Determines on behalf of a third-party user whether a named user
    can access the object specified.

    Format

      SYS$CHECK_ACCESS  [objtyp], [objnam], [usrnam], itmlst,

                        [contxt], [clsnam], [objpro], [usrpro]

    C Prototype

      int sys$check_access  (unsigned int *objtyp, void *objnam,

                            void *usrnam, void *itmlst, unsigned int

                            *contxt, void *clsnam, void *objpro, void

                            *usrpro);

1  –  Arguments

 objtyp

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Type of object being accessed. The objtyp argument is the address
    of a longword containing a value specifying the type of object.

    The appropriate symbols are listed in the following table and are
    defined in the system macro $ACLDEF library:

    Symbol                   Meaning

    ACL$C_CAPABILITY         Object is a restricted resource; use the
                             reserved name VECTOR.
    ACL$C_DEVICE             Object is a device.
    ACL$C_FILE               Object is a Files-11 On-Disk Structure
                             Level 2 file.
    ACL$C_GROUP_GLOBAL_      Object is a group global section.
    SECTION
    ACL$C_JOBCTL_QUEUE       Object is a batch, print, or server
                             queue.
    ACL$C_LOGICAL_NAME_      Object is a logical name table.
    TABLE
    ACL$C_SYSTEM_GLOBAL_     Object is a system global section.
    SECTION

    For further information about these symbols, see the description
    of the clsnam argument.

 objnam

    OpenVMS usage:char_string
    type:         character-coded text string
    access:       read only
    mechanism:    by descriptor-fixed-length string descriptor
    Name of the object being accessed. The objnam argument is the
    address of a character-string descriptor pointing to the object
    name.

 usrnam

    OpenVMS usage:char_string
    type:         character-coded text string
    access:       read only
    mechanism:    by descriptor-fixed-length string descriptor
    Name of the user attempting access. The usrnam argument is the
    address of a descriptor that points to a character string that
    contains the name of the user attempting to gain access to the
    specified object. The user name string can contain a maximum of
    12 alphanumeric characters.

 itmlst

    OpenVMS usage:item_list_3
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Attributes describing how the object is to be accessed and
    information returned after $CHECK_ACCESS performs the protection
    check (for instance, security alarm information).

    For each item code, you must include a set of four elements and
    end the list with a longword containing the value 0 (CHP$_END).

    To view the item code diagram and descriptor fields table, see
    the VSI OpenVMS System Services Reference Manual.

 contxt

    OpenVMS usage:longword
    type:         longword (unsigned)
    access:       read-write
    mechanism:    by reference
    Longword used to maintain the user authorization file (UAF)
    context. The contxt argument is the address of a longword
    to receive a UAI context longword. On the initial call, this
    longword should contain the value -1. On subsequent calls, the
    value of the contxt argument from the previous call should be
    passed back in.

    Using the contxt argument keeps the UAF open across all calls,
    thereby improving the performance of the system on subsequent
    calls. To close the UAF, you must run down the image.

    The resulting contxt value from a $CHECK_ACCESS call can also be
    used as the input contxt argument to the $GETUAI system service,
    and vice versa.

 clsnam

    OpenVMS usage:char_string
    type:         character-coded text string
    access:       read only
    mechanism:    by descriptor
    Object class name associated with the protected object. The
    clsnam argument is the address of a descriptor pointing to the
    name of the object class associated with the object specified by
    either the objnam or the objpro argument. The clsnam and objtyp
    arguments are mutually exclusive. The clsnam argument is the
    preferred argument to $CHECK_ACCESS. The following object class
    names are valid:

    CAPABILITY                  QUEUE
    COMMON_EVENT_CLUSTER        RESOURCE_DOMAIN
    DEVICE                      SECURITY_CLASS
    FILE                        SYSTEM_GLOBAL_SECTION
    GROUP_GLOBAL_SECTION        VOLUME
    LOGICAL_NAME_TABLE

 objpro

    OpenVMS usage:char_string
    type:         opaque byte stream or object handle
    access:       read only
    mechanism:    by descriptor
    Buffer containing an object security profile or object handle.
    The objpro argument is the address of a descriptor pointing to
    a buffer that contains an encoded object security profile or the
    address of a descriptor pointing to an object handle.

    Object handles vary according to the associated security object
    class. Currently, the only supported object handles are for the
    file and device class objects where the object handle is a word
    or longword channel.

    The objpro and objnam arguments are mutually exclusive unless the
    objpro argument is a simple object handle. The objpro and usrpro
    arguments are also mutually exclusive unless the objpro argument
    is an object handle.

 usrpro

    OpenVMS usage:char_string
    type:         opaque byte stream
    access:       read only
    mechanism:    by descriptor
    Buffer containing a user security profile. The usrpro argument is
    the address of a descriptor pointing to a buffer that contains an
    encoded user security profile.

    The $CREATE_USER_PROFILE service can be used to construct a user
    security profile. The usrpro and usrnam arguments are mutually
    exclusive. The objpro and usrpro arguments are also mutually
    exclusive unless the objpro argument is an object handle.