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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 boot
import (
"fmt"
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/host"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/kdefs"
"gvisor.dev/gvisor/pkg/sentry/limits"
)
// createFDMap creates an FD map that contains stdin, stdout, and stderr. If
// console is true, then ioctl calls will be passed through to the host FD.
// Upon success, createFDMap dups then closes stdioFDs.
func createFDMap(ctx context.Context, l *limits.LimitSet, console bool, stdioFDs []int) (*kernel.FDMap, error) {
if len(stdioFDs) != 3 {
return nil, fmt.Errorf("stdioFDs should contain exactly 3 FDs (stdin, stdout, and stderr), but %d FDs received", len(stdioFDs))
}
k := kernel.KernelFromContext(ctx)
fdm := k.NewFDMap()
defer fdm.DecRef()
mounter := fs.FileOwnerFromContext(ctx)
// Maps sandbox FD to host FD.
fdMap := map[int]int{
0: stdioFDs[0],
1: stdioFDs[1],
2: stdioFDs[2],
}
var ttyFile *fs.File
for appFD, hostFD := range fdMap {
var appFile *fs.File
if console && appFD < 3 {
// Import the file as a host TTY file.
if ttyFile == nil {
var err error
appFile, err = host.ImportFile(ctx, hostFD, mounter, true /* isTTY */)
if err != nil {
return nil, err
}
defer appFile.DecRef()
// Remember this in the TTY file, as we will
// use it for the other stdio FDs.
ttyFile = appFile
} else {
// Re-use the existing TTY file, as all three
// stdio FDs must point to the same fs.File in
// order to share TTY state, specifically the
// foreground process group id.
appFile = ttyFile
}
} else {
// Import the file as a regular host file.
var err error
appFile, err = host.ImportFile(ctx, hostFD, mounter, false /* isTTY */)
if err != nil {
return nil, err
}
defer appFile.DecRef()
}
// Add the file to the FD map.
if err := fdm.NewFDAt(kdefs.FD(appFD), appFile, kernel.FDFlags{}, l); err != nil {
return nil, err
}
}
fdm.IncRef()
return fdm, nil
}
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