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/proc/deprecated.go

@@ -0,0 +1,63 @@
+// Deprecated: This package will be removed in 0.4.
+package proc
+
+import (
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"time"
+	_ "unsafe" // for go:linkname
+
+	"hakurei.app/internal/helper/proc"
+)
+
+//go:linkname FulfillmentTimeout hakurei.app/internal/helper/proc.FulfillmentTimeout
+var FulfillmentTimeout time.Duration
+
+// A File is an extra file with deferred initialisation.
+type File = proc.File
+
+// ExtraFilesPre is a linked list storing addresses of [os.File].
+type ExtraFilesPre = proc.ExtraFilesPre
+
+// Fulfill calls the [File.Fulfill] method on all files, starts cmd and blocks until all fulfillment completes.
+//
+//go:linkname Fulfill hakurei.app/internal/helper/proc.Fulfill
+func Fulfill(ctx context.Context,
+	v *[]*os.File, start func() error,
+	files []File, extraFiles *ExtraFilesPre,
+) (err error)
+
+// InitFile initialises f as part of the slice extraFiles points to,
+// and returns its final fd value.
+//
+//go:linkname InitFile hakurei.app/internal/helper/proc.InitFile
+func InitFile(f File, extraFiles *ExtraFilesPre) (fd uintptr)
+
+// BaseFile implements the Init method of the File interface and provides indirect access to extra file state.
+type BaseFile = proc.BaseFile
+
+//go:linkname ExtraFile hakurei.app/internal/helper/proc.ExtraFile
+func ExtraFile(cmd *exec.Cmd, f *os.File) (fd uintptr)
+
+//go:linkname ExtraFileSlice hakurei.app/internal/helper/proc.ExtraFileSlice
+func ExtraFileSlice(extraFiles *[]*os.File, f *os.File) (fd uintptr)
+
+// NewWriterTo returns a [File] that receives content from wt on fulfillment.
+//
+//go:linkname NewWriterTo hakurei.app/internal/helper/proc.NewWriterTo
+func NewWriterTo(wt io.WriterTo) File
+
+// NewStat returns a [File] implementing the behaviour
+// of the receiving end of xdg-dbus-proxy stat fd.
+//
+//go:linkname NewStat hakurei.app/internal/helper/proc.NewStat
+func NewStat(s *io.Closer) File
+
+var (
+	//go:linkname ErrStatFault hakurei.app/internal/helper/proc.ErrStatFault
+	ErrStatFault error
+	//go:linkname ErrStatRead hakurei.app/internal/helper/proc.ErrStatRead
+	ErrStatRead error
+)