mirror of
https://github.com/siderolabs/talos.git
synced 2025-08-19 05:31:14 +02:00
Most of the fixes were automatically applied. Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>
76 lines
1.7 KiB
Go
76 lines
1.7 KiB
Go
// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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// Package vmlinuz provides utilities for reading bzImage kernel format.
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package vmlinuz
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import (
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"bytes"
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"compress/bzip2"
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"compress/gzip"
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"fmt"
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"io"
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"io/ioutil"
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"github.com/smira/go-xz"
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)
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type decompressFunc func(io.Reader) (io.ReadCloser, error)
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// Based on https://github.com/torvalds/linux/blob/master/scripts/extract-vmlinux.
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var bzImageMagic = []struct {
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magic []byte
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reader decompressFunc
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}{
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{
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magic: []byte("\3757zXZ\000"),
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reader: func(r io.Reader) (io.ReadCloser, error) {
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return xz.NewReader(r)
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},
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},
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{
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magic: []byte("\037\213\010"),
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reader: func(r io.Reader) (io.ReadCloser, error) {
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return gzip.NewReader(r)
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},
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},
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{
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magic: []byte("BZh"),
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reader: func(r io.Reader) (io.ReadCloser, error) {
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return ioutil.NopCloser(bzip2.NewReader(r)), nil
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},
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},
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}
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// Decompress the bzImage Linux kernel format and extract vmlinux kernel.
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//
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// Only following formats are supported: gzip, xz and bzip2.
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func Decompress(r io.Reader) (io.ReadCloser, error) {
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// read first 64Kb and look for signature
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head := make([]byte, 65536)
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if _, err := io.ReadFull(r, head); err != nil {
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return nil, fmt.Errorf("error reading 64Kb vmlinuz head: %w", err)
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}
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start := -1
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var decompress decompressFunc
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for _, matcher := range bzImageMagic {
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start = bytes.Index(head, matcher.magic)
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if start != -1 {
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decompress = matcher.reader
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break
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}
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}
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if start == -1 {
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return nil, fmt.Errorf("error looking for vmlinuz magic")
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}
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return decompress(io.MultiReader(bytes.NewReader(head[start:]), r))
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}
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