62 lines
1.6 KiB
Go
62 lines
1.6 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 linux
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import (
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"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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)
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const (
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_SYSLOG_ACTION_READ_ALL = 3
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_SYSLOG_ACTION_SIZE_BUFFER = 10
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)
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// logBufLen is the default syslog buffer size on Linux.
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const logBufLen = 1 << 17
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// Syslog implements part of Linux syscall syslog.
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//
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// Only the unpriviledged commands are implemented, allowing applications to
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// read a fun dmesg.
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func Syslog(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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command := args[0].Int()
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buf := args[1].Pointer()
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size := int(args[2].Int())
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switch command {
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case _SYSLOG_ACTION_READ_ALL:
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if size < 0 {
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return 0, nil, syserror.EINVAL
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}
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if size > logBufLen {
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size = logBufLen
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}
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log := t.Kernel().Syslog().Log()
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if len(log) > size {
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log = log[:size]
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}
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n, err := t.CopyOutBytes(buf, log)
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return uintptr(n), nil, err
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case _SYSLOG_ACTION_SIZE_BUFFER:
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return logBufLen, nil, nil
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default:
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return 0, nil, syserror.ENOSYS
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}
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}
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