361 lines
9.2 KiB
Go
361 lines
9.2 KiB
Go
// Copyright 2018 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 linux
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import (
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"time"
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/sentry/arch"
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"gvisor.dev/gvisor/pkg/sentry/fs"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
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"gvisor.dev/gvisor/pkg/sentry/socket"
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"gvisor.dev/gvisor/pkg/sentry/usermem"
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"gvisor.dev/gvisor/pkg/syserror"
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"gvisor.dev/gvisor/pkg/waiter"
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)
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const (
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// EventMaskWrite contains events that can be triggered on writes.
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//
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// Note that EventHUp is not going to happen for pipes but may for
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// implementations of poll on some sockets, see net/core/datagram.c.
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EventMaskWrite = waiter.EventOut | waiter.EventHUp | waiter.EventErr
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)
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// Write implements linux syscall write(2).
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func Write(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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addr := args[1].Pointer()
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size := args[2].SizeT()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// Check that the file is writable.
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if !file.Flags().Write {
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return 0, nil, syserror.EBADF
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}
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// Check that the size is legitimate.
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si := int(size)
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if si < 0 {
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return 0, nil, syserror.EINVAL
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}
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// Get the source of the write.
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src, err := t.SingleIOSequence(addr, si, usermem.IOOpts{
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AddressSpaceActive: true,
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})
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if err != nil {
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return 0, nil, err
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}
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n, err := writev(t, file, src)
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t.IOUsage().AccountWriteSyscall(n)
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return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "write", file)
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}
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// Pwrite64 implements linux syscall pwrite64(2).
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func Pwrite64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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addr := args[1].Pointer()
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size := args[2].SizeT()
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offset := args[3].Int64()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// Check that the offset is legitimate.
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if offset < 0 {
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return 0, nil, syserror.EINVAL
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}
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// Is writing at an offset supported?
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if !file.Flags().Pwrite {
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return 0, nil, syserror.ESPIPE
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}
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// Check that the file is writable.
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if !file.Flags().Write {
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return 0, nil, syserror.EBADF
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}
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// Check that the size is legitimate.
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si := int(size)
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if si < 0 {
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return 0, nil, syserror.EINVAL
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}
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// Get the source of the write.
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src, err := t.SingleIOSequence(addr, si, usermem.IOOpts{
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AddressSpaceActive: true,
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})
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if err != nil {
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return 0, nil, err
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}
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n, err := pwritev(t, file, src, offset)
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t.IOUsage().AccountWriteSyscall(n)
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return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "pwrite64", file)
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}
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// Writev implements linux syscall writev(2).
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func Writev(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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addr := args[1].Pointer()
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iovcnt := int(args[2].Int())
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// Check that the file is writable.
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if !file.Flags().Write {
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return 0, nil, syserror.EBADF
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}
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// Read the iovecs that specify the source of the write.
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src, err := t.IovecsIOSequence(addr, iovcnt, usermem.IOOpts{
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AddressSpaceActive: true,
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})
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if err != nil {
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return 0, nil, err
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}
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n, err := writev(t, file, src)
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t.IOUsage().AccountWriteSyscall(n)
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return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "writev", file)
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}
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// Pwritev implements linux syscall pwritev(2).
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func Pwritev(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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addr := args[1].Pointer()
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iovcnt := int(args[2].Int())
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offset := args[3].Int64()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// Check that the offset is legitimate.
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if offset < 0 {
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return 0, nil, syserror.EINVAL
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}
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// Is writing at an offset supported?
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if !file.Flags().Pwrite {
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return 0, nil, syserror.ESPIPE
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}
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// Check that the file is writable.
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if !file.Flags().Write {
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return 0, nil, syserror.EBADF
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}
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// Read the iovecs that specify the source of the write.
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src, err := t.IovecsIOSequence(addr, iovcnt, usermem.IOOpts{
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AddressSpaceActive: true,
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})
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if err != nil {
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return 0, nil, err
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}
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n, err := pwritev(t, file, src, offset)
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t.IOUsage().AccountWriteSyscall(n)
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return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "pwritev", file)
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}
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// Pwritev2 implements linux syscall pwritev2(2).
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func Pwritev2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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// While the syscall is
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// pwritev2(int fd, struct iovec* iov, int iov_cnt, off_t offset, int flags)
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// the linux internal call
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// (https://elixir.bootlin.com/linux/v4.18/source/fs/read_write.c#L1354)
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// splits the offset argument into a high/low value for compatibility with
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// 32-bit architectures. The flags argument is the 5th argument.
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fd := args[0].Int()
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addr := args[1].Pointer()
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iovcnt := int(args[2].Int())
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offset := args[3].Int64()
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flags := int(args[5].Int())
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if int(args[4].Int())&0x4 == 1 {
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return 0, nil, syserror.EACCES
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}
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// Check that the offset is legitimate.
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if offset < -1 {
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return 0, nil, syserror.EINVAL
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}
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// Is writing at an offset supported?
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if offset > -1 && !file.Flags().Pwrite {
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return 0, nil, syserror.ESPIPE
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}
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// Note: gVisor does not implement the RWF_HIPRI feature, but the flag is
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// accepted as a valid flag argument for pwritev2.
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if flags&^linux.RWF_VALID != 0 {
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return uintptr(flags), nil, syserror.EOPNOTSUPP
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}
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// Check that the file is writeable.
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if !file.Flags().Write {
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return 0, nil, syserror.EBADF
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}
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// Read the iovecs that specify the source of the write.
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src, err := t.IovecsIOSequence(addr, iovcnt, usermem.IOOpts{
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AddressSpaceActive: true,
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})
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if err != nil {
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return 0, nil, err
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}
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// If pwritev2 is called with an offset of -1, writev is called.
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if offset == -1 {
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n, err := writev(t, file, src)
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t.IOUsage().AccountWriteSyscall(n)
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return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "pwritev2", file)
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}
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n, err := pwritev(t, file, src, offset)
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t.IOUsage().AccountWriteSyscall(n)
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return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "pwritev2", file)
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}
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func writev(t *kernel.Task, f *fs.File, src usermem.IOSequence) (int64, error) {
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n, err := f.Writev(t, src)
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if err != syserror.ErrWouldBlock || f.Flags().NonBlocking {
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if n > 0 {
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// Queue notification if we wrote anything.
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f.Dirent.InotifyEvent(linux.IN_MODIFY, 0)
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}
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return n, err
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}
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// Sockets support write timeouts.
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var haveDeadline bool
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var deadline ktime.Time
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if s, ok := f.FileOperations.(socket.Socket); ok {
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dl := s.SendTimeout()
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if dl < 0 && err == syserror.ErrWouldBlock {
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return n, err
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}
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if dl > 0 {
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deadline = t.Kernel().MonotonicClock().Now().Add(time.Duration(dl) * time.Nanosecond)
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haveDeadline = true
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}
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}
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// Register for notifications.
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w, ch := waiter.NewChannelEntry(nil)
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f.EventRegister(&w, EventMaskWrite)
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total := n
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for {
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// Shorten src to reflect bytes previously written.
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src = src.DropFirst64(n)
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// Issue the request and break out if it completes with
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// anything other than "would block".
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n, err = f.Writev(t, src)
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total += n
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if err != syserror.ErrWouldBlock {
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break
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}
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// Wait for a notification that we should retry.
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if err = t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
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if err == syserror.ETIMEDOUT {
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err = syserror.ErrWouldBlock
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}
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break
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}
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}
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f.EventUnregister(&w)
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if total > 0 {
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// Queue notification if we wrote anything.
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f.Dirent.InotifyEvent(linux.IN_MODIFY, 0)
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}
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return total, err
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}
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func pwritev(t *kernel.Task, f *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
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n, err := f.Pwritev(t, src, offset)
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if err != syserror.ErrWouldBlock || f.Flags().NonBlocking {
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if n > 0 {
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// Queue notification if we wrote anything.
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f.Dirent.InotifyEvent(linux.IN_MODIFY, 0)
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}
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return n, err
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}
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// Register for notifications.
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w, ch := waiter.NewChannelEntry(nil)
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f.EventRegister(&w, EventMaskWrite)
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total := n
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for {
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// Shorten src to reflect bytes previously written.
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src = src.DropFirst64(n)
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// Issue the request and break out if it completes with
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// anything other than "would block".
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n, err = f.Pwritev(t, src, offset+total)
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total += n
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if err != syserror.ErrWouldBlock {
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break
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}
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// Wait for a notification that we should retry.
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if err = t.Block(ch); err != nil {
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break
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}
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}
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f.EventUnregister(&w)
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if total > 0 {
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// Queue notification if we wrote anything.
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f.Dirent.InotifyEvent(linux.IN_MODIFY, 0)
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}
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return total, err
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}
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