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pkg/tarsum: migrate to (tar.Header).PAXRecords

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Fix a silly bug in the implementation which had the effect of
len(h.Xattrs) blank entries being inserted in the middle of
orderedHeaders. Luckily this is not a load-bearing bug: empty headers
are ignored as the tarsum digest is computed by concatenating header
keys and values without any intervening delimiter.

Signed-off-by: Cory Snider <csnider@mirantis.com>
This commit is contained in:
Cory Snider 2023-10-23 14:29:27 -04:00
parent 3cf409aa9e
commit c44c9dfa79
1 changed files with 9 additions and 8 deletions
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17
pkg/tarsum/versioning.go
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@ -115,15 +115,18 @@ func v0TarHeaderSelect(h *tar.Header) (orderedHeaders [][2]string) {
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)
const paxSchilyXattr = "SCHILY.xattr."
var xattrs [][2]string
for k, v := range h.PAXRecords {
if xattr, ok := strings.CutPrefix(k, paxSchilyXattr); ok {
xattrs = append(xattrs, [2]string{xattr, v})
}
sort.Strings(xAttrKeys)
}
sort.Slice(xattrs, func(i, j int) bool { return xattrs[i][0] < xattrs[j][0] })
// 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))
orderedHeaders = make([][2]string, 0, 11+len(xattrs))
// Copy all headers from v0 excluding the 'mtime' header (the 5th element).
v0headers := v0TarHeaderSelect(h)
@ -131,9 +134,7 @@ func v1TarHeaderSelect(h *tar.Header) (orderedHeaders [][2]string) {
orderedHeaders = append(orderedHeaders, v0headers[6:]...)
// Finally, append the sorted xattrs.
for _, k := range xAttrKeys {
orderedHeaders = append(orderedHeaders, [2]string{k, h.Xattrs[k]})
}
orderedHeaders = append(orderedHeaders, xattrs...)
return
}