From 468eca4684d9b51d00e18cb129bebf528a844035 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Sat, 11 Jun 2022 13:52:02 -0600
Subject: Improve formatting of CSums and UUIDs

---
 pkg/btrfs/internal/uuid.go | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

(limited to 'pkg/btrfs/internal/uuid.go')

diff --git a/pkg/btrfs/internal/uuid.go b/pkg/btrfs/internal/uuid.go
index 6169638..cb2c800 100644
--- a/pkg/btrfs/internal/uuid.go
+++ b/pkg/btrfs/internal/uuid.go
@@ -2,7 +2,10 @@ package internal
 
 import (
 	"encoding/hex"
+	"fmt"
 	"strings"
+
+	"lukeshu.com/btrfs-tools/pkg/util"
 )
 
 type UUID [16]byte
@@ -17,3 +20,46 @@ func (uuid UUID) String() string {
 		str[20:32],
 	}, "-")
 }
+
+func (uuid UUID) Format(f fmt.State, verb rune) {
+	util.FormatByteArrayStringer(uuid, uuid[:], f, verb)
+}
+
+func ParseUUID(str string) (UUID, error) {
+	var ret UUID
+	j := 0
+	for i := 0; i < len(str); i++ {
+		if j >= len(ret)*2 {
+			return UUID{}, fmt.Errorf("too long to be a UUID: %q|%q", str[:i], str[i:])
+		}
+		c := str[i]
+		var v byte
+		switch {
+		case '0' <= c && c <= '9':
+			v = c - '0'
+		case 'a' <= c && c <= 'f':
+			v = c - 'a' + 10
+		case 'A' <= c && c <= 'F':
+			v = c - 'A' + 10
+		case c == '-':
+			continue
+		default:
+			return UUID{}, fmt.Errorf("illegal byte in UUID: %q|%q|%q", str[:i], str[i:i+1], str[i+1:])
+		}
+		if j%2 == 0 {
+			ret[j/2] = v << 4
+		} else {
+			ret[j/2] = (ret[j/2] & 0xf0) | (v & 0x0f)
+		}
+		j++
+	}
+	return ret, nil
+}
+
+func MustParseUUID(str string) UUID {
+	ret, err := ParseUUID(str)
+	if err != nil {
+		panic(err)
+	}
+	return ret
+}
-- 
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