helper/bwrap: ordered filesystem args

The argument builder was written based on the incorrect assumption that bwrap arguments are unordered. The argument builder is replaced in this commit to correct that mistake.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

1 files changed, 61 insertions, 158 deletions

diff --git a/helper/bwrap/config.go b/helper/bwrap/config.go
index 3ddb80b5..f62cc24e 100644
--- a/helper/bwrap/config.go
+++ b/helper/bwrap/config.go
@@ -5,75 +5,6 @@ import (
 	"strconv"
 )
 
-func (c *Config) Args() (args []string) {
-	b := c.boolArgs()
-	n := c.intArgs()
-	g := c.interfaceArgs()
-	s := c.stringArgs()
-	p := c.pairArgs()
-
-	argc := 0
-	for i, arg := range b {
-		if arg {
-			argc += len(boolArgs[i])
-		}
-	}
-	for _, arg := range n {
-		if arg != nil {
-			argc += 2
-		}
-	}
-	for _, arg := range g {
-		argc += len(arg) * 3
-	}
-	for _, arg := range s {
-		argc += len(arg) * 2
-	}
-	for _, arg := range p {
-		argc += len(arg) * 3
-	}
-
-	args = make([]string, 0, argc)
-	for i, arg := range b {
-		if arg {
-			args = append(args, boolArgs[i]...)
-		}
-	}
-	for i, arg := range n {
-		if arg != nil {
-			args = append(args, intArgs[i], strconv.Itoa(*arg))
-		}
-	}
-	for i, arg := range g {
-		for _, v := range arg {
-			if v.Later() {
-				continue
-			}
-			args = append(args, v.Value(interfaceArgs[i])...)
-		}
-	}
-	for i, arg := range s {
-		for _, v := range arg {
-			args = append(args, stringArgs[i], v)
-		}
-	}
-	for i, arg := range p {
-		for _, v := range arg {
-			args = append(args, pairArgs[i], v[0], v[1])
-		}
-	}
-	for i, arg := range g {
-		for _, v := range arg {
-			if !v.Later() {
-				continue
-			}
-			args = append(args, v.Value(interfaceArgs[i])...)
-		}
-	}
-
-	return
-}
-
 type Config struct {
 	// unshare every namespace we support by default if nil
 	// (--unshare-all)
@@ -114,53 +45,12 @@ type Config struct {
 	// (--lock-file DEST)
 	LockFile []string `json:"lock_file,omitempty"`
 
-	// bind mount host path on sandbox
-	// (--bind SRC DEST)
-	Bind [][2]string `json:"bind,omitempty"`
-	// equal to Bind but ignores non-existent host path
-	// (--bind-try SRC DEST)
-	BindTry [][2]string `json:"bind_try,omitempty"`
-
-	// bind mount host path on sandbox, allowing device access
-	// (--dev-bind SRC DEST)
-	DevBind [][2]string `json:"dev_bind,omitempty"`
-	// equal to DevBind but ignores non-existent host path
-	// (--dev-bind-try SRC DEST)
-	DevBindTry [][2]string `json:"dev_bind_try,omitempty"`
-
-	// bind mount host path readonly on sandbox
-	// (--ro-bind SRC DEST)
-	ROBind [][2]string `json:"ro_bind,omitempty"`
-	// equal to ROBind but ignores non-existent host path
-	// (--ro-bind-try SRC DEST)
-	ROBindTry [][2]string `json:"ro_bind_try,omitempty"`
-
-	// remount path as readonly; does not recursively remount
-	// (--remount-ro DEST)
-	RemountRO []string `json:"remount_ro,omitempty"`
-
-	// mount new procfs in sandbox
-	// (--proc DEST)
-	Procfs []string `json:"proc,omitempty"`
-	// mount new dev in sandbox
-	// (--dev DEST)
-	DevTmpfs []string `json:"dev,omitempty"`
-	// mount new tmpfs in sandbox
-	// (--tmpfs DEST)
-	Tmpfs []PermConfig[TmpfsConfig] `json:"tmpfs,omitempty"`
-	// mount new mqueue in sandbox
-	// (--mqueue DEST)
-	Mqueue []string `json:"mqueue,omitempty"`
-	// create dir in sandbox
-	// (--dir DEST)
-	Dir []PermConfig[string] `json:"dir,omitempty"`
-	// create symlink within sandbox
-	// (--symlink SRC DEST)
-	Symlink []PermConfig[[2]string] `json:"symlink,omitempty"`
+	// ordered filesystem args
+	Filesystem []FSBuilder
 
 	// change permissions (must already exist)
 	// (--chmod OCTAL PATH)
-	Chmod map[string]os.FileMode `json:"chmod,omitempty"`
+	Chmod ChmodConfig `json:"chmod,omitempty"`
 
 	// create a new terminal session
 	// (--new-session)
@@ -217,6 +107,34 @@ type UnshareConfig struct {
 	CGroup bool `json:"cgroup"`
 }
 
+type PermConfig[T FSBuilder] struct {
+	// set permissions of next argument
+	// (--perms OCTAL)
+	Mode *os.FileMode `json:"mode,omitempty"`
+	// path to get the new permission
+	// (--bind-data, --file, etc.)
+	Inner T `json:"path"`
+}
+
+func (p *PermConfig[T]) Path() string {
+	return p.Inner.Path()
+}
+
+func (p *PermConfig[T]) Len() int {
+	if p.Mode != nil {
+		return p.Inner.Len() + 2
+	} else {
+		return p.Inner.Len()
+	}
+}
+
+func (p *PermConfig[T]) Append(args *[]string) {
+	if p.Mode != nil {
+		*args = append(*args, intArgs[Perms], strconv.FormatInt(int64(*p.Mode), 8))
+	}
+	p.Inner.Append(args)
+}
+
 type TmpfsConfig struct {
 	// set size of tmpfs
 	// (--size BYTES)
@@ -226,62 +144,47 @@ type TmpfsConfig struct {
 	Dir string `json:"dir"`
 }
 
-type argOf interface {
-	Value(arg string) (args []string)
-	Later() bool
+func (t *TmpfsConfig) Path() string {
+	return t.Dir
 }
 
-func copyToArgOfSlice[T [2]string | string | TmpfsConfig](src []PermConfig[T]) (dst []argOf) {
-	dst = make([]argOf, len(src))
-	for i, arg := range src {
-		dst[i] = arg
+func (t *TmpfsConfig) Len() int {
+	if t.Size > 0 {
+		return 4
+	} else {
+		return 2
 	}
-	return
 }
 
-type PermConfig[T [2]string | string | TmpfsConfig] struct {
-	// append this at the end of the argument stream
-	Last bool
+func (t *TmpfsConfig) Append(args *[]string) {
+	if t.Size > 0 {
+		*args = append(*args, intArgs[Size], strconv.Itoa(t.Size))
+	}
+	*args = append(*args, awkwardArgs[Tmpfs], t.Dir)
+}
 
-	// set permissions of next argument
-	// (--perms OCTAL)
-	Mode *os.FileMode `json:"mode,omitempty"`
-	// path to get the new permission
-	// (--bind-data, --file, etc.)
-	Path T
+type SymlinkConfig [2]string
+
+func (s SymlinkConfig) Path() string {
+	return s[1]
 }
 
-func (p PermConfig[T]) Later() bool {
-	return p.Last
+func (s SymlinkConfig) Len() int {
+	return 3
 }
 
-func (p PermConfig[T]) Value(arg string) (args []string) {
-	// max possible size
-	if p.Mode != nil {
-		args = make([]string, 0, 6)
-		args = append(args, "--perms", strconv.FormatInt(int64(*p.Mode), 8))
-	} else {
-		args = make([]string, 0, 4)
-	}
+func (s SymlinkConfig) Append(args *[]string) {
+	*args = append(*args, awkwardArgs[Symlink], s[0], s[1])
+}
+
+type ChmodConfig map[string]os.FileMode
 
-	switch v := any(p.Path).(type) {
-	case string:
-		args = append(args, arg, v)
-		return
-	case [2]string:
-		args = append(args, arg, v[0], v[1])
-		return
-	case TmpfsConfig:
-		if arg != "--tmpfs" {
-			panic("unreachable")
-		}
+func (c ChmodConfig) Len() int {
+	return len(c)
+}
 
-		if v.Size > 0 {
-			args = append(args, "--size", strconv.Itoa(v.Size))
-		}
-		args = append(args, arg, v.Dir)
-		return
-	default:
-		panic("unreachable")
+func (c ChmodConfig) Append(args *[]string) {
+	for path, mode := range c {
+		*args = append(*args, pairArgs[Chmod], strconv.FormatInt(int64(mode), 8), path)
 	}
 }