Remove unused codepage from WideString::GetWideString().

Consolidate code into sole caller, which always retrieves a string
from the "default ANSI code page". Add unit test for this code path.
Fix sign extension bug giving bogus 0xffffff80 codepoint uncovered
by unit test on non-windows. Note windows result is different because
the system conversion routine does actually work.

Change-Id: I1c1246b203ee66e9ff0b6fccf97594788bcd0fca
Reviewed-on: https://pdfium-review.googlesource.com/39730
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 15 insertions, 44 deletions

diff --git a/core/fxcrt/widestring.cpp b/core/fxcrt/widestring.cpp
index 7dd1c30eb0..97073f170d 100644
--- a/core/fxcrt/widestring.cpp
+++ b/core/fxcrt/widestring.cpp
@@ -277,43 +277,6 @@ Optional<WideString> TryVSWPrintf(size_t size,
   return {str};
 }
 
-#ifndef NDEBUG
-bool IsValidWideCodePage(uint16_t codepage) {
-  switch (codepage) {
-    case FX_CODEPAGE_DefANSI:
-    case FX_CODEPAGE_ShiftJIS:
-    case FX_CODEPAGE_ChineseSimplified:
-    case FX_CODEPAGE_Hangul:
-    case FX_CODEPAGE_ChineseTraditional:
-      return true;
-    default:
-      return false;
-  }
-}
-#endif
-
-WideString GetWideString(uint16_t codepage, const ByteStringView& bstr) {
-#ifndef NDEBUG
-  ASSERT(IsValidWideCodePage(codepage));
-#endif
-
-  int src_len = bstr.GetLength();
-  int dest_len = FXSYS_MultiByteToWideChar(
-      codepage, 0, bstr.unterminated_c_str(), src_len, nullptr, 0);
-  if (!dest_len)
-    return WideString();
-
-  WideString wstr;
-  {
-    // Span's lifetime must end before ReleaseBuffer() below.
-    pdfium::span<wchar_t> dest_buf = wstr.GetBuffer(dest_len);
-    FXSYS_MultiByteToWideChar(codepage, 0, bstr.unterminated_c_str(), src_len,
-                              dest_buf.data(), dest_len);
-  }
-  wstr.ReleaseBuffer(dest_len);
-  return wstr;
-}
-
 }  // namespace
 
 namespace fxcrt {
@@ -902,14 +865,22 @@ size_t WideString::Replace(const WideStringView& pOld,
 }
 
 // static
-WideString WideString::FromLocal(const ByteStringView& str) {
-  return FromCodePage(str, 0);
-}
+WideString WideString::FromLocal(const ByteStringView& bstr) {
+  int src_len = bstr.GetLength();
+  int dest_len = FXSYS_MultiByteToWideChar(
+      FX_CODEPAGE_DefANSI, 0, bstr.unterminated_c_str(), src_len, nullptr, 0);
+  if (!dest_len)
+    return WideString();
 
-// static
-WideString WideString::FromCodePage(const ByteStringView& str,
-                                    uint16_t codepage) {
-  return GetWideString(codepage, str);
+  WideString wstr;
+  {
+    // Span's lifetime must end before ReleaseBuffer() below.
+    pdfium::span<wchar_t> dest_buf = wstr.GetBuffer(dest_len);
+    FXSYS_MultiByteToWideChar(FX_CODEPAGE_DefANSI, 0, bstr.unterminated_c_str(),
+                              src_len, dest_buf.data(), dest_len);
+  }
+  wstr.ReleaseBuffer(dest_len);
+  return wstr;
 }
 
 // static