internal/helper: relocate from helper

This package is ugly and is pending removal only kept alive by xdg-dbus-proxy.

Its exported symbols are made available until v0.4.0 where it will be removed for #24.

Signed-off-by: Ophestra <cat@gensokyo.uk>

helper/deprecated.go

@@ -0,0 +1,73 @@
+// Package helper exposes the internal/helper package.
+//
+// Deprecated: This package will be removed in 0.4.
+package helper
+
+import (
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"time"
+	_ "unsafe" // for go:linkname
+
+	"hakurei.app/container"
+	"hakurei.app/container/check"
+	"hakurei.app/internal/helper"
+	"hakurei.app/message"
+)
+
+//go:linkname WaitDelay hakurei.app/internal/helper.WaitDelay
+var WaitDelay time.Duration
+
+const (
+	// HakureiHelper is set to 1 when args fd is enabled and 0 otherwise.
+	HakureiHelper = helper.HakureiHelper
+	// HakureiStatus is set to 1 when stat fd is enabled and 0 otherwise.
+	HakureiStatus = helper.HakureiStatus
+)
+
+type Helper = helper.Helper
+
+// NewCheckedArgs returns a checked null-terminated argument writer for a copy of args.
+//
+//go:linkname NewCheckedArgs hakurei.app/internal/helper.NewCheckedArgs
+func NewCheckedArgs(args ...string) (wt io.WriterTo, err error)
+
+// MustNewCheckedArgs returns a checked null-terminated argument writer for a copy of args.
+// If s contains a NUL byte this function panics instead of returning an error.
+//
+//go:linkname MustNewCheckedArgs hakurei.app/internal/helper.MustNewCheckedArgs
+func MustNewCheckedArgs(args ...string) io.WriterTo
+
+// NewDirect initialises a new direct Helper instance with wt as the null-terminated argument writer.
+// Function argF returns an array of arguments passed directly to the child process.
+//
+//go:linkname NewDirect hakurei.app/internal/helper.NewDirect
+func NewDirect(
+	ctx context.Context,
+	name string,
+	wt io.WriterTo,
+	stat bool,
+	argF func(argsFd, statFd int) []string,
+	cmdF func(cmd *exec.Cmd),
+	extraFiles []*os.File,
+) Helper
+
+// New initialises a Helper instance with wt as the null-terminated argument writer.
+//
+//go:linkname New hakurei.app/internal/helper.New
+func New(
+	ctx context.Context,
+	msg message.Msg,
+	pathname *check.Absolute, name string,
+	wt io.WriterTo,
+	stat bool,
+	argF func(argsFd, statFd int) []string,
+	cmdF func(z *container.Container),
+	extraFiles []*os.File,
+) Helper
+
+// InternalHelperStub is an internal function but exported because it is cross-package;
+// it is part of the implementation of the helper stub.
+func InternalHelperStub() { helper.InternalHelperStub() }