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// Copyright 2018 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 proc
import (
"fmt"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
)
// filesystem is a procfs.
//
// +stateify savable
type filesystem struct{}
func init() {
fs.RegisterFilesystem(&filesystem{})
}
// FilesystemName is the name underwhich the filesystem is registered.
// Name matches fs/proc/root.c:proc_fs_type.name.
const FilesystemName = "proc"
// Name is the name of the file system.
func (*filesystem) Name() string {
return FilesystemName
}
// AllowUserMount allows users to mount(2) this file system.
func (*filesystem) AllowUserMount() bool {
return true
}
// AllowUserList allows this filesystem to be listed in /proc/filesystems.
func (*filesystem) AllowUserList() bool {
return true
}
// Flags returns that there is nothing special about this file system.
//
// In Linux, proc returns FS_USERNS_VISIBLE | FS_USERNS_MOUNT, see fs/proc/root.c.
func (*filesystem) Flags() fs.FilesystemFlags {
return 0
}
// Mount returns the root of a procfs that can be positioned in the vfs.
func (f *filesystem) Mount(ctx context.Context, device string, flags fs.MountSourceFlags, data string, cgroupsInt interface{}) (*fs.Inode, error) {
// device is always ignored.
// Parse generic comma-separated key=value options, this file system expects them.
options := fs.GenericMountSourceOptions(data)
// Proc options parsing checks for either a gid= or hidepid= and barfs on
// anything else, see fs/proc/root.c:proc_parse_options. Since we don't know
// what to do with gid= or hidepid=, we blow up if we get any options.
if len(options) > 0 {
return nil, fmt.Errorf("unsupported mount options: %v", options)
}
var cgroups map[string]string
if cgroupsInt != nil {
cgroups = cgroupsInt.(map[string]string)
}
// Construct the procfs root. Since procfs files are all virtual, we
// never want them cached.
return New(ctx, fs.NewNonCachingMountSource(f, flags), cgroups)
}
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