Marvin Preuss
1d4ae27878
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continuous-integration/drone/push Build is passing
125 lines
3.3 KiB
Go
125 lines
3.3 KiB
Go
/*
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Copyright (c) 2013 Blake Smith <blakesmith0@gmail.com>
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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package ar
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import (
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"errors"
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"io"
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"strconv"
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)
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var (
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ErrWriteTooLong = errors.New("ar: write too long")
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)
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// Writer provides sequential writing of an ar archive.
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// An ar archive is sequence of header file pairs
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// Call WriteHeader to begin writing a new file, then call Write to supply the file's data
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//
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// Example:
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// archive := ar.NewWriter(writer)
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// archive.WriteGlobalHeader()
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// header := new(ar.Header)
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// header.Size = 15 // bytes
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// if err := archive.WriteHeader(header); err != nil {
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// return err
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// }
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// io.Copy(archive, data)
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type Writer struct {
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w io.Writer
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nb int64 // number of unwritten bytes for the current file entry
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}
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// Create a new ar writer that writes to w
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func NewWriter(w io.Writer) *Writer { return &Writer{w: w} }
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func (aw *Writer) numeric(b []byte, x int64) {
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s := strconv.FormatInt(x, 10)
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for len(s) < len(b) {
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s = s + " "
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}
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copy(b, []byte(s))
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}
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func (aw *Writer) octal(b []byte, x int64) {
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s := "100" + strconv.FormatInt(x, 8)
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for len(s) < len(b) {
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s = s + " "
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}
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copy(b, []byte(s))
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}
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func (aw *Writer) string(b []byte, str string) {
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s := str
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for len(s) < len(b) {
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s = s + " "
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}
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copy(b, []byte(s))
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}
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// Writes to the current entry in the ar archive
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// Returns ErrWriteTooLong if more than header.Size
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// bytes are written after a call to WriteHeader
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func (aw *Writer) Write(b []byte) (n int, err error) {
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if int64(len(b)) > aw.nb {
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b = b[0:aw.nb]
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err = ErrWriteTooLong
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}
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n, werr := aw.w.Write(b)
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aw.nb -= int64(n)
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if werr != nil {
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return n, werr
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}
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if len(b)%2 == 1 { // data size must be aligned to an even byte
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n2, _ := aw.w.Write([]byte{'\n'})
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return n+n2, err
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}
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return
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}
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func (aw *Writer) WriteGlobalHeader() error {
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_, err := aw.w.Write([]byte(GLOBAL_HEADER))
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return err
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}
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// Writes the header to the underlying writer and prepares
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// to receive the file payload
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func (aw *Writer) WriteHeader(hdr *Header) error {
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aw.nb = int64(hdr.Size)
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header := make([]byte, HEADER_BYTE_SIZE)
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s := slicer(header)
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aw.string(s.next(16), hdr.Name)
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aw.numeric(s.next(12), hdr.ModTime.Unix())
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aw.numeric(s.next(6), int64(hdr.Uid))
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aw.numeric(s.next(6), int64(hdr.Gid))
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aw.octal(s.next(8), hdr.Mode)
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aw.numeric(s.next(10), hdr.Size)
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aw.string(s.next(2), "`\n")
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_, err := aw.w.Write(header)
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return err
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}
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