diff options
Diffstat (limited to 'vendor/github.com/vbatts/tar-split/archive/tar/reader.go')
| -rw-r--r-- | vendor/github.com/vbatts/tar-split/archive/tar/reader.go | 1377 |
1 files changed, 618 insertions, 759 deletions
diff --git a/vendor/github.com/vbatts/tar-split/archive/tar/reader.go b/vendor/github.com/vbatts/tar-split/archive/tar/reader.go index adf32122e..ea64a3820 100644 --- a/vendor/github.com/vbatts/tar-split/archive/tar/reader.go +++ b/vendor/github.com/vbatts/tar-split/archive/tar/reader.go @@ -4,44 +4,38 @@ package tar -// TODO(dsymonds): -// - pax extensions - import ( "bytes" - "errors" "io" "io/ioutil" - "math" - "os" "strconv" "strings" "time" ) -var ( - ErrHeader = errors.New("archive/tar: invalid tar header") -) - -const maxNanoSecondIntSize = 9 - -// 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. +// Reader provides sequential access to the contents of a tar archive. +// Reader.Next advances to the next file in the archive (including the first), +// and then Reader can be treated as an io.Reader to access the file's data. type Reader struct { - r io.Reader - err error - pad int64 // amount of padding (ignored) after current file entry - curr numBytesReader // reader for current file entry - hdrBuff [blockSize]byte // buffer to use in readHeader + r io.Reader + pad int64 // Amount of padding (ignored) after current file entry + curr fileReader // Reader for current file entry + blk block // Buffer to use as temporary local storage + + // err is a persistent error. + // It is only the responsibility of every exported method of Reader to + // ensure that this error is sticky. + err error RawAccounting bool // Whether to enable the access needed to reassemble the tar from raw bytes. Some performance/memory hit for this. rawBytes *bytes.Buffer // last raw bits } -type parser struct { - err error // Last error seen +type fileReader interface { + io.Reader + fileState + + WriteTo(io.Writer) (int64, error) } // RawBytes accesses the raw bytes of the archive, apart from the file payload itself. @@ -57,87 +51,35 @@ func (tr *Reader) RawBytes() []byte { if tr.rawBytes == nil { tr.rawBytes = bytes.NewBuffer(nil) } - // if we've read them, then flush them. - defer tr.rawBytes.Reset() - return tr.rawBytes.Bytes() -} + defer tr.rawBytes.Reset() // if we've read them, then flush them. -// A numBytesReader is an io.Reader with a numBytes method, returning the number -// of bytes remaining in the underlying encoded data. -type numBytesReader interface { - io.Reader - numBytes() int64 -} - -// A regFileReader is a numBytesReader for reading file data from a tar archive. -type regFileReader struct { - r io.Reader // underlying reader - nb int64 // number of unread bytes for current file entry -} - -// A sparseFileReader is a numBytesReader for reading sparse file data from a -// tar archive. -type sparseFileReader struct { - rfr numBytesReader // Reads the sparse-encoded file data - sp []sparseEntry // The sparse map for the file - pos int64 // Keeps track of file position - total int64 // Total size of the file -} + return tr.rawBytes.Bytes() -// A sparseEntry holds a single entry in a sparse file's sparse map. -// -// Sparse files are represented using a series of sparseEntrys. -// Despite the name, a sparseEntry represents an actual data fragment that -// references data found in the underlying archive stream. All regions not -// covered by a sparseEntry are logically filled with zeros. -// -// For example, if the underlying raw file contains the 10-byte data: -// var compactData = "abcdefgh" -// -// And the sparse map has the following entries: -// var sp = []sparseEntry{ -// {offset: 2, numBytes: 5} // Data fragment for [2..7] -// {offset: 18, numBytes: 3} // Data fragment for [18..21] -// } -// -// Then the content of the resulting sparse file with a "real" size of 25 is: -// var sparseData = "\x00"*2 + "abcde" + "\x00"*11 + "fgh" + "\x00"*4 -type sparseEntry struct { - offset int64 // Starting position of the fragment - numBytes int64 // Length of the fragment } -// Keywords for GNU sparse files in a PAX extended header -const ( - paxGNUSparseNumBlocks = "GNU.sparse.numblocks" - paxGNUSparseOffset = "GNU.sparse.offset" - paxGNUSparseNumBytes = "GNU.sparse.numbytes" - paxGNUSparseMap = "GNU.sparse.map" - paxGNUSparseName = "GNU.sparse.name" - paxGNUSparseMajor = "GNU.sparse.major" - paxGNUSparseMinor = "GNU.sparse.minor" - paxGNUSparseSize = "GNU.sparse.size" - paxGNUSparseRealSize = "GNU.sparse.realsize" -) - -// Keywords for old GNU sparse headers -const ( - oldGNUSparseMainHeaderOffset = 386 - oldGNUSparseMainHeaderIsExtendedOffset = 482 - oldGNUSparseMainHeaderNumEntries = 4 - oldGNUSparseExtendedHeaderIsExtendedOffset = 504 - oldGNUSparseExtendedHeaderNumEntries = 21 - oldGNUSparseOffsetSize = 12 - oldGNUSparseNumBytesSize = 12 -) - // NewReader creates a new Reader reading from r. -func NewReader(r io.Reader) *Reader { return &Reader{r: r} } +func NewReader(r io.Reader) *Reader { + return &Reader{r: r, curr: ®FileReader{r, 0}} +} // Next advances to the next entry in the tar archive. +// The Header.Size determines how many bytes can be read for the next file. +// Any remaining data in the current file is automatically discarded. // // io.EOF is returned at the end of the input. func (tr *Reader) Next() (*Header, error) { + if tr.err != nil { + return nil, tr.err + } + hdr, err := tr.next() + tr.err = err + return hdr, err +} + +func (tr *Reader) next() (*Header, error) { + var paxHdrs map[string]string + var gnuLongName, gnuLongLink string + if tr.RawAccounting { if tr.rawBytes == nil { tr.rawBytes = bytes.NewBuffer(nil) @@ -146,248 +88,245 @@ func (tr *Reader) Next() (*Header, error) { } } - if tr.err != nil { - return nil, tr.err - } - - var hdr *Header - var extHdrs map[string]string - // Externally, Next iterates through the tar archive as if it is a series of // files. Internally, the tar format often uses fake "files" to add meta // data that describes the next file. These meta data "files" should not // normally be visible to the outside. As such, this loop iterates through // one or more "header files" until it finds a "normal file". -loop: + format := FormatUSTAR | FormatPAX | FormatGNU for { - tr.err = tr.skipUnread() - if tr.err != nil { - return nil, tr.err + // Discard the remainder of the file and any padding. + if err := discard(tr, tr.curr.PhysicalRemaining()); err != nil { + return nil, err + } + n, err := tryReadFull(tr.r, tr.blk[:tr.pad]) + if err != nil { + return nil, err } + if tr.RawAccounting { + tr.rawBytes.Write(tr.blk[:n]) + } + tr.pad = 0 - hdr = tr.readHeader() - if tr.err != nil { - return nil, tr.err + hdr, rawHdr, err := tr.readHeader() + if err != nil { + return nil, err + } + if err := tr.handleRegularFile(hdr); err != nil { + return nil, err } + format.mayOnlyBe(hdr.Format) + // Check for PAX/GNU special headers and files. switch hdr.Typeflag { - case TypeXHeader: - extHdrs, tr.err = parsePAX(tr) - if tr.err != nil { - return nil, tr.err + case TypeXHeader, TypeXGlobalHeader: + format.mayOnlyBe(FormatPAX) + paxHdrs, err = parsePAX(tr) + if err != nil { + return nil, err } - continue loop // This is a meta header affecting the next header + if hdr.Typeflag == TypeXGlobalHeader { + mergePAX(hdr, paxHdrs) + return &Header{ + Name: hdr.Name, + Typeflag: hdr.Typeflag, + Xattrs: hdr.Xattrs, + PAXRecords: hdr.PAXRecords, + Format: format, + }, nil + } + continue // This is a meta header affecting the next header case TypeGNULongName, TypeGNULongLink: - var realname []byte - realname, tr.err = ioutil.ReadAll(tr) - if tr.err != nil { - return nil, tr.err + format.mayOnlyBe(FormatGNU) + realname, err := ioutil.ReadAll(tr) + if err != nil { + return nil, err } if tr.RawAccounting { - if _, tr.err = tr.rawBytes.Write(realname); tr.err != nil { - return nil, tr.err - } + tr.rawBytes.Write(realname) } - // Convert GNU extensions to use PAX headers. - if extHdrs == nil { - extHdrs = make(map[string]string) - } var p parser switch hdr.Typeflag { case TypeGNULongName: - extHdrs[paxPath] = p.parseString(realname) + gnuLongName = p.parseString(realname) case TypeGNULongLink: - extHdrs[paxLinkpath] = p.parseString(realname) - } - if p.err != nil { - tr.err = p.err - return nil, tr.err + gnuLongLink = p.parseString(realname) } - continue loop // This is a meta header affecting the next header + continue // This is a meta header affecting the next header default: - mergePAX(hdr, extHdrs) + // The old GNU sparse format is handled here since it is technically + // just a regular file with additional attributes. - // Check for a PAX format sparse file - sp, err := tr.checkForGNUSparsePAXHeaders(hdr, extHdrs) - if err != nil { - tr.err = err + if err := mergePAX(hdr, paxHdrs); err != nil { return nil, err } - if sp != nil { - // Current file is a PAX format GNU sparse file. - // Set the current file reader to a sparse file reader. - tr.curr, tr.err = newSparseFileReader(tr.curr, sp, hdr.Size) - if tr.err != nil { - return nil, tr.err + if gnuLongName != "" { + hdr.Name = gnuLongName + } + if gnuLongLink != "" { + hdr.Linkname = gnuLongLink + } + if hdr.Typeflag == TypeRegA { + if strings.HasSuffix(hdr.Name, "/") { + hdr.Typeflag = TypeDir // Legacy archives use trailing slash for directories + } else { + hdr.Typeflag = TypeReg } } - break loop // This is a file, so stop + + // The extended headers may have updated the size. + // Thus, setup the regFileReader again after merging PAX headers. + if err := tr.handleRegularFile(hdr); err != nil { + return nil, err + } + + // Sparse formats rely on being able to read from the logical data + // section; there must be a preceding call to handleRegularFile. + if err := tr.handleSparseFile(hdr, rawHdr); err != nil { + return nil, err + } + + // Set the final guess at the format. + if format.has(FormatUSTAR) && format.has(FormatPAX) { + format.mayOnlyBe(FormatUSTAR) + } + hdr.Format = format + return hdr, nil // This is a file, so stop } } - return hdr, nil } -// checkForGNUSparsePAXHeaders checks the PAX headers for GNU sparse headers. If they are found, then -// this function reads the sparse map and returns it. Unknown sparse formats are ignored, causing the file to -// be treated as a regular file. -func (tr *Reader) checkForGNUSparsePAXHeaders(hdr *Header, headers map[string]string) ([]sparseEntry, error) { - var sparseFormat string - - // Check for sparse format indicators - major, majorOk := headers[paxGNUSparseMajor] - minor, minorOk := headers[paxGNUSparseMinor] - sparseName, sparseNameOk := headers[paxGNUSparseName] - _, sparseMapOk := headers[paxGNUSparseMap] - sparseSize, sparseSizeOk := headers[paxGNUSparseSize] - sparseRealSize, sparseRealSizeOk := headers[paxGNUSparseRealSize] - - // Identify which, if any, sparse format applies from which PAX headers are set - if majorOk && minorOk { - sparseFormat = major + "." + minor - } else if sparseNameOk && sparseMapOk { - sparseFormat = "0.1" - } else if sparseSizeOk { - sparseFormat = "0.0" - } else { - // Not a PAX format GNU sparse file. - return nil, nil +// handleRegularFile sets up the current file reader and padding such that it +// can only read the following logical data section. It will properly handle +// special headers that contain no data section. +func (tr *Reader) handleRegularFile(hdr *Header) error { + nb := hdr.Size + if isHeaderOnlyType(hdr.Typeflag) { + nb = 0 } - - // Check for unknown sparse format - if sparseFormat != "0.0" && sparseFormat != "0.1" && sparseFormat != "1.0" { - return nil, nil + if nb < 0 { + return ErrHeader } - // Update hdr from GNU sparse PAX headers - if sparseNameOk { - hdr.Name = sparseName + tr.pad = blockPadding(nb) + tr.curr = ®FileReader{r: tr.r, nb: nb} + return nil +} + +// handleSparseFile checks if the current file is a sparse format of any type +// and sets the curr reader appropriately. +func (tr *Reader) handleSparseFile(hdr *Header, rawHdr *block) error { + var spd sparseDatas + var err error + if hdr.Typeflag == TypeGNUSparse { + spd, err = tr.readOldGNUSparseMap(hdr, rawHdr) + } else { + spd, err = tr.readGNUSparsePAXHeaders(hdr) } - if sparseSizeOk { - realSize, err := strconv.ParseInt(sparseSize, 10, 0) - if err != nil { - return nil, ErrHeader + + // If sp is non-nil, then this is a sparse file. + // Note that it is possible for len(sp) == 0. + if err == nil && spd != nil { + if isHeaderOnlyType(hdr.Typeflag) || !validateSparseEntries(spd, hdr.Size) { + return ErrHeader } - hdr.Size = realSize - } else if sparseRealSizeOk { - realSize, err := strconv.ParseInt(sparseRealSize, 10, 0) + sph := invertSparseEntries(spd, hdr.Size) + tr.curr = &sparseFileReader{tr.curr, sph, 0} + } + return err +} + +// readGNUSparsePAXHeaders checks the PAX headers for GNU sparse headers. +// If they are found, then this function reads the sparse map and returns it. +// This assumes that 0.0 headers have already been converted to 0.1 headers +// by the PAX header parsing logic. +func (tr *Reader) readGNUSparsePAXHeaders(hdr *Header) (sparseDatas, error) { + // Identify the version of GNU headers. + var is1x0 bool + major, minor := hdr.PAXRecords[paxGNUSparseMajor], hdr.PAXRecords[paxGNUSparseMinor] + switch { + case major == "0" && (minor == "0" || minor == "1"): + is1x0 = false + case major == "1" && minor == "0": + is1x0 = true + case major != "" || minor != "": + return nil, nil // Unknown GNU sparse PAX version + case hdr.PAXRecords[paxGNUSparseMap] != "": + is1x0 = false // 0.0 and 0.1 did not have explicit version records, so guess + default: + return nil, nil // Not a PAX format GNU sparse file. + } + hdr.Format.mayOnlyBe(FormatPAX) + + // Update hdr from GNU sparse PAX headers. + if name := hdr.PAXRecords[paxGNUSparseName]; name != "" { + hdr.Name = name + } + size := hdr.PAXRecords[paxGNUSparseSize] + if size == "" { + size = hdr.PAXRecords[paxGNUSparseRealSize] + } + if size != "" { + n, err := strconv.ParseInt(size, 10, 64) if err != nil { return nil, ErrHeader } - hdr.Size = realSize + hdr.Size = n } - // Set up the sparse map, according to the particular sparse format in use - var sp []sparseEntry - var err error - switch sparseFormat { - case "0.0", "0.1": - sp, err = readGNUSparseMap0x1(headers) - case "1.0": - sp, err = readGNUSparseMap1x0(tr.curr) + // Read the sparse map according to the appropriate format. + if is1x0 { + return readGNUSparseMap1x0(tr.curr) } - return sp, err + return readGNUSparseMap0x1(hdr.PAXRecords) } -// mergePAX merges well known headers according to PAX standard. -// In general headers with the same name as those found -// in the header struct overwrite those found in the header -// struct with higher precision or longer values. Esp. useful -// for name and linkname fields. -func mergePAX(hdr *Header, headers map[string]string) error { - for k, v := range headers { +// mergePAX merges paxHdrs into hdr for all relevant fields of Header. +func mergePAX(hdr *Header, paxHdrs map[string]string) (err error) { + for k, v := range paxHdrs { + if v == "" { + continue // Keep the original USTAR value + } + var id64 int64 switch k { case paxPath: hdr.Name = v case paxLinkpath: hdr.Linkname = v - case paxGname: - hdr.Gname = v case paxUname: hdr.Uname = v + case paxGname: + hdr.Gname = v case paxUid: - uid, err := strconv.ParseInt(v, 10, 0) - if err != nil { - return err - } - hdr.Uid = int(uid) + id64, err = strconv.ParseInt(v, 10, 64) + hdr.Uid = int(id64) // Integer overflow possible case paxGid: - gid, err := strconv.ParseInt(v, 10, 0) - if err != nil { - return err - } - hdr.Gid = int(gid) + id64, err = strconv.ParseInt(v, 10, 64) + hdr.Gid = int(id64) // Integer overflow possible case paxAtime: - t, err := parsePAXTime(v) - if err != nil { - return err - } - hdr.AccessTime = t + hdr.AccessTime, err = parsePAXTime(v) case paxMtime: - t, err := parsePAXTime(v) - if err != nil { - return err - } - hdr.ModTime = t + hdr.ModTime, err = parsePAXTime(v) case paxCtime: - t, err := parsePAXTime(v) - if err != nil { - return err - } - hdr.ChangeTime = t + hdr.ChangeTime, err = parsePAXTime(v) case paxSize: - size, err := strconv.ParseInt(v, 10, 0) - if err != nil { - return err - } - hdr.Size = int64(size) + hdr.Size, err = strconv.ParseInt(v, 10, 64) default: - if strings.HasPrefix(k, paxXattr) { + if strings.HasPrefix(k, paxSchilyXattr) { if hdr.Xattrs == nil { hdr.Xattrs = make(map[string]string) } - hdr.Xattrs[k[len(paxXattr):]] = v + hdr.Xattrs[k[len(paxSchilyXattr):]] = v } } - } - return nil -} - -// parsePAXTime takes a string of the form %d.%d as described in -// the PAX specification. -func parsePAXTime(t string) (time.Time, error) { - buf := []byte(t) - pos := bytes.IndexByte(buf, '.') - var seconds, nanoseconds int64 - var err error - if pos == -1 { - seconds, err = strconv.ParseInt(t, 10, 0) - if err != nil { - return time.Time{}, err - } - } else { - seconds, err = strconv.ParseInt(string(buf[:pos]), 10, 0) if err != nil { - return time.Time{}, err - } - nano_buf := string(buf[pos+1:]) - // Pad as needed before converting to a decimal. - // For example .030 -> .030000000 -> 30000000 nanoseconds - if len(nano_buf) < maxNanoSecondIntSize { - // Right pad - nano_buf += strings.Repeat("0", maxNanoSecondIntSize-len(nano_buf)) - } else if len(nano_buf) > maxNanoSecondIntSize { - // Right truncate - nano_buf = nano_buf[:maxNanoSecondIntSize] - } - nanoseconds, err = strconv.ParseInt(string(nano_buf), 10, 0) - if err != nil { - return time.Time{}, err + return ErrHeader } } - ts := time.Unix(seconds, nanoseconds) - return ts, nil + hdr.PAXRecords = paxHdrs + return nil } // parsePAX parses PAX headers. @@ -406,12 +345,11 @@ func parsePAX(r io.Reader) (map[string]string, error) { sbuf := string(buf) // For GNU PAX sparse format 0.0 support. - // This function transforms the sparse format 0.0 headers into sparse format 0.1 headers. - var sparseMap bytes.Buffer + // This function transforms the sparse format 0.0 headers into format 0.1 + // headers since 0.0 headers were not PAX compliant. + var sparseMap []string - headers := make(map[string]string) - // Each record is constructed as - // "%d %s=%s\n", length, keyword, value + paxHdrs := make(map[string]string) for len(sbuf) > 0 { key, value, residual, err := parsePAXRecord(sbuf) if err != nil { @@ -419,422 +357,234 @@ func parsePAX(r io.Reader) (map[string]string, error) { } sbuf = residual - keyStr := string(key) - if keyStr == paxGNUSparseOffset || keyStr == paxGNUSparseNumBytes { - // GNU sparse format 0.0 special key. Write to sparseMap instead of using the headers map. - sparseMap.WriteString(value) - sparseMap.Write([]byte{','}) - } else { - // Normal key. Set the value in the headers map. - headers[keyStr] = string(value) - } - } - if sparseMap.Len() != 0 { - // Add sparse info to headers, chopping off the extra comma - sparseMap.Truncate(sparseMap.Len() - 1) - headers[paxGNUSparseMap] = sparseMap.String() - } - return headers, nil -} - -// parsePAXRecord parses the input PAX record string into a key-value pair. -// If parsing is successful, it will slice off the currently read record and -// return the remainder as r. -// -// A PAX record is of the following form: -// "%d %s=%s\n" % (size, key, value) -func parsePAXRecord(s string) (k, v, r string, err error) { - // The size field ends at the first space. - sp := strings.IndexByte(s, ' ') - if sp == -1 { - return "", "", s, ErrHeader - } - - // Parse the first token as a decimal integer. - n, perr := strconv.ParseInt(s[:sp], 10, 0) // Intentionally parse as native int - if perr != nil || n < 5 || int64(len(s)) < n { - return "", "", s, ErrHeader - } - - // Extract everything between the space and the final newline. - rec, nl, rem := s[sp+1:n-1], s[n-1:n], s[n:] - if nl != "\n" { - return "", "", s, ErrHeader - } - - // The first equals separates the key from the value. - eq := strings.IndexByte(rec, '=') - if eq == -1 { - return "", "", s, ErrHeader - } - return rec[:eq], rec[eq+1:], rem, nil -} - -// parseString parses 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 (*parser) parseString(b []byte) string { - n := 0 - for n < len(b) && b[n] != 0 { - n++ - } - return string(b[0:n]) -} - -// parseNumeric parses the input as being encoded in either base-256 or octal. -// This function may return negative numbers. -// If parsing fails or an integer overflow occurs, err will be set. -func (p *parser) parseNumeric(b []byte) int64 { - // Check for base-256 (binary) format first. - // If the first bit is set, then all following bits constitute a two's - // complement encoded number in big-endian byte order. - if len(b) > 0 && b[0]&0x80 != 0 { - // Handling negative numbers relies on the following identity: - // -a-1 == ^a - // - // If the number is negative, we use an inversion mask to invert the - // data bytes and treat the value as an unsigned number. - var inv byte // 0x00 if positive or zero, 0xff if negative - if b[0]&0x40 != 0 { - inv = 0xff - } - - var x uint64 - for i, c := range b { - c ^= inv // Inverts c only if inv is 0xff, otherwise does nothing - if i == 0 { - c &= 0x7f // Ignore signal bit in first byte - } - if (x >> 56) > 0 { - p.err = ErrHeader // Integer overflow - return 0 + switch key { + case paxGNUSparseOffset, paxGNUSparseNumBytes: + // Validate sparse header order and value. + if (len(sparseMap)%2 == 0 && key != paxGNUSparseOffset) || + (len(sparseMap)%2 == 1 && key != paxGNUSparseNumBytes) || + strings.Contains(value, ",") { + return nil, ErrHeader } - x = x<<8 | uint64(c) - } - if (x >> 63) > 0 { - p.err = ErrHeader // Integer overflow - return 0 - } - if inv == 0xff { - return ^int64(x) - } - return int64(x) - } - - // Normal case is base-8 (octal) format. - return p.parseOctal(b) -} - -func (p *parser) parseOctal(b []byte) int64 { - // Because unused fields are filled with NULs, we need - // to skip leading NULs. Fields may also be padded with - // spaces or NULs. - // So we remove leading and trailing NULs and spaces to - // be sure. - b = bytes.Trim(b, " \x00") - - if len(b) == 0 { - return 0 - } - x, perr := strconv.ParseUint(p.parseString(b), 8, 64) - if perr != nil { - p.err = ErrHeader - } - return int64(x) -} - -// skipUnread skips any unread bytes in the existing file entry, as well as any -// alignment padding. It returns io.ErrUnexpectedEOF if any io.EOF is -// encountered in the data portion; it is okay to hit io.EOF in the padding. -// -// Note that this function still works properly even when sparse files are being -// used since numBytes returns the bytes remaining in the underlying io.Reader. -func (tr *Reader) skipUnread() error { - dataSkip := tr.numBytes() // Number of data bytes to skip - totalSkip := dataSkip + tr.pad // Total number of bytes to skip - tr.curr, tr.pad = nil, 0 - if tr.RawAccounting { - _, tr.err = io.CopyN(tr.rawBytes, tr.r, totalSkip) - return tr.err - } - // If possible, Seek to the last byte before the end of the data section. - // Do this because Seek is often lazy about reporting errors; this will mask - // the fact that the tar stream may be truncated. We can rely on the - // io.CopyN done shortly afterwards to trigger any IO errors. - var seekSkipped int64 // Number of bytes skipped via Seek - if sr, ok := tr.r.(io.Seeker); ok && dataSkip > 1 { - // Not all io.Seeker can actually Seek. For example, os.Stdin implements - // io.Seeker, but calling Seek always returns an error and performs - // no action. Thus, we try an innocent seek to the current position - // to see if Seek is really supported. - pos1, err := sr.Seek(0, os.SEEK_CUR) - if err == nil { - // Seek seems supported, so perform the real Seek. - pos2, err := sr.Seek(dataSkip-1, os.SEEK_CUR) - if err != nil { - tr.err = err - return tr.err - } - seekSkipped = pos2 - pos1 + sparseMap = append(sparseMap, value) + default: + paxHdrs[key] = value } } - - var copySkipped int64 // Number of bytes skipped via CopyN - copySkipped, tr.err = io.CopyN(ioutil.Discard, tr.r, totalSkip-seekSkipped) - if tr.err == io.EOF && seekSkipped+copySkipped < dataSkip { - tr.err = io.ErrUnexpectedEOF + if len(sparseMap) > 0 { + paxHdrs[paxGNUSparseMap] = strings.Join(sparseMap, ",") } - return tr.err -} - -func (tr *Reader) verifyChecksum(header []byte) bool { - if tr.err != nil { - return false - } - - var p parser - given := p.parseOctal(header[148:156]) - unsigned, signed := checksum(header) - return p.err == nil && (given == unsigned || given == signed) + return paxHdrs, nil } // readHeader reads the next block header and assumes that the underlying reader -// is already aligned to a block boundary. +// is already aligned to a block boundary. It returns the raw block of the +// header in case further processing is required. // // The err will be set to io.EOF only when one of the following occurs: // * Exactly 0 bytes are read and EOF is hit. // * Exactly 1 block of zeros is read and EOF is hit. // * At least 2 blocks of zeros are read. -func (tr *Reader) readHeader() *Header { - header := tr.hdrBuff[:] - copy(header, zeroBlock) - - if n, err := io.ReadFull(tr.r, header); err != nil { - tr.err = err - // because it could read some of the block, but reach EOF first - if tr.err == io.EOF && tr.RawAccounting { - if _, err := tr.rawBytes.Write(header[:n]); err != nil { - tr.err = err - } - } - return nil // io.EOF is okay here +func (tr *Reader) readHeader() (*Header, *block, error) { + // Two blocks of zero bytes marks the end of the archive. + n, err := io.ReadFull(tr.r, tr.blk[:]) + if tr.RawAccounting && (err == nil || err == io.EOF) { + tr.rawBytes.Write(tr.blk[:n]) } - if tr.RawAccounting { - if _, tr.err = tr.rawBytes.Write(header); tr.err != nil { - return nil - } + if err != nil { + return nil, nil, err // EOF is okay here; exactly 0 bytes read } - // Two blocks of zero bytes marks the end of the archive. - if bytes.Equal(header, zeroBlock[0:blockSize]) { - if n, err := io.ReadFull(tr.r, header); err != nil { - tr.err = err - // because it could read some of the block, but reach EOF first - if tr.err == io.EOF && tr.RawAccounting { - if _, err := tr.rawBytes.Write(header[:n]); err != nil { - tr.err = err - } - } - return nil // io.EOF is okay here + if bytes.Equal(tr.blk[:], zeroBlock[:]) { + n, err = io.ReadFull(tr.r, tr.blk[:]) + if tr.RawAccounting && (err == nil || err == io.EOF) { + tr.rawBytes.Write(tr.blk[:n]) } - if tr.RawAccounting { - if _, tr.err = tr.rawBytes.Write(header); tr.err != nil { - return nil - } + if err != nil { + return nil, nil, err // EOF is okay here; exactly 1 block of zeros read } - if bytes.Equal(header, zeroBlock[0:blockSize]) { - tr.err = io.EOF - } else { - tr.err = ErrHeader // zero block and then non-zero block + if bytes.Equal(tr.blk[:], zeroBlock[:]) { + return nil, nil, io.EOF // normal EOF; exactly 2 block of zeros read } - return nil + return nil, nil, ErrHeader // Zero block and then non-zero block } - if !tr.verifyChecksum(header) { - tr.err = ErrHeader - return nil + // Verify the header matches a known format. + format := tr.blk.GetFormat() + if format == FormatUnknown { + return nil, nil, ErrHeader } - // Unpack var p parser hdr := new(Header) - s := slicer(header) - - hdr.Name = p.parseString(s.next(100)) - hdr.Mode = p.parseNumeric(s.next(8)) - hdr.Uid = int(p.parseNumeric(s.next(8))) - hdr.Gid = int(p.parseNumeric(s.next(8))) - hdr.Size = p.parseNumeric(s.next(12)) - hdr.ModTime = time.Unix(p.parseNumeric(s.next(12)), 0) - s.next(8) // chksum - hdr.Typeflag = s.next(1)[0] - hdr.Linkname = p.parseString(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 { - case magic[:6] == "ustar\x00": // POSIX tar (1003.1-1988) - if string(header[508:512]) == "tar\x00" { - format = "star" - } else { - format = "posix" - } - case magic == "ustar \x00": // old GNU tar - format = "gnu" - } - switch format { - case "posix", "gnu", "star": - hdr.Uname = p.parseString(s.next(32)) - hdr.Gname = p.parseString(s.next(32)) - devmajor := s.next(8) - devminor := s.next(8) - if hdr.Typeflag == TypeChar || hdr.Typeflag == TypeBlock { - hdr.Devmajor = p.parseNumeric(devmajor) - hdr.Devminor = p.parseNumeric(devminor) - } + // Unpack the V7 header. + v7 := tr.blk.V7() + hdr.Typeflag = v7.TypeFlag()[0] + hdr.Name = p.parseString(v7.Name()) + hdr.Linkname = p.parseString(v7.LinkName()) + hdr.Size = p.parseNumeric(v7.Size()) + hdr.Mode = p.parseNumeric(v7.Mode()) + hdr.Uid = int(p.parseNumeric(v7.UID())) + hdr.Gid = int(p.parseNumeric(v7.GID())) + hdr.ModTime = time.Unix(p.parseNumeric(v7.ModTime()), 0) + + // Unpack format specific fields. + if format > formatV7 { + ustar := tr.blk.USTAR() + hdr.Uname = p.parseString(ustar.UserName()) + hdr.Gname = p.parseString(ustar.GroupName()) + hdr.Devmajor = p.parseNumeric(ustar.DevMajor()) + hdr.Devminor = p.parseNumeric(ustar.DevMinor()) + var prefix string - switch format { - case "posix", "gnu": - prefix = p.parseString(s.next(155)) - case "star": - prefix = p.parseString(s.next(131)) - hdr.AccessTime = time.Unix(p.parseNumeric(s.next(12)), 0) - hdr.ChangeTime = time.Unix(p.parseNumeric(s.next(12)), 0) + switch { + case format.has(FormatUSTAR | FormatPAX): + hdr.Format = format + ustar := tr.blk.USTAR() + prefix = p.parseString(ustar.Prefix()) + + // For Format detection, check if block is properly formatted since + // the parser is more liberal than what USTAR actually permits. + notASCII := func(r rune) bool { return r >= 0x80 } + if bytes.IndexFunc(tr.blk[:], notASCII) >= 0 { + hdr.Format = FormatUnknown // Non-ASCII characters in block. + } + nul := func(b []byte) bool { return int(b[len(b)-1]) == 0 } + if !(nul(v7.Size()) && nul(v7.Mode()) && nul(v7.UID()) && nul(v7.GID()) && + nul(v7.ModTime()) && nul(ustar.DevMajor()) && nul(ustar.DevMinor())) { + hdr.Format = FormatUnknown // Numeric fields must end in NUL + } + case format.has(formatSTAR): + star := tr.blk.STAR() + prefix = p.parseString(star.Prefix()) + hdr.AccessTime = time.Unix(p.parseNumeric(star.AccessTime()), 0) + hdr.ChangeTime = time.Unix(p.parseNumeric(star.ChangeTime()), 0) + case format.has(FormatGNU): + hdr.Format = format + var p2 parser + gnu := tr.blk.GNU() + if b := gnu.AccessTime(); b[0] != 0 { + hdr.AccessTime = time.Unix(p2.parseNumeric(b), 0) + } + if b := gnu.ChangeTime(); b[0] != 0 { + hdr.ChangeTime = time.Unix(p2.parseNumeric(b), 0) + } + + // Prior to Go1.8, the Writer had a bug where it would output + // an invalid tar file in certain rare situations because the logic + // incorrectly believed that the old GNU format had a prefix field. + // This is wrong and leads to an output file that mangles the + // atime and ctime fields, which are often left unused. + // + // In order to continue reading tar files created by former, buggy + // versions of Go, we skeptically parse the atime and ctime fields. + // If we are unable to parse them and the prefix field looks like + // an ASCII string, then we fallback on the pre-Go1.8 behavior + // of treating these fields as the USTAR prefix field. + // + // Note that this will not use the fallback logic for all possible + // files generated by a pre-Go1.8 toolchain. If the generated file + // happened to have a prefix field that parses as valid + // atime and ctime fields (e.g., when they are valid octal strings), + // then it is impossible to distinguish between an valid GNU file + // and an invalid pre-Go1.8 file. + // + // See https://golang.org/issues/12594 + // See https://golang.org/issues/21005 + if p2.err != nil { + hdr.AccessTime, hdr.ChangeTime = time.Time{}, time.Time{} + ustar := tr.blk.USTAR() + if s := p.parseString(ustar.Prefix()); isASCII(s) { + prefix = s + } + hdr.Format = FormatUnknown // Buggy file is not GNU + } } if len(prefix) > 0 { hdr.Name = prefix + "/" + hdr.Name } } + return hdr, &tr.blk, p.err +} - if p.err != nil { - tr.err = p.err - return nil - } - - nb := hdr.Size - if isHeaderOnlyType(hdr.Typeflag) { - nb = 0 - } - if nb < 0 { - tr.err = ErrHeader - return nil - } - - // Set the current file reader. - tr.pad = -nb & (blockSize - 1) // blockSize is a power of two - tr.curr = ®FileReader{r: tr.r, nb: nb} - - // Check for old GNU sparse format entry. - if hdr.Typeflag == TypeGNUSparse { - // Get the real size of the file. - hdr.Size = p.parseNumeric(header[483:495]) - if p.err != nil { - tr.err = p.err - return nil - } - - // Read the sparse map. - sp := tr.readOldGNUSparseMap(header) - if tr.err != nil { - return nil - } - - // Current file is a GNU sparse file. Update the current file reader. - tr.curr, tr.err = newSparseFileReader(tr.curr, sp, hdr.Size) - if tr.err != nil { - return nil - } +// readOldGNUSparseMap reads the sparse map from the old GNU sparse format. +// The sparse map is stored in the tar header if it's small enough. +// If it's larger than four entries, then one or more extension headers are used +// to store the rest of the sparse map. +// +// The Header.Size does not reflect the size of any extended headers used. +// Thus, this function will read from the raw io.Reader to fetch extra headers. +// This method mutates blk in the process. +func (tr *Reader) readOldGNUSparseMap(hdr *Header, blk *block) (sparseDatas, error) { + // Make sure that the input format is GNU. + // Unfortunately, the STAR format also has a sparse header format that uses + // the same type flag but has a completely different layout. + if blk.GetFormat() != FormatGNU { + return nil, ErrHeader } + hdr.Format.mayOnlyBe(FormatGNU) - return hdr -} - -// readOldGNUSparseMap reads the sparse map as stored in the old GNU sparse format. -// The sparse map is stored in the tar header if it's small enough. If it's larger than four entries, -// then one or more extension headers are used to store the rest of the sparse map. -func (tr *Reader) readOldGNUSparseMap(header []byte) []sparseEntry { var p parser - isExtended := header[oldGNUSparseMainHeaderIsExtendedOffset] != 0 - spCap := oldGNUSparseMainHeaderNumEntries - if isExtended { - spCap += oldGNUSparseExtendedHeaderNumEntries - } - sp := make([]sparseEntry, 0, spCap) - s := slicer(header[oldGNUSparseMainHeaderOffset:]) - - // Read the four entries from the main tar header - for i := 0; i < oldGNUSparseMainHeaderNumEntries; i++ { - offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize)) - numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize)) - if p.err != nil { - tr.err = p.err - return nil - } - if offset == 0 && numBytes == 0 { - break - } - sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes}) + hdr.Size = p.parseNumeric(blk.GNU().RealSize()) + if p.err != nil { + return nil, p.err } - - for isExtended { - // There are more entries. Read an extension header and parse its entries. - sparseHeader := make([]byte, blockSize) - if _, tr.err = io.ReadFull(tr.r, sparseHeader); tr.err != nil { - return nil - } - if tr.RawAccounting { - if _, tr.err = tr.rawBytes.Write(sparseHeader); tr.err != nil { - return nil + s := blk.GNU().Sparse() + spd := make(sparseDatas, 0, s.MaxEntries()) + for { + for i := 0; i < s.MaxEntries(); i++ { + // This termination condition is identical to GNU and BSD tar. + if s.Entry(i).Offset()[0] == 0x00 { + break // Don't return, need to process extended headers (even if empty) + } + offset := p.parseNumeric(s.Entry(i).Offset()) + length := p.parseNumeric(s.Entry(i).Length()) + if p.err != nil { + return nil, p.err } + spd = append(spd, sparseEntry{Offset: offset, Length: length}) } - isExtended = sparseHeader[oldGNUSparseExtendedHeaderIsExtendedOffset] != 0 - s = slicer(sparseHeader) - for i := 0; i < oldGNUSparseExtendedHeaderNumEntries; i++ { - offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize)) - numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize)) - if p.err != nil { - tr.err = p.err - return nil + if s.IsExtended()[0] > 0 { + // There are more entries. Read an extension header and parse its entries. + if _, err := mustReadFull(tr.r, blk[:]); err != nil { + return nil, err } - if offset == 0 && numBytes == 0 { - break + if tr.RawAccounting { + tr.rawBytes.Write(blk[:]) } - sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes}) + s = blk.Sparse() + continue } + return spd, nil // Done } - return sp } // readGNUSparseMap1x0 reads the sparse map as stored in GNU's PAX sparse format // version 1.0. The format of the sparse map consists of a series of // newline-terminated numeric fields. The first field is the number of entries // and is always present. Following this are the entries, consisting of two -// fields (offset, numBytes). This function must stop reading at the end +// fields (offset, length). This function must stop reading at the end // boundary of the block containing the last newline. // // Note that the GNU manual says that numeric values should be encoded in octal // format. However, the GNU tar utility itself outputs these values in decimal. // As such, this library treats values as being encoded in decimal. -func readGNUSparseMap1x0(r io.Reader) ([]sparseEntry, error) { - var cntNewline int64 - var buf bytes.Buffer - var blk = make([]byte, blockSize) - - // feedTokens copies data in numBlock chunks from r into buf until there are +func readGNUSparseMap1x0(r io.Reader) (sparseDatas, error) { + var ( + cntNewline int64 + buf bytes.Buffer + blk block + ) + + // feedTokens copies data in blocks from r into buf until there are // at least cnt newlines in buf. It will not read more blocks than needed. - var feedTokens = func(cnt int64) error { - for cntNewline < cnt { - if _, err := io.ReadFull(r, blk); err != nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } + feedTokens := func(n int64) error { + for cntNewline < n { + if _, err := mustReadFull(r, blk[:]); err != nil { return err } - buf.Write(blk) + buf.Write(blk[:]) for _, c := range blk { if c == '\n' { cntNewline++ @@ -846,10 +596,10 @@ func readGNUSparseMap1x0(r io.Reader) ([]sparseEntry, error) { // nextToken gets the next token delimited by a newline. This assumes that // at least one newline exists in the buffer. - var nextToken = func() string { + nextToken := func() string { cntNewline-- tok, _ := buf.ReadString('\n') - return tok[:len(tok)-1] // Cut off newline + return strings.TrimRight(tok, "\n") } // Parse for the number of entries. @@ -868,197 +618,306 @@ func readGNUSparseMap1x0(r io.Reader) ([]sparseEntry, error) { if err := feedTokens(2 * numEntries); err != nil { return nil, err } - sp := make([]sparseEntry, 0, numEntries) + spd := make(sparseDatas, 0, numEntries) for i := int64(0); i < numEntries; i++ { - offset, err := strconv.ParseInt(nextToken(), 10, 64) - if err != nil { - return nil, ErrHeader - } - numBytes, err := strconv.ParseInt(nextToken(), 10, 64) - if err != nil { + offset, err1 := strconv.ParseInt(nextToken(), 10, 64) + length, err2 := strconv.ParseInt(nextToken(), 10, 64) + if err1 != nil || err2 != nil { return nil, ErrHeader } - sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes}) + spd = append(spd, sparseEntry{Offset: offset, Length: length}) } - return sp, nil + return spd, nil } // readGNUSparseMap0x1 reads the sparse map as stored in GNU's PAX sparse format // version 0.1. The sparse map is stored in the PAX headers. -func readGNUSparseMap0x1(extHdrs map[string]string) ([]sparseEntry, error) { +func readGNUSparseMap0x1(paxHdrs map[string]string) (sparseDatas, error) { // Get number of entries. // Use integer overflow resistant math to check this. - numEntriesStr := extHdrs[paxGNUSparseNumBlocks] + numEntriesStr := paxHdrs[paxGNUSparseNumBlocks] numEntries, err := strconv.ParseInt(numEntriesStr, 10, 0) // Intentionally parse as native int if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) { return nil, ErrHeader } // There should be two numbers in sparseMap for each entry. - sparseMap := strings.Split(extHdrs[paxGNUSparseMap], ",") + sparseMap := strings.Split(paxHdrs[paxGNUSparseMap], ",") + if len(sparseMap) == 1 && sparseMap[0] == "" { + sparseMap = sparseMap[:0] + } if int64(len(sparseMap)) != 2*numEntries { return nil, ErrHeader } // Loop through the entries in the sparse map. // numEntries is trusted now. - sp := make([]sparseEntry, 0, numEntries) - for i := int64(0); i < numEntries; i++ { - offset, err := strconv.ParseInt(sparseMap[2*i], 10, 64) - if err != nil { + spd := make(sparseDatas, 0, numEntries) + for len(sparseMap) >= 2 { + offset, err1 := strconv.ParseInt(sparseMap[0], 10, 64) + length, err2 := strconv.ParseInt(sparseMap[1], 10, 64) + if err1 != nil || err2 != nil { return nil, ErrHeader } - numBytes, err := strconv.ParseInt(sparseMap[2*i+1], 10, 64) - if err != nil { - return nil, ErrHeader - } - sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes}) + spd = append(spd, sparseEntry{Offset: offset, Length: length}) + sparseMap = sparseMap[2:] } - return sp, nil + return spd, nil } -// numBytes returns the number of bytes left to read in the current file's entry -// in the tar archive, or 0 if there is no current file. -func (tr *Reader) numBytes() int64 { - if tr.curr == nil { - // No current file, so no bytes - return 0 - } - return tr.curr.numBytes() -} - -// Read reads from the current entry in the tar archive. -// It returns 0, io.EOF when it reaches the end of that entry, -// until Next is called to advance to the next entry. +// Read reads from the current file in the tar archive. +// It returns (0, io.EOF) when it reaches the end of that file, +// until Next is called to advance to the next file. +// +// If the current file is sparse, then the regions marked as a hole +// are read back as NUL-bytes. // -// Calling Read on special types like TypeLink, TypeSymLink, TypeChar, -// TypeBlock, TypeDir, and TypeFifo returns 0, io.EOF regardless of what +// Calling Read on special types like TypeLink, TypeSymlink, TypeChar, +// TypeBlock, TypeDir, and TypeFifo returns (0, io.EOF) regardless of what // the Header.Size claims. -func (tr *Reader) Read(b []byte) (n int, err error) { +func (tr *Reader) Read(b []byte) (int, error) { if tr.err != nil { return 0, tr.err } - if tr.curr == nil { - return 0, io.EOF - } - - n, err = tr.curr.Read(b) + n, err := tr.curr.Read(b) if err != nil && err != io.EOF { tr.err = err } - return + return n, err } -func (rfr *regFileReader) Read(b []byte) (n int, err error) { - if rfr.nb == 0 { - // file consumed - return 0, io.EOF +// writeTo writes the content of the current file to w. +// The bytes written matches the number of remaining bytes in the current file. +// +// If the current file is sparse and w is an io.WriteSeeker, +// then writeTo uses Seek to skip past holes defined in Header.SparseHoles, +// assuming that skipped regions are filled with NULs. +// This always writes the last byte to ensure w is the right size. +// +// TODO(dsnet): Re-export this when adding sparse file support. +// See https://golang.org/issue/22735 +func (tr *Reader) writeTo(w io.Writer) (int64, error) { + if tr.err != nil { + return 0, tr.err } - if int64(len(b)) > rfr.nb { - b = b[0:rfr.nb] + n, err := tr.curr.WriteTo(w) + if err != nil { + tr.err = err } - n, err = rfr.r.Read(b) - rfr.nb -= int64(n) + return n, err +} - if err == io.EOF && rfr.nb > 0 { - err = io.ErrUnexpectedEOF +// regFileReader is a fileReader for reading data from a regular file entry. +type regFileReader struct { + r io.Reader // Underlying Reader + nb int64 // Number of remaining bytes to read +} + +func (fr *regFileReader) Read(b []byte) (n int, err error) { + if int64(len(b)) > fr.nb { + b = b[:fr.nb] + } + if len(b) > 0 { + n, err = fr.r.Read(b) + fr.nb -= int64(n) + } + switch { + case err == io.EOF && fr.nb > 0: + return n, io.ErrUnexpectedEOF + case err == nil && fr.nb == 0: + return n, io.EOF + default: + return n, err } - return } -// numBytes returns the number of bytes left to read in the file's data in the tar archive. -func (rfr *regFileReader) numBytes() int64 { - return rfr.nb +func (fr *regFileReader) WriteTo(w io.Writer) (int64, error) { + return io.Copy(w, struct{ io.Reader }{fr}) } -// newSparseFileReader creates a new sparseFileReader, but validates all of the -// sparse entries before doing so. -func newSparseFileReader(rfr numBytesReader, sp []sparseEntry, total int64) (*sparseFileReader, error) { - if total < 0 { - return nil, ErrHeader // Total size cannot be negative +func (fr regFileReader) LogicalRemaining() int64 { + return fr.nb +} + +func (fr regFileReader) PhysicalRemaining() int64 { + return fr.nb +} + +// sparseFileReader is a fileReader for reading data from a sparse file entry. +type sparseFileReader struct { + fr fileReader // Underlying fileReader + sp sparseHoles // Normalized list of sparse holes + pos int64 // Current position in sparse file +} + +func (sr *sparseFileReader) Read(b []byte) (n int, err error) { + finished := int64(len(b)) >= sr.LogicalRemaining() + if finished { + b = b[:sr.LogicalRemaining()] } - // Validate all sparse entries. These are the same checks as performed by - // the BSD tar utility. - for i, s := range sp { - switch { - case s.offset < 0 || s.numBytes < 0: - return nil, ErrHeader // Negative values are never okay - case s.offset > math.MaxInt64-s.numBytes: - return nil, ErrHeader // Integer overflow with large length - case s.offset+s.numBytes > total: - return nil, ErrHeader // Region extends beyond the "real" size - case i > 0 && sp[i-1].offset+sp[i-1].numBytes > s.offset: - return nil, ErrHeader // Regions can't overlap and must be in order + b0 := b + endPos := sr.pos + int64(len(b)) + for endPos > sr.pos && err == nil { + var nf int // Bytes read in fragment + holeStart, holeEnd := sr.sp[0].Offset, sr.sp[0].endOffset() + if sr.pos < holeStart { // In a data fragment + bf := b[:min(int64(len(b)), holeStart-sr.pos)] + nf, err = tryReadFull(sr.fr, bf) + } else { // In a hole fragment + bf := b[:min(int64(len(b)), holeEnd-sr.pos)] + nf, err = tryReadFull(zeroReader{}, bf) + } + b = b[nf:] + sr.pos += int64(nf) + if sr.pos >= holeEnd && len(sr.sp) > 1 { + sr.sp = sr.sp[1:] // Ensure last fragment always remains } } - return &sparseFileReader{rfr: rfr, sp: sp, total: total}, nil -} -// readHole reads a sparse hole ending at endOffset. -func (sfr *sparseFileReader) readHole(b []byte, endOffset int64) int { - n64 := endOffset - sfr.pos - if n64 > int64(len(b)) { - n64 = int64(len(b)) - } - n := int(n64) - for i := 0; i < n; i++ { - b[i] = 0 + n = len(b0) - len(b) + switch { + case err == io.EOF: + return n, errMissData // Less data in dense file than sparse file + case err != nil: + return n, err + case sr.LogicalRemaining() == 0 && sr.PhysicalRemaining() > 0: + return n, errUnrefData // More data in dense file than sparse file + case finished: + return n, io.EOF + default: + return n, nil } - sfr.pos += n64 - return n } -// Read reads the sparse file data in expanded form. -func (sfr *sparseFileReader) Read(b []byte) (n int, err error) { - // Skip past all empty fragments. - for len(sfr.sp) > 0 && sfr.sp[0].numBytes == 0 { - sfr.sp = sfr.sp[1:] +func (sr *sparseFileReader) WriteTo(w io.Writer) (n int64, err error) { + ws, ok := w.(io.WriteSeeker) + if ok { + if _, err := ws.Seek(0, io.SeekCurrent); err != nil { + ok = false // Not all io.Seeker can really seek + } + } + if !ok { + return io.Copy(w, struct{ io.Reader }{sr}) + } + + var writeLastByte bool + pos0 := sr.pos + for sr.LogicalRemaining() > 0 && !writeLastByte && err == nil { + var nf int64 // Size of fragment + holeStart, holeEnd := sr.sp[0].Offset, sr.sp[0].endOffset() + if sr.pos < holeStart { // In a data fragment + nf = holeStart - sr.pos + nf, err = io.CopyN(ws, sr.fr, nf) + } else { // In a hole fragment + nf = holeEnd - sr.pos + if sr.PhysicalRemaining() == 0 { + writeLastByte = true + nf-- + } + _, err = ws.Seek(nf, io.SeekCurrent) + } + sr.pos += nf + if sr.pos >= holeEnd && len(sr.sp) > 1 { + sr.sp = sr.sp[1:] // Ensure last fragment always remains + } } - // If there are no more fragments, then it is possible that there - // is one last sparse hole. - if len(sfr.sp) == 0 { - // This behavior matches the BSD tar utility. - // However, GNU tar stops returning data even if sfr.total is unmet. - if sfr.pos < sfr.total { - return sfr.readHole(b, sfr.total), nil - } - return 0, io.EOF + // If the last fragment is a hole, then seek to 1-byte before EOF, and + // write a single byte to ensure the file is the right size. + if writeLastByte && err == nil { + _, err = ws.Write([]byte{0}) + sr.pos++ } - // In front of a data fragment, so read a hole. - if sfr.pos < sfr.sp[0].offset { - return sfr.readHole(b, sfr.sp[0].offset), nil + n = sr.pos - pos0 + switch { + case err == io.EOF: + return n, errMissData // Less data in dense file than sparse file + case err != nil: + return n, err + case sr.LogicalRemaining() == 0 && sr.PhysicalRemaining() > 0: + return n, errUnrefData // More data in dense file than sparse file + default: + return n, nil } +} - // In a data fragment, so read from it. - // This math is overflow free since we verify that offset and numBytes can - // be safely added when creating the sparseFileReader. - endPos := sfr.sp[0].offset + sfr.sp[0].numBytes // End offset of fragment - bytesLeft := endPos - sfr.pos // Bytes left in fragment - if int64(len(b)) > bytesLeft { - b = b[:bytesLeft] +func (sr sparseFileReader) LogicalRemaining() int64 { + return sr.sp[len(sr.sp)-1].endOffset() - sr.pos +} +func (sr sparseFileReader) PhysicalRemaining() int64 { + return sr.fr.PhysicalRemaining() +} + +type zeroReader struct{} + +func (zeroReader) Read(b []byte) (int, error) { + for i := range b { + b[i] = 0 } + return len(b), nil +} - n, err = sfr.rfr.Read(b) - sfr.pos += int64(n) +// mustReadFull is like io.ReadFull except it returns +// io.ErrUnexpectedEOF when io.EOF is hit before len(b) bytes are read. +func mustReadFull(r io.Reader, b []byte) (int, error) { + n, err := tryReadFull(r, b) if err == io.EOF { - if sfr.pos < endPos { - err = io.ErrUnexpectedEOF // There was supposed to be more data - } else if sfr.pos < sfr.total { - err = nil // There is still an implicit sparse hole at the end - } + err = io.ErrUnexpectedEOF } + return n, err +} - if sfr.pos == endPos { - sfr.sp = sfr.sp[1:] // We are done with this fragment, so pop it +// tryReadFull is like io.ReadFull except it returns +// io.EOF when it is hit before len(b) bytes are read. +func tryReadFull(r io.Reader, b []byte) (n int, err error) { + for len(b) > n && err == nil { + var nn int + nn, err = r.Read(b[n:]) + n += nn + } + if len(b) == n && err == io.EOF { + err = nil } return n, err } -// numBytes returns the number of bytes left to read in the sparse file's -// sparse-encoded data in the tar archive. -func (sfr *sparseFileReader) numBytes() int64 { - return sfr.rfr.numBytes() +// discard skips n bytes in r, reporting an error if unable to do so. +func discard(tr *Reader, n int64) error { + var seekSkipped, copySkipped int64 + var err error + r := tr.r + if tr.RawAccounting { + + copySkipped, err = io.CopyN(tr.rawBytes, tr.r, n) + goto out + } + + // If possible, Seek to the last byte before the end of the data section. + // Do this because Seek is often lazy about reporting errors; this will mask + // the fact that the stream may be truncated. We can rely on the + // io.CopyN done shortly afterwards to trigger any IO errors. + if sr, ok := r.(io.Seeker); ok && n > 1 { + // Not all io.Seeker can actually Seek. For example, os.Stdin implements + // io.Seeker, but calling Seek always returns an error and performs + // no action. Thus, we try an innocent seek to the current position + // to see if Seek is really supported. + pos1, err := sr.Seek(0, io.SeekCurrent) + if pos1 >= 0 && err == nil { + // Seek seems supported, so perform the real Seek. + pos2, err := sr.Seek(n-1, io.SeekCurrent) + if pos2 < 0 || err != nil { + return err + } + seekSkipped = pos2 - pos1 + } + } + + copySkipped, err = io.CopyN(ioutil.Discard, r, n-seekSkipped) +out: + if err == io.EOF && seekSkipped+copySkipped < n { + err = io.ErrUnexpectedEOF + } + return err } |