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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 linux
import (
"path"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/marshal/primitive"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fsbridge"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/sched"
"gvisor.dev/gvisor/pkg/sentry/loader"
"gvisor.dev/gvisor/pkg/usermem"
)
var (
// ExecMaxTotalSize is the maximum length of all argv and envv entries.
//
// N.B. The behavior here is different than Linux. Linux provides a limit on
// individual arguments of 32 pages, and an aggregate limit of at least 32 pages
// but otherwise bounded by min(stack size / 4, 8 MB * 3 / 4). We don't implement
// any behavior based on the stack size, and instead provide a fixed hard-limit of
// 2 MB (which should work well given that 8 MB stack limits are common).
ExecMaxTotalSize = 2 * 1024 * 1024
// ExecMaxElemSize is the maximum length of a single argv or envv entry.
ExecMaxElemSize = 32 * hostarch.PageSize
)
// Getppid implements linux syscall getppid(2).
func Getppid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
parent := t.Parent()
if parent == nil {
return 0, nil, nil
}
return uintptr(t.PIDNamespace().IDOfThreadGroup(parent.ThreadGroup())), nil, nil
}
// Getpid implements linux syscall getpid(2).
func Getpid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return uintptr(t.ThreadGroup().ID()), nil, nil
}
// Gettid implements linux syscall gettid(2).
func Gettid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return uintptr(t.ThreadID()), nil, nil
}
// Execve implements linux syscall execve(2).
func Execve(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
filenameAddr := args[0].Pointer()
argvAddr := args[1].Pointer()
envvAddr := args[2].Pointer()
return execveat(t, linux.AT_FDCWD, filenameAddr, argvAddr, envvAddr, 0)
}
// Execveat implements linux syscall execveat(2).
func Execveat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
dirFD := args[0].Int()
pathnameAddr := args[1].Pointer()
argvAddr := args[2].Pointer()
envvAddr := args[3].Pointer()
flags := args[4].Int()
return execveat(t, dirFD, pathnameAddr, argvAddr, envvAddr, flags)
}
func execveat(t *kernel.Task, dirFD int32, pathnameAddr, argvAddr, envvAddr hostarch.Addr, flags int32) (uintptr, *kernel.SyscallControl, error) {
pathname, err := t.CopyInString(pathnameAddr, linux.PATH_MAX)
if err != nil {
return 0, nil, err
}
var argv, envv []string
if argvAddr != 0 {
var err error
argv, err = t.CopyInVector(argvAddr, ExecMaxElemSize, ExecMaxTotalSize)
if err != nil {
return 0, nil, err
}
}
if envvAddr != 0 {
var err error
envv, err = t.CopyInVector(envvAddr, ExecMaxElemSize, ExecMaxTotalSize)
if err != nil {
return 0, nil, err
}
}
if flags&^(linux.AT_EMPTY_PATH|linux.AT_SYMLINK_NOFOLLOW) != 0 {
return 0, nil, linuxerr.EINVAL
}
atEmptyPath := flags&linux.AT_EMPTY_PATH != 0
if !atEmptyPath && len(pathname) == 0 {
return 0, nil, linuxerr.ENOENT
}
resolveFinal := flags&linux.AT_SYMLINK_NOFOLLOW == 0
root := t.FSContext().RootDirectory()
defer root.DecRef(t)
var wd *fs.Dirent
var executable fsbridge.File
var closeOnExec bool
if dirFD == linux.AT_FDCWD || path.IsAbs(pathname) {
// Even if the pathname is absolute, we may still need the wd
// for interpreter scripts if the path of the interpreter is
// relative.
wd = t.FSContext().WorkingDirectory()
} else {
// Need to extract the given FD.
f, fdFlags := t.FDTable().Get(dirFD)
if f == nil {
return 0, nil, linuxerr.EBADF
}
defer f.DecRef(t)
closeOnExec = fdFlags.CloseOnExec
if atEmptyPath && len(pathname) == 0 {
// TODO(gvisor.dev/issue/160): Linux requires only execute permission,
// not read. However, our backing filesystems may prevent us from reading
// the file without read permission. Additionally, a task with a
// non-readable executable has additional constraints on access via
// ptrace and procfs.
if err := f.Dirent.Inode.CheckPermission(t, fs.PermMask{Read: true, Execute: true}); err != nil {
return 0, nil, err
}
executable = fsbridge.NewFSFile(f)
} else {
wd = f.Dirent
wd.IncRef()
if !fs.IsDir(wd.Inode.StableAttr) {
return 0, nil, linuxerr.ENOTDIR
}
}
}
if wd != nil {
defer wd.DecRef(t)
}
// Load the new TaskImage.
remainingTraversals := uint(linux.MaxSymlinkTraversals)
loadArgs := loader.LoadArgs{
Opener: fsbridge.NewFSLookup(t.MountNamespace(), root, wd),
RemainingTraversals: &remainingTraversals,
ResolveFinal: resolveFinal,
Filename: pathname,
File: executable,
CloseOnExec: closeOnExec,
Argv: argv,
Envv: envv,
Features: t.Arch().FeatureSet(),
}
image, se := t.Kernel().LoadTaskImage(t, loadArgs)
if se != nil {
return 0, nil, se.ToError()
}
ctrl, err := t.Execve(image)
return 0, ctrl, err
}
// Exit implements linux syscall exit(2).
func Exit(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
status := args[0].Int()
t.PrepareExit(linux.WaitStatusExit(status & 0xff))
return 0, kernel.CtrlDoExit, nil
}
// ExitGroup implements linux syscall exit_group(2).
func ExitGroup(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
status := args[0].Int()
t.PrepareGroupExit(linux.WaitStatusExit(status & 0xff))
return 0, kernel.CtrlDoExit, nil
}
// clone is used by Clone, Fork, and VFork.
func clone(t *kernel.Task, flags int, stack hostarch.Addr, parentTID hostarch.Addr, childTID hostarch.Addr, tls hostarch.Addr) (uintptr, *kernel.SyscallControl, error) {
args := linux.CloneArgs{
Flags: uint64(uint32(flags) &^ linux.CSIGNAL),
Pidfd: uint64(parentTID),
ChildTID: uint64(childTID),
ParentTID: uint64(parentTID),
ExitSignal: uint64(flags & linux.CSIGNAL),
Stack: uint64(stack),
TLS: uint64(tls),
}
ntid, ctrl, err := t.Clone(&args)
return uintptr(ntid), ctrl, err
}
// Fork implements Linux syscall fork(2).
func Fork(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
// "A call to fork() is equivalent to a call to clone(2) specifying flags
// as just SIGCHLD." - fork(2)
return clone(t, int(linux.SIGCHLD), 0, 0, 0, 0)
}
// Vfork implements Linux syscall vfork(2).
func Vfork(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
// """
// A call to vfork() is equivalent to calling clone(2) with flags specified as:
//
// CLONE_VM | CLONE_VFORK | SIGCHLD
// """ - vfork(2)
return clone(t, linux.CLONE_VM|linux.CLONE_VFORK|int(linux.SIGCHLD), 0, 0, 0, 0)
}
// parseCommonWaitOptions applies the options common to wait4 and waitid to
// wopts.
func parseCommonWaitOptions(wopts *kernel.WaitOptions, options int) error {
switch options & (linux.WCLONE | linux.WALL) {
case 0:
wopts.NonCloneTasks = true
case linux.WCLONE:
wopts.CloneTasks = true
case linux.WALL:
wopts.NonCloneTasks = true
wopts.CloneTasks = true
default:
return linuxerr.EINVAL
}
if options&linux.WCONTINUED != 0 {
wopts.Events |= kernel.EventGroupContinue
}
if options&linux.WNOHANG == 0 {
wopts.BlockInterruptErr = linuxerr.ERESTARTSYS
}
if options&linux.WNOTHREAD == 0 {
wopts.SiblingChildren = true
}
return nil
}
// wait4 waits for the given child process to exit.
func wait4(t *kernel.Task, pid int, statusAddr hostarch.Addr, options int, rusageAddr hostarch.Addr) (uintptr, error) {
if options&^(linux.WNOHANG|linux.WUNTRACED|linux.WCONTINUED|linux.WNOTHREAD|linux.WALL|linux.WCLONE) != 0 {
return 0, linuxerr.EINVAL
}
wopts := kernel.WaitOptions{
Events: kernel.EventExit | kernel.EventTraceeStop,
ConsumeEvent: true,
}
// There are four cases to consider:
//
// pid < -1 any child process whose process group ID is equal to the absolute value of pid
// pid == -1 any child process
// pid == 0 any child process whose process group ID is equal to that of the calling process
// pid > 0 the child whose process ID is equal to the value of pid
switch {
case pid < -1:
wopts.SpecificPGID = kernel.ProcessGroupID(-pid)
case pid == -1:
// Any process is the default.
case pid == 0:
wopts.SpecificPGID = t.PIDNamespace().IDOfProcessGroup(t.ThreadGroup().ProcessGroup())
default:
wopts.SpecificTID = kernel.ThreadID(pid)
}
if err := parseCommonWaitOptions(&wopts, options); err != nil {
return 0, err
}
if options&linux.WUNTRACED != 0 {
wopts.Events |= kernel.EventChildGroupStop
}
wr, err := t.Wait(&wopts)
if err != nil {
if err == kernel.ErrNoWaitableEvent {
return 0, nil
}
return 0, err
}
if statusAddr != 0 {
if _, err := primitive.CopyUint32Out(t, statusAddr, uint32(wr.Status)); err != nil {
return 0, err
}
}
if rusageAddr != 0 {
ru := getrusage(wr.Task, linux.RUSAGE_BOTH)
if _, err := ru.CopyOut(t, rusageAddr); err != nil {
return 0, err
}
}
return uintptr(wr.TID), nil
}
// Wait4 implements linux syscall wait4(2).
func Wait4(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
pid := int(args[0].Int())
statusAddr := args[1].Pointer()
options := int(args[2].Uint())
rusageAddr := args[3].Pointer()
n, err := wait4(t, pid, statusAddr, options, rusageAddr)
return n, nil, err
}
// WaitPid implements linux syscall waitpid(2).
func WaitPid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
pid := int(args[0].Int())
statusAddr := args[1].Pointer()
options := int(args[2].Uint())
n, err := wait4(t, pid, statusAddr, options, 0)
return n, nil, err
}
// Waitid implements linux syscall waitid(2).
func Waitid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
idtype := args[0].Int()
id := args[1].Int()
infop := args[2].Pointer()
options := int(args[3].Uint())
rusageAddr := args[4].Pointer()
if options&^(linux.WNOHANG|linux.WEXITED|linux.WSTOPPED|linux.WCONTINUED|linux.WNOWAIT|linux.WNOTHREAD|linux.WALL|linux.WCLONE) != 0 {
return 0, nil, linuxerr.EINVAL
}
if options&(linux.WEXITED|linux.WSTOPPED|linux.WCONTINUED) == 0 {
return 0, nil, linuxerr.EINVAL
}
wopts := kernel.WaitOptions{
Events: kernel.EventTraceeStop,
ConsumeEvent: options&linux.WNOWAIT == 0,
}
switch idtype {
case linux.P_ALL:
case linux.P_PID:
wopts.SpecificTID = kernel.ThreadID(id)
case linux.P_PGID:
wopts.SpecificPGID = kernel.ProcessGroupID(id)
default:
return 0, nil, linuxerr.EINVAL
}
if err := parseCommonWaitOptions(&wopts, options); err != nil {
return 0, nil, err
}
if options&linux.WEXITED != 0 {
wopts.Events |= kernel.EventExit
}
if options&linux.WSTOPPED != 0 {
wopts.Events |= kernel.EventChildGroupStop
}
wr, err := t.Wait(&wopts)
if err != nil {
if err == kernel.ErrNoWaitableEvent {
err = nil
// "If WNOHANG was specified in options and there were no children
// in a waitable state, then waitid() returns 0 immediately and the
// state of the siginfo_t structure pointed to by infop is
// unspecified." - waitid(2). But Linux's waitid actually zeroes
// out the fields it would set for a successful waitid in this case
// as well.
if infop != 0 {
var si linux.SignalInfo
_, err = si.CopyOut(t, infop)
}
}
return 0, nil, err
}
if rusageAddr != 0 {
ru := getrusage(wr.Task, linux.RUSAGE_BOTH)
if _, err := ru.CopyOut(t, rusageAddr); err != nil {
return 0, nil, err
}
}
if infop == 0 {
return 0, nil, nil
}
si := linux.SignalInfo{
Signo: int32(linux.SIGCHLD),
}
si.SetPID(int32(wr.TID))
si.SetUID(int32(wr.UID))
s := wr.Status
switch {
case s.Exited():
si.Code = linux.CLD_EXITED
si.SetStatus(int32(s.ExitStatus()))
case s.Signaled():
if s.CoreDumped() {
si.Code = linux.CLD_DUMPED
} else {
si.Code = linux.CLD_KILLED
}
si.SetStatus(int32(s.TerminationSignal()))
case s.Stopped():
if wr.Event == kernel.EventTraceeStop {
si.Code = linux.CLD_TRAPPED
si.SetStatus(int32(s.PtraceEvent()))
} else {
si.Code = linux.CLD_STOPPED
si.SetStatus(int32(s.StopSignal()))
}
case s.Continued():
si.Code = linux.CLD_CONTINUED
si.SetStatus(int32(linux.SIGCONT))
default:
t.Warningf("waitid got incomprehensible wait status %d", s)
}
_, err = si.CopyOut(t, infop)
return 0, nil, err
}
// SetTidAddress implements linux syscall set_tid_address(2).
func SetTidAddress(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
addr := args[0].Pointer()
// Always succeed, return caller's tid.
t.SetClearTID(addr)
return uintptr(t.ThreadID()), nil, nil
}
// Unshare implements linux syscall unshare(2).
func Unshare(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
flags := args[0].Int()
// "CLONE_NEWPID automatically implies CLONE_THREAD as well." - unshare(2)
if flags&linux.CLONE_NEWPID != 0 {
flags |= linux.CLONE_THREAD
}
// "... specifying CLONE_NEWUSER automatically implies CLONE_THREAD. Since
// Linux 3.9, CLONE_NEWUSER also automatically implies CLONE_FS."
if flags&linux.CLONE_NEWUSER != 0 {
flags |= linux.CLONE_THREAD | linux.CLONE_FS
}
return 0, nil, t.Unshare(flags)
}
// SchedYield implements linux syscall sched_yield(2).
func SchedYield(t *kernel.Task, _ arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
t.Yield()
return 0, nil, nil
}
// SchedSetaffinity implements linux syscall sched_setaffinity(2).
func SchedSetaffinity(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
tid := args[0].Int()
size := args[1].SizeT()
maskAddr := args[2].Pointer()
var task *kernel.Task
if tid == 0 {
task = t
} else {
task = t.PIDNamespace().TaskWithID(kernel.ThreadID(tid))
if task == nil {
return 0, nil, linuxerr.ESRCH
}
}
mask := sched.NewCPUSet(t.Kernel().ApplicationCores())
if size > mask.Size() {
size = mask.Size()
}
if _, err := t.CopyInBytes(maskAddr, mask[:size]); err != nil {
return 0, nil, err
}
return 0, nil, task.SetCPUMask(mask)
}
// SchedGetaffinity implements linux syscall sched_getaffinity(2).
func SchedGetaffinity(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
tid := args[0].Int()
size := args[1].SizeT()
maskAddr := args[2].Pointer()
// This limitation is because linux stores the cpumask
// in an array of "unsigned long" so the buffer needs to
// be a multiple of the word size.
if size&(t.Arch().Width()-1) > 0 {
return 0, nil, linuxerr.EINVAL
}
var task *kernel.Task
if tid == 0 {
task = t
} else {
task = t.PIDNamespace().TaskWithID(kernel.ThreadID(tid))
if task == nil {
return 0, nil, linuxerr.ESRCH
}
}
mask := task.CPUMask()
// The buffer needs to be big enough to hold a cpumask with
// all possible cpus.
if size < mask.Size() {
return 0, nil, linuxerr.EINVAL
}
_, err := t.CopyOutBytes(maskAddr, mask)
// NOTE: The syscall interface is slightly different than the glibc
// interface. The raw sched_getaffinity syscall returns the number of
// bytes used to represent a cpu mask.
return uintptr(mask.Size()), nil, err
}
// Getcpu implements linux syscall getcpu(2).
func Getcpu(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
cpu := args[0].Pointer()
node := args[1].Pointer()
// third argument to this system call is nowadays unused.
if cpu != 0 {
if _, err := primitive.CopyInt32Out(t, cpu, t.CPU()); err != nil {
return 0, nil, err
}
}
// We always return node 0.
if node != 0 {
if _, err := t.MemoryManager().ZeroOut(t, node, 4, usermem.IOOpts{
AddressSpaceActive: true,
}); err != nil {
return 0, nil, err
}
}
return 0, nil, nil
}
// Setpgid implements the linux syscall setpgid(2).
func Setpgid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
// Note that throughout this function, pgid is interpreted with respect
// to t's namespace, not with respect to the selected ThreadGroup's
// namespace (which may be different).
pid := kernel.ThreadID(args[0].Int())
pgid := kernel.ProcessGroupID(args[1].Int())
// "If pid is zero, then the process ID of the calling process is used."
tg := t.ThreadGroup()
if pid != 0 {
ot := t.PIDNamespace().TaskWithID(pid)
if ot == nil {
return 0, nil, linuxerr.ESRCH
}
tg = ot.ThreadGroup()
if tg.Leader() != ot {
return 0, nil, linuxerr.EINVAL
}
// Setpgid only operates on child threadgroups.
if tg != t.ThreadGroup() && (tg.Leader().Parent() == nil || tg.Leader().Parent().ThreadGroup() != t.ThreadGroup()) {
return 0, nil, linuxerr.ESRCH
}
}
// "If pgid is zero, then the PGID of the process specified by pid is made
// the same as its process ID."
defaultPGID := kernel.ProcessGroupID(t.PIDNamespace().IDOfThreadGroup(tg))
if pgid == 0 {
pgid = defaultPGID
} else if pgid < 0 {
return 0, nil, linuxerr.EINVAL
}
// If the pgid is the same as the group, then create a new one. Otherwise,
// we attempt to join an existing process group.
if pgid == defaultPGID {
// For convenience, errors line up with Linux syscall API.
if err := tg.CreateProcessGroup(); err != nil {
// Is the process group already as expected? If so,
// just return success. This is the same behavior as
// Linux.
if t.PIDNamespace().IDOfProcessGroup(tg.ProcessGroup()) == defaultPGID {
return 0, nil, nil
}
return 0, nil, err
}
} else {
// Same as CreateProcessGroup, above.
if err := tg.JoinProcessGroup(t.PIDNamespace(), pgid, tg != t.ThreadGroup()); err != nil {
// See above.
if t.PIDNamespace().IDOfProcessGroup(tg.ProcessGroup()) == pgid {
return 0, nil, nil
}
return 0, nil, err
}
}
// Success.
return 0, nil, nil
}
// Getpgrp implements the linux syscall getpgrp(2).
func Getpgrp(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return uintptr(t.PIDNamespace().IDOfProcessGroup(t.ThreadGroup().ProcessGroup())), nil, nil
}
// Getpgid implements the linux syscall getpgid(2).
func Getpgid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
tid := kernel.ThreadID(args[0].Int())
if tid == 0 {
return Getpgrp(t, args)
}
target := t.PIDNamespace().TaskWithID(tid)
if target == nil {
return 0, nil, linuxerr.ESRCH
}
return uintptr(t.PIDNamespace().IDOfProcessGroup(target.ThreadGroup().ProcessGroup())), nil, nil
}
// Setsid implements the linux syscall setsid(2).
func Setsid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
return 0, nil, t.ThreadGroup().CreateSession()
}
// Getsid implements the linux syscall getsid(2).
func Getsid(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
tid := kernel.ThreadID(args[0].Int())
if tid == 0 {
return uintptr(t.PIDNamespace().IDOfSession(t.ThreadGroup().Session())), nil, nil
}
target := t.PIDNamespace().TaskWithID(tid)
if target == nil {
return 0, nil, linuxerr.ESRCH
}
return uintptr(t.PIDNamespace().IDOfSession(target.ThreadGroup().Session())), nil, nil
}
// Getpriority pretends to implement the linux syscall getpriority(2).
//
// This is a stub; real priorities require a full scheduler.
func Getpriority(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
which := args[0].Int()
who := kernel.ThreadID(args[1].Int())
switch which {
case linux.PRIO_PROCESS:
// Look for who, return ESRCH if not found.
var task *kernel.Task
if who == 0 {
task = t
} else {
task = t.PIDNamespace().TaskWithID(who)
}
if task == nil {
return 0, nil, linuxerr.ESRCH
}
// From kernel/sys.c:getpriority:
// "To avoid negative return values, 'getpriority()'
// will not return the normal nice-value, but a negated
// value that has been offset by 20"
return uintptr(20 - task.Niceness()), nil, nil
case linux.PRIO_USER:
fallthrough
case linux.PRIO_PGRP:
// PRIO_USER and PRIO_PGRP have no further implementation yet.
return 0, nil, nil
default:
return 0, nil, linuxerr.EINVAL
}
}
// Setpriority pretends to implement the linux syscall setpriority(2).
//
// This is a stub; real priorities require a full scheduler.
func Setpriority(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
which := args[0].Int()
who := kernel.ThreadID(args[1].Int())
niceval := int(args[2].Int())
// In the kernel's implementation, values outside the range
// of [-20, 19] are truncated to these minimum and maximum
// values.
if niceval < -20 /* min niceval */ {
niceval = -20
} else if niceval > 19 /* max niceval */ {
niceval = 19
}
switch which {
case linux.PRIO_PROCESS:
// Look for who, return ESRCH if not found.
var task *kernel.Task
if who == 0 {
task = t
} else {
task = t.PIDNamespace().TaskWithID(who)
}
if task == nil {
return 0, nil, linuxerr.ESRCH
}
task.SetNiceness(niceval)
case linux.PRIO_USER:
fallthrough
case linux.PRIO_PGRP:
// PRIO_USER and PRIO_PGRP have no further implementation yet.
return 0, nil, nil
default:
return 0, nil, linuxerr.EINVAL
}
return 0, nil, nil
}
// Ptrace implements linux system call ptrace(2).
func Ptrace(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
req := args[0].Int64()
pid := kernel.ThreadID(args[1].Int())
addr := args[2].Pointer()
data := args[3].Pointer()
return 0, nil, t.Ptrace(req, pid, addr, data)
}
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