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-rw-r--r--src/cmd/internal/archive/archive.go466
1 files changed, 466 insertions, 0 deletions
diff --git a/src/cmd/internal/archive/archive.go b/src/cmd/internal/archive/archive.go
new file mode 100644
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--- /dev/null
+++ b/src/cmd/internal/archive/archive.go
@@ -0,0 +1,466 @@
+// Copyright 2013 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.
+
+// Package archive implements reading of archive files generated by the Go
+// toolchain.
+package archive
+
+import (
+ "bufio"
+ "bytes"
+ "cmd/internal/bio"
+ "cmd/internal/goobj"
+ "errors"
+ "fmt"
+ "io"
+ "log"
+ "os"
+ "strconv"
+ "strings"
+ "time"
+ "unicode/utf8"
+)
+
+/*
+The archive format is:
+
+First, on a line by itself
+ !<arch>
+
+Then zero or more file records. Each file record has a fixed-size one-line header
+followed by data bytes followed by an optional padding byte. The header is:
+
+ %-16s%-12d%-6d%-6d%-8o%-10d`
+ name mtime uid gid mode size
+
+(note the trailing backquote). The %-16s here means at most 16 *bytes* of
+the name, and if shorter, space padded on the right.
+*/
+
+// A Data is a reference to data stored in an object file.
+// It records the offset and size of the data, so that a client can
+// read the data only if necessary.
+type Data struct {
+ Offset int64
+ Size int64
+}
+
+type Archive struct {
+ f *os.File
+ Entries []Entry
+}
+
+func (a *Archive) File() *os.File { return a.f }
+
+type Entry struct {
+ Name string
+ Type EntryType
+ Mtime int64
+ Uid int
+ Gid int
+ Mode os.FileMode
+ Data
+ Obj *GoObj // nil if this entry is not a Go object file
+}
+
+type EntryType int
+
+const (
+ EntryPkgDef EntryType = iota
+ EntryGoObj
+ EntryNativeObj
+)
+
+func (e *Entry) String() string {
+ return fmt.Sprintf("%s %6d/%-6d %12d %s %s",
+ (e.Mode & 0777).String(),
+ e.Uid,
+ e.Gid,
+ e.Size,
+ time.Unix(e.Mtime, 0).Format(timeFormat),
+ e.Name)
+}
+
+type GoObj struct {
+ TextHeader []byte
+ Arch string
+ Data
+}
+
+const (
+ entryHeader = "%s%-12d%-6d%-6d%-8o%-10d`\n"
+ // In entryHeader the first entry, the name, is always printed as 16 bytes right-padded.
+ entryLen = 16 + 12 + 6 + 6 + 8 + 10 + 1 + 1
+ timeFormat = "Jan _2 15:04 2006"
+)
+
+var (
+ archiveHeader = []byte("!<arch>\n")
+ archiveMagic = []byte("`\n")
+ goobjHeader = []byte("go objec") // truncated to size of archiveHeader
+
+ errCorruptArchive = errors.New("corrupt archive")
+ errTruncatedArchive = errors.New("truncated archive")
+ errCorruptObject = errors.New("corrupt object file")
+ errNotObject = errors.New("unrecognized object file format")
+)
+
+// An objReader is an object file reader.
+type objReader struct {
+ a *Archive
+ b *bio.Reader
+ err error
+ offset int64
+ limit int64
+ tmp [256]byte
+}
+
+func (r *objReader) init(f *os.File) {
+ r.a = &Archive{f, nil}
+ r.offset, _ = f.Seek(0, io.SeekCurrent)
+ r.limit, _ = f.Seek(0, io.SeekEnd)
+ f.Seek(r.offset, io.SeekStart)
+ r.b = bio.NewReader(f)
+}
+
+// error records that an error occurred.
+// It returns only the first error, so that an error
+// caused by an earlier error does not discard information
+// about the earlier error.
+func (r *objReader) error(err error) error {
+ if r.err == nil {
+ if err == io.EOF {
+ err = io.ErrUnexpectedEOF
+ }
+ r.err = err
+ }
+ // panic("corrupt") // useful for debugging
+ return r.err
+}
+
+// peek returns the next n bytes without advancing the reader.
+func (r *objReader) peek(n int) ([]byte, error) {
+ if r.err != nil {
+ return nil, r.err
+ }
+ if r.offset >= r.limit {
+ r.error(io.ErrUnexpectedEOF)
+ return nil, r.err
+ }
+ b, err := r.b.Peek(n)
+ if err != nil {
+ if err != bufio.ErrBufferFull {
+ r.error(err)
+ }
+ }
+ return b, err
+}
+
+// readByte reads and returns a byte from the input file.
+// On I/O error or EOF, it records the error but returns byte 0.
+// A sequence of 0 bytes will eventually terminate any
+// parsing state in the object file. In particular, it ends the
+// reading of a varint.
+func (r *objReader) readByte() byte {
+ if r.err != nil {
+ return 0
+ }
+ if r.offset >= r.limit {
+ r.error(io.ErrUnexpectedEOF)
+ return 0
+ }
+ b, err := r.b.ReadByte()
+ if err != nil {
+ if err == io.EOF {
+ err = io.ErrUnexpectedEOF
+ }
+ r.error(err)
+ b = 0
+ } else {
+ r.offset++
+ }
+ return b
+}
+
+// read reads exactly len(b) bytes from the input file.
+// If an error occurs, read returns the error but also
+// records it, so it is safe for callers to ignore the result
+// as long as delaying the report is not a problem.
+func (r *objReader) readFull(b []byte) error {
+ if r.err != nil {
+ return r.err
+ }
+ if r.offset+int64(len(b)) > r.limit {
+ return r.error(io.ErrUnexpectedEOF)
+ }
+ n, err := io.ReadFull(r.b, b)
+ r.offset += int64(n)
+ if err != nil {
+ return r.error(err)
+ }
+ return nil
+}
+
+// skip skips n bytes in the input.
+func (r *objReader) skip(n int64) {
+ if n < 0 {
+ r.error(fmt.Errorf("debug/goobj: internal error: misuse of skip"))
+ }
+ if n < int64(len(r.tmp)) {
+ // Since the data is so small, a just reading from the buffered
+ // reader is better than flushing the buffer and seeking.
+ r.readFull(r.tmp[:n])
+ } else if n <= int64(r.b.Buffered()) {
+ // Even though the data is not small, it has already been read.
+ // Advance the buffer instead of seeking.
+ for n > int64(len(r.tmp)) {
+ r.readFull(r.tmp[:])
+ n -= int64(len(r.tmp))
+ }
+ r.readFull(r.tmp[:n])
+ } else {
+ // Seek, giving up buffered data.
+ r.b.MustSeek(r.offset+n, io.SeekStart)
+ r.offset += n
+ }
+}
+
+// New writes to f to make a new archive.
+func New(f *os.File) (*Archive, error) {
+ _, err := f.Write(archiveHeader)
+ if err != nil {
+ return nil, err
+ }
+ return &Archive{f: f}, nil
+}
+
+// Parse parses an object file or archive from f.
+func Parse(f *os.File, verbose bool) (*Archive, error) {
+ var r objReader
+ r.init(f)
+ t, err := r.peek(8)
+ if err != nil {
+ if err == io.EOF {
+ err = io.ErrUnexpectedEOF
+ }
+ return nil, err
+ }
+
+ switch {
+ default:
+ return nil, errNotObject
+
+ case bytes.Equal(t, archiveHeader):
+ if err := r.parseArchive(verbose); err != nil {
+ return nil, err
+ }
+ case bytes.Equal(t, goobjHeader):
+ off := r.offset
+ o := &GoObj{}
+ if err := r.parseObject(o, r.limit-off); err != nil {
+ return nil, err
+ }
+ r.a.Entries = []Entry{{
+ Name: f.Name(),
+ Type: EntryGoObj,
+ Data: Data{off, r.limit - off},
+ Obj: o,
+ }}
+ }
+
+ return r.a, nil
+}
+
+// trimSpace removes trailing spaces from b and returns the corresponding string.
+// This effectively parses the form used in archive headers.
+func trimSpace(b []byte) string {
+ return string(bytes.TrimRight(b, " "))
+}
+
+// parseArchive parses a Unix archive of Go object files.
+func (r *objReader) parseArchive(verbose bool) error {
+ r.readFull(r.tmp[:8]) // consume header (already checked)
+ for r.offset < r.limit {
+ if err := r.readFull(r.tmp[:60]); err != nil {
+ return err
+ }
+ data := r.tmp[:60]
+
+ // Each file is preceded by this text header (slice indices in first column):
+ // 0:16 name
+ // 16:28 date
+ // 28:34 uid
+ // 34:40 gid
+ // 40:48 mode
+ // 48:58 size
+ // 58:60 magic - `\n
+ // We only care about name, size, and magic, unless in verbose mode.
+ // The fields are space-padded on the right.
+ // The size is in decimal.
+ // The file data - size bytes - follows the header.
+ // Headers are 2-byte aligned, so if size is odd, an extra padding
+ // byte sits between the file data and the next header.
+ // The file data that follows is padded to an even number of bytes:
+ // if size is odd, an extra padding byte is inserted betw the next header.
+ if len(data) < 60 {
+ return errTruncatedArchive
+ }
+ if !bytes.Equal(data[58:60], archiveMagic) {
+ return errCorruptArchive
+ }
+ name := trimSpace(data[0:16])
+ var err error
+ get := func(start, end, base, bitsize int) int64 {
+ if err != nil {
+ return 0
+ }
+ var v int64
+ v, err = strconv.ParseInt(trimSpace(data[start:end]), base, bitsize)
+ return v
+ }
+ size := get(48, 58, 10, 64)
+ var (
+ mtime int64
+ uid, gid int
+ mode os.FileMode
+ )
+ if verbose {
+ mtime = get(16, 28, 10, 64)
+ uid = int(get(28, 34, 10, 32))
+ gid = int(get(34, 40, 10, 32))
+ mode = os.FileMode(get(40, 48, 8, 32))
+ }
+ if err != nil {
+ return errCorruptArchive
+ }
+ data = data[60:]
+ fsize := size + size&1
+ if fsize < 0 || fsize < size {
+ return errCorruptArchive
+ }
+ switch name {
+ case "__.PKGDEF":
+ r.a.Entries = append(r.a.Entries, Entry{
+ Name: name,
+ Type: EntryPkgDef,
+ Mtime: mtime,
+ Uid: uid,
+ Gid: gid,
+ Mode: mode,
+ Data: Data{r.offset, size},
+ })
+ r.skip(size)
+ default:
+ var typ EntryType
+ var o *GoObj
+ offset := r.offset
+ p, err := r.peek(8)
+ if err != nil {
+ return err
+ }
+ if bytes.Equal(p, goobjHeader) {
+ typ = EntryGoObj
+ o = &GoObj{}
+ r.parseObject(o, size)
+ } else {
+ typ = EntryNativeObj
+ r.skip(size)
+ }
+ r.a.Entries = append(r.a.Entries, Entry{
+ Name: name,
+ Type: typ,
+ Mtime: mtime,
+ Uid: uid,
+ Gid: gid,
+ Mode: mode,
+ Data: Data{offset, size},
+ Obj: o,
+ })
+ }
+ if size&1 != 0 {
+ r.skip(1)
+ }
+ }
+ return nil
+}
+
+// parseObject parses a single Go object file.
+// The object file consists of a textual header ending in "\n!\n"
+// and then the part we want to parse begins.
+// The format of that part is defined in a comment at the top
+// of src/liblink/objfile.c.
+func (r *objReader) parseObject(o *GoObj, size int64) error {
+ h := make([]byte, 0, 256)
+ var c1, c2, c3 byte
+ for {
+ c1, c2, c3 = c2, c3, r.readByte()
+ h = append(h, c3)
+ // The new export format can contain 0 bytes.
+ // Don't consider them errors, only look for r.err != nil.
+ if r.err != nil {
+ return errCorruptObject
+ }
+ if c1 == '\n' && c2 == '!' && c3 == '\n' {
+ break
+ }
+ }
+ o.TextHeader = h
+ hs := strings.Fields(string(h))
+ if len(hs) >= 4 {
+ o.Arch = hs[3]
+ }
+ o.Offset = r.offset
+ o.Size = size - int64(len(h))
+
+ p, err := r.peek(8)
+ if err != nil {
+ return err
+ }
+ if !bytes.Equal(p, []byte(goobj.Magic)) {
+ return r.error(errCorruptObject)
+ }
+ r.skip(o.Size)
+ return nil
+}
+
+// AddEntry adds an entry to the end of a, with the content from r.
+func (a *Archive) AddEntry(typ EntryType, name string, mtime int64, uid, gid int, mode os.FileMode, size int64, r io.Reader) {
+ off, err := a.f.Seek(0, io.SeekEnd)
+ if err != nil {
+ log.Fatal(err)
+ }
+ n, err := fmt.Fprintf(a.f, entryHeader, exactly16Bytes(name), mtime, uid, gid, mode, size)
+ if err != nil || n != entryLen {
+ log.Fatal("writing entry header: ", err)
+ }
+ n1, _ := io.CopyN(a.f, r, size)
+ if n1 != size {
+ log.Fatal(err)
+ }
+ if (off+size)&1 != 0 {
+ a.f.Write([]byte{0}) // pad to even byte
+ }
+ a.Entries = append(a.Entries, Entry{
+ Name: name,
+ Type: typ,
+ Mtime: mtime,
+ Uid: uid,
+ Gid: gid,
+ Mode: mode,
+ Data: Data{off + entryLen, size},
+ })
+}
+
+// exactly16Bytes truncates the string if necessary so it is at most 16 bytes long,
+// then pads the result with spaces to be exactly 16 bytes.
+// Fmt uses runes for its width calculation, but we need bytes in the entry header.
+func exactly16Bytes(s string) string {
+ for len(s) > 16 {
+ _, wid := utf8.DecodeLastRuneInString(s)
+ s = s[:len(s)-wid]
+ }
+ const sixteenSpaces = " "
+ s += sixteenSpaces[:16-len(s)]
+ return s
+}
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