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path: root/src/pkg/archive/tar/reader.go
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Diffstat (limited to 'src/pkg/archive/tar/reader.go')
-rw-r--r--src/pkg/archive/tar/reader.go817
1 files changed, 0 insertions, 817 deletions
diff --git a/src/pkg/archive/tar/reader.go b/src/pkg/archive/tar/reader.go
deleted file mode 100644
index 920a9b08f..000000000
--- a/src/pkg/archive/tar/reader.go
+++ /dev/null
@@ -1,817 +0,0 @@
-// 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"
- "errors"
- "io"
- "io/ioutil"
- "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.
-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
-}
-
-// 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 *regFileReader // reads the sparse-encoded file data
- sp []sparseEntry // the sparse map for the file
- pos int64 // keeps track of file position
- tot int64 // total size of the file
-}
-
-// 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} }
-
-// Next advances to the next entry in the tar archive.
-func (tr *Reader) Next() (*Header, error) {
- var hdr *Header
- if tr.err == nil {
- tr.skipUnread()
- }
- if tr.err != nil {
- return hdr, tr.err
- }
- hdr = tr.readHeader()
- if hdr == nil {
- return hdr, tr.err
- }
- // Check for PAX/GNU header.
- switch hdr.Typeflag {
- case TypeXHeader:
- // PAX extended header
- headers, err := parsePAX(tr)
- if err != nil {
- return nil, err
- }
- // We actually read the whole file,
- // but this skips alignment padding
- tr.skipUnread()
- hdr = tr.readHeader()
- mergePAX(hdr, headers)
-
- // Check for a PAX format sparse file
- sp, err := tr.checkForGNUSparsePAXHeaders(hdr, headers)
- if err != nil {
- tr.err = err
- 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 = &sparseFileReader{rfr: tr.curr.(*regFileReader), sp: sp, tot: hdr.Size}
- }
- return hdr, nil
- case TypeGNULongName:
- // We have a GNU long name header. Its contents are the real file name.
- realname, err := ioutil.ReadAll(tr)
- if err != nil {
- return nil, err
- }
- hdr, err := tr.Next()
- hdr.Name = cString(realname)
- return hdr, err
- case TypeGNULongLink:
- // We have a GNU long link header.
- realname, err := ioutil.ReadAll(tr)
- if err != nil {
- return nil, err
- }
- hdr, err := tr.Next()
- hdr.Linkname = cString(realname)
- return hdr, err
- }
- return hdr, tr.err
-}
-
-// 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
- }
-
- // Check for unknown sparse format
- if sparseFormat != "0.0" && sparseFormat != "0.1" && sparseFormat != "1.0" {
- return nil, nil
- }
-
- // Update hdr from GNU sparse PAX headers
- if sparseNameOk {
- hdr.Name = sparseName
- }
- if sparseSizeOk {
- realSize, err := strconv.ParseInt(sparseSize, 10, 0)
- if err != nil {
- return nil, ErrHeader
- }
- hdr.Size = realSize
- } else if sparseRealSizeOk {
- realSize, err := strconv.ParseInt(sparseRealSize, 10, 0)
- if err != nil {
- return nil, ErrHeader
- }
- hdr.Size = realSize
- }
-
- // 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)
- }
- return sp, err
-}
-
-// 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 {
- switch k {
- case paxPath:
- hdr.Name = v
- case paxLinkpath:
- hdr.Linkname = v
- case paxGname:
- hdr.Gname = v
- case paxUname:
- hdr.Uname = v
- case paxUid:
- uid, err := strconv.ParseInt(v, 10, 0)
- if err != nil {
- return err
- }
- hdr.Uid = int(uid)
- case paxGid:
- gid, err := strconv.ParseInt(v, 10, 0)
- if err != nil {
- return err
- }
- hdr.Gid = int(gid)
- case paxAtime:
- t, err := parsePAXTime(v)
- if err != nil {
- return err
- }
- hdr.AccessTime = t
- case paxMtime:
- t, err := parsePAXTime(v)
- if err != nil {
- return err
- }
- hdr.ModTime = t
- case paxCtime:
- t, err := parsePAXTime(v)
- if err != nil {
- return err
- }
- hdr.ChangeTime = t
- case paxSize:
- size, err := strconv.ParseInt(v, 10, 0)
- if err != nil {
- return err
- }
- hdr.Size = int64(size)
- default:
- if strings.HasPrefix(k, paxXattr) {
- if hdr.Xattrs == nil {
- hdr.Xattrs = make(map[string]string)
- }
- hdr.Xattrs[k[len(paxXattr):]] = 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
- }
- }
- ts := time.Unix(seconds, nanoseconds)
- return ts, nil
-}
-
-// parsePAX parses PAX headers.
-// If an extended header (type 'x') is invalid, ErrHeader is returned
-func parsePAX(r io.Reader) (map[string]string, error) {
- buf, err := ioutil.ReadAll(r)
- if err != nil {
- return nil, err
- }
-
- // 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
-
- headers := make(map[string]string)
- // Each record is constructed as
- // "%d %s=%s\n", length, keyword, value
- for len(buf) > 0 {
- // or the header was empty to start with.
- var sp int
- // The size field ends at the first space.
- sp = bytes.IndexByte(buf, ' ')
- if sp == -1 {
- return nil, ErrHeader
- }
- // Parse the first token as a decimal integer.
- n, err := strconv.ParseInt(string(buf[:sp]), 10, 0)
- if err != nil {
- return nil, ErrHeader
- }
- // Extract everything between the decimal and the n -1 on the
- // beginning to eat the ' ', -1 on the end to skip the newline.
- var record []byte
- record, buf = buf[sp+1:n-1], buf[n:]
- // The first equals is guaranteed to mark the end of the key.
- // Everything else is value.
- eq := bytes.IndexByte(record, '=')
- if eq == -1 {
- return nil, ErrHeader
- }
- key, value := record[:eq], record[eq+1:]
-
- 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.Write(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
-}
-
-// cString 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 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 {
- // Check for binary format first.
- if len(b) > 0 && b[0]&0x80 != 0 {
- var x int64
- for i, c := range b {
- if i == 0 {
- c &= 0x7f // ignore signal bit in first byte
- }
- x = x<<8 | int64(c)
- }
- return x
- }
-
- // 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, err := strconv.ParseUint(cString(b), 8, 64)
- if err != nil {
- tr.err = err
- }
- return int64(x)
-}
-
-// skipUnread skips any unread bytes in the existing file entry, as well as any alignment padding.
-func (tr *Reader) skipUnread() {
- nr := tr.numBytes() + tr.pad // number of bytes to skip
- tr.curr, tr.pad = nil, 0
- if sr, ok := tr.r.(io.Seeker); ok {
- if _, err := sr.Seek(nr, os.SEEK_CUR); err == nil {
- return
- }
- }
- _, tr.err = io.CopyN(ioutil.Discard, 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 = io.EOF
- } else {
- tr.err = ErrHeader // zero block and then non-zero block
- }
- return nil
- }
-
- if !tr.verifyChecksum(header) {
- tr.err = ErrHeader
- 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.ModTime = time.Unix(tr.octal(s.next(12)), 0)
- 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 {
- 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 = 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.AccessTime = time.Unix(tr.octal(s.next(12)), 0)
- hdr.ChangeTime = time.Unix(tr.octal(s.next(12)), 0)
- }
- if len(prefix) > 0 {
- hdr.Name = prefix + "/" + hdr.Name
- }
- }
-
- if tr.err != nil {
- tr.err = ErrHeader
- return nil
- }
-
- // Maximum value of hdr.Size is 64 GB (12 octal digits),
- // so there's no risk of int64 overflowing.
- nb := int64(hdr.Size)
- tr.pad = -nb & (blockSize - 1) // blockSize is a power of two
-
- // Set the current file reader.
- tr.curr = &regFileReader{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 = tr.octal(header[483:495])
-
- // 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 = &sparseFileReader{rfr: tr.curr.(*regFileReader), sp: sp, tot: hdr.Size}
- }
-
- return hdr
-}
-
-// A sparseEntry holds a single entry in a sparse file's sparse map.
-// A sparse entry indicates the offset and size in a sparse file of a
-// block of data.
-type sparseEntry struct {
- offset int64
- numBytes int64
-}
-
-// 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 {
- 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 := tr.octal(s.next(oldGNUSparseOffsetSize))
- numBytes := tr.octal(s.next(oldGNUSparseNumBytesSize))
- if tr.err != nil {
- tr.err = ErrHeader
- return nil
- }
- if offset == 0 && numBytes == 0 {
- break
- }
- sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
- }
-
- 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
- }
- isExtended = sparseHeader[oldGNUSparseExtendedHeaderIsExtendedOffset] != 0
- s = slicer(sparseHeader)
- for i := 0; i < oldGNUSparseExtendedHeaderNumEntries; i++ {
- offset := tr.octal(s.next(oldGNUSparseOffsetSize))
- numBytes := tr.octal(s.next(oldGNUSparseNumBytesSize))
- if tr.err != nil {
- tr.err = ErrHeader
- return nil
- }
- if offset == 0 && numBytes == 0 {
- break
- }
- sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
- }
- }
- return sp
-}
-
-// readGNUSparseMap1x0 reads the sparse map as stored in GNU's PAX sparse format version 1.0.
-// The sparse map is stored just before the file data and padded out to the nearest block boundary.
-func readGNUSparseMap1x0(r io.Reader) ([]sparseEntry, error) {
- buf := make([]byte, 2*blockSize)
- sparseHeader := buf[:blockSize]
-
- // readDecimal is a helper function to read a decimal integer from the sparse map
- // while making sure to read from the file in blocks of size blockSize
- readDecimal := func() (int64, error) {
- // Look for newline
- nl := bytes.IndexByte(sparseHeader, '\n')
- if nl == -1 {
- if len(sparseHeader) >= blockSize {
- // This is an error
- return 0, ErrHeader
- }
- oldLen := len(sparseHeader)
- newLen := oldLen + blockSize
- if cap(sparseHeader) < newLen {
- // There's more header, but we need to make room for the next block
- copy(buf, sparseHeader)
- sparseHeader = buf[:newLen]
- } else {
- // There's more header, and we can just reslice
- sparseHeader = sparseHeader[:newLen]
- }
-
- // Now that sparseHeader is large enough, read next block
- if _, err := io.ReadFull(r, sparseHeader[oldLen:newLen]); err != nil {
- return 0, err
- }
-
- // Look for a newline in the new data
- nl = bytes.IndexByte(sparseHeader[oldLen:newLen], '\n')
- if nl == -1 {
- // This is an error
- return 0, ErrHeader
- }
- nl += oldLen // We want the position from the beginning
- }
- // Now that we've found a newline, read a number
- n, err := strconv.ParseInt(string(sparseHeader[:nl]), 10, 0)
- if err != nil {
- return 0, ErrHeader
- }
-
- // Update sparseHeader to consume this number
- sparseHeader = sparseHeader[nl+1:]
- return n, nil
- }
-
- // Read the first block
- if _, err := io.ReadFull(r, sparseHeader); err != nil {
- return nil, err
- }
-
- // The first line contains the number of entries
- numEntries, err := readDecimal()
- if err != nil {
- return nil, err
- }
-
- // Read all the entries
- sp := make([]sparseEntry, 0, numEntries)
- for i := int64(0); i < numEntries; i++ {
- // Read the offset
- offset, err := readDecimal()
- if err != nil {
- return nil, err
- }
- // Read numBytes
- numBytes, err := readDecimal()
- if err != nil {
- return nil, err
- }
-
- sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
- }
-
- return sp, 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(headers map[string]string) ([]sparseEntry, error) {
- // Get number of entries
- numEntriesStr, ok := headers[paxGNUSparseNumBlocks]
- if !ok {
- return nil, ErrHeader
- }
- numEntries, err := strconv.ParseInt(numEntriesStr, 10, 0)
- if err != nil {
- return nil, ErrHeader
- }
-
- sparseMap := strings.Split(headers[paxGNUSparseMap], ",")
-
- // There should be two numbers in sparseMap for each entry
- if int64(len(sparseMap)) != 2*numEntries {
- return nil, ErrHeader
- }
-
- // Loop through the entries in the sparse map
- sp := make([]sparseEntry, 0, numEntries)
- for i := int64(0); i < numEntries; i++ {
- offset, err := strconv.ParseInt(sparseMap[2*i], 10, 0)
- if err != nil {
- return nil, ErrHeader
- }
- numBytes, err := strconv.ParseInt(sparseMap[2*i+1], 10, 0)
- if err != nil {
- return nil, ErrHeader
- }
- sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
- }
-
- return sp, 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.
-func (tr *Reader) Read(b []byte) (n int, err error) {
- if tr.curr == nil {
- return 0, io.EOF
- }
- n, err = tr.curr.Read(b)
- if err != nil && err != io.EOF {
- tr.err = err
- }
- return
-}
-
-func (rfr *regFileReader) Read(b []byte) (n int, err error) {
- if rfr.nb == 0 {
- // file consumed
- return 0, io.EOF
- }
- if int64(len(b)) > rfr.nb {
- b = b[0:rfr.nb]
- }
- n, err = rfr.r.Read(b)
- rfr.nb -= int64(n)
-
- if err == io.EOF && rfr.nb > 0 {
- err = io.ErrUnexpectedEOF
- }
- 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
-}
-
-// readHole reads a sparse file hole ending at offset toOffset
-func (sfr *sparseFileReader) readHole(b []byte, toOffset int64) int {
- n64 := toOffset - sfr.pos
- if n64 > int64(len(b)) {
- n64 = int64(len(b))
- }
- n := int(n64)
- for i := 0; i < n; i++ {
- b[i] = 0
- }
- sfr.pos += n64
- return n
-}
-
-// Read reads the sparse file data in expanded form.
-func (sfr *sparseFileReader) Read(b []byte) (n int, err error) {
- if len(sfr.sp) == 0 {
- // No more data fragments to read from.
- if sfr.pos < sfr.tot {
- // We're in the last hole
- n = sfr.readHole(b, sfr.tot)
- return
- }
- // Otherwise, we're at the end of the file
- return 0, io.EOF
- }
- if sfr.pos < sfr.sp[0].offset {
- // We're in a hole
- n = sfr.readHole(b, sfr.sp[0].offset)
- return
- }
-
- // We're not in a hole, so we'll read from the next data fragment
- posInFragment := sfr.pos - sfr.sp[0].offset
- bytesLeft := sfr.sp[0].numBytes - posInFragment
- if int64(len(b)) > bytesLeft {
- b = b[0:bytesLeft]
- }
-
- n, err = sfr.rfr.Read(b)
- sfr.pos += int64(n)
-
- if int64(n) == bytesLeft {
- // We're done with this fragment
- sfr.sp = sfr.sp[1:]
- }
-
- if err == io.EOF && sfr.pos < sfr.tot {
- // We reached the end of the last fragment's data, but there's a final hole
- err = nil
- }
- return
-}
-
-// 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.nb
-}
generated by cgit v1.2.3 (git 2.39.1) at 2025-04-30 16:09:20 +0000