mirror of https://github.com/docker/buildx.git
74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
package mount
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import (
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"golang.org/x/sys/unix"
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)
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const (
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// ptypes is the set propagation types.
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ptypes = unix.MS_SHARED | unix.MS_PRIVATE | unix.MS_SLAVE | unix.MS_UNBINDABLE
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// pflags is the full set valid flags for a change propagation call.
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pflags = ptypes | unix.MS_REC | unix.MS_SILENT
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// broflags is the combination of bind and read only
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broflags = unix.MS_BIND | unix.MS_RDONLY
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)
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// isremount returns true if either device name or flags identify a remount request, false otherwise.
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func isremount(device string, flags uintptr) bool {
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switch {
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// We treat device "" and "none" as a remount request to provide compatibility with
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// requests that don't explicitly set MS_REMOUNT such as those manipulating bind mounts.
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case flags&unix.MS_REMOUNT != 0, device == "", device == "none":
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return true
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default:
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return false
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}
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}
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func mount(device, target, mType string, flags uintptr, data string) error {
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oflags := flags &^ ptypes
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if !isremount(device, flags) || data != "" {
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// Initial call applying all non-propagation flags for mount
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// or remount with changed data
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if err := unix.Mount(device, target, mType, oflags, data); err != nil {
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return &mountError{
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op: "mount",
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source: device,
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target: target,
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flags: oflags,
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data: data,
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err: err,
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}
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}
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}
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if flags&ptypes != 0 {
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// Change the propagation type.
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if err := unix.Mount("", target, "", flags&pflags, ""); err != nil {
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return &mountError{
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op: "remount",
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target: target,
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flags: flags & pflags,
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err: err,
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}
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}
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}
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if oflags&broflags == broflags {
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// Remount the bind to apply read only.
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if err := unix.Mount("", target, "", oflags|unix.MS_REMOUNT, ""); err != nil {
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return &mountError{
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op: "remount-ro",
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target: target,
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flags: oflags | unix.MS_REMOUNT,
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err: err,
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}
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}
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}
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return nil
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}
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