multi_vfs_dns_client example
This example shows how to use an external DNS server in KasperskyOS.
The example also demonstrates the use of various virtual file systems (VFS) in a single solution. The example uses different VFS to access the functions for working with the file system and functions for working with the network:
VfsNetis used for working with the network.VfsRamfsandVfsSdCardFsare used for working with the file system.
The Client entity uses standard libc library functions for accessing a DNS service, which are converted to calls to VFS entities via IPC.
The Env entity is used to pass environment variables and main function arguments to other entities.
The CMake system, which is included with KasperskyOS Community Edition, is used to build and run the example.
Supplied resources
The following configuration files are included in the example:
./resources/include/config.h.incontains a description of the backend file system that will be used in the solution:sdcardorramfs.Each backend in the solution also uses a separate VFS: respectively
VfsSdCardFsorVfsRamfs.- The
./resources/ramfs/etcand/resources/sdcard/etcdirectories contain configuration files for the VFS entities.
Example files
The code of the example and build scripts are available at the following path:
/opt/KasperskyOS-Community-Edition-<version>/examples/multi_vfs_dns_client
Building and running example
To run an example on QEMU, go to the directory containing the example, build the example and run the following commands:
$ cd build/einit
# Before running the following command, be sure that the path to
# the directory with the qemu-system-arm executable file is saved in
# the PATH environment variable. If it is not there,
# add it to the PATH variable.
$ qemu-system-arm -m 2048 -machine vexpress-a15 -nographic -monitor none -sd sdcard0.img -kernel kos-qemu-image
See also Building and running examples section.