github.com/ttpreport/gvisor-ligolo@v0.0.0-20240123134145-a858404967ba/pkg/sentry/fsimpl/host/save_restore.go (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package host
    16  
    17  import (
    18  	"fmt"
    19  	"io"
    20  
    21  	"github.com/ttpreport/gvisor-ligolo/pkg/fdnotifier"
    22  	"github.com/ttpreport/gvisor-ligolo/pkg/hostarch"
    23  	"github.com/ttpreport/gvisor-ligolo/pkg/safemem"
    24  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/hostfd"
    25  	"golang.org/x/sys/unix"
    26  )
    27  
    28  // beforeSave is invoked by stateify.
    29  func (i *inode) beforeSave() {
    30  	if !i.savable {
    31  		panic("host.inode is not savable")
    32  	}
    33  	if i.ftype == unix.S_IFIFO {
    34  		// If this pipe FD is readable, drain it so that bytes in the pipe can
    35  		// be read after restore. (This is a legacy VFS1 feature.) We don't
    36  		// know if the pipe FD is readable, so just try reading and tolerate
    37  		// EBADF from the read.
    38  		i.bufMu.Lock()
    39  		defer i.bufMu.Unlock()
    40  		var buf [hostarch.PageSize]byte
    41  		for {
    42  			n, err := hostfd.Preadv2(int32(i.hostFD), safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf[:])), -1 /* offset */, 0 /* flags */)
    43  			if n != 0 {
    44  				i.buf = append(i.buf, buf[:n]...)
    45  			}
    46  			if err != nil {
    47  				if err == io.EOF || err == unix.EAGAIN || err == unix.EBADF {
    48  					break
    49  				}
    50  				panic(fmt.Errorf("host.inode.beforeSave: buffering from pipe failed: %v", err))
    51  			}
    52  		}
    53  		if len(i.buf) != 0 {
    54  			i.haveBuf.Store(1)
    55  		}
    56  	}
    57  }
    58  
    59  // afterLoad is invoked by stateify.
    60  func (i *inode) afterLoad() {
    61  	if i.epollable {
    62  		if err := unix.SetNonblock(i.hostFD, true); err != nil {
    63  			panic(fmt.Sprintf("host.inode.afterLoad: failed to set host FD %d non-blocking: %v", i.hostFD, err))
    64  		}
    65  		if err := fdnotifier.AddFD(int32(i.hostFD), &i.queue); err != nil {
    66  			panic(fmt.Sprintf("host.inode.afterLoad: fdnotifier.AddFD(%d) failed: %v", i.hostFD, err))
    67  		}
    68  	}
    69  }