57 lines
1.5 KiB
Go
57 lines
1.5 KiB
Go
// Copyright 2019 The gVisor Authors.
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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 strace
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import (
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"fmt"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
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"gvisor.dev/gvisor/pkg/usermem"
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)
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func fdsFromSet(t *kernel.Task, set []byte) []int {
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var fds []int
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// Append n if the n-th bit is 1.
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for i, v := range set {
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for j := 0; j < 8; j++ {
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if (v>>j)&1 == 1 {
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fds = append(fds, i*8+j)
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}
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}
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}
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return fds
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}
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func fdSet(t *kernel.Task, nfds int, addr usermem.Addr) string {
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if nfds < 0 {
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return fmt.Sprintf("%#x (negative nfds)", addr)
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}
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if addr == 0 {
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return "null"
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}
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// Calculate the size of the fd set (one bit per fd).
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nBytes := (nfds + 7) / 8
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nBitsInLastPartialByte := nfds % 8
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set, err := linux.CopyInFDSet(t, addr, nBytes, nBitsInLastPartialByte)
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if err != nil {
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return fmt.Sprintf("%#x (error decoding fdset: %s)", addr, err)
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}
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return fmt.Sprintf("%#x %v", addr, fdsFromSet(t, set))
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}
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