common/buffer: align parameter type in interface & implementation

Signed-off-by: Changcheng Liu <changcheng.liu@aliyun.com>

diff --git a/src/include/buffer.h b/src/include/buffer.h
index a895e1c967ab3bea2b118db969efebe0b9a4de95..91caab2accb29934a7c4282e2a7141ce0d945773 100644 (file)
--- a/src/include/buffer.h
+++ b/src/include/buffer.h
@@ -1132,7 +1132,7 @@ struct error_code;
     void append_zero(unsigned len);
     void prepend_zero(unsigned len);
 
-    reserve_t obtain_contiguous_space(unsigned len);
+    reserve_t obtain_contiguous_space(const unsigned len);
 
     /*
      * get a char