1d27259777
This mainly fixes Linux vs generic Unix differences, with some differences between Darwin and Freebsd (which are close bit not identical). Should make fixing for other Unix platforms easier. Note there are not yet `runc` equivalents for these platforms; my current use case is image manipulation for the `moby` tool. However there is interest in OCI runtime ports for both platforms. Current status is that MacOS can build and run `ctr`, `dist` and `containerd` and some operations are supported. FreeBSD 11 still needs some more fixes to continuity for extended attributes. Signed-off-by: Justin Cormack <justin.cormack@docker.com>
103 lines
3.0 KiB
Go
103 lines
3.0 KiB
Go
// +build !windows
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package fs
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import (
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"bytes"
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"os"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/containerd/continuity/sysx"
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"github.com/pkg/errors"
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)
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// whiteouts are files with a special meaning for the layered filesystem.
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// Docker uses AUFS whiteout files inside exported archives. In other
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// filesystems these files are generated/handled on tar creation/extraction.
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// whiteoutPrefix prefix means file is a whiteout. If this is followed by a
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// filename this means that file has been removed from the base layer.
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const whiteoutPrefix = ".wh."
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// whiteoutMetaPrefix prefix means whiteout has a special meaning and is not
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// for removing an actual file. Normally these files are excluded from exported
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// archives.
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const whiteoutMetaPrefix = whiteoutPrefix + whiteoutPrefix
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// whiteoutLinkDir is a directory AUFS uses for storing hardlink links to other
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// layers. Normally these should not go into exported archives and all changed
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// hardlinks should be copied to the top layer.
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const whiteoutLinkDir = whiteoutMetaPrefix + "plnk"
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// whiteoutOpaqueDir file means directory has been made opaque - meaning
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// readdir calls to this directory do not follow to lower layers.
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const whiteoutOpaqueDir = whiteoutMetaPrefix + ".opq"
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// detectDirDiff returns diff dir options if a directory could
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// be found in the mount info for upper which is the direct
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// diff with the provided lower directory
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func detectDirDiff(upper, lower string) *diffDirOptions {
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// TODO: get mount options for upper
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// TODO: detect AUFS
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// TODO: detect overlay
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return nil
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}
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func aufsMetadataSkip(path string) (skip bool, err error) {
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skip, err = filepath.Match(string(os.PathSeparator)+whiteoutMetaPrefix+"*", path)
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if err != nil {
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skip = true
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}
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return
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}
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func aufsDeletedFile(root, path string, fi os.FileInfo) (string, error) {
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f := filepath.Base(path)
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// If there is a whiteout, then the file was removed
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if strings.HasPrefix(f, whiteoutPrefix) {
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originalFile := f[len(whiteoutPrefix):]
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return filepath.Join(filepath.Dir(path), originalFile), nil
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}
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return "", nil
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}
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// compareSysStat returns whether the stats are equivalent,
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// whether the files are considered the same file, and
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// an error
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func compareSysStat(s1, s2 interface{}) (bool, error) {
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ls1, ok := s1.(*syscall.Stat_t)
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if !ok {
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return false, nil
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}
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ls2, ok := s2.(*syscall.Stat_t)
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if !ok {
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return false, nil
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}
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return ls1.Mode == ls2.Mode && ls1.Uid == ls2.Uid && ls1.Gid == ls2.Gid && ls1.Rdev == ls2.Rdev, nil
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}
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func compareCapabilities(p1, p2 string) (bool, error) {
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c1, err := sysx.LGetxattr(p1, "security.capability")
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if err != nil && err != syscall.ENODATA {
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return false, errors.Wrapf(err, "failed to get xattr for %s", p1)
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}
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c2, err := sysx.LGetxattr(p2, "security.capability")
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if err != nil && err != syscall.ENODATA {
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return false, errors.Wrapf(err, "failed to get xattr for %s", p2)
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}
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return bytes.Equal(c1, c2), nil
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}
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func isLinked(f os.FileInfo) bool {
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s, ok := f.Sys().(*syscall.Stat_t)
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if !ok {
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return false
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}
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return !f.IsDir() && s.Nlink > 1
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}
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