vendor

vendor/github.com/cavaliercoder/go-cpio/reader.go

@@ -0,0 +1,72 @@
+package cpio
+
+import (
+	"io"
+	"io/ioutil"
+)
+
+// A Reader provides sequential access to the contents of a CPIO archive. A CPIO
+// archive consists of a sequence of files. The Next method advances to the next
+// file in the archive (including the first), and then it can be treated as an
+// io.Reader to access the file's data.
+type Reader struct {
+	r   io.Reader // underlying file reader
+	hdr *Header   // current Header
+	eof int64     // bytes until the end of the current file
+}
+
+// NewReader creates a new Reader reading from r.
+func NewReader(r io.Reader) *Reader {
+	return &Reader{
+		r: r,
+	}
+}
+
+// Read reads from the current entry in the CPIO archive. It returns 0, io.EOF
+// when it reaches the end of that entry, until Next is called to advance to the
+// next entry.
+func (r *Reader) Read(p []byte) (n int, err error) {
+	if r.hdr == nil || r.eof == 0 {
+		return 0, io.EOF
+	}
+	rn := len(p)
+	if r.eof < int64(rn) {
+		rn = int(r.eof)
+	}
+	n, err = r.r.Read(p[0:rn])
+	r.eof -= int64(n)
+	return
+}
+
+// Next advances to the next entry in the CPIO archive.
+// io.EOF is returned at the end of the input.
+func (r *Reader) Next() (*Header, error) {
+	if r.hdr == nil {
+		return r.next()
+	}
+	skp := r.eof + r.hdr.pad
+	if skp > 0 {
+		_, err := io.CopyN(ioutil.Discard, r.r, skp)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return r.next()
+}
+
+func (r *Reader) next() (*Header, error) {
+	r.eof = 0
+	hdr, err := readHeader(r.r)
+	if err != nil {
+		return nil, err
+	}
+	r.hdr = hdr
+	r.eof = hdr.Size
+	return hdr, nil
+}
+
+// ReadHeader creates a new Header, reading from r.
+func readHeader(r io.Reader) (*Header, error) {
+	// currently only SVR4 format is supported
+	return readSVR4Header(r)
+}