src: refactor buffer bounds checking

Consolidate buffer bounds checking logic into Buffer namespace and use
it consistently throughout the source.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/node_buffer.h b/src/node_buffer.h
index 7b7cf8e586..cb401b3b72 100644
--- a/src/node_buffer.h
+++ b/src/node_buffer.h
@@ -93,6 +93,20 @@ class NODE_EXTERN Buffer: public ObjectWrap {
     return Buffer::Length(b->handle_);
   }
 
+  // This is verbose to be explicit with inline commenting
+  static inline bool IsWithinBounds(size_t off, size_t len, size_t max) {
+    // Asking to seek too far into the buffer
+    // check to avoid wrapping in subsequent subtraction
+    if (off > max)
+      return false;
+
+    // Asking for more than is left over in the buffer
+    if (max - off < len)
+      return false;
+
+    // Otherwise we're in bounds
+    return true;
+  }
 
   ~Buffer();