must check for zero-length in reader32::read() before calling memcpy

memcpy's behavior is undefined if the dst-ptr is null, but reader32 supports
null as long as the size is 0, so it needs to check explicitly before
calling memcpy. This is implemented (now) by calling sk_careful_memcpy.

BUG=skia:

Change-Id: I7033cc5e6d724f50f0aafd9808e297b953848aa7
Reviewed-on: https://skia-review.googlesource.com/9729
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/core/SkReader32.h b/src/core/SkReader32.h
index 7e31fb9e23..1f027f71bb 100644
--- a/src/core/SkReader32.h
+++ b/src/core/SkReader32.h
@@ -96,7 +96,7 @@ public:
     void read(void* dst, size_t size) {
         SkASSERT(0 == size || dst != nullptr);
         SkASSERT(ptr_align_4(fCurr));
-        memcpy(dst, fCurr, size);
+        sk_careful_memcpy(dst, fCurr, size);
         fCurr += SkAlign4(size);
         SkASSERT(fCurr <= fStop);
     }