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|
package container
import (
"errors"
"fmt"
"os"
"path/filepath"
. "syscall"
"hakurei.app/container/vfs"
)
// bindMount mounts source on target and recursively applies flags if MS_REC is set.
func (p *procPaths) bindMount(source, target string, flags uintptr, eq bool) error {
if eq {
msg.Verbosef("resolved %q flags %#x", target, flags)
} else {
msg.Verbosef("resolved %q on %q flags %#x", source, target, flags)
}
if err := Mount(source, target, "", MS_SILENT|MS_BIND|flags&MS_REC, ""); err != nil {
return wrapErrSuffix(err,
fmt.Sprintf("cannot mount %q on %q:", source, target))
}
return p.remount(target, flags)
}
// remount applies flags on target, recursively if MS_REC is set.
func (p *procPaths) remount(target string, flags uintptr) error {
var targetFinal string
if v, err := filepath.EvalSymlinks(target); err != nil {
return wrapErrSelf(err)
} else {
targetFinal = v
if targetFinal != target {
msg.Verbosef("target resolves to %q", targetFinal)
}
}
// final target path according to the kernel through proc
var targetKFinal string
{
var destFd int
if err := IgnoringEINTR(func() (err error) {
destFd, err = Open(targetFinal, O_PATH|O_CLOEXEC, 0)
return
}); err != nil {
return wrapErrSuffix(err,
fmt.Sprintf("cannot open %q:", targetFinal))
}
if v, err := os.Readlink(p.fd(destFd)); err != nil {
return wrapErrSelf(err)
} else if err = Close(destFd); err != nil {
return wrapErrSuffix(err,
fmt.Sprintf("cannot close %q:", targetFinal))
} else {
targetKFinal = v
}
}
mf := MS_NOSUID | flags&MS_NODEV | flags&MS_RDONLY
return hostProc.mountinfo(func(d *vfs.MountInfoDecoder) error {
n, err := d.Unfold(targetKFinal)
if err != nil {
if errors.Is(err, ESTALE) {
return msg.WrapErr(err,
fmt.Sprintf("mount point %q never appeared in mountinfo", targetKFinal))
}
return wrapErrSuffix(err,
"cannot unfold mount hierarchy:")
}
if err = remountWithFlags(n, mf); err != nil {
return err
}
if flags&MS_REC == 0 {
return nil
}
for cur := range n.Collective() {
err = remountWithFlags(cur, mf)
if err != nil && !errors.Is(err, EACCES) {
return err
}
}
return nil
})
}
// remountWithFlags remounts mount point described by [vfs.MountInfoNode].
func remountWithFlags(n *vfs.MountInfoNode, mf uintptr) error {
kf, unmatched := n.Flags()
if len(unmatched) != 0 {
msg.Verbosef("unmatched vfs options: %q", unmatched)
}
if kf&mf != mf {
return wrapErrSuffix(
Mount("none", n.Clean, "", MS_SILENT|MS_BIND|MS_REMOUNT|kf|mf, ""),
fmt.Sprintf("cannot remount %q:", n.Clean))
}
return nil
}
func mountTmpfs(fsname, name string, flags uintptr, size int, perm os.FileMode) error {
target := toSysroot(name)
if err := os.MkdirAll(target, parentPerm(perm)); err != nil {
return wrapErrSelf(err)
}
opt := fmt.Sprintf("mode=%#o", perm)
if size > 0 {
opt += fmt.Sprintf(",size=%d", size)
}
return wrapErrSuffix(
Mount(fsname, target, "tmpfs", flags, opt),
fmt.Sprintf("cannot mount tmpfs on %q:", name))
}
func parentPerm(perm os.FileMode) os.FileMode {
pperm := 0755
if perm&0070 == 0 {
pperm &= ^0050
}
if perm&0007 == 0 {
pperm &= ^0005
}
return os.FileMode(pperm)
}
|
