H5O_GET_INFO1 specifies an object by its identifier, loc_id, and retrieves the metadata describing that object in oinfo, defined as   a struct of type H5O_info1_t:

Note the following about H50_info1_t:

• Of the four time fields (atime, mtime, ctime, and btime) only ctime has been implemented.
• The atime value is the last time the object was read or written.
• The mtime value is the last time the raw data in the object was changed.
• The ctime value is the last time the metadata for the object was changed.
• The btime value is the time the object was created.
• The fields nested in the meta_size field are for internal library use only.

An H5O_type_t enum indicates the object type and is defined (in H5Opublic.h) as follows:

typedef enum H5O_type_t {
    H5O_TYPE_UNKNOWN = -1,      /* Unknown object type                      */
    H5O_TYPE_GROUP,             /* Object is a group                        */
    H5O_TYPE_DATASET,           /* Object is a dataset                      */
    H5O_TYPE_NAMED_DATATYPE,    /* Object is a committed (named) datatype   */
    H5O_TYPE_NTYPES             /* Number of different object types (must   */
                                /* be last!)                                */
} H5O_type_t;   

Note that object_id refers only to the types specified by H5O_type_t.

An H5O_hdr_info_t struct holds object header metadata and is defined (in H5Opublic.h) as follows:

typedef struct H5O_hdr_info_t {
    unsigned version;           /* Version number of header format in file  */
    unsigned nmesgs;            /* Number of object header messages         */
    unsigned nchunks;           /* Number of object header chunks           */
    unsigned flags;             /* Object header status flags               */
    struct {
        hsize_t total;          /* Total space for storing object header in */ 
                                /*   file                                   */
        hsize_t meta;           /* Space within header for object header    */
                                /*   metadata information                   */
        hsize_t mesg;           /* Space within header for actual message   */
                                /*   information                            */
        hsize_t free;           /* Free space within object header          */
    } space;
    struct {
        uint64_t present;       /* Flags to indicate presence of message    */
                                /*   type in header                         */
        uint64_t shared;        /* Flags to indicate message type is        */
                                /*   shared in header                       */
    } mesg;
} H5O_hdr_info_t;
    

Valid values for the version field are H5O_VERSION_1 and H5O_VERSION_2. Version 2 of the object header is smaller and more efficient than version 1.

Please be aware that the information held by H5O_hdr_info_t may only be useful to developers with extensive HDF5 experience.

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