Return pdfium::span<char> from ByteString::GetBuffer().

Get bounds checking "for free".

Change-Id: I7b14cacbc7130ced7b5cb1869b82c96ccff8e642
Reviewed-on: https://pdfium-review.googlesource.com/30451
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 12 insertions, 9 deletions

diff --git a/core/fxcrt/widestring.cpp b/core/fxcrt/widestring.cpp
index a3525593ee..25f253ea11 100644
--- a/core/fxcrt/widestring.cpp
+++ b/core/fxcrt/widestring.cpp
@@ -667,18 +667,21 @@ ByteString WideString::UTF8Encode() const {
 }
 
 ByteString WideString::UTF16LE_Encode() const {
-  if (!m_pData) {
+  if (!m_pData)
     return ByteString("\0\0", 2);
-  }
-  int len = m_pData->m_nDataLength;
+
   ByteString result;
-  char* buffer = result.GetBuffer(len * 2 + 2);
-  for (int i = 0; i < len; i++) {
-    buffer[i * 2] = m_pData->m_String[i] & 0xff;
-    buffer[i * 2 + 1] = m_pData->m_String[i] >> 8;
+  int len = m_pData->m_nDataLength;
+  {
+    // Span's lifetime must end before ReleaseBuffer() below.
+    pdfium::span<char> buffer = result.GetBuffer(len * 2 + 2);
+    for (int i = 0; i < len; i++) {
+      buffer[i * 2] = m_pData->m_String[i] & 0xff;
+      buffer[i * 2 + 1] = m_pData->m_String[i] >> 8;
+    }
+    buffer[len * 2] = 0;
+    buffer[len * 2 + 1] = 0;
   }
-  buffer[len * 2] = 0;
-  buffer[len * 2 + 1] = 0;
   result.ReleaseBuffer(len * 2 + 2);
   return result;
 }