libust ABI: export streams

[lttng-ust.git] / libringbuffer / shm.h

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index d370375b6929cf913ed568e3e665ead996f515ec..5785b71d8483d26c3684bdd8875c70aa13f00ca2 100644 (file)
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -14,37 +14,43 @@
 #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.
+ *
+ * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
+ * target type, even in the occurrence of shm_ref modification by an
+ * untrusted process having write access to the shm_ref. We return a
+ * NULL pointer if the ranges are invalid.
  */
 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)
 {
@@ -68,4 +74,51 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table,
 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
 void align_shm(struct shm_object *obj, size_t align);
 
+static inline
+int shm_get_wakeup_fd(struct shm_handle *handle, struct shm_ref *ref)
+{
+       struct shm_object_table *table = handle->table;
+       struct shm_object *obj;
+       size_t index;
+
+       index = (size_t) ref->index;
+       if (unlikely(index >= table->allocated_len))
+               return -EPERM;
+       obj = &table->objects[index];
+       return obj->wait_fd[1];
+
+}
+
+static inline
+int shm_get_wait_fd(struct shm_handle *handle, struct shm_ref *ref)
+{
+       struct shm_object_table *table = handle->table;
+       struct shm_object *obj;
+       size_t index;
+
+       index = (size_t) ref->index;
+       if (unlikely(index >= table->allocated_len))
+               return -EPERM;
+       obj = &table->objects[index];
+       return obj->wait_fd[0];
+}
+
+static inline
+int shm_get_object_data(struct shm_handle *handle, struct shm_ref *ref,
+               int *shm_fd, int *wait_fd, uint64_t *memory_map_size)
+{
+       struct shm_object_table *table = handle->table;
+       struct shm_object *obj;
+       size_t index;
+
+       index = (size_t) ref->index;
+       if (unlikely(index >= table->allocated_len))
+               return -EPERM;
+       obj = &table->objects[index];
+       *shm_fd = obj->shm_fd;
+       *wait_fd = obj->wait_fd[0];
+       *memory_map_size = obj->memory_map_size;
+       return 0;
+}
+
 #endif /* _LIBRINGBUFFER_SHM_H */