Vendor in containers/buildah 1.16.1

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

vendor/github.com/containers/buildah/copier/xattrs.go

@@ -0,0 +1,92 @@
+// +build linux netbsd freebsd darwin
+
+package copier
+
+import (
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	xattrsSupported = true
+)
+
+var (
+	relevantAttributes = []string{"security.capability", "security.ima", "user.*"} // the attributes that we preserve - we discard others
+)
+
+// isRelevantXattr checks if "attribute" matches one of the attribute patterns
+// listed in the "relevantAttributes" list.
+func isRelevantXattr(attribute string) bool {
+	for _, relevant := range relevantAttributes {
+		matched, err := filepath.Match(relevant, attribute)
+		if err != nil || !matched {
+			continue
+		}
+		return true
+	}
+	return false
+}
+
+// Lgetxattrs returns a map of the relevant extended attributes set on the given file.
+func Lgetxattrs(path string) (map[string]string, error) {
+	maxSize := 64 * 1024 * 1024
+	listSize := 64 * 1024
+	var list []byte
+	for listSize < maxSize {
+		list = make([]byte, listSize)
+		size, err := unix.Llistxattr(path, list)
+		if err != nil {
+			if unwrapError(err) == syscall.ERANGE {
+				listSize *= 2
+				continue
+			}
+			return nil, errors.Wrapf(err, "error listing extended attributes of %q", path)
+		}
+		list = list[:size]
+		break
+	}
+	if listSize >= maxSize {
+		return nil, errors.Errorf("unable to read list of attributes for %q: size would have been too big", path)
+	}
+	m := make(map[string]string)
+	for _, attribute := range strings.Split(string(list), string('\000')) {
+		if isRelevantXattr(attribute) {
+			attributeSize := 64 * 1024
+			var attributeValue []byte
+			for attributeSize < maxSize {
+				attributeValue = make([]byte, attributeSize)
+				size, err := unix.Lgetxattr(path, attribute, attributeValue)
+				if err != nil {
+					if unwrapError(err) == syscall.ERANGE {
+						attributeSize *= 2
+						continue
+					}
+					return nil, errors.Wrapf(err, "error getting value of extended attribute %q on %q", attribute, path)
+				}
+				m[attribute] = string(attributeValue[:size])
+				break
+			}
+			if attributeSize >= maxSize {
+				return nil, errors.Errorf("unable to read attribute %q of %q: size would have been too big", attribute, path)
+			}
+		}
+	}
+	return m, nil
+}
+
+// Lsetxattrs sets the relevant members of the specified extended attributes on the given file.
+func Lsetxattrs(path string, xattrs map[string]string) error {
+	for attribute, value := range xattrs {
+		if isRelevantXattr(attribute) {
+			if err := unix.Lsetxattr(path, attribute, []byte(value), 0); err != nil {
+				return errors.Wrapf(err, "error setting value of extended attribute %q on %q", attribute, path)
+			}
+		}
+	}
+	return nil
+}