go common 源码
golang common 代码
文件路径：/src/archive/tar/common.go
// 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 implements access to tar archives.
//
// Tape archives (tar) are a file format for storing a sequence of files that
// can be read and written in a streaming manner.
// This package aims to cover most variations of the format,
// including those produced by GNU and BSD tar tools.
package tar
import (
"errors"
"fmt"
"io/fs"
"math"
"path"
"reflect"
"strconv"
"strings"
"time"
)
// BUG: Use of the Uid and Gid fields in Header could overflow on 32-bit
// architectures. If a large value is encountered when decoding, the result
// stored in Header will be the truncated version.
var (
ErrHeader = errors.New("archive/tar: invalid tar header")
ErrWriteTooLong = errors.New("archive/tar: write too long")
ErrFieldTooLong = errors.New("archive/tar: header field too long")
ErrWriteAfterClose = errors.New("archive/tar: write after close")
errMissData = errors.New("archive/tar: sparse file references non-existent data")
errUnrefData = errors.New("archive/tar: sparse file contains unreferenced data")
errWriteHole = errors.New("archive/tar: write non-NUL byte in sparse hole")
)
type headerError []string
func (he headerError) Error() string {
const prefix = "archive/tar: cannot encode header"
var ss []string
for _, s := range he {
if s != "" {
ss = append(ss, s)
}
}
if len(ss) == 0 {
return prefix
}
return fmt.Sprintf("%s: %v", prefix, strings.Join(ss, "; and "))
}
// Type flags for Header.Typeflag.
const (
// Type '0' indicates a regular file.
TypeReg = '0'
TypeRegA = '\x00' // Deprecated: Use TypeReg instead.
// Type '1' to '6' are header-only flags and may not have a data body.
TypeLink = '1' // Hard link
TypeSymlink = '2' // Symbolic link
TypeChar = '3' // Character device node
TypeBlock = '4' // Block device node
TypeDir = '5' // Directory
TypeFifo = '6' // FIFO node
// Type '7' is reserved.
TypeCont = '7'
// Type 'x' is used by the PAX format to store key-value records that
// are only relevant to the next file.
// This package transparently handles these types.
TypeXHeader = 'x'
// Type 'g' is used by the PAX format to store key-value records that
// are relevant to all subsequent files.
// This package only supports parsing and composing such headers,
// but does not currently support persisting the global state across files.
TypeXGlobalHeader = 'g'
// Type 'S' indicates a sparse file in the GNU format.
TypeGNUSparse = 'S'
// Types 'L' and 'K' are used by the GNU format for a meta file
// used to store the path or link name for the next file.
// This package transparently handles these types.
TypeGNULongName = 'L'
TypeGNULongLink = 'K'
)
// Keywords for PAX extended header records.
const (
paxNone = "" // Indicates that no PAX key is suitable
paxPath = "path"
paxLinkpath = "linkpath"
paxSize = "size"
paxUid = "uid"
paxGid = "gid"
paxUname = "uname"
paxGname = "gname"
paxMtime = "mtime"
paxAtime = "atime"
paxCtime = "ctime" // Removed from later revision of PAX spec, but was valid
paxCharset = "charset" // Currently unused
paxComment = "comment" // Currently unused
paxSchilyXattr = "SCHILY.xattr."
// Keywords for GNU sparse files in a PAX extended header.
paxGNUSparse = "GNU.sparse."
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"
)
// basicKeys is a set of the PAX keys for which we have built-in support.
// This does not contain "charset" or "comment", which are both PAX-specific,
// so adding them as first-class features of Header is unlikely.
// Users can use the PAXRecords field to set it themselves.
var basicKeys = map[string]bool{
paxPath: true, paxLinkpath: true, paxSize: true, paxUid: true, paxGid: true,
paxUname: true, paxGname: true, paxMtime: true, paxAtime: true, paxCtime: true,
}
// A Header represents a single header in a tar archive.
// Some fields may not be populated.
//
// For forward compatibility, users that retrieve a Header from Reader.Next,
// mutate it in some ways, and then pass it back to Writer.WriteHeader
// should do so by creating a new Header and copying the fields
// that they are interested in preserving.
type Header struct {
// Typeflag is the type of header entry.
// The zero value is automatically promoted to either TypeReg or TypeDir
// depending on the presence of a trailing slash in Name.
Typeflag byte
Name string // Name of file entry
Linkname string // Target name of link (valid for TypeLink or TypeSymlink)
Size int64 // Logical file size in bytes
Mode int64 // Permission and mode bits
Uid int // User ID of owner
Gid int // Group ID of owner
Uname string // User name of owner
Gname string // Group name of owner
// If the Format is unspecified, then Writer.WriteHeader rounds ModTime
// to the nearest second and ignores the AccessTime and ChangeTime fields.
//
// To use AccessTime or ChangeTime, specify the Format as PAX or GNU.
// To use sub-second resolution, specify the Format as PAX.
ModTime time.Time // Modification time
AccessTime time.Time // Access time (requires either PAX or GNU support)
ChangeTime time.Time // Change time (requires either PAX or GNU support)
Devmajor int64 // Major device number (valid for TypeChar or TypeBlock)
Devminor int64 // Minor device number (valid for TypeChar or TypeBlock)
// Xattrs stores extended attributes as PAX records under the
// "SCHILY.xattr." namespace.
//
// The following are semantically equivalent:
// h.Xattrs[key] = value
// h.PAXRecords["SCHILY.xattr."+key] = value
//
// When Writer.WriteHeader is called, the contents of Xattrs will take
// precedence over those in PAXRecords.
//
// Deprecated: Use PAXRecords instead.
Xattrs map[string]string
// PAXRecords is a map of PAX extended header records.
//
// User-defined records should have keys of the following form:
// VENDOR.keyword
// Where VENDOR is some namespace in all uppercase, and keyword may
// not contain the '=' character (e.g., "GOLANG.pkg.version").
// The key and value should be non-empty UTF-8 strings.
//
// When Writer.WriteHeader is called, PAX records derived from the
// other fields in Header take precedence over PAXRecords.
PAXRecords map[string]string
// Format specifies the format of the tar header.
//
// This is set by Reader.Next as a best-effort guess at the format.
// Since the Reader liberally reads some non-compliant files,
// it is possible for this to be FormatUnknown.
//
// If the format is unspecified when Writer.WriteHeader is called,
// then it uses the first format (in the order of USTAR, PAX, GNU)
// capable of encoding this Header (see Format).
Format Format
}
// sparseEntry represents a Length-sized fragment at Offset in the file.
type sparseEntry struct{ Offset, Length int64 }
func (s sparseEntry) endOffset() int64 { return s.Offset + s.Length }
// A sparse file can be represented as either a sparseDatas or a sparseHoles.
// As long as the total size is known, they are equivalent and one can be
// converted to the other form and back. The various tar formats with sparse
// file support represent sparse files in the sparseDatas form. That is, they
// specify the fragments in the file that has data, and treat everything else as
// having zero bytes. As such, the encoding and decoding logic in this package
// deals with sparseDatas.
//
// However, the external API uses sparseHoles instead of sparseDatas because the
// zero value of sparseHoles logically represents a normal file (i.e., there are
// no holes in it). On the other hand, the zero value of sparseDatas implies
// that the file has no data in it, which is rather odd.
//
// As an example, if the underlying raw file contains the 10-byte data:
//
// var compactFile = "abcdefgh"
//
// And the sparse map has the following entries:
//
// var spd sparseDatas = []sparseEntry{
// {Offset: 2, Length: 5}, // Data fragment for 2..6
// {Offset: 18, Length: 3}, // Data fragment for 18..20
// }
// var sph sparseHoles = []sparseEntry{
// {Offset: 0, Length: 2}, // Hole fragment for 0..1
// {Offset: 7, Length: 11}, // Hole fragment for 7..17
// {Offset: 21, Length: 4}, // Hole fragment for 21..24
// }
//
// Then the content of the resulting sparse file with a Header.Size of 25 is:
//
// var sparseFile = "\x00"*2 + "abcde" + "\x00"*11 + "fgh" + "\x00"*4
type (
sparseDatas []sparseEntry
sparseHoles []sparseEntry
)
// validateSparseEntries reports whether sp is a valid sparse map.
// It does not matter whether sp represents data fragments or hole fragments.
func validateSparseEntries(sp []sparseEntry, size int64) bool {
// Validate all sparse entries. These are the same checks as performed by
// the BSD tar utility.
if size < 0 {
return false
}
var pre sparseEntry
for _, cur := range sp {
switch {
case cur.Offset < 0 || cur.Length < 0:
return false // Negative values are never okay
case cur.Offset > math.MaxInt64-cur.Length:
return false // Integer overflow with large length
case cur.endOffset() > size:
return false // Region extends beyond the actual size
case pre.endOffset() > cur.Offset:
return false // Regions cannot overlap and must be in order
}
pre = cur
}
return true
}
// alignSparseEntries mutates src and returns dst where each fragment's
// starting offset is aligned up to the nearest block edge, and each
// ending offset is aligned down to the nearest block edge.
//
// Even though the Go tar Reader and the BSD tar utility can handle entries
// with arbitrary offsets and lengths, the GNU tar utility can only handle
// offsets and lengths that are multiples of blockSize.
func alignSparseEntries(src []sparseEntry, size int64) []sparseEntry {
dst := src[:0]
for _, s := range src {
pos, end := s.Offset, s.endOffset()
pos += blockPadding(+pos) // Round-up to nearest blockSize
if end != size {
end -= blockPadding(-end) // Round-down to nearest blockSize
}
if pos < end {
dst = append(dst, sparseEntry{Offset: pos, Length: end - pos})
}
}
return dst
}
// invertSparseEntries converts a sparse map from one form to the other.
// If the input is sparseHoles, then it will output sparseDatas and vice-versa.
// The input must have been already validated.
//
// This function mutates src and returns a normalized map where:
// - adjacent fragments are coalesced together
// - only the last fragment may be empty
// - the endOffset of the last fragment is the total size
func invertSparseEntries(src []sparseEntry, size int64) []sparseEntry {
dst := src[:0]
var pre sparseEntry
for _, cur := range src {
if cur.Length == 0 {
continue // Skip empty fragments
}
pre.Length = cur.Offset - pre.Offset
if pre.Length > 0 {
dst = append(dst, pre) // Only add non-empty fragments
}
pre.Offset = cur.endOffset()
}
pre.Length = size - pre.Offset // Possibly the only empty fragment
return append(dst, pre)
}
// fileState tracks the number of logical (includes sparse holes) and physical
// (actual in tar archive) bytes remaining for the current file.
//
// Invariant: logicalRemaining >= physicalRemaining
type fileState interface {
logicalRemaining() int64
physicalRemaining() int64
}
// allowedFormats determines which formats can be used.
// The value returned is the logical OR of multiple possible formats.
// If the value is FormatUnknown, then the input Header cannot be encoded
// and an error is returned explaining why.
//
// As a by-product of checking the fields, this function returns paxHdrs, which
// contain all fields that could not be directly encoded.
// A value receiver ensures that this method does not mutate the source Header.
func (h Header) allowedFormats() (format Format, paxHdrs map[string]string, err error) {
format = FormatUSTAR | FormatPAX | FormatGNU
paxHdrs = make(map[string]string)
var whyNoUSTAR, whyNoPAX, whyNoGNU string
var preferPAX bool // Prefer PAX over USTAR
verifyString := func(s string, size int, name, paxKey string) {
// NUL-terminator is optional for path and linkpath.
// Technically, it is required for uname and gname,
// but neither GNU nor BSD tar checks for it.
tooLong := len(s) > size
allowLongGNU := paxKey == paxPath || paxKey == paxLinkpath
if hasNUL(s) || (tooLong && !allowLongGNU) {
whyNoGNU = fmt.Sprintf("GNU cannot encode %s=%q", name, s)
format.mustNotBe(FormatGNU)
}
if !isASCII(s) || tooLong {
canSplitUSTAR := paxKey == paxPath
if _, _, ok := splitUSTARPath(s); !canSplitUSTAR || !ok {
whyNoUSTAR = fmt.Sprintf("USTAR cannot encode %s=%q", name, s)
format.mustNotBe(FormatUSTAR)
}
if paxKey == paxNone {
whyNoPAX = fmt.Sprintf("PAX cannot encode %s=%q", name, s)
format.mustNotBe(FormatPAX)
} else {
paxHdrs[paxKey] = s
}
}
if v, ok := h.PAXRecords[paxKey]; ok && v == s {
paxHdrs[paxKey] = v
}
}
verifyNumeric := func(n int64, size int, name, paxKey string) {
if !fitsInBase256(size, n) {
whyNoGNU = fmt.Sprintf("GNU cannot encode %s=%d", name, n)
format.mustNotBe(FormatGNU)
}
if !fitsInOctal(size, n) {
whyNoUSTAR = fmt.Sprintf("USTAR cannot encode %s=%d", name, n)
format.mustNotBe(FormatUSTAR)
if paxKey == paxNone {
whyNoPAX = fmt.Sprintf("PAX cannot encode %s=%d", name, n)
format.mustNotBe(FormatPAX)
} else {
paxHdrs[paxKey] = strconv.FormatInt(n, 10)
}
}
if v, ok := h.PAXRecords[paxKey]; ok && v == strconv.FormatInt(n, 10) {
paxHdrs[paxKey] = v
}
}
verifyTime := func(ts time.Time, size int, name, paxKey string) {
if ts.IsZero() {
return // Always okay
}
if !fitsInBase256(size, ts.Unix()) {
whyNoGNU = fmt.Sprintf("GNU cannot encode %s=%v", name, ts)
format.mustNotBe(FormatGNU)
}
isMtime := paxKey == paxMtime
fitsOctal := fitsInOctal(size, ts.Unix())
if (isMtime && !fitsOctal) || !isMtime {
whyNoUSTAR = fmt.Sprintf("USTAR cannot encode %s=%v", name, ts)
format.mustNotBe(FormatUSTAR)
}
needsNano := ts.Nanosecond() != 0
if !isMtime || !fitsOctal || needsNano {
preferPAX = true // USTAR may truncate sub-second measurements
if paxKey == paxNone {
whyNoPAX = fmt.Sprintf("PAX cannot encode %s=%v", name, ts)
format.mustNotBe(FormatPAX)
} else {
paxHdrs[paxKey] = formatPAXTime(ts)
}
}
if v, ok := h.PAXRecords[paxKey]; ok && v == formatPAXTime(ts) {
paxHdrs[paxKey] = v
}
}
// Check basic fields.
var blk block
v7 := blk.toV7()
ustar := blk.toUSTAR()
gnu := blk.toGNU()
verifyString(h.Name, len(v7.name()), "Name", paxPath)
verifyString(h.Linkname, len(v7.linkName()), "Linkname", paxLinkpath)
verifyString(h.Uname, len(ustar.userName()), "Uname", paxUname)
verifyString(h.Gname, len(ustar.groupName()), "Gname", paxGname)
verifyNumeric(h.Mode, len(v7.mode()), "Mode", paxNone)
verifyNumeric(int64(h.Uid), len(v7.uid()), "Uid", paxUid)
verifyNumeric(int64(h.Gid), len(v7.gid()), "Gid", paxGid)
verifyNumeric(h.Size, len(v7.size()), "Size", paxSize)
verifyNumeric(h.Devmajor, len(ustar.devMajor()), "Devmajor", paxNone)
verifyNumeric(h.Devminor, len(ustar.devMinor()), "Devminor", paxNone)
verifyTime(h.ModTime, len(v7.modTime()), "ModTime", paxMtime)
verifyTime(h.AccessTime, len(gnu.accessTime()), "AccessTime", paxAtime)
verifyTime(h.ChangeTime, len(gnu.changeTime()), "ChangeTime", paxCtime)
// Check for header-only types.
var whyOnlyPAX, whyOnlyGNU string
switch h.Typeflag {
case TypeReg, TypeChar, TypeBlock, TypeFifo, TypeGNUSparse:
// Exclude TypeLink and TypeSymlink, since they may reference directories.
if strings.HasSuffix(h.Name, "/") {
return FormatUnknown, nil, headerError{"filename may not have trailing slash"}
}
case TypeXHeader, TypeGNULongName, TypeGNULongLink:
return FormatUnknown, nil, headerError{"cannot manually encode TypeXHeader, TypeGNULongName, or TypeGNULongLink headers"}
case TypeXGlobalHeader:
h2 := Header{Name: h.Name, Typeflag: h.Typeflag, Xattrs: h.Xattrs, PAXRecords: h.PAXRecords, Format: h.Format}
if !reflect.DeepEqual(h, h2) {
return FormatUnknown, nil, headerError{"only PAXRecords should be set for TypeXGlobalHeader"}
}
whyOnlyPAX = "only PAX supports TypeXGlobalHeader"
format.mayOnlyBe(FormatPAX)
}
if !isHeaderOnlyType(h.Typeflag) && h.Size < 0 {
return FormatUnknown, nil, headerError{"negative size on header-only type"}
}
// Check PAX records.
if len(h.Xattrs) > 0 {
for k, v := range h.Xattrs {
paxHdrs[paxSchilyXattr+k] = v
}
whyOnlyPAX = "only PAX supports Xattrs"
format.mayOnlyBe(FormatPAX)
}
if len(h.PAXRecords) > 0 {
for k, v := range h.PAXRecords {
switch _, exists := paxHdrs[k]; {
case exists:
continue // Do not overwrite existing records
case h.Typeflag == TypeXGlobalHeader:
paxHdrs[k] = v // Copy all records
case !basicKeys[k] && !strings.HasPrefix(k, paxGNUSparse):
paxHdrs[k] = v // Ignore local records that may conflict
}
}
whyOnlyPAX = "only PAX supports PAXRecords"
format.mayOnlyBe(FormatPAX)
}
for k, v := range paxHdrs {
if !validPAXRecord(k, v) {
return FormatUnknown, nil, headerError{fmt.Sprintf("invalid PAX record: %q", k+" = "+v)}
}
}
// TODO(dsnet): Re-enable this when adding sparse support.
// See https://golang.org/issue/22735
/*
// Check sparse files.
if len(h.SparseHoles) > 0 || h.Typeflag == TypeGNUSparse {
if isHeaderOnlyType(h.Typeflag) {
return FormatUnknown, nil, headerError{"header-only type cannot be sparse"}
}
if !validateSparseEntries(h.SparseHoles, h.Size) {
return FormatUnknown, nil, headerError{"invalid sparse holes"}
}
if h.Typeflag == TypeGNUSparse {
whyOnlyGNU = "only GNU supports TypeGNUSparse"
format.mayOnlyBe(FormatGNU)
} else {
whyNoGNU = "GNU supports sparse files only with TypeGNUSparse"
format.mustNotBe(FormatGNU)
}
whyNoUSTAR = "USTAR does not support sparse files"
format.mustNotBe(FormatUSTAR)
}
*/
// Check desired format.
if wantFormat := h.Format; wantFormat != FormatUnknown {
if wantFormat.has(FormatPAX) && !preferPAX {
wantFormat.mayBe(FormatUSTAR) // PAX implies USTAR allowed too
}
format.mayOnlyBe(wantFormat) // Set union of formats allowed and format wanted
}
if format == FormatUnknown {
switch h.Format {
case FormatUSTAR:
err = headerError{"Format specifies USTAR", whyNoUSTAR, whyOnlyPAX, whyOnlyGNU}
case FormatPAX:
err = headerError{"Format specifies PAX", whyNoPAX, whyOnlyGNU}
case FormatGNU:
err = headerError{"Format specifies GNU", whyNoGNU, whyOnlyPAX}
default:
err = headerError{whyNoUSTAR, whyNoPAX, whyNoGNU, whyOnlyPAX, whyOnlyGNU}
}
}
return format, paxHdrs, err
}
// FileInfo returns an fs.FileInfo for the Header.
func (h *Header) FileInfo() fs.FileInfo {
return headerFileInfo{h}
}
// headerFileInfo implements fs.FileInfo.
type headerFileInfo struct {
h *Header
}
func (fi headerFileInfo) Size() int64 { return fi.h.Size }
func (fi headerFileInfo) IsDir() bool { return fi.Mode().IsDir() }
func (fi headerFileInfo) ModTime() time.Time { return fi.h.ModTime }
func (fi headerFileInfo) Sys() any { return fi.h }
// Name returns the base name of the file.
func (fi headerFileInfo) Name() string {
if fi.IsDir() {
return path.Base(path.Clean(fi.h.Name))
}
return path.Base(fi.h.Name)
}
// Mode returns the permission and mode bits for the headerFileInfo.
func (fi headerFileInfo) Mode() (mode fs.FileMode) {
// Set file permission bits.
mode = fs.FileMode(fi.h.Mode).Perm()
// Set setuid, setgid and sticky bits.
if fi.h.Mode&c_ISUID != 0 {
mode |= fs.ModeSetuid
}
if fi.h.Mode&c_ISGID != 0 {
mode |= fs.ModeSetgid
}
if fi.h.Mode&c_ISVTX != 0 {
mode |= fs.ModeSticky
}
// Set file mode bits; clear perm, setuid, setgid, and sticky bits.
switch m := fs.FileMode(fi.h.Mode) &^ 07777; m {
case c_ISDIR:
mode |= fs.ModeDir
case c_ISFIFO:
mode |= fs.ModeNamedPipe
case c_ISLNK:
mode |= fs.ModeSymlink
case c_ISBLK:
mode |= fs.ModeDevice
case c_ISCHR:
mode |= fs.ModeDevice
mode |= fs.ModeCharDevice
case c_ISSOCK:
mode |= fs.ModeSocket
}
switch fi.h.Typeflag {
case TypeSymlink:
mode |= fs.ModeSymlink
case TypeChar:
mode |= fs.ModeDevice
mode |= fs.ModeCharDevice
case TypeBlock:
mode |= fs.ModeDevice
case TypeDir:
mode |= fs.ModeDir
case TypeFifo:
mode |= fs.ModeNamedPipe
}
return mode
}
// sysStat, if non-nil, populates h from system-dependent fields of fi.
var sysStat func(fi fs.FileInfo, h *Header) error
const (
// Mode constants from the USTAR spec:
// See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
c_ISUID = 04000 // Set uid
c_ISGID = 02000 // Set gid
c_ISVTX = 01000 // Save text (sticky bit)
// Common Unix mode constants; these are not defined in any common tar standard.
// Header.FileInfo understands these, but FileInfoHeader will never produce these.
c_ISDIR = 040000 // Directory
c_ISFIFO = 010000 // FIFO
c_ISREG = 0100000 // Regular file
c_ISLNK = 0120000 // Symbolic link
c_ISBLK = 060000 // Block special file
c_ISCHR = 020000 // Character special file
c_ISSOCK = 0140000 // Socket
)
// FileInfoHeader creates a partially-populated Header from fi.
// If fi describes a symlink, FileInfoHeader records link as the link target.
// If fi describes a directory, a slash is appended to the name.
//
// Since fs.FileInfo's Name method only returns the base name of
// the file it describes, it may be necessary to modify Header.Name
// to provide the full path name of the file.
func FileInfoHeader(fi fs.FileInfo, link string) (*Header, error) {
if fi == nil {
return nil, errors.New("archive/tar: FileInfo is nil")
}
fm := fi.Mode()
h := &Header{
Name: fi.Name(),
ModTime: fi.ModTime(),
Mode: int64(fm.Perm()), // or'd with c_IS* constants later
}
switch {
case fm.IsRegular():
h.Typeflag = TypeReg
h.Size = fi.Size()
case fi.IsDir():
h.Typeflag = TypeDir
h.Name += "/"
case fm&fs.ModeSymlink != 0:
h.Typeflag = TypeSymlink
h.Linkname = link
case fm&fs.ModeDevice != 0:
if fm&fs.ModeCharDevice != 0 {
h.Typeflag = TypeChar
} else {
h.Typeflag = TypeBlock
}
case fm&fs.ModeNamedPipe != 0:
h.Typeflag = TypeFifo
case fm&fs.ModeSocket != 0:
return nil, fmt.Errorf("archive/tar: sockets not supported")
default:
return nil, fmt.Errorf("archive/tar: unknown file mode %v", fm)
}
if fm&fs.ModeSetuid != 0 {
h.Mode |= c_ISUID
}
if fm&fs.ModeSetgid != 0 {
h.Mode |= c_ISGID
}
if fm&fs.ModeSticky != 0 {
h.Mode |= c_ISVTX
}
// If possible, populate additional fields from OS-specific
// FileInfo fields.
if sys, ok := fi.Sys().(*Header); ok {
// This FileInfo came from a Header (not the OS). Use the
// original Header to populate all remaining fields.
h.Uid = sys.Uid
h.Gid = sys.Gid
h.Uname = sys.Uname
h.Gname = sys.Gname
h.AccessTime = sys.AccessTime
h.ChangeTime = sys.ChangeTime
if sys.Xattrs != nil {
h.Xattrs = make(map[string]string)
for k, v := range sys.Xattrs {
h.Xattrs[k] = v
}
}
if sys.Typeflag == TypeLink {
// hard link
h.Typeflag = TypeLink
h.Size = 0
h.Linkname = sys.Linkname
}
if sys.PAXRecords != nil {
h.PAXRecords = make(map[string]string)
for k, v := range sys.PAXRecords {
h.PAXRecords[k] = v
}
}
}
if sysStat != nil {
return h, sysStat(fi, h)
}
return h, nil
}
// isHeaderOnlyType checks if the given type flag is of the type that has no
// data section even if a size is specified.
func isHeaderOnlyType(flag byte) bool {
switch flag {
case TypeLink, TypeSymlink, TypeChar, TypeBlock, TypeDir, TypeFifo:
return true
default:
return false
}
}
func min(a, b int64) int64 {
if a < b {
return a
}
return b
}
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