Adding upstream version 0.0~git20190502.809d437.

Signed-off-by: Daniel Baumann <daniel@debian.org>

writer.go

@@ -0,0 +1,124 @@
+/* 
+Copyright (c) 2013 Blake Smith <blakesmith0@gmail.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+package ar
+
+import (
+	"errors"
+	"io"
+	"strconv"
+)
+
+var (
+	ErrWriteTooLong    = errors.New("ar: write too long")
+)
+
+// Writer provides sequential writing of an ar archive.
+// An ar archive is sequence of header file pairs
+// Call WriteHeader to begin writing a new file, then call Write to supply the file's data
+//
+// Example:
+// archive := ar.NewWriter(writer)
+// archive.WriteGlobalHeader()
+// header := new(ar.Header)
+// header.Size = 15 // bytes
+// if err := archive.WriteHeader(header); err != nil {
+// 	return err
+// }
+// io.Copy(archive, data)
+type Writer struct {
+	w io.Writer
+	nb int64 // number of unwritten bytes for the current file entry
+}
+
+// Create a new ar writer that writes to w
+func NewWriter(w io.Writer) *Writer { return &Writer{w: w} }
+
+func (aw *Writer) numeric(b []byte, x int64) {
+	s := strconv.FormatInt(x, 10)
+	for len(s) < len(b) {
+		s = s + " "
+	}
+	copy(b, []byte(s))
+}
+
+func (aw *Writer) octal(b []byte, x int64) {
+	s := "100" + strconv.FormatInt(x, 8)
+	for len(s) < len(b) {
+		s = s + " "
+	}
+	copy(b, []byte(s))
+}
+
+func (aw *Writer) string(b []byte, str string) {
+	s := str
+	for len(s) < len(b) {
+		s = s + " "
+	}
+	copy(b, []byte(s))
+}
+
+// Writes to the current entry in the ar archive
+// Returns ErrWriteTooLong if more than header.Size
+// bytes are written after a call to WriteHeader
+func (aw *Writer) Write(b []byte) (n int, err error) {
+	if int64(len(b)) > aw.nb {
+		b = b[0:aw.nb]
+		err = ErrWriteTooLong
+	}
+	n, werr := aw.w.Write(b)
+	aw.nb -= int64(n)
+	if werr != nil {
+		return n, werr
+	}
+
+	if len(b)%2 == 1 { // data size must be aligned to an even byte
+		n2, _ := aw.w.Write([]byte{'\n'})
+		return n+n2, err
+	}
+
+	return
+}
+
+func (aw *Writer) WriteGlobalHeader() error {
+	_, err := aw.w.Write([]byte(GLOBAL_HEADER))
+	return err
+}
+
+// Writes the header to the underlying writer and prepares
+// to receive the file payload
+func (aw *Writer) WriteHeader(hdr *Header) error {
+	aw.nb = int64(hdr.Size)
+	header := make([]byte, HEADER_BYTE_SIZE)
+	s := slicer(header)
+
+	aw.string(s.next(16), hdr.Name)
+	aw.numeric(s.next(12), hdr.ModTime.Unix())
+	aw.numeric(s.next(6), int64(hdr.Uid))
+	aw.numeric(s.next(6), int64(hdr.Gid))
+	aw.octal(s.next(8), hdr.Mode)
+	aw.numeric(s.next(10), hdr.Size)
+	aw.string(s.next(2), "`\n")
+
+	_, err := aw.w.Write(header)
+
+	return err
+}