2019-11-19 00:25:03 +00:00
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// Copyright 2019 The gVisor Authors.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package vfs
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import (
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"strings"
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2019-12-11 21:40:57 +00:00
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"gvisor.dev/gvisor/pkg/fspath"
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2019-11-19 00:25:03 +00:00
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)
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// GenericParseMountOptions parses a comma-separated list of options of the
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// form "key" or "key=value", where neither key nor value contain commas, and
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// returns it as a map. If str contains duplicate keys, then the last value
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// wins. For example:
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//
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// str = "key0=value0,key1,key2=value2,key0=value3" -> map{'key0':'value3','key1':'','key2':'value2'}
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//
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// GenericParseMountOptions is not appropriate if values may contain commas,
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// e.g. in the case of the mpol mount option for tmpfs(5).
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func GenericParseMountOptions(str string) map[string]string {
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m := make(map[string]string)
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for _, opt := range strings.Split(str, ",") {
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if len(opt) > 0 {
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res := strings.SplitN(opt, "=", 2)
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if len(res) == 2 {
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m[res[0]] = res[1]
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} else {
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m[opt] = ""
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}
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}
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}
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return m
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}
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2019-12-11 21:40:57 +00:00
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// GenericPrependPath may be used by implementations of
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// FilesystemImpl.PrependPath() for which a single statically-determined lock
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// or set of locks is sufficient to ensure its preconditions (as opposed to
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// e.g. per-Dentry locks).
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//
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// Preconditions: Dentry.Name() and Dentry.Parent() must be held constant for
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// vd.Dentry() and all of its ancestors.
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func GenericPrependPath(vfsroot, vd VirtualDentry, b *fspath.Builder) error {
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mnt, d := vd.mount, vd.dentry
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for {
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if mnt == vfsroot.mount && d == vfsroot.dentry {
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return PrependPathAtVFSRootError{}
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}
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if d == mnt.root {
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return nil
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}
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if d.parent == nil {
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return PrependPathAtNonMountRootError{}
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}
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b.PrependComponent(d.name)
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d = d.parent
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}
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}
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