process.go

// SPDX-License-Identifier: Apache-2.0
// Copyright 2014 Docker, Inc.
// Copyright 2023 Unikraft GmbH and The KraftKit Authors

package libmocktainer

import (
	"errors"
	"io"
	"math"
	"os"
)

var errInvalidProcess = errors.New("invalid process")

type processOperations interface {
	wait() (*os.ProcessState, error)
	signal(sig os.Signal) error
	pid() int
}

// Process specifies the configuration and IO for a process inside
// a container.
type Process struct {
	// The command to be run followed by any arguments.
	Args []string

	// Env specifies the environment variables for the process.
	Env []string

	// Stdin is a pointer to a reader which provides the standard input stream.
	Stdin io.Reader

	// Stdout is a pointer to a writer which receives the standard output stream.
	Stdout io.Writer

	// Stderr is a pointer to a writer which receives the standard error stream.
	Stderr io.Writer

	// ExtraFiles specifies additional open files to be inherited by the container
	ExtraFiles []*os.File

	// AppArmorProfile specifies the profile to apply to the process and is
	// changed at the time the process is execed
	AppArmorProfile string

	// Label specifies the label to apply to the process.  It is commonly used by selinux
	Label string

	ops processOperations

	// LogLevel is a string containing a numeric representation of the current
	// log level (i.e. "4", but never "info"). It is passed on to runc init as
	// _LIBCONTAINER_LOGLEVEL environment variable.
	LogLevel string
}

// Wait waits for the process to exit.
// Wait releases any resources associated with the Process
func (p Process) Wait() (*os.ProcessState, error) {
	if p.ops == nil {
		return nil, errInvalidProcess
	}
	return p.ops.wait()
}

// Pid returns the process ID
func (p Process) Pid() (int, error) {
	// math.MinInt32 is returned here, because it's invalid value
	// for the kill() system call.
	if p.ops == nil {
		return math.MinInt32, errInvalidProcess
	}
	return p.ops.pid(), nil
}

// Signal sends a signal to the Process.
func (p Process) Signal(sig os.Signal) error {
	if p.ops == nil {
		return errInvalidProcess
	}
	return p.ops.signal(sig)
}