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>

3 files changed, 63 insertions, 272 deletions

diff --git a/helper/proc/deprecated.go b/helper/proc/deprecated.go
new file mode 100644
index 00000000..91897526
--- /dev/null
+++ b/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
+)
diff --git a/helper/proc/files.go b/helper/proc/files.go
deleted file mode 100644
index 0612718e..00000000
--- a/helper/proc/files.go
+++ /dev/null
@@ -1,162 +0,0 @@
-package proc
-
-import (
-	"context"
-	"os"
-	"os/exec"
-	"sync/atomic"
-	"syscall"
-	"testing"
-	"time"
-)
-
-var FulfillmentTimeout = 2 * time.Second
-
-func init() {
-	if testing.Testing() {
-		FulfillmentTimeout *= 10
-	}
-}
-
-// A File is an extra file with deferred initialisation.
-type File interface {
-	// Init initialises File state. Init must not be called more than once.
-	Init(fd uintptr, v **os.File) uintptr
-	// Fd returns the fd value set on initialisation.
-	Fd() uintptr
-	// ErrCount returns count of error values emitted during fulfillment.
-	ErrCount() int
-	// Fulfill is called prior to process creation and must populate its corresponding file address.
-	// Calls to dispatchErr must match the return value of ErrCount.
-	// Fulfill must not be called more than once.
-	Fulfill(ctx context.Context, dispatchErr func(error)) error
-}
-
-// ExtraFilesPre is a linked list storing addresses of [os.File].
-type ExtraFilesPre struct {
-	n *ExtraFilesPre
-	v *os.File
-}
-
-// Append grows the list by one entry and returns an address of the address of [os.File] stored in the new entry.
-func (f *ExtraFilesPre) Append() (uintptr, **os.File) { return f.append(3) }
-
-// Files returns a slice pointing to a continuous segment of memory containing all addresses stored in f in order.
-func (f *ExtraFilesPre) Files() []*os.File { return f.copy(make([]*os.File, 0, f.len())) }
-
-func (f *ExtraFilesPre) append(i uintptr) (uintptr, **os.File) {
-	if f.n == nil {
-		f.n = new(ExtraFilesPre)
-		return i, &f.v
-	}
-	return f.n.append(i + 1)
-}
-func (f *ExtraFilesPre) len() uintptr {
-	if f == nil {
-		return 0
-	}
-	return f.n.len() + 1
-}
-func (f *ExtraFilesPre) copy(e []*os.File) []*os.File {
-	if f == nil {
-		// the public methods ensure the first call is never nil;
-		// the last element is unused, slice it off here
-		return e[:len(e)-1]
-	}
-	return f.n.copy(append(e, f.v))
-}
-
-// Fulfill calls the [File.Fulfill] method on all files, starts cmd and blocks until all fulfillment completes.
-func Fulfill(ctx context.Context,
-	v *[]*os.File, start func() error,
-	files []File, extraFiles *ExtraFilesPre,
-) (err error) {
-	var ecs int
-	for _, o := range files {
-		ecs += o.ErrCount()
-	}
-	ec := make(chan error, ecs)
-
-	c, cancel := context.WithTimeout(ctx, FulfillmentTimeout)
-	defer cancel()
-
-	for _, f := range files {
-		err = f.Fulfill(c, makeDispatchErr(f, ec))
-		if err != nil {
-			return
-		}
-	}
-
-	*v = extraFiles.Files()
-	if err = start(); err != nil {
-		return
-	}
-
-	for ecs > 0 {
-		select {
-		case err = <-ec:
-			ecs--
-			if err != nil {
-				break
-			}
-		case <-ctx.Done():
-			err = syscall.ECANCELED
-			break
-		}
-	}
-	return
-}
-
-// InitFile initialises f as part of the slice extraFiles points to,
-// and returns its final fd value.
-func InitFile(f File, extraFiles *ExtraFilesPre) (fd uintptr) { return f.Init(extraFiles.Append()) }
-
-// BaseFile implements the Init method of the File interface and provides indirect access to extra file state.
-type BaseFile struct {
-	fd uintptr
-	v  **os.File
-}
-
-func (f *BaseFile) Init(fd uintptr, v **os.File) uintptr {
-	if v == nil || fd < 3 {
-		panic("invalid extra file initial state")
-	}
-	if f.v != nil {
-		panic("extra file initialised twice")
-	}
-	f.fd, f.v = fd, v
-	return fd
-}
-
-func (f *BaseFile) Fd() uintptr {
-	if f.v == nil {
-		panic("use of uninitialised extra file")
-	}
-	return f.fd
-}
-
-func (f *BaseFile) Set(v *os.File) {
-	*f.v = v // runtime guards against use before init
-}
-
-func makeDispatchErr(f File, ec chan<- error) func(error) {
-	c := new(atomic.Int32)
-	c.Store(int32(f.ErrCount()))
-	return func(err error) {
-		if c.Add(-1) < 0 {
-			panic("unexpected error dispatches")
-		}
-		ec <- err
-	}
-}
-
-func ExtraFile(cmd *exec.Cmd, f *os.File) (fd uintptr) {
-	return ExtraFileSlice(&cmd.ExtraFiles, f)
-}
-
-func ExtraFileSlice(extraFiles *[]*os.File, f *os.File) (fd uintptr) {
-	// ExtraFiles: If non-nil, entry i becomes file descriptor 3+i.
-	fd = uintptr(3 + len(*extraFiles))
-	*extraFiles = append(*extraFiles, f)
-	return
-}
diff --git a/helper/proc/pipe.go b/helper/proc/pipe.go
deleted file mode 100644
index 838c4ae4..00000000
--- a/helper/proc/pipe.go
+++ /dev/null
@@ -1,110 +0,0 @@
-package proc
-
-import (
-	"context"
-	"errors"
-	"io"
-	"os"
-	"runtime"
-)
-
-// NewWriterTo returns a [File] that receives content from wt on fulfillment.
-func NewWriterTo(wt io.WriterTo) File { return &writeToFile{wt: wt} }
-
-// writeToFile exports the read end of a pipe with data written by an [io.WriterTo].
-type writeToFile struct {
-	wt io.WriterTo
-	BaseFile
-}
-
-func (f *writeToFile) ErrCount() int { return 3 }
-func (f *writeToFile) Fulfill(ctx context.Context, dispatchErr func(error)) error {
-	r, w, err := os.Pipe()
-	if err != nil {
-		return err
-	}
-	f.Set(r)
-
-	done := make(chan struct{})
-	go func() {
-		_, err = f.wt.WriteTo(w)
-		dispatchErr(err)
-		dispatchErr(w.Close())
-		close(done)
-		runtime.KeepAlive(r)
-	}()
-	go func() {
-		select {
-		case <-done:
-			dispatchErr(nil)
-		case <-ctx.Done():
-			dispatchErr(w.Close()) // this aborts WriteTo with file already closed
-			runtime.KeepAlive(r)
-		}
-	}()
-
-	return nil
-}
-
-// NewStat returns a [File] implementing the behaviour
-// of the receiving end of xdg-dbus-proxy stat fd.
-func NewStat(s *io.Closer) File { return &statFile{s: s} }
-
-var (
-	ErrStatFault = errors.New("generic stat fd fault")
-	ErrStatRead  = errors.New("unexpected stat behaviour")
-)
-
-// statFile implements xdg-dbus-proxy stat fd behaviour.
-type statFile struct {
-	s *io.Closer
-	BaseFile
-}
-
-func (f *statFile) ErrCount() int { return 2 }
-func (f *statFile) Fulfill(ctx context.Context, dispatchErr func(error)) error {
-	r, w, err := os.Pipe()
-	if err != nil {
-		return err
-	}
-	f.Set(w)
-
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		var n int
-
-		n, err = r.Read(make([]byte, 1))
-		switch n {
-		case -1:
-			if err == nil {
-				err = ErrStatFault
-			}
-			dispatchErr(err)
-		case 0:
-			if err == nil {
-				err = ErrStatRead
-			}
-			dispatchErr(err)
-		case 1:
-			dispatchErr(err)
-		default:
-			panic("unreachable")
-		}
-		runtime.KeepAlive(w)
-	}()
-
-	go func() {
-		select {
-		case <-done:
-			dispatchErr(nil)
-		case <-ctx.Done():
-			dispatchErr(r.Close()) // this aborts Read with file already closed
-			runtime.KeepAlive(w)
-		}
-	}()
-
-	// this gets closed by the caller
-	*f.s = r
-	return nil
-}