Connecting a client entity to one or two VFS entities
Calls of network- and file POSIX functions can be forwarded to two separate VFS components by connecting a client entity to two different VFS entities. If such data stream separation is not required (for example, if the client only works with the network), connecting the client entity to a single VFS entity is enough.
Connecting to one VFS entity
The name of the IPC channel between the client entity and the VFS entity must be defined by the _VFS_CONNECTION_ID macro declared in the vfs/defs.h file. In this case, "network" calls and "file" calls will be sent to this VFS entity.
Example:
init.yaml
- name: ClientEntity
connections:
- target: VfsEntity
id: {var: _VFS_CONNECTION_ID, include: vfs/defs.h}
- name: VfsEntity
Connecting to two VFS entities
Let's examine a client entity that is connected to two different VFS entities. We will name them "network" VFS and "file" VFS.
The _VFS_NETWORK_BACKEND environment variable is used so that "network" calls from the client entity are sent only to the "network" VFS:
- For the "network" VFS entity:
_VFS_NETWORK_BACKEND=server:<name of the IPC channel to the "network" VFS> - For the client entity:
_VFS_NETWORK_BACKEND=client: <name of the IPC channel to the "network" VFS>
The analogous _VFS_FILESYSTEM_BACKEND environment variable is used to send "file" calls:
- For the "file" VFS entity:
_VFS_FILESYSTEM_BACKEND=server:<name of the IPC channel to the "file" VFS> - For the client entity:
_VFS_FILESYSTEM_BACKEND=client: <name of the IPC channel to the "file" VFS>
As a result, the functions for working with the network and files will be sent to two different VFS entities.
In the next example, the Client entity is connected to two VFS entities – the "network" VfsFirst entity and the "file" VfsSecond entity:
init.yaml
entities:
- name: Env
- name: Client
connections:
- target: Env
id: {var: ENV_SERVICE_NAME, include: env/env.h}
- target: VfsFirst
id: VFS1
- target: VfsSecond
id: VFS2
- name: VfsFirst
connections:
- target: Env
id: {var: ENV_SERVICE_NAME, include: env/env.h}
- name: VfsSecond
connections:
- target: Env
id: {var: ENV_SERVICE_NAME, include: env/env.h}
Env entity code:
env.c
int main(void)
{
const char* vfs_first_args[] = { "_VFS_NETWORK_BACKEND=server:VFS1" };
ENV_REGISTER_VARS("VfsFirst", vfs_first_args);
const char* vfs_second_args[] = { "_VFS_FILESYSTEM_BACKEND=server:VFS2" };
ENV_REGISTER_VARS("VfsSecond", vfs_second_args);
const char* client_envs[] = { "_VFS_NETWORK_BACKEND=client:VFS1", "_VFS_FILESYSTEM_BACKEND=client:VFS2" };
ENV_REGISTER_VARS("Client", client_envs);
envServerRun();
return EXIT_SUCCESS;
}
Please also refer to the multi_vfs_dhcpcd, multi_vfs_dns_client and multi_vfs_ntpd examples provided in KasperskyOS Community Edition.