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, 2 insertions, 1 deletions

diff --git a/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp b/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp
index 84064efb45..9028642b76 100644
--- a/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fm2jscontext.cpp
@@ -374,7 +374,8 @@ bool PatternStringType(const CFX_ByteStringC& szPattern,
     return true;
   }
   if (L"date" == wsPattern.Left(4)) {
-    patternType = wsPattern.Find(L"time") > 0 ? XFA_VT_DATETIME : XFA_VT_DATE;
+    FX_STRSIZE ret = wsPattern.Find(L"time");
+    patternType = ret != 0 && ret != FX_STRNPOS ? XFA_VT_DATETIME : XFA_VT_DATE;
     return true;
   }
   if (L"time" == wsPattern.Left(4)) {