1
0
Fork 0
mirror of https://github.com/moby/moby.git synced 2022-11-09 12:21:53 -05:00
moby--moby/vendor/github.com/moby/buildkit/cache/contenthash/tarsum.go
Tonis Tiigi 6fcb36ff14 vendor: add buildkit dependency
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
2018-06-10 10:05:19 -07:00

60 lines
1.7 KiB
Go

package contenthash
import (
"archive/tar"
"io"
"sort"
"strconv"
)
// WriteV1TarsumHeaders writes a tar header to a writer in V1 tarsum format.
func WriteV1TarsumHeaders(h *tar.Header, w io.Writer) {
for _, elem := range v1TarHeaderSelect(h) {
w.Write([]byte(elem[0] + elem[1]))
}
}
// Functions below are from docker legacy tarsum implementation.
// There is no valid technical reason to continue using them.
func v0TarHeaderSelect(h *tar.Header) (orderedHeaders [][2]string) {
return [][2]string{
{"name", h.Name},
{"mode", strconv.FormatInt(h.Mode, 10)},
{"uid", strconv.Itoa(h.Uid)},
{"gid", strconv.Itoa(h.Gid)},
{"size", strconv.FormatInt(h.Size, 10)},
{"mtime", strconv.FormatInt(h.ModTime.UTC().Unix(), 10)},
{"typeflag", string([]byte{h.Typeflag})},
{"linkname", h.Linkname},
{"uname", h.Uname},
{"gname", h.Gname},
{"devmajor", strconv.FormatInt(h.Devmajor, 10)},
{"devminor", strconv.FormatInt(h.Devminor, 10)},
}
}
func v1TarHeaderSelect(h *tar.Header) (orderedHeaders [][2]string) {
// Get extended attributes.
xAttrKeys := make([]string, len(h.Xattrs))
for k := range h.Xattrs {
xAttrKeys = append(xAttrKeys, k)
}
sort.Strings(xAttrKeys)
// Make the slice with enough capacity to hold the 11 basic headers
// we want from the v0 selector plus however many xattrs we have.
orderedHeaders = make([][2]string, 0, 11+len(xAttrKeys))
// Copy all headers from v0 excluding the 'mtime' header (the 5th element).
v0headers := v0TarHeaderSelect(h)
orderedHeaders = append(orderedHeaders, v0headers[0:5]...)
orderedHeaders = append(orderedHeaders, v0headers[6:]...)
// Finally, append the sorted xattrs.
for _, k := range xAttrKeys {
orderedHeaders = append(orderedHeaders, [2]string{k, h.Xattrs[k]})
}
return
}