lib: shared memory map

The shared memory map will allow passing SDU's between IPCPs
efficiently. It is a single block of managed memory. SDU's are stored
in a shm_du_buff datastructure, which is a list of blocks inside the
shared memory region. The mechanism for passing SDU's is not yet
implemented and could be either within the region or using another
local IPC mechanism.

The following things are configured at compile time:

SHM_FILE_NAME         : the name. Default is "ouroboros_du_map".
SHM_DU_BUFF_BLOCK_SIZE: size of a block inside the shared memory
                        region. Default is the pagesize of the system.
SHM_DU_MAP_SIZE       : the approximate size in bytes of the shared
                        memory map. The actual filesize may differ by
                        a small margin. Default is 4MB.

2 files changed, 76 insertions, 0 deletions

diff --git a/include/ouroboros/CMakeLists.txt b/include/ouroboros/CMakeLists.txt
index 167cf0e2..a196140b 100644
--- a/include/ouroboros/CMakeLists.txt
+++ b/include/ouroboros/CMakeLists.txt
@@ -14,6 +14,7 @@ set(HEADER_FILES
         list.h
         logs.h
         rina_name.h
+        shm_du_map.h
         sockets.h
         utils.h
 )
diff --git a/include/ouroboros/shm_du_map.h b/include/ouroboros/shm_du_map.h
new file mode 100644
index 00000000..948a6727
--- /dev/null
+++ b/include/ouroboros/shm_du_map.h
@@ -0,0 +1,75 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Shared memory map for data units
+ *
+ *    Dimitri Staessens <[email protected]>
+ *    Sander Vrijders   <[email protected]>
+ *
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef OUROBOROS_SHM_DU_MAP_H
+#define OUROBOROS_SHM_DU_MAP_H
+
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 199506L
+#endif
+
+#define OUROBOROS_PREFIX "shm_du_map"
+
+#ifndef SHM_DU_BUFF_BLOCK_SIZE
+#define SHM_DU_BUFF_BLOCK_SIZE sysconf(_SC_PAGESIZE)
+#endif
+
+#ifndef SHM_DU_MAP_FILENAME
+#define SHM_DU_MAP_FILENAME "ouroboros_du_map"
+#endif
+
+#ifndef SHM_DU_MAP_SIZE
+#define SHM_DU_MAP_SIZE (1 << 22)
+#endif
+
+#include "common.h"
+#include "logs.h"
+
+struct shm_du_buff;
+
+struct shm_du_map;
+
+struct shm_du_map  * shm_du_map_create();
+struct shm_du_map  * shm_du_map_open();
+void                 shm_du_map_close(struct shm_du_map * dum);
+
+struct shm_du_buff * shm_create_du_buff(struct shm_du_map * dum,
+                                        size_t              size,
+                                        size_t              headspace,
+                                        uint8_t           * data,
+                                        size_t              len);
+void                 shm_release_du_buff(struct shm_du_map  * dum,
+                                         struct shm_du_buff * sdb);
+
+uint8_t * shm_du_buff_head_alloc(struct shm_du_map * dum,
+                                 struct shm_du_buff * sdb,
+                                 size_t size);
+uint8_t * shm_du_buff_tail_alloc(struct shm_du_map * dum,
+                                 struct shm_du_buff * sdb,
+                                 size_t size);
+int       shm_du_buff_head_release(struct shm_du_buff * sdb,
+                                   size_t size);
+int       shm_du_buff_tail_release(struct shm_du_buff * sdb,
+                                   size_t size);
+
+#endif /* OUROBOROS_SHM_DU_MAP_H */