Vendor continuity

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

vendor/github.com/stevvooe/continuity/sysx/xattr.go

@@ -0,0 +1,64 @@
+package sysx
+
+import (
+	"bytes"
+	"syscall"
+)
+
+const defaultXattrBufferSize = 5
+
+type listxattrFunc func(path string, dest []byte) (int, error)
+
+func listxattrAll(path string, listFunc listxattrFunc) ([]string, error) {
+	var p []byte // nil on first execution
+
+	for {
+		n, err := listFunc(path, p) // first call gets buffer size.
+		if err != nil {
+			return nil, err
+		}
+
+		if n > len(p) {
+			p = make([]byte, n)
+			continue
+		}
+
+		p = p[:n]
+
+		ps := bytes.Split(bytes.TrimSuffix(p, []byte{0}), []byte{0})
+		var entries []string
+		for _, p := range ps {
+			s := string(p)
+			if s != "" {
+				entries = append(entries, s)
+			}
+		}
+
+		return entries, nil
+	}
+}
+
+type getxattrFunc func(string, string, []byte) (int, error)
+
+func getxattrAll(path, attr string, getFunc getxattrFunc) ([]byte, error) {
+	p := make([]byte, defaultXattrBufferSize)
+	for {
+		n, err := getFunc(path, attr, p)
+		if err != nil {
+			if errno, ok := err.(syscall.Errno); ok && errno == syscall.ERANGE {
+				p = make([]byte, len(p)*2) // this can't be ideal.
+				continue                   // try again!
+			}
+
+			return nil, err
+		}
+
+		// realloc to correct size and repeat
+		if n > len(p) {
+			p = make([]byte, n)
+			continue
+		}
+
+		return p[:n], nil
+	}
+}