55 lines
2.0 KiB
Go
55 lines
2.0 KiB
Go
// Copyright 2018 Google Inc.
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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 dev
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import (
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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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"gvisor.googlesource.com/gvisor/pkg/rand"
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/safemem"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
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)
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type randomDevice struct {
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ramfs.Entry
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}
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func newRandomDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *randomDevice {
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r := &randomDevice{}
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r.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
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return r
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}
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// DeprecatedPreadv reads random data.
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func (*randomDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
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return dst.CopyOutFrom(ctx, safemem.FromIOReader{rand.Reader})
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}
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// DeprecatedPwritev implements fs.HandleOperations.DeprecatedPwritev.
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func (*randomDevice) DeprecatedPwritev(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
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// On Linux, "Writing to /dev/random or /dev/urandom will update the
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// entropy pool with the data written, but this will not result in a higher
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// entropy count" - random(4). We don't need to support this, but we do
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// need to support the write, so just make it a no-op a la /dev/null.
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return src.NumBytes(), nil
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}
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// Truncate should be simply ignored for character devices on linux.
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func (r *randomDevice) Truncate(context.Context, *fs.Inode, int64) error {
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return nil
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}
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