Remove single param Mid() method from string classes

This support is being removed from CFX_ByteString, CFX_ByteStringC,
CFX_WideString, and CFX_WideStringC. This standardizes all of these
classes to only have one Mid method that takes in 2 params, offset and
count. Count now must be positive. The old behaviour of calculating
the length for the user if -1 is passed in for the count has been
removed. This work is in preperation for converting these classes to
not accept negative lengths anywhere and thus make the underlying size
type unsigned.

BUG=pdfium:828

Change-Id: I5f15e7b7b00b264231817f143e2da88ee6f69e7b
Reviewed-on: https://pdfium-review.googlesource.com/9430
Reviewed-by: (OOO Jul 28 - Aug 8) dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

4 files changed, 15 insertions, 10 deletions

diff --git a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
index a3f4ce9519..e3565835c3 100644
--- a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
@@ -162,7 +162,7 @@ CXFA_Node* ResolveBreakTarget(CXFA_Node* pPageSetRoot,
     if (wsExpr.GetAt(0) == '#') {
       CXFA_Node* pNode = pDocument->GetNodeByID(
           ToNode(pDocument->GetXFAObject(XFA_HASHCODE_Template)),
-          wsExpr.Mid(1).AsStringC());
+          wsExpr.Mid(1, wsExpr.GetLength() - 1).AsStringC());
       if (pNode)
         return pNode;
     } else if (bNewExprStyle) {
diff --git a/xfa/fxfa/parser/cxfa_measurement.cpp b/xfa/fxfa/parser/cxfa_measurement.cpp
index f161e49e49..50076583bb 100644
--- a/xfa/fxfa/parser/cxfa_measurement.cpp
+++ b/xfa/fxfa/parser/cxfa_measurement.cpp
@@ -40,7 +40,8 @@ void CXFA_Measurement::SetString(const CFX_WideStringC& wsMeasure) {
   int32_t iOffset = (wsMeasure.GetAt(0) == L'=') ? 1 : 0;
   float fValue = FXSYS_wcstof(wsMeasure.unterminated_c_str() + iOffset,
                               wsMeasure.GetLength() - iOffset, &iUsedLen);
-  XFA_UNIT eUnit = GetUnitFromString(wsMeasure.Mid(iOffset + iUsedLen));
+  XFA_UNIT eUnit = GetUnitFromString(wsMeasure.Mid(
+      iOffset + iUsedLen, wsMeasure.GetLength() - (iOffset + iUsedLen)));
   Set(fValue, eUnit);
 }
 
diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index eac7ac04b0..1265988902 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -77,7 +77,7 @@ int32_t GetCount(CXFA_Node* pInstMgrNode) {
       CFX_WideStringC wsName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       CFX_WideStringC wsInstName = pInstMgrNode->GetCData(XFA_ATTRIBUTE_Name);
       if (wsInstName.GetLength() < 1 || wsInstName.GetAt(0) != '_' ||
-          wsInstName.Mid(1) != wsName) {
+          wsInstName.Mid(1, wsInstName.GetLength() - 1) != wsName) {
         return iCount;
       }
       dwNameHash = pNode->GetNameHash();
@@ -198,7 +198,7 @@ CXFA_Node* GetItem(CXFA_Node* pInstMgrNode, int32_t iIndex) {
       CFX_WideStringC wsName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       CFX_WideStringC wsInstName = pInstMgrNode->GetCData(XFA_ATTRIBUTE_Name);
       if (wsInstName.GetLength() < 1 || wsInstName.GetAt(0) != '_' ||
-          wsInstName.Mid(1) != wsName) {
+          wsInstName.Mid(1, wsInstName.GetLength() - 1) != wsName) {
         return nullptr;
       }
       dwNameHash = pNode->GetNameHash();
@@ -2737,7 +2737,7 @@ void CXFA_Node::Script_Subform_InstanceManager(CFXJSE_Value* pValue,
     if (pNode->GetElementType() == XFA_Element::InstanceManager) {
       CFX_WideStringC wsInstMgrName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       if (wsInstMgrName.GetLength() >= 1 && wsInstMgrName.GetAt(0) == '_' &&
-          wsInstMgrName.Mid(1) == wsName) {
+          wsInstMgrName.Mid(1, wsInstMgrName.GetLength() - 1) == wsName) {
         pInstanceMgr = pNode;
       }
       break;
@@ -3162,9 +3162,10 @@ int32_t CXFA_Node::InstanceManager_SetInstances(int32_t iDesired) {
   }
   if (iDesired < iCount) {
     CFX_WideStringC wsInstManagerName = GetCData(XFA_ATTRIBUTE_Name);
-    CFX_WideString wsInstanceName =
-        CFX_WideString(wsInstManagerName.IsEmpty() ? wsInstManagerName
-                                                   : wsInstManagerName.Mid(1));
+    CFX_WideString wsInstanceName = CFX_WideString(
+        wsInstManagerName.IsEmpty()
+            ? wsInstManagerName
+            : wsInstManagerName.Mid(1, wsInstManagerName.GetLength() - 1));
     uint32_t dInstanceNameHash =
         FX_HashCode_GetW(wsInstanceName.AsStringC(), false);
     CXFA_Node* pPrevSibling =
@@ -4664,7 +4665,7 @@ CXFA_Node* CXFA_Node::GetInstanceMgrOfSubform() {
         CFX_WideStringC wsName = GetCData(XFA_ATTRIBUTE_Name);
         CFX_WideStringC wsInstName = pNode->GetCData(XFA_ATTRIBUTE_Name);
         if (wsInstName.GetLength() > 0 && wsInstName.GetAt(0) == '_' &&
-            wsInstName.Mid(1) == wsName) {
+            wsInstName.Mid(1, wsInstName.GetLength() - 1) == wsName) {
           pInstanceMgr = pNode;
         }
         break;
diff --git a/xfa/fxfa/parser/cxfa_widgetdata.cpp b/xfa/fxfa/parser/cxfa_widgetdata.cpp
index cbe0d14c91..1920e9f3fd 100644
--- a/xfa/fxfa/parser/cxfa_widgetdata.cpp
+++ b/xfa/fxfa/parser/cxfa_widgetdata.cpp
@@ -1323,7 +1323,10 @@ bool CXFA_WidgetData::GetBarcodeAttribute_WideNarrowRatio(float* val) {
     } else {
       int32_t fA, fB;
       fA = FXSYS_wtoi(wsWideNarrowRatio.Left(ptPos).c_str());
-      fB = FXSYS_wtoi(wsWideNarrowRatio.Mid(ptPos + 1).c_str());
+      fB = FXSYS_wtoi(
+          wsWideNarrowRatio
+              .Mid(ptPos + 1, wsWideNarrowRatio.GetLength() - (ptPos + 1))
+              .c_str());
       if (fB)
         fRatio = (float)fA / fB;
     }