INTERNAL: Refactor the memcached_io_read function

libmemcached/io.cc

@@ -538,8 +538,12 @@ memcached_return_t memcached_io_read(memcached_server_write_instance_st ptr,
     return MEMCACHED_CONNECTION_FAILURE;
   }
 
+  ssize_t unused_nread;
+  if (nread == NULL) nread= &unused_nread;
+
   char *buffer_ptr= static_cast<char *>(buffer);
-  while (length)
+  *nread= 0;
+  while ((size_t)*nread < length)
   {
     if (ptr->read_buffer_length == 0)
     {
@@ -551,27 +555,23 @@ memcached_return_t memcached_io_read(memcached_server_write_instance_st ptr,
         return io_fill_ret;
       }
     }
-    if (length > 1)
-    {
-      size_t difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
-      memcpy(buffer_ptr, ptr->read_ptr, difference);
 
-      length-= difference;
-      ptr->read_ptr+= difference;
-      ptr->read_buffer_length-= difference;
-      buffer_ptr+= difference;
-    }
-    else
+    size_t to_copy= (length - (size_t)*nread) < ptr->read_buffer_length ?
+                    (length - (size_t)*nread) : ptr->read_buffer_length;
+    if (buffer_ptr)
     {
-      *buffer_ptr= *ptr->read_ptr;
-      ptr->read_ptr++;
-      ptr->read_buffer_length--;
-      buffer_ptr++;
-      break;
+      if (to_copy > 1) {
+        memcpy(buffer_ptr, ptr->read_ptr, to_copy);
+      } else {
+        *buffer_ptr = *ptr->read_ptr;
+      }
+      buffer_ptr += to_copy;
     }
-  }
 
-  *nread = (ssize_t)(buffer_ptr - (char*)buffer);
+    *nread += to_copy;
+    ptr->read_ptr+= to_copy;
+    ptr->read_buffer_length-= to_copy;
+  }
 
   return MEMCACHED_SUCCESS;
 }