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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 vfs2
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/signalfd"
"gvisor.dev/gvisor/pkg/sentry/kernel"
slinux "gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
"gvisor.dev/gvisor/pkg/syserror"
)
// sharedSignalfd is shared between the two calls.
func sharedSignalfd(t *kernel.Task, fd int32, sigset hostarch.Addr, sigsetsize uint, flags int32) (uintptr, *kernel.SyscallControl, error) {
// Copy in the signal mask.
mask, err := slinux.CopyInSigSet(t, sigset, sigsetsize)
if err != nil {
return 0, nil, err
}
// Always check for valid flags, even if not creating.
if flags&^(linux.SFD_NONBLOCK|linux.SFD_CLOEXEC) != 0 {
return 0, nil, linuxerr.EINVAL
}
// Is this a change to an existing signalfd?
//
// The spec indicates that this should adjust the mask.
if fd != -1 {
file := t.GetFileVFS2(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef(t)
// Is this a signalfd?
if sfd, ok := file.Impl().(*signalfd.SignalFileDescription); ok {
sfd.SetMask(mask)
return 0, nil, nil
}
// Not a signalfd.
return 0, nil, linuxerr.EINVAL
}
fileFlags := uint32(linux.O_RDWR)
if flags&linux.SFD_NONBLOCK != 0 {
fileFlags |= linux.O_NONBLOCK
}
// Create a new file.
vfsObj := t.Kernel().VFS()
file, err := signalfd.New(vfsObj, t, mask, fileFlags)
if err != nil {
return 0, nil, err
}
defer file.DecRef(t)
// Create a new descriptor.
fd, err = t.NewFDFromVFS2(0, file, kernel.FDFlags{
CloseOnExec: flags&linux.SFD_CLOEXEC != 0,
})
if err != nil {
return 0, nil, err
}
// Done.
return uintptr(fd), nil, nil
}
// Signalfd implements the linux syscall signalfd(2).
func Signalfd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
sigset := args[1].Pointer()
sigsetsize := args[2].SizeT()
return sharedSignalfd(t, fd, sigset, sigsetsize, 0)
}
// Signalfd4 implements the linux syscall signalfd4(2).
func Signalfd4(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
sigset := args[1].Pointer()
sigsetsize := args[2].SizeT()
flags := args[3].Int()
return sharedSignalfd(t, fd, sigset, sigsetsize, flags)
}
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