STRUCT_DECL(9F) (man pages section 9F: DDI and DKI Kernel Functions)

man pages section 9F: DDI and DKI Kernel Functions

STRUCT_DECL(9F)

NAME

STRUCT_DECL, SIZEOF_PTR, SIZEOF_STRUCT, STRUCT_BUF, STRUCT_FADDR, STRUCT_FGET, STRUCT_FGETP, STRUCT_FSET, STRUCT_FSETP, STRUCT_HANDLE, STRUCT_INIT, STRUCT_SIZE, STRUCT_SET_HANDLE- 32-bit application data access macros

SYNOPSIS

#include <sys/ddi.h>
#include <sys/sunddi.h>

structname

handle

structname

handle

umodel

handle

umodel

*addr

handle

field

handle

field

handle

field

val

handle

field

val

handle

field

handle

structname

umodel

handle

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

PARAMETERS

The macros take the following parameters:

structname: The structure name (as would appear after the C keyword "struct" ) of the native form.
umodel: A bit field containing either ILP32 model bit (DATAMODEL_ILP32), or the LP64 model get (DATAMODEL_ILP64). In an ioctl(9E) , these bits will be present in the flag parameter; in a devmap(9E) , they will be present in the model parameter mmap(9E) and can call ddi_mmap_get_model(9F) to get the data model of the current thread.
handle: The variable name used to refer to a particular instance of a structure which is handled by these macros.
field: The field name within the structure contain substructures. If the structures contain substructures, unions, or arrays, then field can be whether complex expression could occur after the first "." or "->" .

DESCRIPTION

The above macros allow a device driver to access data consumed from a 32-bit application regardless whether the driver was compiled to the ILP32 or LP64 data model. These macros effectively hide the difference between the data model of the user application and the driver.

The macros can be broken up into two main categories, the macros that declare and initialize structure handles and the macros that operate on these structures using the structure handles.

Declaration and Initialization Macros

The macros STRUCT_DECL() and STRUCT_HANDLE() declare structure handles on the stack, whereas the macros STRUCT_INIT() and STRUCT_SET_HANDLE() initialize the structure handles to point to an instance of the native form structure.

The macros STRUCT_HANDLE() and STRUCT_SET_HANDLE() are used to declare and initialize a structure handle to an existing data structure, for example, ioctls within a STREAMS module.

The macros STRUCT_DECL() and STRUCT_INIT() , on the other hand, are used in modules which declare and initialize a structure handle to a data structure allocated by STRUCT_DECL() , that is, any standard character or block device driver ioctl(9E) routine that needs to copy in data from a user-mode program.

STRUCT_DECL(structname, handle): Declares a "structure handle" for a "struct" and allocates an instance of its native form on the stack. It is assumed that the native form is larger than or equal to the ILP32 form. handle is a variable name and is declared as a variable by this macro.
void STRUCT_INIT(handle, model_t umodel): Initializes handle to point to the instance allocated by STRUCT_DECL() , it also sets data model for handle to umodel , and must be called before any access is made through the macros that operate on these structures. When used in an ioctl(9E) routine umodel is the flag parameter; in adevmap(9E) routine umodel is the model parameter and in a mmap(9E) routine, is the return value of ddi_mmap_get_model(9F) . This macro is intended for handles created with STRUCT_DECL() only.
STRUCT_HANDLE(structname, handle): Declares a "structure handle" handle but unlike STRUCT_DECL() does not allocate an instance of "struct ".
void STRUCT_SET_HANDLE(handle, model_t umodel, void *addr): Initializes to point to the native form instance at addr , it also sets the data model for handle to umodel . This is intended for handles created with STRUCT_HANDLE() . Fields cannot be referenced via the handle until this macro has been invoked. Typically, addr is the address of the native form structure containing the user-mode programs data. When used in an ioctl(9E) umodel is the flag parameter, in a devmap(9E) routine is the model parameter and in a mmap(9E) routine, umodel is the return value of ddi_mmap_get_model(9F) .

Operation Macros

size_t STRUCT_SIZE(handle): Returns size of the structure referred to by handle . It will return the size depending upon the data model associated with handle . If the data model stored by STRUCT_INIT() or STRUCT_SET_HANDLE() was DATAMODEL_ILP32, it will return the size of the ILP32 form, else it will return the size of the native form.
STRUCT_FGET(handle, field): Returns the contents of field in the structure described by handle according to the data model associated with handle .
STRUCT_FGETP(handle, field): This is the same as STRUCT_FGET() except that the field in question is a pointer of some kind. This macro will cast caddr32_t to a (void *) when it is accessed. Failure to use this macro for a pointer will lead to compiler warnings or failures.
STRUCT_FSET(handle, field, val): Assigns val to the (non pointer) in the structure handle described by . It should not be used within any other expression, but rather only as a statement.
STRUCT_FSETP(handle, field, val): Returns a pointer to the in the structure described by handle .
struct structname *STRUCT_BUF(handle): Returns a pointer to the native mode instance of the structure described by handle .

Macros Not Using Handles

size_t SIZEOF_STRUCT(structname, umodel): Returns size of structname based on umodel .
size_t SIZEOF_PTR(umodel): Returns the size of a pointer based on umodel .

EXAMPLES

Example 1 Copying a Structure

The following example uses an ioctl(9E) on a regular character device that copies a data structure that looks like this into the kernel:

struct opdata {
    size_t  size;
    uint_t  flag;
};

Example 2 Defining a Structure

This data structure definition describes what the ioctl(9E) would look like in a 32-bit application using fixed width types.

#if defined(_MULTI_DATAMODEL)
struct opdata32 {
    size32_t    size;
    uint32_t    flag;
};
#endif

Example 3 Using `STRUCT_DECL()` and `STRUCT_INIT()`

Note: This example uses the STRUCT_DECL() and STRUCT_INIT() macros to declare and initialize the structure handle.

int
xxioctl(dev_t dev, int cmd, intptr_t arg, int mode,
    cred_t *cr, int *rval_p);
{
    STRUCT_DECL(opdata, op);

    if (cmd != OPONE)
        return (ENOTTY);

    STRUCT_INIT(op, mode);

    if (copyin((void *)data,
        STRUCT_BUF(op), STRUCT_SIZE(op)))
        return (EFAULT);

    if (STRUCT_FGET(op, flag) != FACTIVE ||
        STRUCT_FGET(op, size) > sizeof (device_state))
        return (EINVAL);
    xxdowork(device_state, STRUCT_FGET(op, size));
    return (0);
}

This piece of code is an excerpt from a STREAMS module that handles ioctl(9E) data (M_IOCDATA) messages and uses the data structure defined above. This code has been written to run in the ILP32 environment only.

Example 4 Using `STRUCT_HANDLE()` and `STRUCT_SET_HANDLE()`

The next example illustrates the use of the STRUCT_HANDLE() and STRUCT_SET_HANDLE() macros which declare and initialize the structure handle to point to an already existing instance of the structure.

The above code example can be converted to run in the LP64 environment using the STRUCT_HANDLE() and STRUCT_SET_HANDLE() as follows:

struct strbuf {
int maxlen;     /* no. of bytes in buffer */
int len;        /* no. of bytes returned */
caddr_t buf;        /* pointer to data */
};

static void
wput_iocdata(queue_t *q, mblk_t *msgp)
{
        mblk_t  *data;  /* message block descriptor */
        STRUCT_HANDLE(strbuf, sb);

    /* copyin the data */
    if (mi_copy_state(q, mp, &data) == -1) {
                return;
    }

        STRUCT_SET_HANDLE(sb,((struct iocblk *)msgp->b_rptr)->ioc_flag,
            (void *)data->b_rptr);
        if (STRUCT_FGET(sb, maxlen) < (int)sizeof (ipa_t)) {
                mi_copy_done(q, msgp, EINVAL);
        return;
    }
}

STRUCT_DECL(9F)

NAME

SYNOPSIS

INTERFACE LEVEL

PARAMETERS

DESCRIPTION

Declaration and Initialization Macros

Operation Macros

Macros Not Using Handles

EXAMPLES

Example 1 Copying a Structure

Example 2 Defining a Structure

Example 3 Using STRUCT_DECL() and STRUCT_INIT()

Example 4 Using STRUCT_HANDLE() and STRUCT_SET_HANDLE()

SEE ALSO

Example 3 Using `STRUCT_DECL()` and `STRUCT_INIT()`

Example 4 Using `STRUCT_HANDLE()` and `STRUCT_SET_HANDLE()`