door_getparam

, door_setparam

- retrieve and set door parameters

Synopsis

cc -mt [ flag... ] file... [ library... ]
#include <door.h>

int door_getparam(int d, int param, size_t *out);

int door_setparam(int d, int param, size_t val);

Description

The door_getparam() function retrieves the value of param for the door descriptor d and writes it through the pointer out. The door_setparam() function sets the value of param for the door descriptor d to val. The param argument names the parameter to view or change and can be one of the following values:

DOOR_PARAM_DATA_MAX

This parameter represents the maximum amount of data that can be passed to the door routine. Any attempt to call door_call(3C) on a door with a data_size value larger than the door's DOOR_PARAM_DATA_MAX parameter will fail with ENOBUFS. At door creation time, this parameter is initialized to SIZE_MAX and can be set to any value from 0 to SIZE_MAX, inclusive. This parameter must be greater than or equal to the DOOR_PARAM_DATA_MIN parameter.

DOOR_PARAM_DATA_MIN

This parameter represents the the minimum amount of data that can be passed to the door routine. Any attempt to call door_call(3C) on a door with a data_size value smaller than the door's DOOR_PARAM_DATA_MIN parameter will fail with ENOBUFS. At door creation time, this parameter is initialized to 0, and can be set to any value from 0 to SIZE_MAX, inclusive. This parameter must be less than or equal to the DOOR_PARAM_DATA_MAX parameter.

DOOR_PARAM_DESC_MAX

This parameter represents the the maximum number of argument descriptors that can be passed to the door routine. Any attempt to call door_call(3C) on a door with a desc_num value larger than the door's DOOR_PARAM_DESC_MAX parameter will fail with ENFILE. If the door was created with the DOOR_REFUSE_DESC flag, this parameter is initialized to 0 and cannot be changed to any other value. Otherwise, it is initialized to INT_MAX and can be set to any value from 0 to INT_MAX, inclusive.

The door_setparam() function can only affect doors that were created by the current process.

Return Values

Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

Errors

The door_getparam() function will fail if:

EBADF

The d argument is not a door descriptor.

EFAULT

The out argument is not a valid address.

EINVAL

The param argument is not a recognized parameter.

EOVERFLOW

The value of the parameter is larger than the SIZE_MAX. This condition can occur only if the calling process is 32-bit and the door targets a 64-bit process or the kernel.

The door_setparam() function will fail if:

EBADF

The d argument is not a door descriptor or has been revoked.

EINVAL

The param argument is not a recognized parameter, or the requested change would make DOOR_PARAM_DATA_MIN greater than DOOR_PARAM_DATA_MAX.

ENOTSUP

The param argument is DOOR_PARAM_DESC_MAX, d was created with the DOOR_REFUSE_DESC flag, and val is not zero.

EPERM

The d argument was not created by this process.

ERANGE

The val argument is not in supported range of param.

Examples

Example 1 Set up a door with a fixed request size.

typedef struct my_request {
     int request;
ar buffer[4096];
} my_request_t;

fd = door_create(my_handler, DOOR_REFUSE_DESC);
if (fd < 0)
     /* handle error */

if (door_setparam(fd, DOOR_PARAM_DATA_MIN,
    sizeof (my_request_t)) < 0 ||
    door_setparam(fd, DOOR_PARAM_DATA_MAX,
    sizeof (my_request_t)) < 0)
 /* handle error */

/*
 * the door will only accept door_call(3DOOR)s with a
 * data_size which is exactly sizeof (my_request_t).
 */

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

door_call(3C), door_create(3C), attributes(5)

Notes

The parameters that can be manipulated by door_setparam() are not the only limitation on the size of requests. If the door server thread's stack size is not large enough to hold all of the data requested plus room for processing the request, the door call will fail with E2BIG.

The DOOR_PARAM_DATA_MIN parameter will not prevent DOOR_UNREF_DATA notifications from being sent to the door.