sandbox: document less obvious parts of setup

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

1 files changed, 0 insertions, 426 deletions

diff --git a/sandbox/sequential.go b/sandbox/sequential.go
deleted file mode 100644
index 39a7525d..00000000
--- a/sandbox/sequential.go
+++ /dev/null
@@ -1,426 +0,0 @@
-package sandbox
-
-import (
-	"encoding/gob"
-	"fmt"
-	"math"
-	"os"
-	"path"
-	"path/filepath"
-	"slices"
-	"strings"
-	"syscall"
-	"unsafe"
-)
-
-func init() { gob.Register(new(BindMount)) }
-
-// BindMount bind mounts host path Source on container path Target.
-type BindMount struct {
-	Source, SourceFinal, Target string
-
-	Flags int
-}
-
-const (
-	BindOptional = 1 << iota
-	BindWritable
-	BindDevice
-)
-
-func (b *BindMount) early(*Params) error {
-	if !path.IsAbs(b.Source) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", b.Source))
-	}
-
-	if v, err := filepath.EvalSymlinks(b.Source); err != nil {
-		if os.IsNotExist(err) && b.Flags&BindOptional != 0 {
-			b.SourceFinal = "\x00"
-			return nil
-		}
-		return wrapErrSelf(err)
-	} else {
-		b.SourceFinal = v
-		return nil
-	}
-}
-
-func (b *BindMount) apply(*Params) error {
-	if b.SourceFinal == "\x00" {
-		if b.Flags&BindOptional == 0 {
-			// unreachable
-			return syscall.EBADE
-		}
-		return nil
-	}
-
-	if !path.IsAbs(b.SourceFinal) || !path.IsAbs(b.Target) {
-		return msg.WrapErr(syscall.EBADE,
-			"path is not absolute")
-	}
-
-	source := toHost(b.SourceFinal)
-	target := toSysroot(b.Target)
-
-	// this perm value emulates bwrap behaviour as it clears bits from 0755 based on
-	// op->perms which is never set for any bind setup op so always results in 0700
-	if fi, err := os.Stat(source); err != nil {
-		return wrapErrSelf(err)
-	} else if fi.IsDir() {
-		if err = os.MkdirAll(target, 0700); err != nil {
-			return wrapErrSelf(err)
-		}
-	} else if err = ensureFile(target, 0444, 0700); err != nil {
-		return err
-	}
-
-	var flags uintptr = syscall.MS_REC
-	if b.Flags&BindWritable == 0 {
-		flags |= syscall.MS_RDONLY
-	}
-	if b.Flags&BindDevice == 0 {
-		flags |= syscall.MS_NODEV
-	}
-
-	return hostProc.bindMount(source, target, flags, b.SourceFinal == b.Target)
-}
-
-func (b *BindMount) Is(op Op) bool { vb, ok := op.(*BindMount); return ok && *b == *vb }
-func (*BindMount) prefix() string  { return "mounting" }
-func (b *BindMount) String() string {
-	if b.Source == b.Target {
-		return fmt.Sprintf("%q flags %#x", b.Source, b.Flags)
-	}
-	return fmt.Sprintf("%q on %q flags %#x", b.Source, b.Target, b.Flags&BindWritable)
-}
-func (f *Ops) Bind(source, target string, flags int) *Ops {
-	*f = append(*f, &BindMount{source, "", target, flags})
-	return f
-}
-
-func init() { gob.Register(new(MountProc)) }
-
-// MountProc mounts a private instance of proc.
-type MountProc string
-
-func (p MountProc) early(*Params) error { return nil }
-func (p MountProc) apply(params *Params) error {
-	v := string(p)
-
-	if !path.IsAbs(v) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", v))
-	}
-
-	target := toSysroot(v)
-	if err := os.MkdirAll(target, params.ParentPerm); err != nil {
-		return wrapErrSelf(err)
-	}
-	return wrapErrSuffix(syscall.Mount("proc", target, "proc",
-		syscall.MS_NOSUID|syscall.MS_NOEXEC|syscall.MS_NODEV, ""),
-		fmt.Sprintf("cannot mount proc on %q:", v))
-}
-
-func (p MountProc) Is(op Op) bool  { vp, ok := op.(MountProc); return ok && p == vp }
-func (MountProc) prefix() string   { return "mounting" }
-func (p MountProc) String() string { return fmt.Sprintf("proc on %q", string(p)) }
-func (f *Ops) Proc(dest string) *Ops {
-	*f = append(*f, MountProc(dest))
-	return f
-}
-
-func init() { gob.Register(new(MountDev)) }
-
-// MountDev mounts part of host dev.
-type MountDev string
-
-func (d MountDev) early(*Params) error { return nil }
-func (d MountDev) apply(params *Params) error {
-	v := string(d)
-
-	if !path.IsAbs(v) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", v))
-	}
-	target := toSysroot(v)
-
-	if err := mountTmpfs("devtmpfs", v, 0, params.ParentPerm); err != nil {
-		return err
-	}
-
-	for _, name := range []string{"null", "zero", "full", "random", "urandom", "tty"} {
-		targetPath := toSysroot(path.Join(v, name))
-		if err := ensureFile(targetPath, 0444, params.ParentPerm); err != nil {
-			return err
-		}
-		if err := hostProc.bindMount(
-			toHost("/dev/"+name),
-			targetPath,
-			0,
-			true,
-		); err != nil {
-			return err
-		}
-	}
-	for i, name := range []string{"stdin", "stdout", "stderr"} {
-		if err := os.Symlink(
-			"/proc/self/fd/"+string(rune(i+'0')),
-			path.Join(target, name),
-		); err != nil {
-			return wrapErrSelf(err)
-		}
-	}
-	for _, pair := range [][2]string{
-		{"/proc/self/fd", "fd"},
-		{"/proc/kcore", "core"},
-		{"pts/ptmx", "ptmx"},
-	} {
-		if err := os.Symlink(pair[0], path.Join(target, pair[1])); err != nil {
-			return wrapErrSelf(err)
-		}
-	}
-
-	devPtsPath := path.Join(target, "pts")
-	for _, name := range []string{path.Join(target, "shm"), devPtsPath} {
-		if err := os.Mkdir(name, params.ParentPerm); err != nil {
-			return wrapErrSelf(err)
-		}
-	}
-
-	if err := syscall.Mount("devpts", devPtsPath, "devpts",
-		syscall.MS_NOSUID|syscall.MS_NOEXEC,
-		"newinstance,ptmxmode=0666,mode=620"); err != nil {
-		return wrapErrSuffix(err,
-			fmt.Sprintf("cannot mount devpts on %q:", devPtsPath))
-	}
-
-	if params.Flags&FAllowTTY != 0 {
-		var buf [8]byte
-		if _, _, errno := syscall.Syscall(
-			syscall.SYS_IOCTL, 1, syscall.TIOCGWINSZ,
-			uintptr(unsafe.Pointer(&buf[0])),
-		); errno == 0 {
-			consolePath := toSysroot(path.Join(v, "console"))
-			if err := ensureFile(consolePath, 0444, params.ParentPerm); err != nil {
-				return err
-			}
-			if name, err := os.Readlink(hostProc.stdout()); err != nil {
-				return wrapErrSelf(err)
-			} else if err = hostProc.bindMount(
-				toHost(name),
-				consolePath,
-				0,
-				false,
-			); err != nil {
-				return err
-			}
-		}
-	}
-
-	return nil
-}
-
-func (d MountDev) Is(op Op) bool  { vd, ok := op.(MountDev); return ok && d == vd }
-func (MountDev) prefix() string   { return "mounting" }
-func (d MountDev) String() string { return fmt.Sprintf("dev on %q", string(d)) }
-func (f *Ops) Dev(dest string) *Ops {
-	*f = append(*f, MountDev(dest))
-	return f
-}
-
-func init() { gob.Register(new(MountMqueue)) }
-
-// MountMqueue mounts a private mqueue instance on container Path.
-type MountMqueue string
-
-func (m MountMqueue) early(*Params) error { return nil }
-func (m MountMqueue) apply(params *Params) error {
-	v := string(m)
-
-	if !path.IsAbs(v) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", v))
-	}
-
-	target := toSysroot(v)
-	if err := os.MkdirAll(target, params.ParentPerm); err != nil {
-		return wrapErrSelf(err)
-	}
-	return wrapErrSuffix(syscall.Mount("mqueue", target, "mqueue",
-		syscall.MS_NOSUID|syscall.MS_NOEXEC|syscall.MS_NODEV, ""),
-		fmt.Sprintf("cannot mount mqueue on %q:", v))
-}
-
-func (m MountMqueue) Is(op Op) bool  { vm, ok := op.(MountMqueue); return ok && m == vm }
-func (MountMqueue) prefix() string   { return "mounting" }
-func (m MountMqueue) String() string { return fmt.Sprintf("mqueue on %q", string(m)) }
-func (f *Ops) Mqueue(dest string) *Ops {
-	*f = append(*f, MountMqueue(dest))
-	return f
-}
-
-func init() { gob.Register(new(MountTmpfs)) }
-
-// MountTmpfs mounts tmpfs on container Path.
-type MountTmpfs struct {
-	Path string
-	Size int
-	Perm os.FileMode
-}
-
-func (t *MountTmpfs) early(*Params) error { return nil }
-func (t *MountTmpfs) apply(*Params) error {
-	if !path.IsAbs(t.Path) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", t.Path))
-	}
-	if t.Size < 0 || t.Size > math.MaxUint>>1 {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("size %d out of bounds", t.Size))
-	}
-	return mountTmpfs("tmpfs", t.Path, t.Size, t.Perm)
-}
-
-func (t *MountTmpfs) Is(op Op) bool  { vt, ok := op.(*MountTmpfs); return ok && *t == *vt }
-func (*MountTmpfs) prefix() string   { return "mounting" }
-func (t *MountTmpfs) String() string { return fmt.Sprintf("tmpfs on %q size %d", t.Path, t.Size) }
-func (f *Ops) Tmpfs(dest string, size int, perm os.FileMode) *Ops {
-	*f = append(*f, &MountTmpfs{dest, size, perm})
-	return f
-}
-
-func init() { gob.Register(new(Symlink)) }
-
-// Symlink creates a symlink in the container filesystem.
-type Symlink [2]string
-
-func (l *Symlink) early(*Params) error {
-	if strings.HasPrefix(l[0], "*") {
-		l[0] = l[0][1:]
-		if !path.IsAbs(l[0]) {
-			return msg.WrapErr(syscall.EBADE,
-				fmt.Sprintf("path %q is not absolute", l[0]))
-		}
-		if name, err := os.Readlink(l[0]); err != nil {
-			return wrapErrSelf(err)
-		} else {
-			l[0] = name
-		}
-	}
-	return nil
-}
-func (l *Symlink) apply(params *Params) error {
-	// symlink target is an arbitrary path value, so only validate link name here
-	if !path.IsAbs(l[1]) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", l[1]))
-	}
-
-	target := toSysroot(l[1])
-	if err := os.MkdirAll(path.Dir(target), params.ParentPerm); err != nil {
-		return wrapErrSelf(err)
-	}
-	if err := os.Symlink(l[0], target); err != nil {
-		return wrapErrSelf(err)
-	}
-	return nil
-}
-
-func (l *Symlink) Is(op Op) bool  { vl, ok := op.(*Symlink); return ok && *l == *vl }
-func (*Symlink) prefix() string   { return "creating" }
-func (l *Symlink) String() string { return fmt.Sprintf("symlink on %q target %q", l[1], l[0]) }
-func (f *Ops) Link(target, linkName string) *Ops {
-	*f = append(*f, &Symlink{target, linkName})
-	return f
-}
-
-func init() { gob.Register(new(Mkdir)) }
-
-// Mkdir creates a directory in the container filesystem.
-type Mkdir struct {
-	Path string
-	Perm os.FileMode
-}
-
-func (m *Mkdir) early(*Params) error { return nil }
-func (m *Mkdir) apply(*Params) error {
-	if !path.IsAbs(m.Path) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", m.Path))
-	}
-
-	if err := os.MkdirAll(toSysroot(m.Path), m.Perm); err != nil {
-		return wrapErrSelf(err)
-	}
-	return nil
-}
-
-func (m *Mkdir) Is(op Op) bool  { vm, ok := op.(*Mkdir); return ok && m == vm }
-func (*Mkdir) prefix() string   { return "creating" }
-func (m *Mkdir) String() string { return fmt.Sprintf("directory %q perm %s", m.Path, m.Perm) }
-func (f *Ops) Mkdir(dest string, perm os.FileMode) *Ops {
-	*f = append(*f, &Mkdir{dest, perm})
-	return f
-}
-
-func init() { gob.Register(new(Tmpfile)) }
-
-// Tmpfile places a file in container Path containing Data.
-type Tmpfile struct {
-	Path string
-	Data []byte
-}
-
-func (t *Tmpfile) early(*Params) error { return nil }
-func (t *Tmpfile) apply(params *Params) error {
-	if !path.IsAbs(t.Path) {
-		return msg.WrapErr(syscall.EBADE,
-			fmt.Sprintf("path %q is not absolute", t.Path))
-	}
-
-	var tmpPath string
-	if f, err := os.CreateTemp("/", "tmp.*"); err != nil {
-		return wrapErrSelf(err)
-	} else if _, err = f.Write(t.Data); err != nil {
-		return wrapErrSuffix(err,
-			"cannot write to intermediate file:")
-	} else if err = f.Close(); err != nil {
-		return wrapErrSuffix(err,
-			"cannot close intermediate file:")
-	} else {
-		tmpPath = f.Name()
-	}
-
-	target := toSysroot(t.Path)
-	if err := ensureFile(target, 0444, params.ParentPerm); err != nil {
-		return err
-	} else if err = hostProc.bindMount(
-		tmpPath,
-		target,
-		syscall.MS_RDONLY|syscall.MS_NODEV,
-		false,
-	); err != nil {
-		return err
-	} else if err = os.Remove(tmpPath); err != nil {
-		return wrapErrSelf(err)
-	}
-	return nil
-}
-
-func (t *Tmpfile) Is(op Op) bool {
-	vt, ok := op.(*Tmpfile)
-	return ok && t.Path == vt.Path && slices.Equal(t.Data, vt.Data)
-}
-func (*Tmpfile) prefix() string { return "placing" }
-func (t *Tmpfile) String() string {
-	return fmt.Sprintf("tmpfile %q (%d bytes)", t.Path, len(t.Data))
-}
-func (f *Ops) Place(name string, data []byte) *Ops { *f = append(*f, &Tmpfile{name, data}); return f }
-func (f *Ops) PlaceP(name string, dataP **[]byte) *Ops {
-	t := &Tmpfile{Path: name}
-	*dataP = &t.Data
-
-	*f = append(*f, t)
-	return f
-}