mirror of
https://github.com/42wim/matterbridge.git
synced 2024-11-24 03:32:02 -08:00
384 lines
9.4 KiB
Go
384 lines
9.4 KiB
Go
// Copyright 2021 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package pkgbits
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto/md5"
|
|
"encoding/binary"
|
|
"go/constant"
|
|
"io"
|
|
"math/big"
|
|
"runtime"
|
|
)
|
|
|
|
// currentVersion is the current version number.
|
|
//
|
|
// - v0: initial prototype
|
|
//
|
|
// - v1: adds the flags uint32 word
|
|
const currentVersion uint32 = 1
|
|
|
|
// A PkgEncoder provides methods for encoding a package's Unified IR
|
|
// export data.
|
|
type PkgEncoder struct {
|
|
// elems holds the bitstream for previously encoded elements.
|
|
elems [numRelocs][]string
|
|
|
|
// stringsIdx maps previously encoded strings to their index within
|
|
// the RelocString section, to allow deduplication. That is,
|
|
// elems[RelocString][stringsIdx[s]] == s (if present).
|
|
stringsIdx map[string]Index
|
|
|
|
// syncFrames is the number of frames to write at each sync
|
|
// marker. A negative value means sync markers are omitted.
|
|
syncFrames int
|
|
}
|
|
|
|
// SyncMarkers reports whether pw uses sync markers.
|
|
func (pw *PkgEncoder) SyncMarkers() bool { return pw.syncFrames >= 0 }
|
|
|
|
// NewPkgEncoder returns an initialized PkgEncoder.
|
|
//
|
|
// syncFrames is the number of caller frames that should be serialized
|
|
// at Sync points. Serializing additional frames results in larger
|
|
// export data files, but can help diagnosing desync errors in
|
|
// higher-level Unified IR reader/writer code. If syncFrames is
|
|
// negative, then sync markers are omitted entirely.
|
|
func NewPkgEncoder(syncFrames int) PkgEncoder {
|
|
return PkgEncoder{
|
|
stringsIdx: make(map[string]Index),
|
|
syncFrames: syncFrames,
|
|
}
|
|
}
|
|
|
|
// DumpTo writes the package's encoded data to out0 and returns the
|
|
// package fingerprint.
|
|
func (pw *PkgEncoder) DumpTo(out0 io.Writer) (fingerprint [8]byte) {
|
|
h := md5.New()
|
|
out := io.MultiWriter(out0, h)
|
|
|
|
writeUint32 := func(x uint32) {
|
|
assert(binary.Write(out, binary.LittleEndian, x) == nil)
|
|
}
|
|
|
|
writeUint32(currentVersion)
|
|
|
|
var flags uint32
|
|
if pw.SyncMarkers() {
|
|
flags |= flagSyncMarkers
|
|
}
|
|
writeUint32(flags)
|
|
|
|
// Write elemEndsEnds.
|
|
var sum uint32
|
|
for _, elems := range &pw.elems {
|
|
sum += uint32(len(elems))
|
|
writeUint32(sum)
|
|
}
|
|
|
|
// Write elemEnds.
|
|
sum = 0
|
|
for _, elems := range &pw.elems {
|
|
for _, elem := range elems {
|
|
sum += uint32(len(elem))
|
|
writeUint32(sum)
|
|
}
|
|
}
|
|
|
|
// Write elemData.
|
|
for _, elems := range &pw.elems {
|
|
for _, elem := range elems {
|
|
_, err := io.WriteString(out, elem)
|
|
assert(err == nil)
|
|
}
|
|
}
|
|
|
|
// Write fingerprint.
|
|
copy(fingerprint[:], h.Sum(nil))
|
|
_, err := out0.Write(fingerprint[:])
|
|
assert(err == nil)
|
|
|
|
return
|
|
}
|
|
|
|
// StringIdx adds a string value to the strings section, if not
|
|
// already present, and returns its index.
|
|
func (pw *PkgEncoder) StringIdx(s string) Index {
|
|
if idx, ok := pw.stringsIdx[s]; ok {
|
|
assert(pw.elems[RelocString][idx] == s)
|
|
return idx
|
|
}
|
|
|
|
idx := Index(len(pw.elems[RelocString]))
|
|
pw.elems[RelocString] = append(pw.elems[RelocString], s)
|
|
pw.stringsIdx[s] = idx
|
|
return idx
|
|
}
|
|
|
|
// NewEncoder returns an Encoder for a new element within the given
|
|
// section, and encodes the given SyncMarker as the start of the
|
|
// element bitstream.
|
|
func (pw *PkgEncoder) NewEncoder(k RelocKind, marker SyncMarker) Encoder {
|
|
e := pw.NewEncoderRaw(k)
|
|
e.Sync(marker)
|
|
return e
|
|
}
|
|
|
|
// NewEncoderRaw returns an Encoder for a new element within the given
|
|
// section.
|
|
//
|
|
// Most callers should use NewEncoder instead.
|
|
func (pw *PkgEncoder) NewEncoderRaw(k RelocKind) Encoder {
|
|
idx := Index(len(pw.elems[k]))
|
|
pw.elems[k] = append(pw.elems[k], "") // placeholder
|
|
|
|
return Encoder{
|
|
p: pw,
|
|
k: k,
|
|
Idx: idx,
|
|
}
|
|
}
|
|
|
|
// An Encoder provides methods for encoding an individual element's
|
|
// bitstream data.
|
|
type Encoder struct {
|
|
p *PkgEncoder
|
|
|
|
Relocs []RelocEnt
|
|
RelocMap map[RelocEnt]uint32
|
|
Data bytes.Buffer // accumulated element bitstream data
|
|
|
|
encodingRelocHeader bool
|
|
|
|
k RelocKind
|
|
Idx Index // index within relocation section
|
|
}
|
|
|
|
// Flush finalizes the element's bitstream and returns its Index.
|
|
func (w *Encoder) Flush() Index {
|
|
var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
|
|
|
|
// Backup the data so we write the relocations at the front.
|
|
var tmp bytes.Buffer
|
|
io.Copy(&tmp, &w.Data)
|
|
|
|
// TODO(mdempsky): Consider writing these out separately so they're
|
|
// easier to strip, along with function bodies, so that we can prune
|
|
// down to just the data that's relevant to go/types.
|
|
if w.encodingRelocHeader {
|
|
panic("encodingRelocHeader already true; recursive flush?")
|
|
}
|
|
w.encodingRelocHeader = true
|
|
w.Sync(SyncRelocs)
|
|
w.Len(len(w.Relocs))
|
|
for _, rEnt := range w.Relocs {
|
|
w.Sync(SyncReloc)
|
|
w.Len(int(rEnt.Kind))
|
|
w.Len(int(rEnt.Idx))
|
|
}
|
|
|
|
io.Copy(&sb, &w.Data)
|
|
io.Copy(&sb, &tmp)
|
|
w.p.elems[w.k][w.Idx] = sb.String()
|
|
|
|
return w.Idx
|
|
}
|
|
|
|
func (w *Encoder) checkErr(err error) {
|
|
if err != nil {
|
|
errorf("unexpected encoding error: %v", err)
|
|
}
|
|
}
|
|
|
|
func (w *Encoder) rawUvarint(x uint64) {
|
|
var buf [binary.MaxVarintLen64]byte
|
|
n := binary.PutUvarint(buf[:], x)
|
|
_, err := w.Data.Write(buf[:n])
|
|
w.checkErr(err)
|
|
}
|
|
|
|
func (w *Encoder) rawVarint(x int64) {
|
|
// Zig-zag encode.
|
|
ux := uint64(x) << 1
|
|
if x < 0 {
|
|
ux = ^ux
|
|
}
|
|
|
|
w.rawUvarint(ux)
|
|
}
|
|
|
|
func (w *Encoder) rawReloc(r RelocKind, idx Index) int {
|
|
e := RelocEnt{r, idx}
|
|
if w.RelocMap != nil {
|
|
if i, ok := w.RelocMap[e]; ok {
|
|
return int(i)
|
|
}
|
|
} else {
|
|
w.RelocMap = make(map[RelocEnt]uint32)
|
|
}
|
|
|
|
i := len(w.Relocs)
|
|
w.RelocMap[e] = uint32(i)
|
|
w.Relocs = append(w.Relocs, e)
|
|
return i
|
|
}
|
|
|
|
func (w *Encoder) Sync(m SyncMarker) {
|
|
if !w.p.SyncMarkers() {
|
|
return
|
|
}
|
|
|
|
// Writing out stack frame string references requires working
|
|
// relocations, but writing out the relocations themselves involves
|
|
// sync markers. To prevent infinite recursion, we simply trim the
|
|
// stack frame for sync markers within the relocation header.
|
|
var frames []string
|
|
if !w.encodingRelocHeader && w.p.syncFrames > 0 {
|
|
pcs := make([]uintptr, w.p.syncFrames)
|
|
n := runtime.Callers(2, pcs)
|
|
frames = fmtFrames(pcs[:n]...)
|
|
}
|
|
|
|
// TODO(mdempsky): Save space by writing out stack frames as a
|
|
// linked list so we can share common stack frames.
|
|
w.rawUvarint(uint64(m))
|
|
w.rawUvarint(uint64(len(frames)))
|
|
for _, frame := range frames {
|
|
w.rawUvarint(uint64(w.rawReloc(RelocString, w.p.StringIdx(frame))))
|
|
}
|
|
}
|
|
|
|
// Bool encodes and writes a bool value into the element bitstream,
|
|
// and then returns the bool value.
|
|
//
|
|
// For simple, 2-alternative encodings, the idiomatic way to call Bool
|
|
// is something like:
|
|
//
|
|
// if w.Bool(x != 0) {
|
|
// // alternative #1
|
|
// } else {
|
|
// // alternative #2
|
|
// }
|
|
//
|
|
// For multi-alternative encodings, use Code instead.
|
|
func (w *Encoder) Bool(b bool) bool {
|
|
w.Sync(SyncBool)
|
|
var x byte
|
|
if b {
|
|
x = 1
|
|
}
|
|
err := w.Data.WriteByte(x)
|
|
w.checkErr(err)
|
|
return b
|
|
}
|
|
|
|
// Int64 encodes and writes an int64 value into the element bitstream.
|
|
func (w *Encoder) Int64(x int64) {
|
|
w.Sync(SyncInt64)
|
|
w.rawVarint(x)
|
|
}
|
|
|
|
// Uint64 encodes and writes a uint64 value into the element bitstream.
|
|
func (w *Encoder) Uint64(x uint64) {
|
|
w.Sync(SyncUint64)
|
|
w.rawUvarint(x)
|
|
}
|
|
|
|
// Len encodes and writes a non-negative int value into the element bitstream.
|
|
func (w *Encoder) Len(x int) { assert(x >= 0); w.Uint64(uint64(x)) }
|
|
|
|
// Int encodes and writes an int value into the element bitstream.
|
|
func (w *Encoder) Int(x int) { w.Int64(int64(x)) }
|
|
|
|
// Uint encodes and writes a uint value into the element bitstream.
|
|
func (w *Encoder) Uint(x uint) { w.Uint64(uint64(x)) }
|
|
|
|
// Reloc encodes and writes a relocation for the given (section,
|
|
// index) pair into the element bitstream.
|
|
//
|
|
// Note: Only the index is formally written into the element
|
|
// bitstream, so bitstream decoders must know from context which
|
|
// section an encoded relocation refers to.
|
|
func (w *Encoder) Reloc(r RelocKind, idx Index) {
|
|
w.Sync(SyncUseReloc)
|
|
w.Len(w.rawReloc(r, idx))
|
|
}
|
|
|
|
// Code encodes and writes a Code value into the element bitstream.
|
|
func (w *Encoder) Code(c Code) {
|
|
w.Sync(c.Marker())
|
|
w.Len(c.Value())
|
|
}
|
|
|
|
// String encodes and writes a string value into the element
|
|
// bitstream.
|
|
//
|
|
// Internally, strings are deduplicated by adding them to the strings
|
|
// section (if not already present), and then writing a relocation
|
|
// into the element bitstream.
|
|
func (w *Encoder) String(s string) {
|
|
w.Sync(SyncString)
|
|
w.Reloc(RelocString, w.p.StringIdx(s))
|
|
}
|
|
|
|
// Strings encodes and writes a variable-length slice of strings into
|
|
// the element bitstream.
|
|
func (w *Encoder) Strings(ss []string) {
|
|
w.Len(len(ss))
|
|
for _, s := range ss {
|
|
w.String(s)
|
|
}
|
|
}
|
|
|
|
// Value encodes and writes a constant.Value into the element
|
|
// bitstream.
|
|
func (w *Encoder) Value(val constant.Value) {
|
|
w.Sync(SyncValue)
|
|
if w.Bool(val.Kind() == constant.Complex) {
|
|
w.scalar(constant.Real(val))
|
|
w.scalar(constant.Imag(val))
|
|
} else {
|
|
w.scalar(val)
|
|
}
|
|
}
|
|
|
|
func (w *Encoder) scalar(val constant.Value) {
|
|
switch v := constant.Val(val).(type) {
|
|
default:
|
|
errorf("unhandled %v (%v)", val, val.Kind())
|
|
case bool:
|
|
w.Code(ValBool)
|
|
w.Bool(v)
|
|
case string:
|
|
w.Code(ValString)
|
|
w.String(v)
|
|
case int64:
|
|
w.Code(ValInt64)
|
|
w.Int64(v)
|
|
case *big.Int:
|
|
w.Code(ValBigInt)
|
|
w.bigInt(v)
|
|
case *big.Rat:
|
|
w.Code(ValBigRat)
|
|
w.bigInt(v.Num())
|
|
w.bigInt(v.Denom())
|
|
case *big.Float:
|
|
w.Code(ValBigFloat)
|
|
w.bigFloat(v)
|
|
}
|
|
}
|
|
|
|
func (w *Encoder) bigInt(v *big.Int) {
|
|
b := v.Bytes()
|
|
w.String(string(b)) // TODO: More efficient encoding.
|
|
w.Bool(v.Sign() < 0)
|
|
}
|
|
|
|
func (w *Encoder) bigFloat(v *big.Float) {
|
|
b := v.Append(nil, 'p', -1)
|
|
w.String(string(b)) // TODO: More efficient encoding.
|
|
}
|