474a257b16
Using symlinks for bind mounts means we are not protecting an RO-mounted layer against modification. Windows doesn't currently appear to offer a better approach though, as we cannot create arbitrary empty WCOW scratch layers at this time. For windows-layer mounts, Unmount does not have access to the mounts used to create it. So we store the relevant data in an Alternate Data Stream on the mountpoint in order to be able to Unmount later. Based on approach in https://github.com/containerd/containerd/pull/2366, with sign-offs recorded as 'Based-on-work-by' trailers below. This also partially-reverts some changes made in #6034 as they are not needed with this mounting implmentation, which no longer needs to be handled specially by the caller compared to non-Windows mounts. Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com> Based-on-work-by: Michael Crosby <crosbymichael@gmail.com> Based-on-work-by: Darren Stahl <darst@microsoft.com>
76 lines
2.4 KiB
Go
76 lines
2.4 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package mount
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// Simple wrappers around SetVolumeMountPoint and DeleteVolumeMountPoint
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import (
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"fmt"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/containerd/containerd/errdefs"
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"golang.org/x/sys/windows"
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)
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// Mount volumePath (in format '\\?\Volume{GUID}' at targetPath.
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// https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setvolumemountpointw
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func setVolumeMountPoint(targetPath string, volumePath string) error {
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if !strings.HasPrefix(volumePath, "\\\\?\\Volume{") {
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return fmt.Errorf("unable to mount non-volume path %s: %w", volumePath, errdefs.ErrInvalidArgument)
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}
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// Both must end in a backslash
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slashedTarget := filepath.Clean(targetPath) + string(filepath.Separator)
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slashedVolume := volumePath + string(filepath.Separator)
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targetP, err := syscall.UTF16PtrFromString(slashedTarget)
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if err != nil {
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return fmt.Errorf("unable to utf16-ise %s: %w", slashedTarget, err)
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}
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volumeP, err := syscall.UTF16PtrFromString(slashedVolume)
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if err != nil {
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return fmt.Errorf("unable to utf16-ise %s: %w", slashedVolume, err)
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}
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if err := windows.SetVolumeMountPoint(targetP, volumeP); err != nil {
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return fmt.Errorf("failed calling SetVolumeMount('%s', '%s'): %w", slashedTarget, slashedVolume, err)
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}
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return nil
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}
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// Remove the volume mount at targetPath
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// https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-deletevolumemountpointa
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func deleteVolumeMountPoint(targetPath string) error {
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// Must end in a backslash
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slashedTarget := filepath.Clean(targetPath) + string(filepath.Separator)
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targetP, err := syscall.UTF16PtrFromString(slashedTarget)
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if err != nil {
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return fmt.Errorf("unable to utf16-ise %s: %w", slashedTarget, err)
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}
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if err := windows.DeleteVolumeMountPoint(targetP); err != nil {
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return fmt.Errorf("failed calling DeleteVolumeMountPoint('%s'): %w", slashedTarget, err)
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}
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return nil
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}
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