1 files changed, 135 insertions, 0 deletions
diff --git a/src/pkg/go/types/exportdata.go b/src/pkg/go/types/exportdata.go
new file mode 100644
index 000000000..cb08ffe18
--- /dev/null
+++ b/src/pkg/go/types/exportdata.go
@@ -0,0 +1,135 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements ExportData.
+
+package types
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+
+func readGopackHeader(buf *bufio.Reader) (name string, size int, err os.Error) {
+	// See $GOROOT/include/ar.h.
+	hdr := make([]byte, 64+12+6+6+8+10+2)
+	_, err = io.ReadFull(buf, hdr)
+	if err != nil {
+		return
+	}
+	if trace {
+		fmt.Printf("header: %s", hdr)
+	}
+	s := strings.TrimSpace(string(hdr[64+12+6+6+8:][:10]))
+	size, err = strconv.Atoi(s)
+	if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
+		err = os.ErrorString("invalid archive header")
+		return
+	}
+	name = strings.TrimSpace(string(hdr[:64]))
+	return
+}
+
+
+type dataReader struct {
+	*bufio.Reader
+	io.Closer
+}
+
+
+// ExportData returns a readCloser positioned at the beginning of the
+// export data section of the given object/archive file, or an error.
+// It is the caller's responsibility to close the readCloser.
+//
+func ExportData(filename string) (rc io.ReadCloser, err os.Error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return
+	}
+
+	defer func() {
+		if err != nil {
+			file.Close()
+			// Add file name to error.
+			err = fmt.Errorf("reading export data: %s: %v", filename, err)
+		}
+	}()
+
+	buf := bufio.NewReader(file)
+
+	// Read first line to make sure this is an object file.
+	line, err := buf.ReadSlice('\n')
+	if err != nil {
+		return
+	}
+	if string(line) == "!<arch>\n" {
+		// Archive file.  Scan to __.PKGDEF, which should
+		// be second archive entry.
+		var name string
+		var size int
+
+		// First entry should be __.SYMDEF.
+		// Read and discard.
+		if name, size, err = readGopackHeader(buf); err != nil {
+			return
+		}
+		if name != "__.SYMDEF" {
+			err = os.ErrorString("go archive does not begin with __.SYMDEF")
+			return
+		}
+		const block = 4096
+		tmp := make([]byte, block)
+		for size > 0 {
+			n := size
+			if n > block {
+				n = block
+			}
+			_, err = io.ReadFull(buf, tmp[:n])
+			if err != nil {
+				return
+			}
+			size -= n
+		}
+
+		// Second entry should be __.PKGDEF.
+		if name, size, err = readGopackHeader(buf); err != nil {
+			return
+		}
+		if name != "__.PKGDEF" {
+			err = os.ErrorString("go archive is missing __.PKGDEF")
+			return
+		}
+
+		// Read first line of __.PKGDEF data, so that line
+		// is once again the first line of the input.
+		line, err = buf.ReadSlice('\n')
+		if err != nil {
+			return
+		}
+	}
+
+	// Now at __.PKGDEF in archive or still at beginning of file.
+	// Either way, line should begin with "go object ".
+	if !strings.HasPrefix(string(line), "go object ") {
+		err = os.ErrorString("not a go object file")
+		return
+	}
+
+	// Skip over object header to export data.
+	// Begins after first line with $$.
+	for line[0] != '$' {
+		line, err = buf.ReadSlice('\n')
+		if err != nil {
+			return
+		}
+	}
+
+	rc = &dataReader{buf, file}
+	return
+}