Return pdfium::span<wchar_t> from WideString::GetBuffer().

Adds bounds checking "for free", but beware of span outliving
a ReleaseBuffer() call.  Scoping as such avoids the possibility
of using an invalid span (and it is flagged as a lifetime issue).

Change-Id: Ica63f4b1429823d0254ec6951aeaeb08160cb93c
Reviewed-on: https://pdfium-review.googlesource.com/30310
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 11 insertions, 10 deletions

diff --git a/core/fxcrt/widestring_unittest.cpp b/core/fxcrt/widestring_unittest.cpp
index 473d59c491..ad91249c8e 100644
--- a/core/fxcrt/widestring_unittest.cpp
+++ b/core/fxcrt/widestring_unittest.cpp
@@ -813,20 +813,21 @@ TEST(WideString, Reserve) {
 }
 
 TEST(WideString, GetBuffer) {
+  WideString str1;
   {
-    WideString str;
-    wchar_t* buffer = str.GetBuffer(12);
-    wcscpy(buffer, L"clams");
-    str.ReleaseBuffer(str.GetStringLength());
-    EXPECT_EQ(L"clams", str);
+    pdfium::span<wchar_t> buffer = str1.GetBuffer(12);
+    wcscpy(buffer.data(), L"clams");
   }
+  str1.ReleaseBuffer(str1.GetStringLength());
+  EXPECT_EQ(L"clams", str1);
+
+  WideString str2(L"cl");
   {
-    WideString str(L"cl");
-    wchar_t* buffer = str.GetBuffer(12);
-    wcscpy(buffer + 2, L"ams");
-    str.ReleaseBuffer(str.GetStringLength());
-    EXPECT_EQ(L"clams", str);
+    pdfium::span<wchar_t> buffer = str2.GetBuffer(12);
+    wcscpy(buffer.data() + 2, L"ams");
   }
+  str2.ReleaseBuffer(str2.GetStringLength());
+  EXPECT_EQ(L"clams", str2);
 }
 
 TEST(WideString, ReleaseBuffer) {