Page tree









Retrieves the metadata for an object specified by an identifier

As of the release of HDF5-1.12 this function has been deprecated in favor of the function H5O_GET_INFO3 or the macro H5O_GET_INFO.


H5O_GET_INFO2 (loc_id, oinfo, fields)


herr_t H5Oget_info2 ( hid_t loc_id, H5O_info1_t *oinfo, unsigned fields )

SUBROUTINE h5oget_info_f(object_id, object_info, hdferr, fields)

    INTEGER(HID_T)  , INTENT(IN)            :: object_id
    TYPE(h5o_info_t), INTENT(OUT), TARGET   :: object_info
    INTEGER         , INTENT(OUT)           :: hdferr
    INTEGER         , INTENT(IN), OPTIONAL  :: fields

Related Fortran2003 Derived Type: h5o_info_t

  TYPE, BIND(C) :: space_t
     INTEGER(hsize_t) :: total ! Total space for storing object header in file
     INTEGER(hsize_t) :: meta  ! Space within header for object header metadata 
                               ! information
     INTEGER(hsize_t) :: mesg  ! Space within header for actual message 
                               ! information
     INTEGER(hsize_t) :: free  ! Free space within object header
  END TYPE space_t

  TYPE, BIND(C) :: mesg_t
     INTEGER(c_int64_t) :: present ! Flags to indicate presence of message type 
                                   ! in header 
     INTEGER(c_int64_t) :: shared  ! Flags to indicate message type is shared 
                                   ! in header
  END TYPE mesg_t
  TYPE, BIND(C) :: hdr_t
     INTEGER :: version ! Version number of header format in file
     INTEGER :: nmesgs  ! Number of object header messages
     INTEGER :: nchunks ! Number of object header chunks
     INTEGER :: flags   ! Object header status flags
     TYPE(space_t)  :: space   
     TYPE(mesg_t)   :: mesg
  END TYPE hdr_t

  ! Extra metadata storage for obj & attributes
  TYPE, BIND(C) :: H5_ih_info_t
     INTEGER(hsize_t) :: index_size ! btree and/or list
     INTEGER(hsize_t) :: heap_size
  END TYPE H5_ih_info_t

  TYPE, BIND(C) :: meta_size_t
     TYPE(H5_ih_info_t) :: obj  ! v1/v2 B-tree & local/fractal heap for 
                                ! groups, B-tree for chunked datasets
     TYPE(H5_ih_info_t) :: attr ! v2 B-tree & heap for attributes
  ENDTYPE meta_size_t
  TYPE, BIND(C) :: h5o_info_t
     INTEGER(C_LONG)  :: fileno     ! File number that object is located in
     INTEGER(haddr_t) :: addr       ! Object address in file  
     INTEGER(C_INT)   :: type       ! Basic object type (group, dataset, etc.) 
     INTEGER          :: rc         ! Reference count of object

     INTEGER, DIMENSION(8) :: atime ! Access time        !    -- NOTE --
     INTEGER, DIMENSION(8) :: mtime ! Modification time  ! Returns an integer 
     INTEGER, DIMENSION(8) :: ctime ! Change time        ! array as specified 
     INTEGER, DIMENSION(8) :: btime ! Birth time         ! in Fortran intrinsic 
                                                         ! DATE_AND_TIME(VALUES)

     INTEGER(hsize_t) :: num_attrs  ! # of attributes attached to object

     TYPE(hdr_t) :: hdr

     TYPE(meta_size_t) :: meta_size
  END TYPE h5o_info_t

! C interoperable structure for h5o_info_t. The Fortran derived type returns the time
! values as an integer array as specified in the Fortran intrinsic DATE_AND_TIME(VALUES).
! Whereas, this derived type does not.

  TYPE, BIND(C) :: c_h5o_info_t
     INTEGER(C_LONG)  :: fileno     ! File number that object is located in
     INTEGER(haddr_t) :: addr       ! Object address in file
     INTEGER(C_INT)   :: type       ! Basic object type (group, dataset, etc.)
     INTEGER(C_INT)   :: rc         ! Reference count of object

     INTEGER(KIND=TIME_T) :: atime ! Access time
     INTEGER(KIND=TIME_T) :: mtime ! modify time
     INTEGER(KIND=TIME_T) :: ctime ! create time
     INTEGER(KIND=TIME_T) :: btime ! Access time

     INTEGER(hsize_t) :: num_attrs  ! # of attributes attached to object

     TYPE(c_hdr_t) :: hdr

     TYPE(meta_size_t) :: meta_size
  END TYPE c_h5o_info_t

hid_t object_idIN: Identifier for object of type specified by H5O_type_t; may be a file, group, dataset, named datatype or attribute identifier
H5O_info1_t *oinfo    OUT: Buffer in which to return object information
unsigned int fieldsIN: Flags specifying the fields to include in oinfo


H5O_GET_INFO2 specifies an object by its identifier, object_id, and retrieves the metadata describing that object in oinfo, an H5O_info1_t struct. This struct type is described in H5O_GET_INFO1.

The fields parameter contains flags to determine which fields will be filled in in the H5O_info1_t struct returned in oinfo. These flags are defined in the H5Opublic.h file:

H5O_INFO_BASICFill in the fileno, addr, type, and rc fields
H5O_INFO_TIMEFill in the atime, mtime, ctime, and btime fields
H5O_INFO_NUM_ATTRSFill in the num_attrs field
H5O_INFO_HDRFill in the hdr field
H5O_INFO_META_SIZEFill in the meta_size field

If you are iterating through a lot of different objects to retrieve information via the H5O_GET_INFO family of routines, you may see memory building up. This can be due to memory allocation for metadata such as  object headers and messages when the iterated objects are put into the metadata cache.

If the memory buildup is not desirable, you can configure a smaller cache via H5F_SET_MDC_CONFIG or set the file access property list via H5P_SET_MDC_CONFIG. A smaller sized cache will force metadata entries to be evicted from the cache, thus freeing the memory associated with the entries.


Returns a non-negative value if successful; otherwise returns a negative value.

Release    Change
1.10.3C function introduced in this release.

--- Last Modified: February 19, 2020 | 03:13 PM