCODATION]) {
           int32_t p = startpos + charsProcessed + 1;
-          while (p < msg.GetLength()) {
+          int32_t checked_length =
+              pdfium::base::checked_cast<int32_t>(msg.GetLength());
+          while (p < checked_length) {
             wchar_t tc = msg[p];
             if (isX12TermSep(tc)) {
               return X12_ENCODATION;
diff --git a/fxbarcode/qrcode/BC_QRCoderEncoder.cpp b/fxbarcode/qrcode/BC_QRCoderEncoder.cpp
index 911730fbe5..4c488418d9 100644
--- a/fxbarcode/qrcode/BC_QRCoderEncoder.cpp
+++ b/fxbarcode/qrcode/BC_QRCoderEncoder.cpp
@@ -380,8 +380,8 @@ void MergeString(std::vector<ModeStringPair>* result,
                                      CBC_QRCoderMode::sBYTE, versionNum, e);
       if (e != BCExceptionNO)
         return;
-      if (element2.first == CBC_QRCoderMode::sBYTE &&
-          element1.second.GetLength() < tmp) {
+      if (element2.first == CBC_QRCoderMode::sBYTE && tmp >= 0 &&
+          element1.second.GetLength() < static_cast<FX_STRSIZE>(tmp)) {
         element2.second = element1.second + element2.second;
         result->erase(result->begin() + i);
         i--;
@@ -399,8 +399,8 @@ void MergeString(std::vector<ModeStringPair>* result,
                                      CBC_QRCoderMode::sBYTE, versionNum, e);
       if (e != BCExceptionNO)
         return;
-      if (element2.first == CBC_QRCoderMode::sBYTE &&
-          element1.second.GetLength() < tmp) {
+      if (element2.first == CBC_QRCoderMode::sBYTE && tmp >= 0 &&
+          element1.second.GetLength() < static_cast<FX_STRSIZE>(tmp)) {
         element2.second = element1.second + element2.second;
         result->erase(result->begin() + i);
         i--;
@@ -410,8 +410,8 @@ void MergeString(std::vector<ModeStringPair>* result,
                              CBC_QRCoderMode::sALPHANUMERIC, versionNum, e);
       if (e != BCExceptionNO)
         return;
-      if (element2.first == CBC_QRCoderMode::sALPHANUMERIC &&
-          element1.second.GetLength() < tmp) {
+      if (element2.first == CBC_QRCoderMode::sALPHANUMERIC && tmp >= 0 &&
+          element1.second.GetLength() < static_cast<FX_STRSIZE>(tmp)) {
         element2.second = element1.second + element2.second;
         result->erase(result->begin() + i);
         i--;