1 // Copyright 2011 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // This file is a copy of $GOROOT/src/go/internal/gcimporter/exportdata.go.
7 // This file implements FindExportData.
19 func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
20 // See $GOROOT/include/ar.h.
21 hdr := make([]byte, 16+12+6+6+8+10+2)
22 _, err = io.ReadFull(r, hdr)
26 // leave for debugging
28 fmt.Printf("header: %s", hdr)
30 s := strings.TrimSpace(string(hdr[16+12+6+6+8:][:10]))
31 size, err = strconv.Atoi(s)
32 if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
33 err = fmt.Errorf("invalid archive header")
36 name = strings.TrimSpace(string(hdr[:16]))
40 // FindExportData positions the reader r at the beginning of the
41 // export data section of an underlying GC-created object/archive
42 // file by reading from it. The reader must be positioned at the
43 // start of the file before calling this function. The hdr result
44 // is the string before the export data, either "$$" or "$$B".
46 func FindExportData(r *bufio.Reader) (hdr string, err error) {
47 // Read first line to make sure this is an object file.
48 line, err := r.ReadSlice('\n')
50 err = fmt.Errorf("can't find export data (%v)", err)
54 if string(line) == "!<arch>\n" {
55 // Archive file. Scan to __.PKGDEF.
57 if name, _, err = readGopackHeader(r); err != nil {
61 // First entry should be __.PKGDEF.
62 if name != "__.PKGDEF" {
63 err = fmt.Errorf("go archive is missing __.PKGDEF")
67 // Read first line of __.PKGDEF data, so that line
68 // is once again the first line of the input.
69 if line, err = r.ReadSlice('\n'); err != nil {
70 err = fmt.Errorf("can't find export data (%v)", err)
75 // Now at __.PKGDEF in archive or still at beginning of file.
76 // Either way, line should begin with "go object ".
77 if !strings.HasPrefix(string(line), "go object ") {
78 err = fmt.Errorf("not a Go object file")
82 // Skip over object header to export data.
83 // Begins after first line starting with $$.
85 if line, err = r.ReadSlice('\n'); err != nil {
86 err = fmt.Errorf("can't find export data (%v)", err)