iofunc_read_verify()

Подтвердить наличие у клиента прав доступа на чтение ресурса

Прототип:

#include <sys/iofunc.h>
                                       
int iofunc_read_verify( resmgr_context_t *ctp,
                        io_read_t *msg,
                        iofunc_ocb_t *ocb,
                        int *nonblock );

Аргументы:

ctp

A pointer to a resmgr_context_t structure that the resource-manager library uses to pass context information between functions.

msg

A pointer to the io_read_t structure that contains the message that the resource manager received.

ocb

A pointer to the iofunc_ocb_t structure for the Open Control Block that was created when the client opened the resource.

nonblock

NULL, or a pointer to a location where the function can store a value that indicates whether or not the device is nonblocking:

• ≠0 — the client doesn't want to be blocked (i.e. O_NONBLOCK was set).
• 0 — the client wants to be blocked.

Библиотека:

libc

Описание:

The iofunc_read_verify() helper function checks that the client that sent the _IO_READ message actually has read access to the resource, and, if nonblock isn't NULL, sets nonblock to O_NONBLOCK or 0).

The read permission check is done against ocb->ioflag.

Note that the io_read_t message has an override flag called msg->i.xtype. This flag allows the client to override the default blocking behavior for the resource on a per-request basis. This override flag is checked, and returned in the optional nonblock.

Note that if you're reading from a directory entry, you must return struct dirent structures in the read callout for your resource manager.

You'll also need to indicate how many bytes were read. You can do this with the macro:

_IO_SET_READ_NBYTES( resmgr_context_t *ctp, int nbytes );

Возвращаемое значение:

EOK

The client has read access to this resource.

EBADF

The client doesn't have read access to this resource.

Классификация:

ЗОСРВ «Нейтрино»

Точка остановки потока

Нет

Обработчик прерываний

Нет

Обработчик сигналов

Да

В потоке

Да

Тематические ссылки:

struct dirent, io_read_t, iofunc_open(), iofunc_write_verify(), resmgr_context_t

Предыдущий раздел: Описание API системной библиотеки