bfc1465a2c
After these changes, in order to add Darwin bind-mount implementation, one only needs: * Adjust HasBindMounts definition in mount.go * Provide implementation in mount_darwin.go There was no consensus on adding dependency on bindfs, that seems to be the only working solution for bind-mounts on Darwin as of today, in https://github.com/containerd/containerd/pull/8789, that's why the actual implementation is not added in current PR. As a bonus, Linux FUSE-related code was moved to a separate file and possibly could be reused on FreeBSD, though this needs testing. Signed-off-by: Marat Radchenko <marat@slonopotamus.org>
73 lines
2.2 KiB
Go
73 lines
2.2 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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import (
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"errors"
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"fmt"
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"os/exec"
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"golang.org/x/sys/unix"
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)
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// Mount to the provided target.
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//
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// The "syscall" and "golang.org/x/sys/unix" packages do not define a Mount
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// function for FreeBSD, so instead we execute mount(8) and trust it to do
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// the right thing
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func (m *Mount) mount(target string) error {
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// target: "/foo/target"
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// command: "mount -o ro -t nullfs /foo/source /foo/merged"
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// Note: FreeBSD mount(8) is particular about the order of flags and arguments
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var args []string
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for _, o := range m.Options {
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args = append(args, "-o", o)
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}
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args = append(args, "-t", m.Type)
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args = append(args, m.Source, target)
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infoBeforeMount, err := Lookup(target)
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if err != nil {
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return err
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}
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// cmd.CombinedOutput() may intermittently return ECHILD because of our signal handling in shim.
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// See #4387 and wait(2).
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const retriesOnECHILD = 10
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for i := 0; i < retriesOnECHILD; i++ {
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cmd := exec.Command("mount", args...)
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out, err := cmd.CombinedOutput()
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if err == nil {
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return nil
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}
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if !errors.Is(err, unix.ECHILD) {
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return fmt.Errorf("mount [%v] failed: %q: %w", args, string(out), err)
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}
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// We got ECHILD, we are not sure whether the mount was successful.
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// If the mount ID has changed, we are sure we got some new mount, but still not sure it is fully completed.
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// So we attempt to unmount the new mount before retrying.
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infoAfterMount, err := Lookup(target)
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if err != nil {
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return err
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}
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if infoAfterMount.ID != infoBeforeMount.ID {
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_ = unmount(target, 0)
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}
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}
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return fmt.Errorf("mount [%v] failed with ECHILD (retried %d times)", args, retriesOnECHILD)
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}
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