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// Copyright 2020 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 vfs2
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
)
// Getcwd implements Linux syscall getcwd(2).
func Getcwd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
size := args[1].SizeT()
root := t.FSContext().RootDirectoryVFS2()
wd := t.FSContext().WorkingDirectoryVFS2()
s, err := t.Kernel().VFS().PathnameForGetcwd(t, root, wd)
root.DecRef(t)
wd.DecRef(t)
if err != nil {
return 0, nil, err
}
// Note this is >= because we need a terminator.
if uint(len(s)) >= size {
return 0, nil, syserror.ERANGE
}
// Construct a byte slice containing a NUL terminator.
buf := t.CopyScratchBuffer(len(s) + 1)
copy(buf, s)
buf[len(buf)-1] = 0
// Write the pathname slice.
n, err := t.CopyOutBytes(addr, buf)
if err != nil {
return 0, nil, err
}
return uintptr(n), nil, nil
}
// Chdir implements Linux syscall chdir(2).
func Chdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
path, err := copyInPath(t, addr)
if err != nil {
return 0, nil, err
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink)
if err != nil {
return 0, nil, err
}
defer tpop.Release(t)
vd, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{
CheckSearchable: true,
})
if err != nil {
return 0, nil, err
}
t.FSContext().SetWorkingDirectoryVFS2(t, vd)
vd.DecRef(t)
return 0, nil, nil
}
// Fchdir implements Linux syscall fchdir(2).
func Fchdir(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
tpop, err := getTaskPathOperation(t, fd, fspath.Path{}, allowEmptyPath, nofollowFinalSymlink)
if err != nil {
return 0, nil, err
}
defer tpop.Release(t)
vd, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{
CheckSearchable: true,
})
if err != nil {
return 0, nil, err
}
t.FSContext().SetWorkingDirectoryVFS2(t, vd)
vd.DecRef(t)
return 0, nil, nil
}
// Chroot implements Linux syscall chroot(2).
func Chroot(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
if !t.HasCapability(linux.CAP_SYS_CHROOT) {
return 0, nil, linuxerr.EPERM
}
path, err := copyInPath(t, addr)
if err != nil {
return 0, nil, err
}
tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink)
if err != nil {
return 0, nil, err
}
defer tpop.Release(t)
vd, err := t.Kernel().VFS().GetDentryAt(t, t.Credentials(), &tpop.pop, &vfs.GetDentryOptions{
CheckSearchable: true,
})
if err != nil {
return 0, nil, err
}
t.FSContext().SetRootDirectoryVFS2(t, vd)
vd.DecRef(t)
return 0, nil, nil
}
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