From 325178506187df037f9a85eb2e09100eb794f4f9 Mon Sep 17 00:00:00 2001 From: Luke Shumaker Date: Sat, 22 Jul 2023 23:27:02 -0600 Subject: Pull the json-hex-encoding from shortsum to jsonutil --- lib/btrfs/btrfssum/shortsum.go | 67 +++--------------------------------------- lib/jsonutil/hex_decoder.go | 61 ++++++++++++++++++++++++++++++++++++++ lib/jsonutil/hex_string.go | 42 ++++++++++++++++++++++++++ 3 files changed, 107 insertions(+), 63 deletions(-) create mode 100644 lib/jsonutil/hex_decoder.go create mode 100644 lib/jsonutil/hex_string.go diff --git a/lib/btrfs/btrfssum/shortsum.go b/lib/btrfs/btrfssum/shortsum.go index 754a79d..490c40a 100644 --- a/lib/btrfs/btrfssum/shortsum.go +++ b/lib/btrfs/btrfssum/shortsum.go @@ -5,12 +5,12 @@ package btrfssum import ( - "fmt" "io" - "math" "strings" "git.lukeshu.com/go/lowmemjson" + + "git.lukeshu.com/btrfs-progs-ng/lib/jsonutil" ) type ShortSum string @@ -27,72 +27,13 @@ func (sum ShortSum) ToFullSum() CSum { } func (sum ShortSum) EncodeJSON(w io.Writer) error { - const hextable = "0123456789abcdef" - var buf [2]byte - buf[0] = '"' - if _, err := w.Write(buf[:1]); err != nil { - return err - } - for i := 0; i < len(sum); i++ { - buf[0] = hextable[sum[i]>>4] - buf[1] = hextable[sum[i]&0x0f] - if _, err := w.Write(buf[:]); err != nil { - return err - } - } - buf[0] = '"' - if _, err := w.Write(buf[:1]); err != nil { - return err - } - return nil -} - -func deHex(r rune) (byte, bool) { - if r > math.MaxUint8 { - return 0, false - } - c := byte(r) - //nolint:gomnd // Hex conversion. - switch { - case '0' <= c && c <= '9': - return c - '0', true - case 'a' <= c && c <= 'f': - return c - 'a' + 10, true - case 'A' <= c && c <= 'F': - return c - 'A' + 10, true - default: - return 0, false - } + return jsonutil.EncodeHexString(w, sum) } func (sum *ShortSum) DecodeJSON(r io.RuneScanner) error { var out strings.Builder - if c, _, err := r.ReadRune(); err != nil { + if err := jsonutil.DecodeHexString(r, &out); err != nil { return err - } else if c != '"' { - return fmt.Errorf("expected %q, got %q", '"', c) - } - for { - a, _, err := r.ReadRune() - if err != nil { - return err - } - if a == '"' { - break - } - aN, ok := deHex(a) - if !ok { - return fmt.Errorf("expected a hex digit, got %q", a) - } - b, _, err := r.ReadRune() - if err != nil { - return err - } - bN, ok := deHex(b) - if !ok { - return fmt.Errorf("expected a hex digit, got %q", b) - } - out.WriteByte(aN<<4 | bN) } *sum = ShortSum(out.String()) return nil diff --git a/lib/jsonutil/hex_decoder.go b/lib/jsonutil/hex_decoder.go new file mode 100644 index 0000000..e5c84a7 --- /dev/null +++ b/lib/jsonutil/hex_decoder.go @@ -0,0 +1,61 @@ +// Copyright (C) 2023 Luke Shumaker +// +// SPDX-License-Identifier: GPL-2.0-or-later + +package jsonutil + +import ( + "fmt" + "io" + "math" +) + +type invalidHexRuneError rune + +func (e invalidHexRuneError) Error() string { + return fmt.Sprintf("jsonutil: invalid hex digit: %q", rune(e)) +} + +// hexDecoder is like an encoding/hex.Decoder, but has a "push" +// interface rather than a "pull" interface. +type hexDecoder struct { + dst io.ByteWriter + + buf byte + bufOK bool +} + +func (d *hexDecoder) WriteRune(r rune) (int, error) { + if r > math.MaxUint8 { + return 0, invalidHexRuneError(r) + } + + c := byte(r) + var v byte + //nolint:gomnd // Hex conversion. + 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 + default: + return 0, invalidHexRuneError(r) + } + + if !d.bufOK { + d.buf = v + d.bufOK = true + return 1, nil + } + d.bufOK = false + return 1, d.dst.WriteByte(d.buf<<4 | v) +} + +func (d *hexDecoder) Close() error { + if d.bufOK { + return io.ErrUnexpectedEOF + } + return nil +} diff --git a/lib/jsonutil/hex_string.go b/lib/jsonutil/hex_string.go new file mode 100644 index 0000000..06970ce --- /dev/null +++ b/lib/jsonutil/hex_string.go @@ -0,0 +1,42 @@ +// Copyright (C) 2023 Luke Shumaker +// +// SPDX-License-Identifier: GPL-2.0-or-later + +// Package jsonutil provides utilities for implementing the interfaces +// consumed by the "git.lukeshu.com/go/lowmemjson" package. +package jsonutil + +import ( + "io" + + "git.lukeshu.com/go/lowmemjson" +) + +func EncodeHexString[T ~[]byte | ~string](w io.Writer, str T) error { + const hextable = "0123456789abcdef" + var buf [2]byte + buf[0] = '"' + if _, err := w.Write(buf[:1]); err != nil { + return err + } + for i := 0; i < len(str); i++ { + buf[0] = hextable[str[i]>>4] + buf[1] = hextable[str[i]&0x0f] + if _, err := w.Write(buf[:]); err != nil { + return err + } + } + buf[0] = '"' + if _, err := w.Write(buf[:1]); err != nil { + return err + } + return nil +} + +func DecodeHexString(r io.RuneScanner, dst io.ByteWriter) error { + dec := &hexDecoder{dst: dst} + if err := lowmemjson.DecodeString(r, dec); err != nil { + return err + } + return dec.Close() +} -- cgit v1.1-4-g5e80