container: remove PATH lookup behaviour

This is way higher level than the container package and does not even work unless every path is mounted in the exact same location.

This behaviour causes nothing but confusion and problems,

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

container/container.go

@@ -27,8 +27,6 @@ type (
 	// Container represents a container environment being prepared or run.
 	// None of [Container] methods are safe for concurrent use.
 	Container struct {
-		// Name of initial process in the container.
-		name string
 		// Cgroup fd, nil to disable.
 		Cgroup *int
 		// ExtraFiles passed through to initial process in the container,
@@ -190,31 +188,12 @@ func (p *Container) Serve() error {
 	setup := p.setup
 	p.setup = nil
 
-	if p.Path != "" && !path.IsAbs(p.Path) {
+	if !path.IsAbs(p.Path) {
 		p.cancel()
 		return msg.WrapErr(EINVAL,
 			fmt.Sprintf("invalid executable path %q", p.Path))
 	}
 
-	if p.Path == "" {
-		if p.name == "" {
-			p.Path = os.Getenv("SHELL")
-			if !path.IsAbs(p.Path) {
-				p.cancel()
-				return msg.WrapErr(EBADE,
-					"no command specified and $SHELL is invalid")
-			}
-			p.name = path.Base(p.Path)
-		} else if path.IsAbs(p.name) {
-			p.Path = p.name
-		} else if v, err := exec.LookPath(p.name); err != nil {
-			p.cancel()
-			return msg.WrapErr(err, err.Error())
-		} else {
-			p.Path = v
-		}
-	}
-
 	if p.SeccompRules == nil {
 		// do not transmit nil
 		p.SeccompRules = make([]seccomp.NativeRule, 0)
@@ -251,8 +230,15 @@ func (p *Container) ProcessState() *os.ProcessState {
 	return p.cmd.ProcessState
 }
 
-func New(ctx context.Context, name string, args ...string) *Container {
-	return &Container{name: name, ctx: ctx,
-		Params: Params{Args: append([]string{name}, args...), Dir: FHSRoot, Ops: new(Ops)},
-	}
+// New returns the address to a new instance of [Container] that requires further initialisation before use.
+func New(ctx context.Context) *Container {
+	return &Container{ctx: ctx, Params: Params{Dir: FHSRoot, Ops: new(Ops)}}
+}
+
+// NewCommand calls [New] and initialises the [Params.Path] and [Params.Args] fields.
+func NewCommand(ctx context.Context, pathname, name string, args ...string) *Container {
+	z := New(ctx)
+	z.Path = pathname
+	z.Args = append([]string{name}, args...)
+	return z
 }

container/container_test.go

@@ -392,7 +392,7 @@ func testContainerCancel(
 }
 
 func TestContainerString(t *testing.T) {
-	c := container.New(t.Context(), "ldd", "/usr/bin/env")
+	c := container.NewCommand(t.Context(), "/run/current-system/sw/bin/ldd", "ldd", "/usr/bin/env")
 	c.SeccompFlags |= seccomp.AllowMultiarch
 	c.SeccompRules = seccomp.Preset(
 		seccomp.PresetExt|seccomp.PresetDenyNS|seccomp.PresetDenyTTY,

container/init_test.go

@@ -47,7 +47,7 @@ func TestMain(m *testing.M) {
 }
 
 func helperNewContainerLibPaths(ctx context.Context, libPaths *[]string, args ...string) (c *container.Container) {
-	c = container.New(ctx, helperInnerPath, args...)
+	c = container.NewCommand(ctx, helperInnerPath, "helper", args...)
 	c.Env = append(c.Env, envDoCheck+"=1")
 	c.Bind(os.Args[0], helperInnerPath, 0)
 

helper/container.go

@@ -16,7 +16,7 @@ import (
 // New initialises a Helper instance with wt as the null-terminated argument writer.
 func New(
 	ctx context.Context,
-	name string,
+	pathname *container.Absolute, name string,
 	wt io.WriterTo,
 	stat bool,
 	argF func(argsFd, statFd int) []string,
@@ -26,7 +26,7 @@ func New(
 	var args []string
 	h := new(helperContainer)
 	h.helperFiles, args = newHelperFiles(ctx, wt, stat, argF, extraFiles)
-	h.Container = container.New(ctx, name, args...)
+	h.Container = container.NewCommand(ctx, pathname.String(), name, args...)
 	h.WaitDelay = WaitDelay
 	if cmdF != nil {
 		cmdF(h.Container)

helper/container_test.go

@@ -12,7 +12,7 @@ import (
 
 func TestContainer(t *testing.T) {
 	t.Run("start empty container", func(t *testing.T) {
-		h := helper.New(t.Context(), container.Nonexistent, argsWt, false, argF, nil, nil)
+		h := helper.New(t.Context(), container.MustAbs(container.Nonexistent), "hakurei", argsWt, false, argF, nil, nil)
 
 		wantErr := "container: starting an empty container"
 		if err := h.Start(); err == nil || err.Error() != wantErr {
@@ -22,7 +22,7 @@ func TestContainer(t *testing.T) {
 	})
 
 	t.Run("valid new helper nil check", func(t *testing.T) {
-		if got := helper.New(t.Context(), "hakurei", argsWt, false, argF, nil, nil); got == nil {
+		if got := helper.New(t.Context(), container.MustAbs(container.Nonexistent), "hakurei", argsWt, false, argF, nil, nil); got == nil {
 			t.Errorf("New(%q, %q) got nil",
 				argsWt, "hakurei")
 			return
@@ -31,7 +31,7 @@ func TestContainer(t *testing.T) {
 
 	t.Run("implementation compliance", func(t *testing.T) {
 		testHelper(t, func(ctx context.Context, setOutput func(stdoutP, stderrP *io.Writer), stat bool) helper.Helper {
-			return helper.New(ctx, os.Args[0], argsWt, stat, argF, func(z *container.Container) {
+			return helper.New(ctx, container.MustAbs(os.Args[0]), "helper", argsWt, stat, argF, func(z *container.Container) {
 				setOutput(&z.Stdout, &z.Stderr)
 				z.Bind("/", "/", 0).Proc("/proc").Dev("/dev", true)
 			}, nil)

internal/app/shim_linux.go

@@ -157,13 +157,9 @@ func ShimMain() {
 		log.Fatalf("path %q is not a directory", params.Home)
 	}
 
-	var name string
-	if len(params.Container.Args) > 0 {
-		name = params.Container.Args[0]
-	}
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
 	cancelContainer.Store(&stop)
-	z := container.New(ctx, name)
+	z := container.New(ctx)
 	z.Params = *params.Container
 	z.Stdin, z.Stdout, z.Stderr = os.Stdin, os.Stdout, os.Stderr
 

ldd/exec.go

@@ -5,13 +5,17 @@ import (
 	"context"
 	"io"
 	"os"
+	"os/exec"
 	"time"
 
 	"hakurei.app/container"
 	"hakurei.app/container/seccomp"
 )
 
-const lddTimeout = 2 * time.Second
+const (
+	lddName    = "ldd"
+	lddTimeout = 2 * time.Second
+)
 
 var (
 	msgStatic      = []byte("Not a valid dynamic program")
@@ -21,8 +25,16 @@ var (
 func Exec(ctx context.Context, p string) ([]*Entry, error) {
 	c, cancel := context.WithTimeout(ctx, lddTimeout)
 	defer cancel()
-	z := container.New(c, "ldd", p)
-	z.Hostname = "hakurei-ldd"
+
+	var toolPath *container.Absolute
+	if s, err := exec.LookPath(lddName); err != nil {
+		return nil, err
+	} else if toolPath, err = container.NewAbsolute(s); err != nil {
+		return nil, err
+	}
+
+	z := container.NewCommand(c, toolPath.String(), lddName, p)
+	z.Hostname = "hakurei-" + lddName
 	z.SeccompFlags |= seccomp.AllowMultiarch
 	z.SeccompPresets |= seccomp.PresetStrict
 	stdout, stderr := new(bytes.Buffer), new(bytes.Buffer)

system/dbus/dbus_test.go

@@ -153,7 +153,7 @@ func testProxyFinaliseStartWaitCloseString(t *testing.T, useSandbox bool) {
 				t.Run("string", func(t *testing.T) {
 					wantSubstr := fmt.Sprintf("%s --args=3 --fd=4", os.Args[0])
 					if useSandbox {
-						wantSubstr = fmt.Sprintf(`argv: ["%s" "--args=3" "--fd=4"], filter: true, rules: 0, flags: 0x1, presets: 0xf`, os.Args[0])
+						wantSubstr = `argv: ["xdg-dbus-proxy" "--args=3" "--fd=4"], filter: true, rules: 0, flags: 0x1, presets: 0xf`
 					}
 					if got := p.String(); !strings.Contains(got, wantSubstr) {
 						t.Errorf("String: %q, want %q",

system/dbus/proc.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"os/exec"
 	"path"
-	"path/filepath"
 	"slices"
 	"strconv"
 	"syscall"
@@ -43,24 +42,26 @@ func (p *Proxy) Start() error {
 			cmd.Env = make([]string, 0)
 		}, nil)
 	} else {
-		toolPath := p.name
-		if filepath.Base(p.name) == p.name {
-			if s, err := exec.LookPath(p.name); err != nil {
+		var toolPath *container.Absolute
+		if a, err := container.NewAbsolute(p.name); err != nil {
+			if p.name, err = exec.LookPath(p.name); err != nil {
+				return err
+			} else if toolPath, err = container.NewAbsolute(p.name); err != nil {
 				return err
-			} else {
-				toolPath = s
 			}
+		} else {
+			toolPath = a
 		}
 
 		var libPaths []string
-		if entries, err := ldd.Exec(ctx, toolPath); err != nil {
+		if entries, err := ldd.Exec(ctx, toolPath.String()); err != nil {
 			return err
 		} else {
 			libPaths = ldd.Path(entries)
 		}
 
 		p.helper = helper.New(
-			ctx, toolPath,
+			ctx, toolPath, "xdg-dbus-proxy",
 			p.final, true,
 			argF, func(z *container.Container) {
 				z.SeccompFlags |= seccomp.AllowMultiarch
@@ -111,7 +112,7 @@ func (p *Proxy) Start() error {
 				}
 
 				// xdg-dbus-proxy bin path
-				binPath := path.Dir(toolPath)
+				binPath := path.Dir(toolPath.String())
 				z.Bind(binPath, binPath, 0)
 			}, nil)
 	}