obj_id is an identifier for any object in the file of interest.

An H5F_info2_t struct is defined in H5Fpublic.h as follows:

        typedef struct H5F_info2_t {
	    struct {
		unsigned      vers;	
		hsize_t	      super_size;
		hsize_t	      super_ext_size;	
	    } super;
	    struct {
		unsigned      vers;
		hsize_t	      hdr_size;
		hsize_t	      tot_space;
	    } free;
            struct {
		unsigned      vers;
                hsize_t       hdr_size;		
                H5_ih_info_t  msgs_info; 
            } sohm;
        } H5F_info2_t; 

• vers is the version number of the superblock.
• super_size is the size of the superblock.
• super_ext_size is the size of the superblock extension.

The free sub-struct contains the following information:

• vers is the version number of the free-space manager.
• hdr_size is the size of the free-space manager header.
• tot_space is the total amount of free space in the file.

The sohm sub-struct contains shared object header message information as follows:

• vers is the version number of the shared object header information.
• hdr_size is the size of the shared object header message.
• msgs_info is an H5_ih_info_t struct defined in H5public.h as follows:

          typedef struct H5_ih_info_t {
              hsize_t     index_size;     
              hsize_t     heap_size;
          } H5_ih_info_t;
  

  • index_size is the summed size of all the shared object header indexes. Each index might be either a B-tree or a list.
  • heap_size is the size of the heap.