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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/context"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/host"
vfshost "gvisor.dev/gvisor/pkg/sentry/fsimpl/host"
"gvisor.dev/gvisor/pkg/sentry/kernel"
)
// createFDTable creates an FD table 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 createFDTable(ctx context.Context, console bool, stdioFDs []int) (*kernel.FDTable, 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))
}
if kernel.VFS2Enabled {
return createFDTableVFS2(ctx, console, stdioFDs)
}
k := kernel.KernelFromContext(ctx)
fdTable := k.NewFDTable()
defer fdTable.DecRef()
var ttyFile *fs.File
for appFD, hostFD := range stdioFDs {
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, 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, false /* isTTY */)
if err != nil {
return nil, err
}
defer appFile.DecRef()
}
// Add the file to the FD map.
if err := fdTable.NewFDAt(ctx, int32(appFD), appFile, kernel.FDFlags{}); err != nil {
return nil, err
}
}
fdTable.IncRef()
return fdTable, nil
}
func createFDTableVFS2(ctx context.Context, console bool, stdioFDs []int) (*kernel.FDTable, error) {
k := kernel.KernelFromContext(ctx)
fdTable := k.NewFDTable()
defer fdTable.DecRef()
hostMount, err := vfshost.NewMount(k.VFS())
if err != nil {
return nil, fmt.Errorf("creating host mount: %w", err)
}
for appFD, hostFD := range stdioFDs {
// TODO(gvisor.dev/issue/1482): Add TTY support.
appFile, err := vfshost.ImportFD(hostMount, hostFD, false)
if err != nil {
return nil, err
}
if err := fdTable.NewFDAtVFS2(ctx, int32(appFD), appFile, kernel.FDFlags{}); err != nil {
appFile.DecRef()
return nil, err
}
appFile.DecRef()
}
fdTable.IncRef()
return fdTable, nil
}
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