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