Contents of the VFS component

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File systems and network

Contents of the VFS component

21 May 2024

ID vfs_overview

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The VFS component implements the virtual file system. In the KasperskyOS SDK, the VFS component consists of a set of executable files, libraries, formal specification files and header files that enable the use of file systems and/or a network stack.

VFS libraries

The vfs CMake package contains the following libraries:

vfs_fs contains implementations of the devfs, ramfs and ROMFS file systems, and adds implementations of other file systems to VFS.
vfs_net contains the implementation of the devfs file system and the network stack.
vfs_imp contains the vfs_fs and vfs_net libraries.
vfs_remote is the client transport library that converts local calls into IPC requests to VFS and receives IPC responses.
vfs_server is the VFS server transport library that receives IPC requests, converts them into local calls, and sends IPC responses.
vfs_local is used to include VFS functionality in a program.

VFS executable files

The precompiled_vfs CMake package contains the following executable files:

VfsRamFs
VfsSdCardFs
VfsNet

The VfsRamFs and VfsSdCardFs executable files include the vfs_server, vfs_fs, vfat and lwext4 libraries. The VfsNet executable file includes the vfs_server, vfs_imp libraries.

Each of these executable files has its own default values for startup parameters and environment variables.

Formal specification files and header files of VFS

The sysroot-*-kos/include/kl directory from the KasperskyOS SDK contains the following VFS files:

Formal specification files VfsRamFs.edl, VfsSdCardFs.edl, VfsNet.edl and VfsEntity.edl, and the header files generated from them.
Formal specification file Vfs.cdl and the header file Vfs.cdl.h generated from it.
Formal specification files Vfs*.idl and the header files generated from them.

Libc library API supported by VFS

VFS functionality is available to programs through the API provided by the libc library.

The functions implemented by the vfs_fs and vfs_net libraries are presented in the table below. The * character denotes the functions that are optionally included in the vfs_fs library (depending on the library build parameters).

Functions implemented by the vfs_fs library

`mount()`	`unlink()`	`ftruncate()`	`lsetxattr()*`
`umount()`	`rmdir()`	`chdir()`	`fsetxattr()*`
`open()`	`mkdir()`	`fchdir()`	`getxattr()*`
`openat()`	`mkdirat()`	`chmod()`	`lgetxattr()*`
`read()`	`fcntl()`	`fchmod()`	`fgetxattr()*`
`readv()`	`statvfs()`	`fchmodat()`	`listxattr()*`
`write()`	`fstatvfs()`	`chroot()`	`llistxattr()*`
`writev()`	`getvfsstat()`	`fsync()`	`flistxattr()*`
`stat()`	`pipe()`	`fdatasync()`	`removexattr()*`
`lstat()`	`futimens()`	`pread()`	`lremovexattr()*`
`fstat()`	`utimensat()`	`pwrite()`	`fremovexattr()*`
`fstatat()`	`link()`	`sendfile()`	`acl_set_file()*`
`lseek()`	`linkat()`	`getdents()`	`acl_get_file()*`
`close()`	`symlink()`	`sync()`	`acl_delete_def_file()*`
`rename()`	`symlinkat()`	`ioctl()`
`renameat()`	`unlinkat()`	`setxattr()*`

Functions implemented by the vfs_net library

`read()`	`bind()`	`getsockname()`	`recvfrom()`
`readv()`	`listen()`	`gethostbyname()`	`recvmsg()`
`write()`	`connect()`	`getnetbyaddr()`	`send()`
`writev()`	`accept()`	`getnetbyname()`	`sendto()`
`fstat()`	`poll()`	`getnetent()`	`sendmsg()`
`close()`	`shutdown()`	`setnetent()`	`ioctl()`
`fcntl()`	`getnameinfo()`	`endnetent()`	`sysctl()`
`fstatvfs()`	`getaddrinfo()`	`getprotobyname()`
`pipe()`	`freeaddrinfo()`	`getprotobynumber()`
`futimens()`	`getifaddrs()`	`getsockopt()`
`socket()`	`freeifaddrs()`	`setsockopt()`
`socketpair()`	`getpeername()`	`recv()`

If there is no implementation of a called function in VFS, the EIO error code is returned.

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