From 13b65d51ffc9768464e8330fdb73b6febd7410af Mon Sep 17 00:00:00 2001 From: Luke Shumaker Date: Sat, 30 Jul 2022 02:36:25 -0600 Subject: json: Implement a bunch of streaming JSON encoding/decoding --- lib/btrfs/btrfsitem/item_extentcsum.go | 34 +++++++++++++++ lib/btrfs/btrfssum/csum.go | 20 +++++++++ lib/btrfsprogs/btrfsinspect/csums.go | 80 ++++++++++++++++++++++++++++++++++ lib/containers/optional.go | 26 +++++++++++ 4 files changed, 160 insertions(+) (limited to 'lib') diff --git a/lib/btrfs/btrfsitem/item_extentcsum.go b/lib/btrfs/btrfsitem/item_extentcsum.go index b35d333..eedd044 100644 --- a/lib/btrfs/btrfsitem/item_extentcsum.go +++ b/lib/btrfs/btrfsitem/item_extentcsum.go @@ -5,7 +5,11 @@ package btrfsitem import ( + "encoding/hex" "fmt" + "io" + + "git.lukeshu.com/go/lowmemjson" "git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfssum" ) @@ -43,3 +47,33 @@ func (o ExtentCSum) MarshalBinary() ([]byte, error) { } return dat, nil } + +var ( + _ lowmemjson.Encodable = ExtentCSum{} +) + +func (o ExtentCSum) EncodeJSON(w io.Writer) error { + if _, err := fmt.Fprintf(w, `{"ChecksumSize":%d,"Sums":[`, o.ChecksumSize); err != nil { + return err + } + for i, sum := range o.Sums { + if i > 0 { + if _, err := w.Write([]byte(",")); err != nil { + return err + } + } + if _, err := w.Write([]byte(`"`)); err != nil { + return err + } + if _, err := hex.NewEncoder(w).Write(sum[:o.ChecksumSize]); err != nil { + return err + } + if _, err := w.Write([]byte(`"`)); err != nil { + return err + } + } + if _, err := w.Write([]byte(`]}`)); err != nil { + return err + } + return nil +} diff --git a/lib/btrfs/btrfssum/csum.go b/lib/btrfs/btrfssum/csum.go index 8f9ac1a..c7c1f37 100644 --- a/lib/btrfs/btrfssum/csum.go +++ b/lib/btrfs/btrfssum/csum.go @@ -5,6 +5,7 @@ package btrfssum import ( + "encoding" "encoding/binary" "encoding/hex" "fmt" @@ -15,10 +16,29 @@ import ( type CSum [0x20]byte +var ( + _ fmt.Stringer = CSum{} + _ fmt.Formatter = CSum{} + _ encoding.TextMarshaler = CSum{} + _ encoding.TextUnmarshaler = (*CSum)(nil) +) + func (csum CSum) String() string { return hex.EncodeToString(csum[:]) } +func (csum CSum) MarshalText() ([]byte, error) { + var ret [len(csum) * 2]byte + hex.Encode(ret[:], csum[:]) + return ret[:], nil +} + +func (csum *CSum) UnmarshalText(text []byte) error { + *csum = CSum{} + _, err := hex.Decode(csum[:], text) + return err +} + func (csum CSum) Fmt(typ CSumType) string { return hex.EncodeToString(csum[:typ.Size()]) } diff --git a/lib/btrfsprogs/btrfsinspect/csums.go b/lib/btrfsprogs/btrfsinspect/csums.go index 78bf915..6335cb9 100644 --- a/lib/btrfsprogs/btrfsinspect/csums.go +++ b/lib/btrfsprogs/btrfsinspect/csums.go @@ -6,7 +6,11 @@ package btrfsinspect import ( "context" + "fmt" "io" + "strings" + + "git.lukeshu.com/go/lowmemjson" "git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem" "git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol" @@ -17,6 +21,82 @@ import ( type ShortSum string +var ( + _ lowmemjson.Encodable = ShortSum("") + _ lowmemjson.Decodable = (*ShortSum)(nil) +) + +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 > 0xff { + return 0, false + } + c := byte(r) + 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 + } +} + +func (sum *ShortSum) DecodeJSON(r io.RuneScanner) error { + var out strings.Builder + if c, _, err := r.ReadRune(); 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 +} + // SumRun //////////////////////////////////////////////////////////// type SumRun[Addr btrfsvol.IntAddr[Addr]] struct { diff --git a/lib/containers/optional.go b/lib/containers/optional.go index 3055308..c0e7b32 100644 --- a/lib/containers/optional.go +++ b/lib/containers/optional.go @@ -4,7 +4,33 @@ package containers +import ( + "encoding/json" +) + type Optional[T any] struct { OK bool Val T } + +var ( + _ json.Marshaler = Optional[bool]{} + _ json.Unmarshaler = (*Optional[bool])(nil) +) + +func (o Optional[T]) MarshalJSON() ([]byte, error) { + if o.OK { + return json.Marshal(o.Val) + } else { + return []byte("null"), nil + } +} + +func (o *Optional[T]) UnmarshalJSON(dat []byte) error { + if string(dat) == "null" { + *o = Optional[T]{} + return nil + } + o.OK = true + return json.Unmarshal(dat, &o.Val) +} -- cgit v1.2.3-54-g00ecf