hst: improve doc comments

These now read a lot better both in source and on pkgsite.

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

9 files changed, 211 insertions, 114 deletions

diff --git a/hst/config.go b/hst/config.go
index 0c66c274..51ac62ec 100644
--- a/hst/config.go
+++ b/hst/config.go
@@ -8,74 +8,97 @@ import (
 	"hakurei.app/container/check"
 )
 
-// Config configures an application container, implemented in internal/app.
+// Config configures an application container.
 type Config struct {
 	// Reverse-DNS style configured arbitrary identifier string.
-	// Passed to wayland security-context-v1 and used as part of defaults in dbus session proxy.
+	//
+	// This value is passed as is to Wayland security-context-v1 and used as
+	// part of defaults in D-Bus session proxy. The zero value causes a default
+	// value to be derived from the container instance.
 	ID string `json:"id,omitempty"`
 
 	// System services to make available in the container.
 	Enablements *Enablements `json:"enablements,omitempty"`
 
 	// Session D-Bus proxy configuration.
-	// If set to nil, session bus proxy assume built-in defaults.
+	//
+	// Has no effect if [EDBus] but is not set in Enablements. The zero value
+	// assumes built-in defaults derived from ID.
 	SessionBus *BusConfig `json:"session_bus,omitempty"`
 	// System D-Bus proxy configuration.
-	// If set to nil, system bus proxy is disabled.
+	//
+	// Has no effect if [EDBus] but is not set in Enablements. The zero value
+	// disables system bus proxy.
 	SystemBus *BusConfig `json:"system_bus,omitempty"`
 
-	// Direct access to wayland socket, no attempt is made to attach security-context-v1
-	// and the bare socket is made available to the container.
+	// Direct access to Wayland socket, no attempt is made to attach
+	// security-context-v1 and the bare socket is made available to the
+	// container.
 	//
-	// This option is unsupported and most likely enables full control over the Wayland
-	// session. Do not set this to true unless you are sure you know what you are doing.
+	// This option is unsupported and will most likely enable full control over
+	// the Wayland session from within the container. Do not set this to true
+	// unless you are sure you know what you are doing.
 	DirectWayland bool `json:"direct_wayland,omitempty"`
-	// Direct access to the PipeWire socket established via SecurityContext::Create, no
-	// attempt is made to start the pipewire-pulse server.
+
+	// Direct access to the PipeWire socket established via SecurityContext::Create,
+	// no attempt is made to start the pipewire-pulse server.
+	//
+	// The SecurityContext machinery is fatally flawed, it unconditionally sets
+	// read and execute bits on all objects for clients with the lowest achievable
+	// privilege level (by setting PW_KEY_ACCESS to "restricted" or by satisfying
+	// all conditions of [the /.flatpak-info hack]). This enables them to call
+	// any method targeting any object, and since Registry::Destroy checks for
+	// the read and execute bit, allows the destruction of any object other than
+	// PW_ID_CORE as well.
 	//
-	// The SecurityContext machinery is fatally flawed, it blindly sets read and execute
-	// bits on all objects for clients with the lowest achievable privilege level (by
-	// setting PW_KEY_ACCESS to "restricted"). This enables them to call any method
-	// targeting any object, and since Registry::Destroy checks for the read and execute bit,
-	// allows the destruction of any object other than PW_ID_CORE as well. This behaviour
-	// is implemented separately in media-session and wireplumber, with the wireplumber
-	// implementation in Lua via an embedded Lua vm. In all known setups, wireplumber is
-	// in use, and there is no known way to change its behaviour and set permissions
-	// differently without replacing the Lua script. Also, since PipeWire relies on these
-	// permissions to work, reducing them is not possible.
+	// This behaviour is implemented separately in media-session and wireplumber,
+	// with the wireplumber implementation in Lua via an embedded Lua vm. In all
+	// known setups, wireplumber is in use, and in that case, no option for
+	// configuring this behaviour exists, without replacing the Lua script.
+	// Also, since PipeWire relies on these permissions to work, reducing them
+	// was never possible in the first place.
 	//
-	// Currently, the only other sandboxed use case is flatpak, which is not aware of
-	// PipeWire and blindly exposes the bare PulseAudio socket to the container (behaves
-	// like DirectPulse). This socket is backed by the pipewire-pulse compatibility daemon,
-	// which obtains client pid via the SO_PEERCRED option. The PipeWire daemon, pipewire-pulse
-	// daemon and the session manager daemon then separately performs the /.flatpak-info hack
-	// described in https://git.gensokyo.uk/security/hakurei/issues/21. Under such use case,
-	// since the client has no direct access to PipeWire, insecure parts of the protocol are
-	// obscured by pipewire-pulse simply not implementing them, and thus hiding the flaws
-	// described above.
+	// Currently, the only other sandboxed use case is flatpak, which is not
+	// aware of PipeWire and blindly exposes the bare PulseAudio socket to the
+	// container (behaves like DirectPulse). This socket is backed by the
+	// pipewire-pulse compatibility daemon, which obtains client pid via the
+	// SO_PEERCRED option. The PipeWire daemon, pipewire-pulse daemon and the
+	// session manager daemon then separately performs [the /.flatpak-info hack].
+	// Under such use case, since the client has no direct access to PipeWire,
+	// insecure parts of the protocol are obscured by the absence of an
+	// equivalent API in PulseAudio, or pipewire-pulse simply not implementing
+	// them.
 	//
-	// Hakurei does not rely on the /.flatpak-info hack. Instead, a socket is sets up via
-	// SecurityContext. A pipewire-pulse server connected through it achieves the same
-	// permissions as flatpak does via the /.flatpak-info hack and is maintained for the
-	// life of the container.
+	// Hakurei does not rely on [the /.flatpak-info hack]. Instead, a socket is
+	// sets up via SecurityContext. A pipewire-pulse server connected through it
+	// achieves the same permissions as flatpak does via [the /.flatpak-info hack]
+	// and is maintained for the life of the container.
+	//
+	// This option is unsupported and enables a denial-of-service attack as the
+	// sandboxed client is able to destroy any client object and thus
+	// disconnecting them from PipeWire, or destroy the SecurityContext object,
+	// preventing any further container creation.
 	//
-	// This option is unsupported and enables a denial-of-service attack as the sandboxed
-	// client is able to destroy any client object and thus disconnecting them from PipeWire,
-	// or destroy the SecurityContext object preventing any further container creation.
 	// Do not set this to true, it is insecure under any configuration.
+	//
+	// [the /.flatpak-info hack]: https://git.gensokyo.uk/security/hakurei/issues/21
 	DirectPipeWire bool `json:"direct_pipewire,omitempty"`
-	// Direct access to PulseAudio socket, no attempt is made to establish pipewire-pulse
-	// server via a PipeWire socket with a SecurityContext attached and the bare socket
-	// is made available to the container.
+
+	// Direct access to PulseAudio socket, no attempt is made to establish
+	// pipewire-pulse server via a PipeWire socket with a SecurityContext
+	// attached, and the bare socket is made available to the container.
 	//
-	// This option is unsupported and enables arbitrary code execution as the PulseAudio
-	// server. Do not set this to true, it is insecure under any configuration.
+	// This option is unsupported and enables arbitrary code execution as the
+	// PulseAudio server.
+	//
+	// Do not set this to true, it is insecure under any configuration.
 	DirectPulse bool `json:"direct_pulse,omitempty"`
 
 	// Extra acl updates to perform before setuid.
 	ExtraPerms []ExtraPermConfig `json:"extra_perms,omitempty"`
 
-	// Numerical application id, passed to hsu, used to derive init user namespace credentials.
+	// Numerical application id, passed to hsu, used to derive init user
+	// namespace credentials.
 	Identity int `json:"identity"`
 	// Init user namespace supplementary groups inherited by all container processes.
 	Groups []string `json:"groups"`
@@ -85,17 +108,20 @@ type Config struct {
 }
 
 var (
-	// ErrConfigNull is returned by [Config.Validate] for an invalid configuration that contains a null value for any
-	// field that must not be null.
+	// ErrConfigNull is returned by [Config.Validate] for an invalid configuration
+	// that contains a null value for any field that must not be null.
 	ErrConfigNull = errors.New("unexpected null in config")
 
-	// ErrIdentityBounds is returned by [Config.Validate] for an out of bounds [Config.Identity] value.
+	// ErrIdentityBounds is returned by [Config.Validate] for an out of bounds
+	// [Config.Identity] value.
 	ErrIdentityBounds = errors.New("identity out of bounds")
 
-	// ErrEnviron is returned by [Config.Validate] if an environment variable name contains '=' or NUL.
+	// ErrEnviron is returned by [Config.Validate] if an environment variable
+	// name contains '=' or NUL.
 	ErrEnviron = errors.New("invalid environment variable name")
 
-	// ErrInsecure is returned by [Config.Validate] if the configuration is considered insecure.
+	// ErrInsecure is returned by [Config.Validate] if the configuration is
+	// considered insecure.
 	ErrInsecure = errors.New("configuration is insecure")
 )
 
diff --git a/hst/container.go b/hst/container.go
index f9cc95ed..8696d85b 100644
--- a/hst/container.go
+++ b/hst/container.go
@@ -16,18 +16,20 @@ const PrivateTmp = "/.hakurei"
 var AbsPrivateTmp = check.MustAbs(PrivateTmp)
 
 const (
-	// WaitDelayDefault is used when WaitDelay has its zero value.
+	// WaitDelayDefault is used when WaitDelay has the zero value.
 	WaitDelayDefault = 5 * time.Second
-	// WaitDelayMax is used if WaitDelay exceeds its value.
+	// WaitDelayMax is used when WaitDelay exceeds its value.
 	WaitDelayMax = 30 * time.Second
 )
 
 const (
 	// ExitFailure is returned if the container fails to start.
 	ExitFailure = iota + 1
-	// ExitCancel is returned if the container is terminated by a shim-directed signal which cancels its context.
+	// ExitCancel is returned if the container is terminated by a shim-directed
+	// signal which cancels its context.
 	ExitCancel
-	// ExitOrphan is returned when the shim is orphaned before priv side delivers a signal.
+	// ExitOrphan is returned when the shim is orphaned before priv side process
+	// delivers a signal.
 	ExitOrphan
 
 	// ExitRequest is returned when the priv side process requests shim exit.
@@ -38,10 +40,12 @@ const (
 type Flags uintptr
 
 const (
-	// FMultiarch unblocks syscalls required for multiarch to work on applicable targets.
+	// FMultiarch unblocks system calls required for multiarch to work on
+	// multiarch-enabled targets (amd64, arm64).
 	FMultiarch Flags = 1 << iota
 
-	// FSeccompCompat changes emitted seccomp filter programs to be identical to that of Flatpak.
+	// FSeccompCompat changes emitted seccomp filter programs to be identical to
+	// that of Flatpak in enabled rulesets.
 	FSeccompCompat
 	// FDevel unblocks ptrace and friends.
 	FDevel
@@ -54,12 +58,15 @@ const (
 	// FTty unblocks dangerous terminal I/O (faking input).
 	FTty
 
-	// FMapRealUID maps the target user uid to the privileged user uid in the container user namespace.
-	//	Some programs fail to connect to dbus session running as a different uid,
-	//	this option works around it by mapping priv-side caller uid in container.
+	// FMapRealUID maps the target user uid to the privileged user uid in the
+	// container user namespace.
+	//
+	// Some programs fail to connect to dbus session running as a different uid,
+	// this option works around it by mapping priv-side caller uid in container.
 	FMapRealUID
 
-	// FDevice mount /dev/ from the init mount namespace as-is in the container mount namespace.
+	// FDevice mount /dev/ from the init mount namespace as is in the container
+	// mount namespace.
 	FDevice
 
 	// FShareRuntime shares XDG_RUNTIME_DIR between containers under the same identity.
@@ -112,30 +119,37 @@ func (flags Flags) String() string {
 	}
 }
 
-// ContainerConfig describes the container configuration to be applied to an underlying [container].
+// ContainerConfig describes the container configuration to be applied to an
+// underlying [container]. It is validated by [Config.Validate].
 type ContainerConfig struct {
 	// Container UTS namespace hostname.
 	Hostname string `json:"hostname,omitempty"`
 
 	// Duration in nanoseconds to wait for after interrupting the initial process.
-	// Defaults to [WaitDelayDefault] if zero, or [WaitDelayMax] if greater than [WaitDelayMax].
-	// Values lesser than zero is equivalent to zero, bypassing [WaitDelayDefault].
+	//
+	// Defaults to [WaitDelayDefault] if zero, or [WaitDelayMax] if greater than
+	// [WaitDelayMax]. Values lesser than zero is equivalent to zero, bypassing
+	// [WaitDelayDefault].
 	WaitDelay time.Duration `json:"wait_delay,omitempty"`
 
 	// Initial process environment variables.
 	Env map[string]string `json:"env"`
 
-	/* Container mount points.
-
-	If the first element targets /, it is inserted early and excluded from path hiding. */
+	// Container mount points.
+	//
+	// If the first element targets /, it is inserted early and excluded from
+	// path hiding. Otherwise, an anonymous instance of tmpfs is set up on /.
 	Filesystem []FilesystemConfigJSON `json:"filesystem"`
 
-	// String used as the username of the emulated user, validated against the default NAME_REGEX from adduser.
+	// String used as the username of the emulated user, validated against the
+	// default NAME_REGEX from adduser.
+	//
 	// Defaults to passwd name of target uid or chronos.
 	Username string `json:"username,omitempty"`
 	// Pathname of shell in the container filesystem to use for the emulated user.
 	Shell *check.Absolute `json:"shell"`
-	// Directory in the container filesystem to enter and use as the home directory of the emulated user.
+	// Directory in the container filesystem to enter and use as the home
+	// directory of the emulated user.
 	Home *check.Absolute `json:"home"`
 
 	// Pathname to executable file in the container filesystem.
@@ -148,6 +162,7 @@ type ContainerConfig struct {
 }
 
 // ContainerConfigF is [ContainerConfig] stripped of its methods.
+//
 // The [ContainerConfig.Flags] field does not survive a [json] round trip.
 type ContainerConfigF ContainerConfig
 
diff --git a/hst/dbus.go b/hst/dbus.go
index 6dd1a2c3..5c4620cc 100644
--- a/hst/dbus.go
+++ b/hst/dbus.go
@@ -5,8 +5,26 @@ import (
 	"strings"
 )
 
-// BadInterfaceError is returned when Interface fails an undocumented check in xdg-dbus-proxy,
-// which would have cause a silent failure.
+// BadInterfaceError is returned when Interface fails an undocumented check in
+// xdg-dbus-proxy, which would have cause a silent failure.
+//
+// xdg-dbus-proxy fails without output when this condition is not met:
+//
+//	char *dot = strrchr (filter->interface, '.');
+//	if (dot != NULL)
+//	  {
+//	    *dot = 0;
+//	    if (strcmp (dot + 1, "*") != 0)
+//	      filter->member = g_strdup (dot + 1);
+//	  }
+//
+// trim ".*" since they are removed before searching for '.':
+//
+//	if (g_str_has_suffix (name, ".*"))
+//	  {
+//	    name[strlen (name) - 2] = 0;
+//	    wildcard = TRUE;
+//	  }
 type BadInterfaceError struct {
 	// Interface is the offending interface string.
 	Interface string
@@ -19,7 +37,8 @@ func (e *BadInterfaceError) Error() string {
 	if e == nil {
 		return "<nil>"
 	}
-	return "bad interface string " + strconv.Quote(e.Interface) + " in " + e.Segment + " bus configuration"
+	return "bad interface string " + strconv.Quote(e.Interface) +
+		" in " + e.Segment + " bus configuration"
 }
 
 // BusConfig configures the xdg-dbus-proxy process.
@@ -76,31 +95,14 @@ func (c *BusConfig) Interfaces(yield func(string) bool) {
 	}
 }
 
-// CheckInterfaces checks for invalid interface strings based on an undocumented check in xdg-dbus-error,
-// returning [BadInterfaceError] if one is encountered.
+// CheckInterfaces checks for invalid interface strings based on an undocumented
+// check in xdg-dbus-error, returning [BadInterfaceError] if one is encountered.
 func (c *BusConfig) CheckInterfaces(segment string) error {
 	if c == nil {
 		return nil
 	}
 
 	for iface := range c.Interfaces {
-		/*
-			xdg-dbus-proxy fails without output when this condition is not met:
-				char *dot = strrchr (filter->interface, '.');
-				if (dot != NULL)
-				  {
-				    *dot = 0;
-				    if (strcmp (dot + 1, "*") != 0)
-				      filter->member = g_strdup (dot + 1);
-				  }
-
-			trim ".*" since they are removed before searching for '.':
-				if (g_str_has_suffix (name, ".*"))
-				  {
-				    name[strlen (name) - 2] = 0;
-				    wildcard = TRUE;
-				  }
-		*/
 		if strings.IndexByte(strings.TrimSuffix(iface, ".*"), '.') == -1 {
 			return &BadInterfaceError{iface, segment}
 		}
diff --git a/hst/enablement.go b/hst/enablement.go
index 9024078d..71ddecab 100644
--- a/hst/enablement.go
+++ b/hst/enablement.go
@@ -11,15 +11,17 @@ import (
 type Enablement byte
 
 const (
-	// EWayland exposes a wayland pathname socket via security-context-v1.
+	// EWayland exposes a Wayland pathname socket via security-context-v1.
 	EWayland Enablement = 1 << iota
-	// EX11 adds the target user via X11 ChangeHosts and exposes the X11 pathname socket.
+	// EX11 adds the target user via X11 ChangeHosts and exposes the X11
+	// pathname socket.
 	EX11
 	// EDBus enables the per-container xdg-dbus-proxy daemon.
 	EDBus
 	// EPipeWire exposes a pipewire pathname socket via SecurityContext.
 	EPipeWire
-	// EPulse copies the PulseAudio cookie to [hst.PrivateTmp] and exposes the PulseAudio socket.
+	// EPulse copies the PulseAudio cookie to [hst.PrivateTmp] and exposes the
+	// PulseAudio socket.
 	EPulse
 
 	// EM is a noop.
diff --git a/hst/fs.go b/hst/fs.go
index 3cecac88..3f0f6017 100644
--- a/hst/fs.go
+++ b/hst/fs.go
@@ -24,7 +24,8 @@ type FilesystemConfig interface {
 	fmt.Stringer
 }
 
-// The Ops interface enables [FilesystemConfig] to queue container ops without depending on the container package.
+// The Ops interface enables [FilesystemConfig] to queue container ops without
+// depending on the container package.
 type Ops interface {
 	// Tmpfs appends an op that mounts tmpfs on a container path.
 	Tmpfs(target *check.Absolute, size int, perm os.FileMode) Ops
@@ -41,12 +42,15 @@ type Ops interface {
 	// Link appends an op that creates a symlink in the container filesystem.
 	Link(target *check.Absolute, linkName string, dereference bool) Ops
 
-	// Root appends an op that expands a directory into a toplevel bind mount mirror on container root.
+	// Root appends an op that expands a directory into a toplevel bind mount
+	// mirror on container root.
 	Root(host *check.Absolute, flags int) Ops
-	// Etc appends an op that expands host /etc into a toplevel symlink mirror with /etc semantics.
+	// Etc appends an op that expands host /etc into a toplevel symlink mirror
+	// with /etc semantics.
 	Etc(host *check.Absolute, prefix string) Ops
 
-	// Daemon appends an op that starts a daemon in the container and blocks until target appears.
+	// Daemon appends an op that starts a daemon in the container and blocks
+	// until target appears.
 	Daemon(target, path *check.Absolute, args ...string) Ops
 }
 
@@ -61,7 +65,8 @@ type ApplyState struct {
 // ErrFSNull is returned by [json] on encountering a null [FilesystemConfig] value.
 var ErrFSNull = errors.New("unexpected null in mount point")
 
-// FSTypeError is returned when [ContainerConfig.Filesystem] contains an entry with invalid type.
+// FSTypeError is returned when [ContainerConfig.Filesystem] contains an entry
+// with invalid type.
 type FSTypeError string
 
 func (f FSTypeError) Error() string { return fmt.Sprintf("invalid filesystem type %q", string(f)) }
diff --git a/hst/fslink.go b/hst/fslink.go
index 2a1e3795..57c1ffc7 100644
--- a/hst/fslink.go
+++ b/hst/fslink.go
@@ -18,7 +18,9 @@ type FSLink struct {
 	Target *check.Absolute `json:"dst"`
 	// Arbitrary linkname value store in the symlink.
 	Linkname string `json:"linkname"`
-	// Whether to treat Linkname as an absolute pathname and dereference before creating the link.
+
+	// Whether to treat Linkname as an absolute pathname and dereference before
+	// creating the link.
 	Dereference bool `json:"dereference,omitempty"`
 }
 
diff --git a/hst/fsoverlay.go b/hst/fsoverlay.go
index de4e14dd..72df1deb 100644
--- a/hst/fsoverlay.go
+++ b/hst/fsoverlay.go
@@ -19,9 +19,11 @@ type FSOverlay struct {
 
 	// Any filesystem, does not need to be on a writable filesystem, must not be nil.
 	Lower []*check.Absolute `json:"lower"`
-	// The upperdir is normally on a writable filesystem, leave as nil to mount Lower readonly.
+	// The upperdir is normally on a writable filesystem, leave as nil to mount
+	// Lower readonly.
 	Upper *check.Absolute `json:"upper,omitempty"`
-	// The workdir needs to be an empty directory on the same filesystem as Upper, must not be nil if Upper is populated.
+	// The workdir needs to be an empty directory on the same filesystem as
+	// Upper, must not be nil if Upper is populated.
 	Work *check.Absolute `json:"work,omitempty"`
 }
 
diff --git a/hst/hst.go b/hst/hst.go
index 439f4b2d..45f1eb83 100644
--- a/hst/hst.go
+++ b/hst/hst.go
@@ -44,11 +44,13 @@ func (e *AppError) Message() string {
 type Paths struct {
 	// Temporary directory returned by [os.TempDir], usually equivalent to [fhs.AbsTmp].
 	TempDir *check.Absolute `json:"temp_dir"`
-	// Shared directory specific to the hsu userid, usually (`/tmp/hakurei.%d`, [Info.User]).
+	// Shared directory specific to the hsu userid, usually
+	// (`/tmp/hakurei.%d`, [Info.User]).
 	SharePath *check.Absolute `json:"share_path"`
 	// Checked XDG_RUNTIME_DIR value, usually (`/run/user/%d`, uid).
 	RuntimePath *check.Absolute `json:"runtime_path"`
-	// Shared directory specific to the hsu userid located in RuntimePath, usually (`/run/user/%d/hakurei`, uid).
+	// Shared directory specific to the hsu userid located in RuntimePath,
+	// usually (`/run/user/%d/hakurei`, uid).
 	RunDirPath *check.Absolute `json:"run_dir_path"`
 }
 
@@ -74,10 +76,23 @@ func Template() *Config {
 
 		SessionBus: &BusConfig{
 			See: nil,
-			Talk: []string{"org.freedesktop.Notifications", "org.freedesktop.FileManager1", "org.freedesktop.ScreenSaver",
-				"org.freedesktop.secrets", "org.kde.kwalletd5", "org.kde.kwalletd6", "org.gnome.SessionManager"},
-			Own: []string{"org.chromium.Chromium.*", "org.mpris.MediaPlayer2.org.chromium.Chromium.*",
-				"org.mpris.MediaPlayer2.chromium.*"},
+			Talk: []string{
+				"org.freedesktop.Notifications",
+				"org.freedesktop.FileManager1",
+				"org.freedesktop.ScreenSaver",
+				"org.freedesktop.secrets",
+
+				"org.kde.kwalletd5",
+				"org.kde.kwalletd6",
+
+				"org.gnome.SessionManager",
+			},
+			Own: []string{
+				"org.chromium.Chromium.*",
+
+				"org.mpris.MediaPlayer2.org.chromium.Chromium.*",
+				"org.mpris.MediaPlayer2.chromium.*",
+			},
 			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
 			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
 			Log:       false,
@@ -112,7 +127,12 @@ func Template() *Config {
 				"GOOGLE_DEFAULT_CLIENT_SECRET": "OTJgUOQcT7lO7GsGZq2G4IlT",
 			},
 			Filesystem: []FilesystemConfigJSON{
-				{&FSBind{Target: fhs.AbsRoot, Source: fhs.AbsVarLib.Append("hakurei/base/org.debian"), Write: true, Special: true}},
+				{&FSBind{
+					Target:  fhs.AbsRoot,
+					Source:  fhs.AbsVarLib.Append("hakurei/base/org.debian"),
+					Write:   true,
+					Special: true,
+				}},
 				{&FSBind{Target: fhs.AbsEtc, Source: fhs.AbsEtc, Special: true}},
 				{&FSEphemeral{Target: fhs.AbsTmp, Write: true, Perm: 0755}},
 				{&FSOverlay{
@@ -121,11 +141,27 @@ func Template() *Config {
 					Upper:  fhs.AbsVarLib.Append("hakurei/nix/u0/org.chromium.Chromium/rw-store/upper"),
 					Work:   fhs.AbsVarLib.Append("hakurei/nix/u0/org.chromium.Chromium/rw-store/work"),
 				}},
-				{&FSLink{Target: fhs.AbsRun.Append("current-system"), Linkname: "/run/current-system", Dereference: true}},
-				{&FSLink{Target: fhs.AbsRun.Append("opengl-driver"), Linkname: "/run/opengl-driver", Dereference: true}},
-				{&FSBind{Source: fhs.AbsVarLib.Append("hakurei/u0/org.chromium.Chromium"),
-					Target: check.MustAbs("/data/data/org.chromium.Chromium"), Write: true, Ensure: true}},
-				{&FSBind{Source: fhs.AbsDev.Append("dri"), Device: true, Optional: true}},
+				{&FSLink{
+					Target:      fhs.AbsRun.Append("current-system"),
+					Linkname:    "/run/current-system",
+					Dereference: true,
+				}},
+				{&FSLink{
+					Target:      fhs.AbsRun.Append("opengl-driver"),
+					Linkname:    "/run/opengl-driver",
+					Dereference: true,
+				}},
+				{&FSBind{
+					Source: fhs.AbsVarLib.Append("hakurei/u0/org.chromium.Chromium"),
+					Target: check.MustAbs("/data/data/org.chromium.Chromium"),
+					Write:  true,
+					Ensure: true,
+				}},
+				{&FSBind{
+					Source:   fhs.AbsDev.Append("dri"),
+					Device:   true,
+					Optional: true,
+				}},
 			},
 
 			Username: "chronos",
diff --git a/hst/instance.go b/hst/instance.go
index b59a7684..282472ae 100644
--- a/hst/instance.go
+++ b/hst/instance.go
@@ -12,10 +12,12 @@ import (
 // An ID is a unique identifier held by a running hakurei container.
 type ID [16]byte
 
-// ErrIdentifierLength is returned when encountering a [hex] representation of [ID] with unexpected length.
+// ErrIdentifierLength is returned when encountering a [hex] representation of
+// [ID] with unexpected length.
 var ErrIdentifierLength = errors.New("identifier string has unexpected length")
 
-// IdentifierDecodeError is returned by [ID.UnmarshalText] to provide relevant error descriptions.
+// IdentifierDecodeError is returned by [ID.UnmarshalText] to provide relevant
+// error descriptions.
 type IdentifierDecodeError struct{ Err error }
 
 func (e IdentifierDecodeError) Unwrap() error { return e.Err }
@@ -23,7 +25,10 @@ func (e IdentifierDecodeError) Error() string {
 	var invalidByteError hex.InvalidByteError
 	switch {
 	case errors.As(e.Err, &invalidByteError):
-		return fmt.Sprintf("got invalid byte %#U in identifier", rune(invalidByteError))
+		return fmt.Sprintf(
+			"got invalid byte %#U in identifier",
+			rune(invalidByteError),
+		)
 	case errors.Is(e.Err, hex.ErrLength):
 		return "odd length identifier hex string"
 
@@ -41,7 +46,9 @@ func (a *ID) CreationTime() time.Time {
 }
 
 // NewInstanceID creates a new unique [ID].
-func NewInstanceID(id *ID) error { return newInstanceID(id, uint64(time.Now().UnixNano())) }
+func NewInstanceID(id *ID) error {
+	return newInstanceID(id, uint64(time.Now().UnixNano()))
+}
 
 // newInstanceID creates a new unique [ID] with the specified timestamp.
 func newInstanceID(id *ID, p uint64) error {