From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- libgo/go/archive/tar/reader.go | 226 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 226 insertions(+) create mode 100644 libgo/go/archive/tar/reader.go (limited to 'libgo/go/archive/tar/reader.go') diff --git a/libgo/go/archive/tar/reader.go b/libgo/go/archive/tar/reader.go new file mode 100644 index 000000000..35a15f74b --- /dev/null +++ b/libgo/go/archive/tar/reader.go @@ -0,0 +1,226 @@ +// Copyright 2009 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 tar + +// TODO(dsymonds): +// - pax extensions + +import ( + "bytes" + "io" + "os" + "strconv" +) + +var ( + HeaderError os.Error = os.ErrorString("invalid tar header") +) + +// A Reader provides sequential access to the contents of a tar archive. +// A tar 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. +// +// Example: +// tr := tar.NewReader(r) +// for { +// hdr, err := tr.Next() +// if err != nil { +// // handle error +// } +// if hdr == nil { +// // end of tar archive +// break +// } +// io.Copy(data, tr) +// } +type Reader struct { + r io.Reader + err os.Error + nb int64 // number of unread bytes for current file entry + pad int64 // amount of padding (ignored) after current file entry +} + +// NewReader creates a new Reader reading from r. +func NewReader(r io.Reader) *Reader { return &Reader{r: r} } + +// Next advances to the next entry in the tar archive. +func (tr *Reader) Next() (*Header, os.Error) { + var hdr *Header + if tr.err == nil { + tr.skipUnread() + } + if tr.err == nil { + hdr = tr.readHeader() + } + return hdr, tr.err +} + +// Parse bytes as a NUL-terminated C-style string. +// If a NUL byte is not found then the whole slice is returned as a string. +func cString(b []byte) string { + n := 0 + for n < len(b) && b[n] != 0 { + n++ + } + return string(b[0:n]) +} + +func (tr *Reader) octal(b []byte) int64 { + // Removing leading spaces. + for len(b) > 0 && b[0] == ' ' { + b = b[1:] + } + // Removing trailing NULs and spaces. + for len(b) > 0 && (b[len(b)-1] == ' ' || b[len(b)-1] == '\x00') { + b = b[0 : len(b)-1] + } + x, err := strconv.Btoui64(cString(b), 8) + if err != nil { + tr.err = err + } + return int64(x) +} + +type ignoreWriter struct{} + +func (ignoreWriter) Write(b []byte) (n int, err os.Error) { + return len(b), nil +} + +// Skip any unread bytes in the existing file entry, as well as any alignment padding. +func (tr *Reader) skipUnread() { + nr := tr.nb + tr.pad // number of bytes to skip + tr.nb, tr.pad = 0, 0 + if sr, ok := tr.r.(io.Seeker); ok { + if _, err := sr.Seek(nr, 1); err == nil { + return + } + } + _, tr.err = io.Copyn(ignoreWriter{}, tr.r, nr) +} + +func (tr *Reader) verifyChecksum(header []byte) bool { + if tr.err != nil { + return false + } + + given := tr.octal(header[148:156]) + unsigned, signed := checksum(header) + return given == unsigned || given == signed +} + +func (tr *Reader) readHeader() *Header { + header := make([]byte, blockSize) + if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil { + return nil + } + + // Two blocks of zero bytes marks the end of the archive. + if bytes.Equal(header, zeroBlock[0:blockSize]) { + if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil { + return nil + } + if bytes.Equal(header, zeroBlock[0:blockSize]) { + tr.err = os.EOF + } else { + tr.err = HeaderError // zero block and then non-zero block + } + return nil + } + + if !tr.verifyChecksum(header) { + tr.err = HeaderError + return nil + } + + // Unpack + hdr := new(Header) + s := slicer(header) + + hdr.Name = cString(s.next(100)) + hdr.Mode = tr.octal(s.next(8)) + hdr.Uid = int(tr.octal(s.next(8))) + hdr.Gid = int(tr.octal(s.next(8))) + hdr.Size = tr.octal(s.next(12)) + hdr.Mtime = tr.octal(s.next(12)) + s.next(8) // chksum + hdr.Typeflag = s.next(1)[0] + hdr.Linkname = cString(s.next(100)) + + // The remainder of the header depends on the value of magic. + // The original (v7) version of tar had no explicit magic field, + // so its magic bytes, like the rest of the block, are NULs. + magic := string(s.next(8)) // contains version field as well. + var format string + switch magic { + case "ustar\x0000": // POSIX tar (1003.1-1988) + if string(header[508:512]) == "tar\x00" { + format = "star" + } else { + format = "posix" + } + case "ustar \x00": // old GNU tar + format = "gnu" + } + + switch format { + case "posix", "gnu", "star": + hdr.Uname = cString(s.next(32)) + hdr.Gname = cString(s.next(32)) + devmajor := s.next(8) + devminor := s.next(8) + if hdr.Typeflag == TypeChar || hdr.Typeflag == TypeBlock { + hdr.Devmajor = tr.octal(devmajor) + hdr.Devminor = tr.octal(devminor) + } + var prefix string + switch format { + case "posix", "gnu": + prefix = cString(s.next(155)) + case "star": + prefix = cString(s.next(131)) + hdr.Atime = tr.octal(s.next(12)) + hdr.Ctime = tr.octal(s.next(12)) + } + if len(prefix) > 0 { + hdr.Name = prefix + "/" + hdr.Name + } + } + + if tr.err != nil { + tr.err = HeaderError + return nil + } + + // Maximum value of hdr.Size is 64 GB (12 octal digits), + // so there's no risk of int64 overflowing. + tr.nb = int64(hdr.Size) + tr.pad = -tr.nb & (blockSize - 1) // blockSize is a power of two + + return hdr +} + +// Read reads from the current entry in the tar archive. +// It returns 0, os.EOF when it reaches the end of that entry, +// until Next is called to advance to the next entry. +func (tr *Reader) Read(b []byte) (n int, err os.Error) { + if tr.nb == 0 { + // file consumed + return 0, os.EOF + } + + if int64(len(b)) > tr.nb { + b = b[0:tr.nb] + } + n, err = tr.r.Read(b) + tr.nb -= int64(n) + + if err == os.EOF && tr.nb > 0 { + err = io.ErrUnexpectedEOF + } + tr.err = err + return +} -- cgit v1.2.3