Replace raw value for constant error value in string operations

Currently Find() and other methods that return a FX_STRSIZE return -1
to indicate error/failure. This means that there is a lot of magic
numbers and magic checks floating around. The standard library for
similar operations uses a npos constant. This CL implements
FX_STRNPOS, and replaces usages of magic number checking. It also does
some type cleanup along the way where it was obvious that FX_STRSIZE
should be being used.

Removing the magic numbers should make eventually changing FX_STRSIZE
to be unsigned easier in the future.

BUG=pdfium:828

Change-Id: I67e481e44cf2f75a1698afa8fbee4f375a74c490
Reviewed-on: https://pdfium-review.googlesource.com/9651
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/core/fxcrt/cfx_bytestring.cpp b/core/fxcrt/cfx_bytestring.cpp
index e7e55de8e3..6e01933682 100644
--- a/core/fxcrt/cfx_bytestring.cpp
+++ b/core/fxcrt/cfx_bytestring.cpp
@@ -562,41 +562,41 @@ CFX_ByteString CFX_ByteString::Left(FX_STRSIZE nCount) const {
 
 FX_STRSIZE CFX_ByteString::Find(char ch, FX_STRSIZE nStart) const {
   if (!m_pData)
-    return -1;
+    return FX_STRNPOS;
 
   if (nStart < 0 || nStart >= m_pData->m_nDataLength)
-    return -1;
+    return FX_STRNPOS;
 
   const char* pStr = static_cast<const char*>(
       memchr(m_pData->m_String + nStart, ch, m_pData->m_nDataLength - nStart));
-  return pStr ? pStr - m_pData->m_String : -1;
+  return pStr ? pStr - m_pData->m_String : FX_STRNPOS;
 }
 
 FX_STRSIZE CFX_ByteString::ReverseFind(char ch) const {
   if (!m_pData)
-    return -1;
+    return FX_STRNPOS;
 
   FX_STRSIZE nLength = m_pData->m_nDataLength;
   while (nLength--) {
     if (m_pData->m_String[nLength] == ch)
       return nLength;
   }
-  return -1;
+  return FX_STRNPOS;
 }
 
 FX_STRSIZE CFX_ByteString::Find(const CFX_ByteStringC& pSub,
                                 FX_STRSIZE nStart) const {
   if (!m_pData)
-    return -1;
+    return FX_STRNPOS;
 
   FX_STRSIZE nLength = m_pData->m_nDataLength;
   if (nStart > nLength)
-    return -1;
+    return FX_STRNPOS;
 
   const char* pStr =
       FX_strstr(m_pData->m_String + nStart, m_pData->m_nDataLength - nStart,
                 pSub.unterminated_c_str(), pSub.GetLength());
-  return pStr ? (int)(pStr - m_pData->m_String) : -1;
+  return pStr ? (int)(pStr - m_pData->m_String) : FX_STRNPOS;
 }
 
 void CFX_ByteString::MakeLower() {