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mount.go
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mount.go
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// Copyright (C) 2019-Present CloudFoundry.org Foundation, Inc. All rights reserved.
//
// This program and the accompanying materials are made available under
// the terms of the under the Apache License, Version 2.0 (the "License”);
// you may not use this file except in compliance with the License.
//
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
package adapter
import (
"sort"
"strings"
"code.cloudfoundry.org/lager"
specs "github.com/opencontainers/runtime-spec/specs-go"
)
// Mount creates a bind mount description with "to" as the destination and
// "from" as the source. Various MountOptions can be specified to modify the
// mount options. By default, the most restrictive set of mount options are
// used.
func Mount(from, to string, opts ...MountOption) specs.Mount {
mountOpts := &mountOptions{}
for _, opt := range opts {
opt(mountOpts)
}
return specs.Mount{
Destination: to,
Source: from,
Type: "bind",
Options: mountOpts.opts(),
}
}
// IdentityMount provides a shorthand for Mount which has the same from and to.
func IdentityMount(path string, opts ...MountOption) specs.Mount {
return Mount(path, path, opts...)
}
// MountOption can be used to alter the mount options to Mount or
// IdentityMount.
type MountOption func(*mountOptions)
// AllowExec allows binaries to be executed from a mount. It maps to the
// exec/noexec mount option.
func AllowExec() MountOption {
return func(options *mountOptions) {
options.exec = true
}
}
// AllowWrites allows writes to a mount. It maps to the ro/rw mount option.
func AllowWrites() MountOption {
return func(options *mountOptions) {
options.writable = true
}
}
// WithRecursiveBind mounts other bind mounts in the source to the destination
// recursively. It maps to the bind/rbind mount option.
func WithRecursiveBind() MountOption {
return func(options *mountOptions) {
options.rbind = true
}
}
type mountOptions struct {
rbind bool
exec bool
suid bool
dev bool
writable bool
}
func (mo mountOptions) opts() []string {
var opts []string
if mo.rbind {
opts = append(opts, "rbind")
} else {
opts = append(opts, "bind")
}
if mo.exec {
opts = append(opts, "exec")
} else {
opts = append(opts, "noexec")
}
if mo.suid {
opts = append(opts, "suid")
} else {
opts = append(opts, "nosuid")
}
if mo.dev {
opts = append(opts, "dev")
} else {
opts = append(opts, "nodev")
}
if mo.writable {
opts = append(opts, "rw")
} else {
opts = append(opts, "ro")
}
return opts
}
type dedupMounts struct {
set map[string]specs.Mount
logger lager.Logger
}
func newMountDedup(logger lager.Logger) *dedupMounts {
return &dedupMounts{
set: make(map[string]specs.Mount),
logger: logger,
}
}
func (d *dedupMounts) addMounts(ms []specs.Mount) {
for _, mount := range ms {
dst := mount.Destination
if _, ok := d.set[dst]; ok {
d.logger.Info("duplicate-mount", lager.Data{"mount": dst})
continue
}
d.set[dst] = mount
}
}
func (d *dedupMounts) mounts() []specs.Mount {
ms := make([]specs.Mount, 0, len(d.set))
for _, mount := range d.set {
ms = append(ms, mount)
}
sort.Slice(ms, func(i, j int) bool {
iElems := strings.Split(ms[i].Destination, "/")
jElems := strings.Split(ms[j].Destination, "/")
return len(iElems) < len(jElems)
})
return ms
}