135 lines
4.4 KiB
Go
135 lines
4.4 KiB
Go
// 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 sys implements sysfs.
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package sys
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import (
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"bytes"
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"fmt"
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/syserror"
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)
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// Name is the default filesystem name.
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const Name = "sysfs"
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// FilesystemType implements vfs.FilesystemType.
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type FilesystemType struct{}
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// filesystem implements vfs.FilesystemImpl.
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type filesystem struct {
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kernfs.Filesystem
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}
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// Name implements vfs.FilesystemType.Name.
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func (FilesystemType) Name() string {
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return Name
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}
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// GetFilesystem implements vfs.FilesystemType.GetFilesystem.
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func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
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fs := &filesystem{}
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fs.VFSFilesystem().Init(vfsObj, &fsType, fs)
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k := kernel.KernelFromContext(ctx)
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maxCPUCores := k.ApplicationCores()
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defaultSysDirMode := linux.FileMode(0755)
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root := fs.newDir(creds, defaultSysDirMode, map[string]*kernfs.Dentry{
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"block": fs.newDir(creds, defaultSysDirMode, nil),
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"bus": fs.newDir(creds, defaultSysDirMode, nil),
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"class": fs.newDir(creds, defaultSysDirMode, map[string]*kernfs.Dentry{
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"power_supply": fs.newDir(creds, defaultSysDirMode, nil),
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}),
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"dev": fs.newDir(creds, defaultSysDirMode, nil),
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"devices": fs.newDir(creds, defaultSysDirMode, map[string]*kernfs.Dentry{
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"system": fs.newDir(creds, defaultSysDirMode, map[string]*kernfs.Dentry{
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"cpu": fs.newDir(creds, defaultSysDirMode, map[string]*kernfs.Dentry{
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"online": fs.newCPUFile(creds, maxCPUCores, linux.FileMode(0444)),
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"possible": fs.newCPUFile(creds, maxCPUCores, linux.FileMode(0444)),
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"present": fs.newCPUFile(creds, maxCPUCores, linux.FileMode(0444)),
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}),
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}),
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}),
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"firmware": fs.newDir(creds, defaultSysDirMode, nil),
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"fs": fs.newDir(creds, defaultSysDirMode, nil),
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"kernel": fs.newDir(creds, defaultSysDirMode, nil),
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"module": fs.newDir(creds, defaultSysDirMode, nil),
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"power": fs.newDir(creds, defaultSysDirMode, nil),
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})
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return fs.VFSFilesystem(), root.VFSDentry(), nil
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}
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// dir implements kernfs.Inode.
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type dir struct {
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kernfs.InodeAttrs
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kernfs.InodeNoDynamicLookup
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kernfs.InodeNotSymlink
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kernfs.InodeDirectoryNoNewChildren
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kernfs.OrderedChildren
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dentry kernfs.Dentry
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}
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func (fs *filesystem) newDir(creds *auth.Credentials, mode linux.FileMode, contents map[string]*kernfs.Dentry) *kernfs.Dentry {
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d := &dir{}
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d.InodeAttrs.Init(creds, fs.NextIno(), linux.ModeDirectory|0755)
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d.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
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d.dentry.Init(d)
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d.IncLinks(d.OrderedChildren.Populate(&d.dentry, contents))
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return &d.dentry
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}
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// SetStat implements Inode.SetStat not allowing inode attributes to be changed.
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func (*dir) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.SetStatOptions) error {
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return syserror.EPERM
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}
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// Open implements kernfs.Inode.Open.
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func (d *dir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
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fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts)
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if err != nil {
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return nil, err
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}
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return fd.VFSFileDescription(), nil
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}
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// cpuFile implements kernfs.Inode.
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type cpuFile struct {
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kernfs.DynamicBytesFile
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maxCores uint
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}
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// Generate implements vfs.DynamicBytesSource.Generate.
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func (c *cpuFile) Generate(ctx context.Context, buf *bytes.Buffer) error {
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fmt.Fprintf(buf, "0-%d", c.maxCores-1)
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return nil
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}
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func (fs *filesystem) newCPUFile(creds *auth.Credentials, maxCores uint, mode linux.FileMode) *kernfs.Dentry {
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c := &cpuFile{maxCores: maxCores}
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c.DynamicBytesFile.Init(creds, fs.NextIno(), c, mode)
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d := &kernfs.Dentry{}
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d.Init(c)
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return d
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}
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