159 lines
3.7 KiB
Go
159 lines
3.7 KiB
Go
/*
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* Copyright (c) SAS Institute, 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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*/
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package cpio
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import (
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"errors"
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"fmt"
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"io"
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)
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const TRAILER = "TRAILER!!!"
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var ErrStrippedHeader = errors.New("invalid cpio header: rpm-style stripped cpio requires supplemental size info")
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type CpioEntry struct {
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Header *Cpio_newc_header
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payload *file_stream
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}
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type CpioStream struct {
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stream *countingReader
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next_pos int64
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sizes []int64
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}
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type countingReader struct {
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stream io.Reader
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curr_pos int64
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}
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func NewCpioStream(stream io.Reader) *CpioStream {
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return &CpioStream{
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stream: &countingReader{
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stream: stream,
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curr_pos: 0,
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},
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next_pos: 0,
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}
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}
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// Provide supplemental file size info so that RPMs with files > 4GiB can be read
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func (cs *CpioStream) SetFileSizes(sizes []int64) {
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cs.sizes = sizes
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}
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func (cs *CpioStream) ReadNextEntry() (*CpioEntry, error) {
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if cs.next_pos != cs.stream.curr_pos {
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logger.Debugf("seeking %d, curr_pos: %d, next_pos: %d", cs.next_pos-cs.stream.curr_pos, cs.stream.curr_pos, cs.next_pos)
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_, err := cs.stream.Seek(cs.next_pos-cs.stream.curr_pos, 1)
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if err != nil {
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return nil, err
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}
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}
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// Read header
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hdr, err := readHeader(cs.stream)
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if err != nil {
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return nil, err
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} else if hdr.stripped {
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return cs.readStrippedEntry(hdr)
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}
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// Read filename
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buf := make([]byte, hdr.c_namesize)
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if _, err = io.ReadFull(cs.stream, buf); err != nil {
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return nil, err
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}
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filename := string(buf[:len(buf)-1])
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logger.Debugf("filename: %s", filename)
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offset := pad(cpio_newc_header_length+int(hdr.c_namesize)) - cpio_newc_header_length - int(hdr.c_namesize)
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if offset > 0 {
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_, err := cs.stream.Seek(int64(offset), 1)
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if err != nil {
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return nil, err
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}
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}
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// Find the next entry
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cs.next_pos = pad64(cs.stream.curr_pos + int64(hdr.c_filesize))
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// Find the payload
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payload, err := newFileStream(cs.stream, int64(hdr.c_filesize))
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if err != nil {
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return nil, err
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}
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// Create then entry
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hdr.filename = filename
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entry := CpioEntry{
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Header: hdr,
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payload: payload,
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}
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return &entry, nil
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}
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func (cs *CpioStream) readStrippedEntry(hdr *Cpio_newc_header) (*CpioEntry, error) {
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// magic has already been read
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if cs.sizes == nil {
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return nil, ErrStrippedHeader
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} else if hdr.index >= len(cs.sizes) {
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return nil, fmt.Errorf("stripped cpio refers to invalid file index %d", hdr.index)
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}
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size := cs.sizes[hdr.index]
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cs.next_pos = pad64(cs.stream.curr_pos + size)
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payload, err := newFileStream(cs.stream, size)
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if err != nil {
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return nil, err
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}
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return &CpioEntry{Header: hdr, payload: payload}, nil
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}
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func (cr *countingReader) Read(p []byte) (n int, err error) {
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n, err = cr.stream.Read(p)
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cr.curr_pos += int64(n)
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return
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}
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func (cr *countingReader) Seek(offset int64, whence int) (int64, error) {
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if whence != 1 {
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return 0, fmt.Errorf("only seeking from current location supported")
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}
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if offset == 0 {
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return cr.curr_pos, nil
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}
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logger.Debugf("offset: %d, curr_pos: %d", offset, cr.curr_pos)
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b := make([]byte, offset)
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n, err := io.ReadFull(cr, b)
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if err != nil && err != io.EOF {
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return 0, err
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}
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return int64(n), nil
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}
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func pad(num int) int {
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return num + 3 - (num+3)%4
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}
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func pad64(num int64) int64 {
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return num + 3 - (num+3)%4
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}
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