// Copyright 2015 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 gcimporter
import (
"encoding/binary"
"fmt"
"go/constant"
"go/token"
"go/types"
"sort"
"strconv"
"strings"
"sync"
)
type importer struct {
imports map[string]*types.Package
data []byte
importpath string
buf []byte // for reading strings
version int // export format version
// object lists
strList []string // in order of appearance
pathList []string // in order of appearance
pkgList []*types.Package // in order of appearance
typList []types.Type // in order of appearance
interfaceList []*types.Interface // for delayed completion only
trackAllTypes bool
// position encoding
posInfoFormat bool
prevFile string
prevLine int
fake fakeFileSet
// debugging support
debugFormat bool
read int // bytes read
}
// BImportData imports a package from the serialized package data
// and returns the number of bytes consumed and a reference to the package.
// If the export data version is not recognized or the format is otherwise
// compromised, an error is returned.
func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
// catch panics and return them as errors
const currentVersion = 6
version := -1 // unknown version
defer func() {
if e := recover(); e != nil {
// Return a (possibly nil or incomplete) package unchanged (see #16088).
if version > currentVersion {
err = fmt.Errorf("cannot import %q (%v), export data is newer version - update tool", path, e)
} else {
err = fmt.Errorf("cannot import %q (%v), possibly version skew - reinstall package", path, e)
}
}
}()
p := importer{
imports: imports,
data: data,
importpath: path,
version: version,
strList: []string{""}, // empty string is mapped to 0
pathList: []string{""}, // empty string is mapped to 0
fake: fakeFileSet{
fset: fset,
files: make(map[string]*token.File),
},
}
// read version info
var versionstr string
if b := p.rawByte(); b == 'c' || b == 'd' {
// Go1.7 encoding; first byte encodes low-level
// encoding format (compact vs debug).
// For backward-compatibility only (avoid problems with
// old installed packages). Newly compiled packages use
// the extensible format string.
// TODO(gri) Remove this support eventually; after Go1.8.
if b == 'd' {
p.debugFormat = true
}
p.trackAllTypes = p.rawByte() == 'a'
p.posInfoFormat = p.int() != 0
versionstr = p.string()
if versionstr == "v1" {
version = 0
}
} else {
// Go1.8 extensible encoding
// read version string and extract version number (ignore anything after the version number)
versionstr = p.rawStringln(b)
if s := strings.SplitN(versionstr, " ", 3); len(s) >= 2 && s[0] == "version" {
if v, err := strconv.Atoi(s[1]); err == nil && v > 0 {
version = v
}
}
}
p.version = version
// read version specific flags - extend as necessary
switch p.version {
// case currentVersion:
// ...
// fallthrough
case currentVersion, 5, 4, 3, 2, 1:
p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
p.trackAllTypes = p.int() != 0
p.posInfoFormat = p.int() != 0
case 0:
// Go1.7 encoding format - nothing to do here
default:
errorf("unknown bexport format version %d (%q)", p.version, versionstr)
}
// --- generic export data ---
// populate typList with predeclared "known" types
p.typList = append(p.typList, predeclared...)
// read package data
pkg = p.pkg()
// read objects of phase 1 only (see cmd/compile/internal/gc/bexport.go)
objcount := 0
for {
tag := p.tagOrIndex()
if tag == endTag {
break
}
p.obj(tag)
objcount++
}
// self-verification
if count := p.int(); count != objcount {
errorf("got %d objects; want %d", objcount, count)
}
// ignore compiler-specific import data
// complete interfaces
// TODO(gri) re-investigate if we still need to do this in a delayed fashion
for _, typ := range p.interfaceList {
typ.Complete()
}
// record all referenced packages as imports
list := append(([]*types.Package)(nil), p.pkgList[1:]...)
sort.Sort(byPath(list))
pkg.SetImports(list)
// package was imported completely and without errors
pkg.MarkComplete()
return p.read, pkg, nil
}
func errorf(format string, args ...interface{}) {
panic(fmt.Sprintf(format, args...))
}
func (p *importer) pkg() *types.Package {
// if the package was seen before, i is its index (>= 0)
i := p.tagOrIndex()
if i >= 0 {
return p.pkgList[i]
}
// otherwise, i is the package tag (< 0)
if i != packageTag {
errorf("unexpected package tag %d version %d", i, p.version)
}
// read package data
name := p.string()
var path string
if p.version >= 5 {
path = p.path()
} else {
path = p.string()
}
if p.version >= 6 {
p.int() // package height; unused by go/types
}
// we should never see an empty package name
if name == "" {
errorf("empty package name in import")
}
// an empty path denotes the package we are currently importing;
// it must be the first package we see
if (path == "") != (len(p.pkgList) == 0) {
errorf("package path %q for pkg index %d", path, len(p.pkgList))
}
// if the package was imported before, use that one; otherwise create a new one
if path == "" {
path = p.importpath
}
pkg := p.imports[path]
if pkg == nil {
pkg = types.NewPackage(path, name)
p.imports[path] = pkg
} else if pkg.Name() != name {
errorf("conflicting names %s and %s for package %q", pkg.Name(), name, path)
}
p.pkgList = append(p.pkgList, pkg)
return pkg
}
// objTag returns the tag value for each object kind.
func objTag(obj types.Object) int {
switch obj.(type) {
case *types.Const:
return constTag
case *types.TypeName:
return typeTag
case *types.Var:
return varTag
case *types.Func:
return funcTag
default:
errorf("unexpected object: %v (%T)", obj, obj) // panics
panic("unreachable")
}
}
func sameObj(a, b types.Object) bool {
// Because unnamed types are not canonicalized, we cannot simply compare types for
// (pointer) identity.
// Ideally we'd check equality of constant values as well, but this is good enough.
return objTag(a) == objTag(b) && types.Identical(a.Type(), b.Type())
}
func (p *importer) declare(obj types.Object) {
pkg := obj.Pkg()
if alt := pkg.Scope().Insert(obj); alt != nil {
// This can only trigger if we import a (non-type) object a second time.
// Excluding type aliases, this cannot happen because 1) we only import a package
// once; and b) we ignore compiler-specific export data which may contain
// functions whose inlined function bodies refer to other functions that
// were already imported.
// However, type aliases require reexporting the original type, so we need
// to allow it (see also the comment in cmd/compile/internal/gc/bimport.go,
// method importer.obj, switch case importing functions).
// TODO(gri) review/update this comment once the gc compiler handles type aliases.
if !sameObj(obj, alt) {
errorf("inconsistent import:\n\t%v\npreviously imported as:\n\t%v\n", obj, alt)
}
}
}
func (p *importer) obj(tag int) {
switch tag {
case constTag:
pos := p.pos()
pkg, name := p.qualifiedName()
typ := p.typ(nil, nil)
val := p.value()
p.declare(types.NewConst(pos, pkg, name, typ, val))
case aliasTag:
// TODO(gri) verify type alias hookup is correct
pos := p.pos()
pkg, name := p.qualifiedName()
typ := p.typ(nil, nil)
p.declare(types.NewTypeName(pos, pkg, name, typ))
case typeTag:
p.typ(nil, nil)
case varTag:
pos := p.pos()
pkg, name := p.qualifiedName()
typ := p.typ(nil, nil)
p.declare(types.NewVar(pos, pkg, name, typ))
case funcTag:
pos := p.pos()
pkg, name := p.qualifiedName()
params, isddd := p.paramList()
result, _ := p.paramList()
sig := types.NewSignature(nil, params, result, isddd)
p.declare(types.NewFunc(pos, pkg, name, sig))
default:
errorf("unexpected object tag %d", tag)
}
}
const deltaNewFile = -64 // see cmd/compile/internal/gc/bexport.go
func (p *importer) pos() token.Pos {
if !p.posInfoFormat {
return token.NoPos
}
file := p.prevFile
line := p.prevLine
delta := p.int()
line += delta
if p.version >= 5 {
if delta == deltaNewFile {
if n := p.int(); n >= 0 {
// file changed
file = p.path()
line = n
}
}
} else {
if delta == 0 {
if n := p.int(); n >= 0 {
// file changed
file = p.prevFile[:n] + p.string()
line = p.int()
}
}
}
p.prevFile = file
p.prevLine = line
return p.fake.pos(file, line)
}
// Synthesize a token.Pos
type fakeFileSet struct {
fset *token.FileSet
files map[string]*token.File
}
func (s *fakeFileSet) pos(file string, line int) token.Pos {
// Since we don't know the set of needed file positions, we
// reserve maxlines positions per file.
const maxlines = 64 * 1024
f := s.files[file]
if f == nil {
f = s.fset.AddFile(file, -1, maxlines)
s.files[file] = f
// Allocate the fake linebreak indices on first use.
// TODO(adonovan): opt: save ~512KB using a more complex scheme?
fakeLinesOnce.Do(func() {
fakeLines = make([]int, maxlines)
for i := range fakeLines {
fakeLines[i] = i
}
})
f.SetLines(fakeLines)
}
if line > maxlines {
line = 1
}
// Treat the file as if it contained only newlines
// and column=1: use the line number as the offset.
return f.Pos(line - 1)
}
var (
fakeLines []int
fakeLinesOnce sync.Once
)
func (p *importer) qualifiedName() (pkg *types.Package, name string) {
name = p.string()
pkg = p.pkg()
return
}
func (p *importer) record(t types.Type) {
p.typList = append(p.typList, t)
}
// A dddSlice is a types.Type representing ...T parameters.
// It only appears for parameter types and does not escape
// the importer.
type dddSlice struct {
elem types.Type
}
func (t *dddSlice) Underlying() types.Type { return t }
func (t *dddSlice) String() string { return "..." + t.elem.String() }
// parent is the package which declared the type; parent == nil means
// the package currently imported. The parent package is needed for
// exported struct fields and interface methods which don't contain
// explicit package information in the export data.
//
// A non-nil tname is used as the "owner" of the result type; i.e.,
// the result type is the underlying type of tname. tname is used
// to give interface methods a named receiver type where possible.
func (p *importer) typ(parent *types.Package, tname *types.Named) types.Type {
// if the type was seen before, i is its index (>= 0)
i := p.tagOrIndex()
if i >= 0 {
return p.typList[i]
}
// otherwise, i is the type tag (< 0)
switch i {
case namedTag:
// read type object
pos := p.pos()
parent, name := p.qualifiedName()
scope := parent.Scope()
obj := scope.Lookup(name)
// if the object doesn't exist yet, create and insert it
if obj == nil {
obj = types.NewTypeName(pos, parent, name, nil)
scope.Insert(obj)
}
if _, ok := obj.(*types.TypeName); !ok {
errorf("pkg = %s, name = %s => %s", parent, name, obj)
}
// associate new named type with obj if it doesn't exist yet
t0 := types.NewNamed(obj.(*types.TypeName), nil, nil)
// but record the existing type, if any
tname := obj.Type().(*types.Named) // tname is either t0 or the existing type
p.record(tname)
// read underlying type
t0.SetUnderlying(p.typ(parent, t0))
// interfaces don't have associated methods
if types.IsInterface(t0) {
return tname
}
// read associated methods
for i := p.int(); i > 0; i-- {
// TODO(gri) replace this with something closer to fieldName
pos := p.pos()
name := p.string()
if !token.IsExported(name) {
p.pkg()
}
recv, _ := p.paramList() // TODO(gri) do we need a full param list for the receiver?
params, isddd := p.paramList()
result, _ := p.paramList()
p.int() // go:nointerface pragma - discarded
sig := types.NewSignature(recv.At(0), params, result, isddd)
t0.AddMethod(types.NewFunc(pos, parent, name, sig))
}
return tname
case arrayTag:
t := new(types.Array)
if p.trackAllTypes {
p.record(t)
}
n := p.int64()
*t = *types.NewArray(p.typ(parent, nil), n)
return t
case sliceTag:
t := new(types.Slice)
if p.trackAllTypes {
p.record(t)
}
*t = *types.NewSlice(p.typ(parent, nil))
return t
case dddTag:
t := new(dddSlice)
if p.trackAllTypes {
p.record(t)
}
t.elem = p.typ(parent, nil)
return t
case structTag:
t := new(types.Struct)
if p.trackAllTypes {
p.record(t)
}
*t = *types.NewStruct(p.fieldList(parent))
return t
case pointerTag:
t := new(types.Pointer)
if p.trackAllTypes {
p.record(t)
}
*t = *types.NewPointer(p.typ(parent, nil))
return t
case signatureTag:
t := new(types.Signature)
if p.trackAllTypes {
p.record(t)
}
params, isddd := p.paramList()
result, _ := p.paramList()
*t = *types.NewSignature(nil, params, result, isddd)
return t
case interfaceTag:
// Create a dummy entry in the type list. This is safe because we
// cannot expect the interface type to appear in a cycle, as any
// such cycle must contain a named type which would have been
// first defined earlier.
// TODO(gri) Is this still true now that we have type aliases?
// See issue #23225.
n := len(p.typList)
if p.trackAllTypes {
p.record(nil)
}
var embeddeds []types.Type
for n := p.int(); n > 0; n-- {
p.pos()
embeddeds = append(embeddeds, p.typ(parent, nil))
}
t := types.NewInterfaceType(p.methodList(parent, tname), embeddeds)
p.interfaceList = append(p.interfaceList, t)
if p.trackAllTypes {
p.typList[n] = t
}
return t
case mapTag:
t := new(types.Map)
if p.trackAllTypes {
p.record(t)
}
key := p.typ(parent, nil)
val := p.typ(parent, nil)
*t = *types.NewMap(key, val)
return t
case chanTag:
t := new(types.Chan)
if p.trackAllTypes {
p.record(t)
}
dir := chanDir(p.int())
val := p.typ(parent, nil)
*t = *types.NewChan(dir, val)
return t
default:
errorf("unexpected type tag %d", i) // panics
panic("unreachable")
}
}
func chanDir(d int) types.ChanDir {
// tag values must match the constants in cmd/compile/internal/gc/go.go
switch d {
case 1 /* Crecv */ :
return types.RecvOnly
case 2 /* Csend */ :
return types.SendOnly
case 3 /* Cboth */ :
return types.SendRecv
default:
errorf("unexpected channel dir %d", d)
return 0
}
}
func (p *importer) fieldList(parent *types.Package) (fields []*types.Var, tags []string) {
if n := p.int(); n > 0 {
fields = make([]*types.Var, n)
tags = make([]string, n)
for i := range fields {
fields[i], tags[i] = p.field(parent)
}
}
return
}
func (p *importer) field(parent *types.Package) (*types.Var, string) {
pos := p.pos()
pkg, name, alias := p.fieldName(parent)
typ := p.typ(parent, nil)
tag := p.string()
anonymous := false
if name == "" {
// anonymous field - typ must be T or *T and T must be a type name
switch typ := deref(typ).(type) {
case *types.Basic: // basic types are named types
pkg = nil // // objects defined in Universe scope have no package
name = typ.Name()
case *types.Named:
name = typ.Obj().Name()
default:
errorf("named base type expected")
}
anonymous = true
} else if alias {
// anonymous field: we have an explicit name because it's an alias
anonymous = true
}
return types.NewField(pos, pkg, name, typ, anonymous), tag
}
func (p *importer) methodList(parent *types.Package, baseType *types.Named) (methods []*types.Func) {
if n := p.int(); n > 0 {
methods = make([]*types.Func, n)
for i := range methods {
methods[i] = p.method(parent, baseType)
}
}
return
}
func (p *importer) method(parent *types.Package, baseType *types.Named) *types.Func {
pos := p.pos()
pkg, name, _ := p.fieldName(parent)
// If we don't have a baseType, use a nil receiver.
// A receiver using the actual interface type (which
// we don't know yet) will be filled in when we call
// types.Interface.Complete.
var recv *types.Var
if baseType != nil {
recv = types.NewVar(token.NoPos, parent, "", baseType)
}
params, isddd := p.paramList()
result, _ := p.paramList()
sig := types.NewSignature(recv, params, result, isddd)
return types.NewFunc(pos, pkg, name, sig)
}
func (p *importer) fieldName(parent *types.Package) (pkg *types.Package, name string, alias bool) {
name = p.string()
pkg = parent
if pkg == nil {
// use the imported package instead
pkg = p.pkgList[0]
}
if p.version == 0 && name == "_" {
// version 0 didn't export a package for _ fields
return
}
switch name {
case "":
// 1) field name matches base type name and is exported: nothing to do
case "?":
// 2) field name matches base type name and is not exported: need package
name = ""
pkg = p.pkg()
case "@":
// 3) field name doesn't match type name (alias)
name = p.string()
alias = true
fallthrough
default:
if !token.IsExported(name) {
pkg = p.pkg()
}
}
return
}
func (p *importer) paramList() (*types.Tuple, bool) {
n := p.int()
if n == 0 {
return nil, false
}
// negative length indicates unnamed parameters
named := true
if n < 0 {
n = -n
named = false
}
// n > 0
params := make([]*types.Var, n)
isddd := false
for i := range params {
params[i], isddd = p.param(named)
}
return types.NewTuple(params...), isddd
}
func (p *importer) param(named bool) (*types.Var, bool) {
t := p.typ(nil, nil)
td, isddd := t.(*dddSlice)
if isddd {
t = types.NewSlice(td.elem)
}
var pkg *types.Package
var name string
if named {
name = p.string()
if name == "" {
errorf("expected named parameter")
}
if name != "_" {
pkg = p.pkg()
}
if i := strings.Index(name, "·"); i > 0 {
name = name[:i] // cut off gc-specific parameter numbering
}
}
// read and discard compiler-specific info
p.string()
return types.NewVar(token.NoPos, pkg, name, t), isddd
}
func (p *importer) value() constant.Value {
switch tag := p.tagOrIndex(); tag {
case falseTag:
return constant.MakeBool(false)
case trueTag:
return constant.MakeBool(true)
case int64Tag:
return constant.MakeInt64(p.int64())
case floatTag:
return p.float()
case complexTag:
re := p.float()
im := p.float()
return constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
case stringTag:
return constant.MakeString(p.string())
case unknownTag:
return constant.MakeUnknown()
default:
errorf("unexpected value tag %d", tag) // panics
panic("unreachable")
}
}
func (p *importer) float() constant.Value {
sign := p.int()
if sign == 0 {
return constant.MakeInt64(0)
}
exp := p.int()
mant := []byte(p.string()) // big endian
// remove leading 0's if any
for len(mant) > 0 && mant[0] == 0 {
mant = mant[1:]
}
// convert to little endian
// TODO(gri) go/constant should have a more direct conversion function
// (e.g., once it supports a big.Float based implementation)
for i, j := 0, len(mant)-1; i < j; i, j = i+1, j-1 {
mant[i], mant[j] = mant[j], mant[i]
}
// adjust exponent (constant.MakeFromBytes creates an integer value,
// but mant represents the mantissa bits such that 0.5 <= mant < 1.0)
exp -= len(mant) << 3
if len(mant) > 0 {
for msd := mant[len(mant)-1]; msd&0x80 == 0; msd <<= 1 {
exp++
}
}
x := constant.MakeFromBytes(mant)
switch {
case exp < 0:
d := constant.Shift(constant.MakeInt64(1), token.SHL, uint(-exp))
x = constant.BinaryOp(x, token.QUO, d)
case exp > 0:
x = constant.Shift(x, token.SHL, uint(exp))
}
if sign < 0 {
x = constant.UnaryOp(token.SUB, x, 0)
}
return x
}
// ----------------------------------------------------------------------------
// Low-level decoders
func (p *importer) tagOrIndex() int {
if p.debugFormat {
p.marker('t')
}
return int(p.rawInt64())
}
func (p *importer) int() int {
x := p.int64()
if int64(int(x)) != x {
errorf("exported integer too large")
}
return int(x)
}
func (p *importer) int64() int64 {
if p.debugFormat {
p.marker('i')
}
return p.rawInt64()
}
func (p *importer) path() string {
if p.debugFormat {
p.marker('p')
}
// if the path was seen before, i is its index (>= 0)
// (the empty string is at index 0)
i := p.rawInt64()
if i >= 0 {
return p.pathList[i]
}
// otherwise, i is the negative path length (< 0)
a := make([]string, -i)
for n := range a {
a[n] = p.string()
}
s := strings.Join(a, "/")
p.pathList = append(p.pathList, s)
return s
}
func (p *importer) string() string {
if p.debugFormat {
p.marker('s')
}
// if the string was seen before, i is its index (>= 0)
// (the empty string is at index 0)
i := p.rawInt64()
if i >= 0 {
return p.strList[i]
}
// otherwise, i is the negative string length (< 0)
if n := int(-i); n <= cap(p.buf) {
p.buf = p.buf[:n]
} else {
p.buf = make([]byte, n)
}
for i := range p.buf {
p.buf[i] = p.rawByte()
}
s := string(p.buf)
p.strList = append(p.strList, s)
return s
}
func (p *importer) marker(want byte) {
if got := p.rawByte(); got != want {
errorf("incorrect marker: got %c; want %c (pos = %d)", got, want, p.read)
}
pos := p.read
if n := int(p.rawInt64()); n != pos {
errorf("incorrect position: got %d; want %d", n, pos)
}
}
// rawInt64 should only be used by low-level decoders.
func (p *importer) rawInt64() int64 {
i, err := binary.ReadVarint(p)
if err != nil {
errorf("read error: %v", err)
}
return i
}
// rawStringln should only be used to read the initial version string.
func (p *importer) rawStringln(b byte) string {
p.buf = p.buf[:0]
for b != '\n' {
p.buf = append(p.buf, b)
b = p.rawByte()
}
return string(p.buf)
}
// needed for binary.ReadVarint in rawInt64
func (p *importer) ReadByte() (byte, error) {
return p.rawByte(), nil
}
// byte is the bottleneck interface for reading p.data.
// It unescapes '|' 'S' to '$' and '|' '|' to '|'.
// rawByte should only be used by low-level decoders.
func (p *importer) rawByte() byte {
b := p.data[0]
r := 1
if b == '|' {
b = p.data[1]
r = 2
switch b {
case 'S':
b = '$'
case '|':
// nothing to do
default:
errorf("unexpected escape sequence in export data")
}
}
p.data = p.data[r:]
p.read += r
return b
}
// ----------------------------------------------------------------------------
// Export format
// Tags. Must be < 0.
const (
// Objects
packageTag = -(iota + 1)
constTag
typeTag
varTag
funcTag
endTag
// Types
namedTag
arrayTag
sliceTag
dddTag
structTag
pointerTag
signatureTag
interfaceTag
mapTag
chanTag
// Values
falseTag
trueTag
int64Tag
floatTag
fractionTag // not used by gc
complexTag
stringTag
nilTag // only used by gc (appears in exported inlined function bodies)
unknownTag // not used by gc (only appears in packages with errors)
// Type aliases
aliasTag
)
var predeclared = []types.Type{
// basic types
types.Typ[types.Bool],
types.Typ[types.Int],
types.Typ[types.Int8],
types.Typ[types.Int16],
types.Typ[types.Int32],
types.Typ[types.Int64],
types.Typ[types.Uint],
types.Typ[types.Uint8],
types.Typ[types.Uint16],
types.Typ[types.Uint32],
types.Typ[types.Uint64],
types.Typ[types.Uintptr],
types.Typ[types.Float32],
types.Typ[types.Float64],
types.Typ[types.Complex64],
types.Typ[types.Complex128],
types.Typ[types.String],
// basic type aliases
types.Universe.Lookup("byte").Type(),
types.Universe.Lookup("rune").Type(),
// error
types.Universe.Lookup("error").Type(),
// untyped types
types.Typ[types.UntypedBool],
types.Typ[types.UntypedInt],
types.Typ[types.UntypedRune],
types.Typ[types.UntypedFloat],
types.Typ[types.UntypedComplex],
types.Typ[types.UntypedString],
types.Typ[types.UntypedNil],
// package unsafe
types.Typ[types.UnsafePointer],
// invalid type
types.Typ[types.Invalid], // only appears in packages with errors
// used internally by gc; never used by this package or in .a files
anyType{},
}
type anyType struct{}
func (t anyType) Underlying() types.Type { return t }
func (t anyType) String() string { return "any" }
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