Adding an endpoint to a solution
To ensure that a Client program can use some specific functionality via the IPC mechanism, the following is required:
- In KasperskyOS Community Edition, find the executable file (we'll call it
Server) that implements the necessary functionality. (The term "functionality" used here refers to one or more endpoints that have their own IPC interfaces) - Inhclude the CMake package containing the
Serverfile and its client library. - Add the
Serverexecutable file to the solution image. - Edit the init description so that when the solution starts, the
Einitprogram starts a new server process from theServerexecutable file and connects it, using an IPC channel, to the process started from theClientfile.You must indicate the correct name of the IPC channel so that the transport libraries can identify this channel and find its IPC handles. The correct name of the IPC channel normally matches the name of the server process class. VFS is an exception in this case.
- Edit the PSL description to allow startup of the server process and IPC interaction between the client and the server.
- In the source code of the
Clientprogram, include the server methods header file. - Link the
Clientprogram with the client library.
Example of adding a GPIO driver to a solution
KasperskyOS Community Edition includes a gpio_hw file that implements GPIO driver functionality.
The following commands connect the gpio CMake package:
.\CMakeLists.txt
...
find_package (gpio REQUIRED COMPONENTS CLIENT_LIB ENTITY)
include_directories (${gpio_INCLUDE})
...
The gpio_hw executable file is added to a solution image by using the gpio_HW_ENTITY variable, whose name can be found in the configuration file of the package at /opt/KasperskyOS-Community-Edition-<version>/sysroot-aarch64-kos/lib/cmake/gpio/gpio-config.cmake:
einit\CMakeLists.txt
...
set (ENTITIES Client ${gpio_HW_ENTITY})
...
The following strings need to be added to the init description:
init.yaml.in
...
- name: client.Client
connections:
- target: kl.drivers.GPIO
id: kl.drivers.GPIO
- name: kl.drivers.GPIO
path: gpio_hw
The following strings need to be added to the PSL description:
security.psl.in
...
execute src=Einit, dst=kl.drivers.GPIO
{
grant()
}
request src=client.Client, dst=kl.drivers.GPIO
{
grant()
}
response src=kl.drivers.GPIO, dst=client.Client
{
grant()
}
...
In the code of the Client program, you need to include the header file in which the GPIO driver methods are declared:
client.c
...
...
Finally, you need to link the Client program with the GPIO client library:
client\CMakeLists.txt
...
target_link_libraries (Client ${gpio_CLIENT_LIB})
...
To ensure correct operation of the GPIO driver, you may need to add the BSP component to the solution. To avoid overcomplicating this example, BSP is not examined here. For more details, see the gpio_output example: /opt/KasperskyOS-Community-Edition-<version>/examples/gpio_output