Fix crash in CFDE_CSSSyntaxParser when parsing empty url

When parsing "url('')", Subtract() should be called to correctly set
m_iDatLen. But iLength will be 0 because there is no url. So I changed
the ASSERT. Also replaced some non-const refs with pointers to make the
code more readable.

BUG=659509

Review-Url: https://codereview.chromium.org/2535663003

1 files changed, 10 insertions, 8 deletions

diff --git a/xfa/fde/css/fde_cssdeclaration.cpp b/xfa/fde/css/fde_cssdeclaration.cpp
index 2196d6bd91..f6af900042 100644
--- a/xfa/fde/css/fde_cssdeclaration.cpp
+++ b/xfa/fde/css/fde_cssdeclaration.cpp
@@ -301,33 +301,35 @@ IFDE_CSSValue* CFDE_CSSDeclaration::ParseColor(const FDE_CSSPROPERTYARGS* pArgs,
   }
   return FXTARGET_NewWith(pArgs->pStaticStore) CFDE_CSSPrimitiveValue(dwColor);
 }
+
 IFDE_CSSValue* CFDE_CSSDeclaration::ParseURI(const FDE_CSSPROPERTYARGS* pArgs,
                                              const FX_WCHAR* pszValue,
                                              int32_t iValueLen) {
   int32_t iOffset;
-  if (!FDE_ParseCSSURI(pszValue, iValueLen, iOffset, iValueLen)) {
+  if (!FDE_ParseCSSURI(pszValue, &iOffset, &iValueLen))
     return nullptr;
-  }
-  if (iValueLen <= 0) {
+
+  if (iValueLen <= 0)
     return nullptr;
-  }
+
   pszValue = CopyToLocal(pArgs, pszValue + iOffset, iValueLen);
   return pszValue
              ? FXTARGET_NewWith(pArgs->pStaticStore)
                    CFDE_CSSPrimitiveValue(FDE_CSSPRIMITIVETYPE_URI, pszValue)
              : nullptr;
 }
+
 IFDE_CSSValue* CFDE_CSSDeclaration::ParseString(
     const FDE_CSSPROPERTYARGS* pArgs,
     const FX_WCHAR* pszValue,
     int32_t iValueLen) {
   int32_t iOffset;
-  if (!FDE_ParseCSSString(pszValue, iValueLen, iOffset, iValueLen)) {
+  if (!FDE_ParseCSSString(pszValue, iValueLen, &iOffset, &iValueLen))
     return nullptr;
-  }
-  if (iValueLen <= 0) {
+
+  if (iValueLen <= 0)
     return nullptr;
-  }
+
   pszValue = CopyToLocal(pArgs, pszValue + iOffset, iValueLen);
   return pszValue
              ? FXTARGET_NewWith(pArgs->pStaticStore)