syscall

Documentation

Overview

Package syscall provides support for system call for TamaGo unikernels launched in supervised mode through monitor.Exec (see monitor package).

This package is only meant to be used with `GOOS=tamago` as supported by the TamaGo framework for bare metal Go on ARM/RISC-V SoCs, see https://github.com/usbarmory/tamago.

Index

• Constants
• func Call(serviceMethod string, args interface{}, reply interface{}) error
• func Exit()
• func GetRandom(b []byte, n uint)
• func Nanotime() int64
• func NewClient() *rpc.Client
• func Print(c byte)
• func Read(trap uint, p []byte, n uint) int
• func Supervisor()
• func Write(trap uint, p []byte, n uint)
• type Stream
  • func (s *Stream) Close() error
  • func (s *Stream) Read(p []byte) (n int, err error)
  • func (s *Stream) Write(p []byte) (n int, err error)

Constants

const (
	SYS_EXIT = iota
	SYS_WRITE
	SYS_NANOTIME
	SYS_GETRANDOM
	SYS_RPC_REQ
	SYS_RPC_RES
)

Functions

func Call

func Call(serviceMethod string, args interface{}, reply interface{}) error

Call is a convenience method that issues an RPC call on a disposable client created with NewClient(), to avoid concurrent reads and writes a mutex is held to prevent interleaved invocations.

func Exit

func Exit()

Exit terminates the execution context scheduling through a system call to the supervisor.

func GetRandom

func GetRandom(b []byte, n uint)

GetRandom fills a byte array with random values through a system call to the supervisor.

func Nanotime

func Nanotime() int64

Nanotime returns the system time in nanoseconds through a system call to the supervisor.

func NewClient

func NewClient() *rpc.Client

NewClient returns a new client suitable for RPC calls to the supervisor. The client automatically closes after Call() is invoked on it the first time, therefore a new instance is needed for each call (also see Call()).

func Print

func Print(c byte)

Print prints a single character on standard output through a system call to the supervisor.

func Read

func Read(trap uint, p []byte, n uint) int

Read requests a transfer of n bytes into p from the supervisor through the syscall specified as first argument. It can be used to implement syscalls that require request/responses data streams, along with Write().

The underlying connection used by the RPC client (see NewClient()) is an example of such implementation.

func Supervisor

func Supervisor()

Supervisors triggers a supervisor call (SWI/SVC).

func Write

func Write(trap uint, p []byte, n uint)

Write requests a transfer of n bytes from p to the supervisor through the syscall specified as first argument. It can be used to implement syscalls that require request/responses data streams, along with Read().

The underlying connection used by the RPC client (see NewClient()) is an example of such implementation.

Types

type Stream

type Stream struct {
	// ReadSyscall is the syscall number associated to Read()
	ReadSyscall uint
	// ReadSyscall is the syscall number associated to Write()
	WriteSyscall uint
}

Stream implements a data stream interface to exchange data buffers between the security monitor and a lower privilege execution context over syscalls.

It is used by NewClient() to stream JSON-RPC calls from an applet and receive responses from the supervisor, over syscalls.

The implementation is not safe against concurrent reads and writes, which should be avoided.

func (*Stream) Close

func (s *Stream) Close() error

Close has no effect.

func (*Stream) Read

func (s *Stream) Read(p []byte) (n int, err error)

Read reads up to len(p) bytes into p, it never returns an error. The read is requested, through the Stream ReadSyscall, to the supervisor.

func (*Stream) Write

func (s *Stream) Write(p []byte) (n int, err error)

Write writes len(p) bytes from p to the underlying data stream, it never returns an error. The write is issued, through the Stream WriteSyscall, to the supervisor.