container: explicitly order initialisation

This avoids accessing uninitialised hostProc in some build modes.

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

3 files changed, 30 insertions, 12 deletions

diff --git a/container/init.go b/container/init.go
index 510d9f59..07fff357 100644
--- a/container/init.go
+++ b/container/init.go
@@ -644,6 +644,8 @@ func initEntrypoint(k syscallDispatcher, msg message.Msg) {
 const initName = "init"
 
 var _ = func() struct{} {
+	_ = hostProc
+
 	for _, v := range []any{
 		(*AutoEtcOp)(nil),
 		(*AutoRootOp)(nil),
diff --git a/container/mount.go b/container/mount.go
index 37a9445c..84415fa8 100644
--- a/container/mount.go
+++ b/container/mount.go
@@ -95,7 +95,7 @@ const (
 )
 
 // bindMount mounts source on target and recursively applies flags if MS_REC is set.
-func (p *procPaths) bindMount(msg message.Msg, source, target string, flags uintptr) error {
+func (p procPaths) bindMount(msg message.Msg, source, target string, flags uintptr) error {
 	// syscallDispatcher.bindMount and procPaths.remount must not be called from this function
 
 	if err := p.k.mount(source, target, FstypeNULL, MS_SILENT|MS_BIND|flags&MS_REC, zeroString); err != nil {
@@ -105,7 +105,7 @@ func (p *procPaths) bindMount(msg message.Msg, source, target string, flags uint
 }
 
 // remount applies flags on target, recursively if MS_REC is set.
-func (p *procPaths) remount(msg message.Msg, target string, flags uintptr) error {
+func (p procPaths) remount(msg message.Msg, target string, flags uintptr) error {
 	// syscallDispatcher methods bindMount, remount must not be called from this function
 
 	var targetFinal string
diff --git a/container/path.go b/container/path.go
index 5ae52dee..8d91abd7 100644
--- a/container/path.go
+++ b/container/path.go
@@ -21,22 +21,29 @@ const (
 	// mounted at all. Neither configuration is supported by this package.
 	Nonexistent = fhs.Proc + "nonexistent"
 
-	hostPath    = fhs.Root + hostDir
-	hostDir     = "host"
+	// hostPath is the pathname where the host root filesystem is mounted.
+	hostPath = fhs.Root + hostDir
+	// hostDir is the name of hostPath.
+	hostDir = "host"
+	// sysrootPath is the pathname where the new root filesystem is mounted.
 	sysrootPath = fhs.Root + sysrootDir
-	sysrootDir  = "sysroot"
+	// sysrootDir is the name of sysrootPath.
+	sysrootDir = "sysroot"
 )
 
+// toSysroot prefixes name with sysrootPath.
 func toSysroot(name string) string {
 	name = strings.TrimLeftFunc(name, func(r rune) bool { return r == '/' })
 	return filepath.Join(sysrootPath, name)
 }
 
+// toHost prefixes name with hostPath.
 func toHost(name string) string {
 	name = strings.TrimLeftFunc(name, func(r rune) bool { return r == '/' })
 	return filepath.Join(hostPath, name)
 }
 
+// createFile places a file at name.
 func createFile(name string, perm, pperm os.FileMode, content []byte) error {
 	if err := os.MkdirAll(filepath.Dir(name), pperm); err != nil {
 		return err
@@ -51,6 +58,7 @@ func createFile(name string, perm, pperm os.FileMode, content []byte) error {
 	return errors.Join(f.Close(), err)
 }
 
+// ensureFile ensures the existence of a file at name.
 func ensureFile(name string, perm, pperm os.FileMode) error {
 	fi, err := os.Stat(name)
 	if err != nil {
@@ -66,21 +74,26 @@ func ensureFile(name string, perm, pperm os.FileMode) error {
 	return err
 }
 
-var hostProc = newProcPaths(direct{}, hostPath)
-
-func newProcPaths(k syscallDispatcher, prefix string) *procPaths {
-	return &procPaths{k, prefix + "/proc", prefix + "/proc/self"}
+// newProcPaths returns a populated procPaths.
+func newProcPaths(k syscallDispatcher, prefix string) procPaths {
+	return procPaths{k, prefix + "/proc", prefix + "/proc/self"}
 }
 
+// procPaths describes [fhs.Proc] paths.
 type procPaths struct {
 	k      syscallDispatcher
 	prefix string
 	self   string
 }
 
-func (p *procPaths) stdout() string   { return p.self + "/fd/1" }
-func (p *procPaths) fd(fd int) string { return p.self + "/fd/" + strconv.Itoa(fd) }
-func (p *procPaths) mountinfo(f func(d *vfs.MountInfoDecoder) error) error {
+// stdout returns the pathname of the magic symlink representing standard output.
+func (p procPaths) stdout() string { return p.self + "/fd/1" }
+
+// fd returns the pathname of the magic symlink representing the specified file.
+func (p procPaths) fd(fd int) string { return p.self + "/fd/" + strconv.Itoa(fd) }
+
+// mountinfo returns the pathname of the mountinfo file.
+func (p procPaths) mountinfo(f func(d *vfs.MountInfoDecoder) error) error {
 	if r, err := p.k.openNew(p.self + "/mountinfo"); err != nil {
 		return err
 	} else {
@@ -94,3 +107,6 @@ func (p *procPaths) mountinfo(f func(d *vfs.MountInfoDecoder) error) error {
 		return err0
 	}
 }
+
+// hostProc is a procPaths instance referring to [fhs.Proc] located in hostPath.
+var hostProc = newProcPaths(direct{}, hostPath)