Make buffer data point to memory blocks

Make buffer data point to a registered memory block by its mem_id.
Add some more helpers to allocate memfd backed memory.
Allocate buffers in memfd so that we easily share them between client
and server.
Update pts and seq in v4l2 now that this change will actually be visible
at the client.

spa/include/spa/buffer.h

@@ -98,39 +98,15 @@ typedef struct {
   size_t       size;
 } SpaMeta;
 
-/**
- * SpaDataType:
- * @SPA_DATA_TYPE_INVALID: invalid data type, is ignored
- * @SPA_DATA_TYPE_MEMPTR: data and size point to memory accessible by the
- *                        CPU.
- * @SPA_DATA_TYPE_FD: data points to an int file descriptor that can be
- *                    mmapped.
- * @SPA_DATA_TYPE_MEMID: data points to the id of the memory block to use
- * @SPA_DATA_TYPE_POINTER: data points to some other datastructure, the
- *        type can be found in ptr_type
- */
-typedef enum {
-  SPA_DATA_TYPE_INVALID               = 0,
-  SPA_DATA_TYPE_MEMPTR,
-  SPA_DATA_TYPE_FD,
-  SPA_DATA_TYPE_MEMID,
-  SPA_DATA_TYPE_POINTER,
-} SpaDataType;
-
 /**
  * SpaData:
- * @id: user id
- * @type: the type of data
- * @ptr_type: more info about the type of @ptr
- * @ptr: pointer to data or fd
- * @offset: offset of data
- * @size: size of data
- * @stride: stride of data if applicable
+ * @mem_id: the memory id to use
+ * @offset: offset of memory
+ * @size: size of memory
+ * @stride: stride of memory if applicable
  */
 typedef struct {
-  SpaDataType  type;
-  const char  *ptr_type;
-  void        *ptr;
+  uint32_t     mem_id;
   off_t        offset;
   size_t       size;
   size_t       stride;
@@ -139,6 +115,8 @@ typedef struct {
 /**
  * SpaBuffer:
  * @id: buffer id
+ * @mem_id: memory id of the buffer
+ * @offset: offset into the memory
  * @size: total size of the buffer structure
  * @n_metas: number of metadata
  * @metas: offset of array of @n_metas metadata
@@ -147,6 +125,8 @@ typedef struct {
  */
 struct _SpaBuffer {
   uint32_t          id;
+  uint32_t          mem_id;
+  off_t             offset;
   size_t            size;
   unsigned int      n_metas;
   off_t             metas;

spa/include/spa/control.h

@@ -165,7 +165,7 @@ typedef struct {
   uint32_t mem_id;
   uint32_t mem_type;
   uint32_t fd_index;
-  uint64_t offset;
+  uint32_t flags;
   uint64_t size;
 } SpaControlCmdAddMem;
 
@@ -179,7 +179,7 @@ typedef struct {
 typedef struct {
   uint32_t port_id;
   uint32_t buffer_id;
-  int      fd_index;
+  uint32_t mem_id;
   uint64_t offset;
   uint64_t size;
 } SpaControlCmdAddBuffer;

spa/include/spa/memory.h

@@ -41,6 +41,8 @@ typedef enum {
   SPA_MEMORY_FLAG_WRITABLE           = (1 << 1),
 } SpaMemoryFlags;
 
+#define SPA_MEMORY_FLAG_READWRITE   (SPA_MEMORY_FLAG_READABLE|SPA_MEMORY_FLAG_WRITABLE)
+
 /**
  * SpaMemory:
  * @refcount: a refcount
@@ -65,15 +67,21 @@ struct _SpaMemory {
   size_t          size;
 };
 
+void             spa_memory_init           (void);
+
 uint32_t         spa_memory_pool_get       (uint32_t type);
 uint32_t         spa_memory_pool_new       (void);
 void             spa_memory_pool_free      (uint32_t);
 
 SpaMemory *      spa_memory_alloc          (uint32_t pool_id);
+SpaMemory *      spa_memory_alloc_with_fd  (uint32_t pool_id, void *data, size_t size);
 SpaResult        spa_memory_free           (uint32_t pool_id, uint32_t id);
+SpaMemory *      spa_memory_import         (uint32_t pool_id, uint32_t id);
 
 SpaMemory *      spa_memory_find           (uint32_t pool_id, uint32_t id);
 
+void *           spa_memory_ensure_ptr     (SpaMemory *mem);
+
 #ifdef __cplusplus
 }  /* extern "C" */
 #endif