X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Fshm.h;h=9f72a5a248657f73c3176877d2e6357930dd10db;hb=cba4b7a3bf98faff4c905f71064f7d66b9869e79;hp=008c5c415f3d8d9c383fdcaa3620cb36a06bc46d;hpb=5d61a504c6d395914d78f97e82f6fd0fdf0f98a0;p=lttng-ust.git

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index 008c5c41..9f72a5a2 100644
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -14,37 +14,38 @@
 #include "ust/core.h"
 #include "shm_types.h"
 
-#define SHM_MAGIC	0x54335433
-#define SHM_MAJOR	0
-#define SHM_MINOR	1
-
 /*
  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  * both the index and offset with known boundaries.
  */
 static inline
-char *_shmp(struct shm_object_table *table, struct shm_ref *ref)
+char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
+		   size_t idx, size_t elem_size)
 {
 	struct shm_object *obj;
-	size_t index, offset;
+	size_t objindex, ref_offset;
 
-	index = (size_t) ref->index;
-	if (unlikely(index >= table->allocated_len))
+	objindex = (size_t) ref->index;
+	if (unlikely(objindex >= table->allocated_len))
 		return NULL;
-	obj = &table->objects[index];
-	offset = (size_t) ref->offset;
-	if (unlikely(offset >= obj->memory_map_size))
+	obj = &table->objects[objindex];
+	ref_offset = (size_t) ref->offset;
+	ref_offset += idx * elem_size;
+	/* Check if part of the element returned would exceed the limits. */
+	if (unlikely(ref_offset + elem_size > obj->memory_map_size))
 		return NULL;
-	return &obj->memory_map[offset];
+	return &obj->memory_map[ref_offset];
 }
 
-#define shmp(handle, ref)						\
+#define shmp_index(handle, ref, index)					\
 	({								\
 		__typeof__((ref)._type) ____ptr_ret;			\
-		____ptr_ret = (__typeof__(____ptr_ret)) _shmp((handle)->table, &(ref)._ref);	\
+		____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));	\
 		____ptr_ret;						\
 	})
 
+#define shmp(handle, ref)	shmp_index(handle, ref, 0)
+
 static inline
 void _set_shmp(struct shm_ref *ref, struct shm_ref src)
 {