Re-land "Return pdfium::span<char> from ByteString::GetBuffer().""

This reverts commit 3d523e3cf89440e2ffc6571b1c687ad5e3f0318f.
Fixes bounding errors now caught by tests.

Change-Id: I4d0f1791bdcc45a10615a62abf7a4d20e7e538f2
Reviewed-on: https://pdfium-review.googlesource.com/30799
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/core/fpdfapi/page/cpdf_image.cpp b/core/fpdfapi/page/cpdf_image.cpp
index 68a6a3243c..9ce4268a36 100644
--- a/core/fpdfapi/page/cpdf_image.cpp
+++ b/core/fpdfapi/page/cpdf_image.cpp
@@ -202,13 +202,16 @@ void CPDF_Image::SetImage(const RetainPtr<CFX_DIBitmap>& pBitmap) {
       pCS->AddNew<CPDF_Name>("DeviceRGB");
       pCS->AddNew<CPDF_Number>(1);
       ByteString ct;
-      char* pBuf = ct.GetBuffer(6);
-      pBuf[0] = (char)reset_r;
-      pBuf[1] = (char)reset_g;
-      pBuf[2] = (char)reset_b;
-      pBuf[3] = (char)set_r;
-      pBuf[4] = (char)set_g;
-      pBuf[5] = (char)set_b;
+      {
+        // Span's lifetime must end before ReleaseBuffer() below.
+        pdfium::span<char> pBuf = ct.GetBuffer(6);
+        pBuf[0] = (char)reset_r;
+        pBuf[1] = (char)reset_g;
+        pBuf[2] = (char)reset_b;
+        pBuf[3] = (char)set_r;
+        pBuf[4] = (char)set_g;
+        pBuf[5] = (char)set_b;
+      }
       ct.ReleaseBuffer(6);
       pCS->AddNew<CPDF_String>(ct, true);
     }