qpb: Add support for protobuf.

Infrastructure that allows protocol buffers to be used in Quagga. The
changes below comprise of:

  - Build hooks

  - Protobuf definitions for common types.

  - Library routines for working with protobuf, including functions
    that help translate between common quagga types and their protobuf
    equivalents.

Changes:

  * qpb/{Makefile.am,README.txt,qpb.h,.gitignore}

    Add the qpb library, which provides shared code and definitions
    for using protocol buffers in quagga code.

  * qpb/qpb.proto

    Protobuf definitions that can be shared by all of quagga.

  * qpb/linear_allocator.h

    An allocator that allocates memory by walking down towards the end
    of a buffer. This is used to cheaply allocate/deallocate memory on
    the stack for protobuf operations.

  * qpb/qpb_allocator.[ch]

    Thin layer that allows a linear allocator to be used with the
    protobuf-c library.

  * common.am

    This is an automake fragment that is intended to be shared by
    Makefile.am files in the tree. It currently includes definitions
    related to protobuf.

  * configure.ac

    - Add logic to optionally build protobuf code.

      By default, protobuf support is enabled if the protobuf C
      compiler (protoc-c) is available, and the associated header
      files/library can be found.

      The user can choose to override this behavior via the new
      --disable-protobuf/--enable-protobuf flags.

    - Include the quagga protobuf library (qpb) in the build.

  * .gitignore

    Ignore source code generated by protobuf compiler.

  * Makefile.am

    Add 'qpb' to the list of subdirectories.

Signed-off-by: Avneesh Sachdev <avneesh@sproute.com>

Edited: Paul Jakma <paul.jakma@hpe.com>: Change the sense of the
        configure enable option to require explicit specifying, as
        an experimental feature.

1 files changed, 113 insertions, 0 deletions

diff --git a/qpb/qpb_allocator.h b/qpb/qpb_allocator.h
new file mode 100644
index 0000000000..83ddf56cbc
--- /dev/null
+++ b/qpb/qpb_allocator.h
@@ -0,0 +1,113 @@
+/*
+ * qpb_allocator.h
+ *
+ * @copyright Copyright (C) 2016 Sproute Networks, Inc.
+ *
+ * @author Avneesh Sachdev <avneesh@sproute.com>
+ *
+ * This file is part of Quagga.
+ *
+ * Quagga is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * Quagga is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Quagga; see the file COPYING.  If not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+/*
+ * Header file for quagga protobuf memory management code.
+ */
+
+#ifndef _QPB_ALLOCATOR_H_
+#define _QPB_ALLOCATOR_H_
+
+#include <google/protobuf-c/protobuf-c.h>
+
+struct linear_allocator_t_;
+
+/*
+ * Alias for ProtobufCAllocator that is easier on the fingers.
+ */
+typedef ProtobufCAllocator qpb_allocator_t;
+
+/*
+ * qpb_alloc
+ */
+static inline void *
+qpb_alloc (qpb_allocator_t *allocator, size_t size)
+{
+  return allocator->alloc (allocator->allocator_data, size);
+}
+
+/*
+ * qpb_alloc_ptr_array
+ *
+ * Allocate space for the specified number of pointers.
+ */
+static inline void *
+qpb_alloc_ptr_array (qpb_allocator_t *allocator, size_t num_ptrs)
+{
+  return qpb_alloc (allocator, num_ptrs * sizeof (void *));
+}
+
+/*
+ * qpb_free
+ */
+static inline void
+qpb_free (qpb_allocator_t *allocator, void *ptr)
+{
+  allocator->free (allocator->allocator_data, ptr);
+}
+
+/*
+ * QPB_ALLOC
+ *
+ * Convenience macro to reduce the probability of allocating memory of
+ * incorrect size. It returns enough memory to store the given type,
+ * and evaluates to an appropriately typed pointer.
+ */
+#define QPB_ALLOC(allocator, type)		\
+  (type *) qpb_alloc(allocator, sizeof(type))
+
+
+/*
+ * Externs.
+ */
+extern void qpb_allocator_init_linear (qpb_allocator_t *,
+				       struct linear_allocator_t_ *);
+
+/*
+ * The following macros are for the common case where a qpb allocator
+ * is being used alongside a linear allocator that allocates memory
+ * off of the stack.
+ */
+#define QPB_DECLARE_STACK_ALLOCATOR(allocator, size)	\
+    qpb_allocator_t allocator;				\
+    linear_allocator_t lin_ ## allocator;		\
+    char lin_ ## allocator ## _buf[size]
+
+#define QPB_INIT_STACK_ALLOCATOR(allocator)				\
+  do									\
+    {									\
+      linear_allocator_init(&(lin_ ## allocator),			\
+			    lin_ ## allocator ## _buf,			\
+			    sizeof(lin_ ## allocator ## _buf));		\
+      qpb_allocator_init_linear(&allocator, &(lin_ ## allocator));	\
+    } while (0)
+
+#define QPB_RESET_STACK_ALLOCATOR(allocator)		\
+  do							\
+    {							\
+      linear_allocator_reset (&(lin_ ## allocator));	\
+    } while (0)
+
+#endif /* _QPB_ALLOCATOR_H_ */