Export consumer ABI, implement ring buffer modifications for consumer

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

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 0d92572d7b5b6170d79ed7e457e115bba957b7ef..ae63b004fd50723cd9c73511049bb8d042928f59 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -165,6 +165,39 @@ error_pipe:
        
 }
 
+struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
+                       int shm_fd, int wait_fd, size_t memory_map_size)
+{
+       struct shm_object *obj;
+       char *memory_map;
+
+       if (table->allocated_len >= table->size)
+               return NULL;
+       obj = &table->objects[table->allocated_len];
+
+       /* wait_fd: set read end of the pipe. */
+       obj->wait_fd[0] = wait_fd;
+       obj->wait_fd[1] = -1;   /* write end is unset. */
+       obj->shm_fd = shm_fd;
+
+       /* memory_map: mmap */
+       memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
+                         MAP_SHARED, shm_fd, 0);
+       if (memory_map == MAP_FAILED) {
+               PERROR("mmap");
+               goto error_mmap;
+       }
+       obj->memory_map = memory_map;
+       obj->memory_map_size = memory_map_size;
+       obj->allocated_len = memory_map_size;
+       obj->index = table->allocated_len++;
+
+       return obj;
+
+error_mmap:
+       return NULL;
+}
+
 static
 void shmp_object_destroy(struct shm_object *obj)
 {