Executing system calls (syscalls.h)

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Executing system calls (syscalls.h)

May 21, 2024

ID libkos_syscalls_api

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This API is defined in the header file sysroot-*-kos/include/coresrv/syscalls.h from the KasperskyOS SDK.

The API allows execution of the Call(), Recv(), and Reply() system calls for sending and receiving IPC messages.

Information about API functions is provided in the table below.

Using the API

Pointers to buffers containing the constant part and arena of IPC messages are passed to API functions by using an IPC message header whose type is defined in the header file sysroot-*-kos/include/ipc/if_rend.h from the KasperskyOS SDK. Prior to API function calls, the headers of IPC messages must be bound to buffers containing the constant part and arena of IPC messages. To do so, use the PackInMsg() and PackOutMsg() functions that are declared in the header file sysroot-*-kos/include/services/rtl/nk_msg.h from the KasperskyOS SDK.

The Call(), CallEx(), Recv(), and RecvEx() functions lock execution of the calling thread while waiting for the system calls to complete. The CallEx() and RecvEx() functions let you define the timeout for completion of a system call. When this timeout is reached, an uncompleted system call is interrupted and the thread that is waiting for its completion resumes execution. A system call is also interrupted if an error occurs during its execution (such as an error due to termination of a server process). If a thread waiting on the completion of a system call is terminated externally, this system call is also interrupted. A system call executed by the CallEx() or RecvEx() function can be interrupted (for example, for correct termination of a process) by using the API ipc_api.h.

If a system call was interrupted using the API ipc_api.h, the CallEx() and RecvEx() functions return the error code rcIpcInterrupt. If IPC message transmission is prohibited by security mechanisms (such as the Kaspersky Security Module or a capability-based security mechanism implemented by the KasperskyOS kernel), the Call(), CallEx(), and Reply() functions return the error code rcSecurityDisallow.

Information about API functions

syscalls.h functions

Function	Information about the function
`Call()`	Purpose Executes the `Call()` system call with an unlimited timeout for its completion. Parameters [in] `handle` – client IPC handle. [in] `msgOut` – pointer to the header of IPC requests. [in,out] `msgIn` – pointer to the header of IPC responses. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code.
`CallEx()`	Purpose Executes the `Call()` system call with a defined timeout for its completion and the capability to interrupt its execution. Parameters [in] `handle` – client IPC handle. [in] `msgOut` – pointer to the header of IPC requests. [in,out] `msgIn` – pointer to the header of IPC responses. [in] `mdelay` – timeout (in milliseconds) for completion of a `Call()` system call, or `INFINITE_TIMEOUT` to define an unlimited timeout. [in,optional] `syncHandle` – handle of the IPC synchronization object, or `INVALID_HANDLE` if an interrupt of the `Call()` system call is not required. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code.
`Reply()`	Purpose Executes the `Reply()` system call. Parameters [in] `handle` – server IPC handle. [in] `msgOut` – pointer to the header of IPC responses. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code.
`Recv()`	Purpose Executes the `Recv()` system call with an unlimited timeout for its completion. Parameters [in] `handle` – server IPC handle. [in,out] `msgIn` – pointer to the header of IPC requests. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code.
`RecvEx()`	Purpose Executes the `Recv()` system call with a defined timeout for its completion and the capability to interrupt its execution. Parameters [in] `handle` – server IPC handle. [in,out] `msgIn` – pointer to the header of IPC responses. [in] `mdelay` – timeout (in milliseconds) for completion of a `Recv()` system call, or `INFINITE_TIMEOUT` to define an unlimited timeout. [in,optional] `syncHandle` – handle of the IPC synchronization object, or `INVALID_HANDLE` if an interrupt of the `Recv()` system call is not required. Returned values If successful, the function returns `rcOk`, otherwise it returns an error code.

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