/
read.go
928 lines (829 loc) · 25.7 KB
/
read.go
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// Copyright 2022 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 modindex
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"go/build"
"go/build/constraint"
"go/token"
"internal/goroot"
"internal/unsafeheader"
"io/fs"
"math"
"os"
"path"
"path/filepath"
"runtime"
"runtime/debug"
"sort"
"strings"
"sync"
"unsafe"
"cmd/go/internal/base"
"cmd/go/internal/cache"
"cmd/go/internal/cfg"
"cmd/go/internal/fsys"
"cmd/go/internal/imports"
"cmd/go/internal/par"
"cmd/go/internal/str"
)
// enabled is used to flag off the behavior of the module index on tip.
// It will be removed before the release.
// TODO(matloob): Remove enabled once we have more confidence on the
// module index.
var enabled = func() bool {
debug := strings.Split(os.Getenv("GODEBUG"), ",")
for _, f := range debug {
if f == "goindex=0" {
return false
}
}
return true
}()
// ModuleIndex represents and encoded module index file. It is used to
// do the equivalent of build.Import of packages in the module and answer other
// questions based on the index file's data.
type ModuleIndex struct {
modroot string
od offsetDecoder
packages map[string]int // offsets of each package
packagePaths []string // paths to package directories relative to modroot; these are the keys of packages
}
var fcache par.Cache
func moduleHash(modroot string, ismodcache bool) (cache.ActionID, error) {
h := cache.NewHash("moduleIndex")
fmt.Fprintf(h, "module index %s %s %v\n", runtime.Version(), indexVersion, modroot)
if ismodcache || str.HasFilePathPrefix(modroot, cfg.GOROOT) {
return h.Sum(), nil
}
// walkdir happens in deterministic order.
err := fsys.Walk(modroot, func(path string, info fs.FileInfo, err error) error {
if modroot == path {
// Check for go.mod in root directory, and return ErrNotIndexed
// if it doesn't exist. Outside the module cache, it's not a module
// if it doesn't have a go.mod file.
}
if err := moduleWalkErr(modroot, path, info, err); err != nil {
return err
}
if info.IsDir() {
return nil
}
fmt.Fprintf(h, "file %v %v\n", info.Name(), info.ModTime())
if info.Mode()&fs.ModeSymlink != 0 {
targ, err := fsys.Stat(path)
if err != nil {
return err
}
fmt.Fprintf(h, "target %v %v\n", targ.Name(), targ.ModTime())
}
return nil
})
if err != nil {
return cache.ActionID{}, err
}
return h.Sum(), nil
}
var modrootCache par.Cache
var ErrNotIndexed = errors.New("not in module index")
// Get returns the ModuleIndex for the module rooted at modroot.
// It will return ErrNotIndexed if the directory should be read without
// using the index, for instance because the index is disabled, or the packgae
// is not in a module.
func Get(modroot string) (*ModuleIndex, error) {
if !enabled || cache.DefaultDir() == "off" || cfg.BuildMod == "vendor" {
return nil, ErrNotIndexed
}
if modroot == "" {
panic("modindex.Get called with empty modroot")
}
modroot = filepath.Clean(modroot)
isModCache := str.HasFilePathPrefix(modroot, cfg.GOMODCACHE)
return openIndex(modroot, isModCache)
}
// openIndex returns the module index for modPath.
// It will return ErrNotIndexed if the module can not be read
// using the index because it contains symlinks.
func openIndex(modroot string, ismodcache bool) (*ModuleIndex, error) {
type result struct {
mi *ModuleIndex
err error
}
r := fcache.Do(modroot, func() any {
id, err := moduleHash(modroot, ismodcache)
if err != nil {
return result{nil, err}
}
data, _, err := cache.Default().GetMmap(id)
if err != nil {
// Couldn't read from modindex. Assume we couldn't read from
// the index because the module hasn't been indexed yet.
data, err = indexModule(modroot)
if err != nil {
return result{nil, err}
}
if err = cache.Default().PutBytes(id, data); err != nil {
return result{nil, err}
}
}
mi, err := fromBytes(modroot, data)
if err != nil {
return result{nil, err}
}
return result{mi, nil}
}).(result)
return r.mi, r.err
}
// fromBytes returns a *ModuleIndex given the encoded representation.
func fromBytes(moddir string, data []byte) (mi *ModuleIndex, err error) {
if !enabled {
panic("use of index")
}
// SetPanicOnFault's errors _may_ satisfy this interface. Even though it's not guaranteed
// that all its errors satisfy this interface, we'll only check for these errors so that
// we don't suppress panics that could have been produced from other sources.
type addrer interface {
Addr() uintptr
}
// set PanicOnFault to true so that we can catch errors on the initial reads of the slice,
// in case it's mmapped (the common case).
old := debug.SetPanicOnFault(true)
defer func() {
debug.SetPanicOnFault(old)
if e := recover(); e != nil {
if _, ok := e.(addrer); ok {
// This panic was almost certainly caused by SetPanicOnFault.
err = fmt.Errorf("error reading module index: %v", e)
return
}
// The panic was likely not caused by SetPanicOnFault.
panic(e)
}
}()
gotVersion, unread, _ := bytes.Cut(data, []byte{'\n'})
if string(gotVersion) != indexVersion {
return nil, fmt.Errorf("bad index version string: %q", gotVersion)
}
stringTableOffset, unread := binary.LittleEndian.Uint32(unread[:4]), unread[4:]
st := newStringTable(data[stringTableOffset:])
d := decoder{unread, st}
numPackages := d.int()
packagePaths := make([]string, numPackages)
for i := range packagePaths {
packagePaths[i] = d.string()
}
packageOffsets := make([]int, numPackages)
for i := range packageOffsets {
packageOffsets[i] = d.int()
}
packages := make(map[string]int, numPackages)
for i := range packagePaths {
packages[packagePaths[i]] = packageOffsets[i]
}
return &ModuleIndex{
moddir,
offsetDecoder{data, st},
packages,
packagePaths,
}, nil
}
// Returns a list of directory paths, relative to the modroot, for
// packages contained in the module index.
func (mi *ModuleIndex) Packages() []string {
return mi.packagePaths
}
// RelPath returns the path relative to the module's root.
func (mi *ModuleIndex) RelPath(path string) string {
return str.TrimFilePathPrefix(filepath.Clean(path), mi.modroot) // mi.modroot is already clean
}
// ImportPackage is the equivalent of build.Import given the information in ModuleIndex.
func (mi *ModuleIndex) Import(bctxt build.Context, relpath string, mode build.ImportMode) (p *build.Package, err error) {
rp := mi.indexPackage(relpath)
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("error reading module index: %v", e)
}
}()
ctxt := (*Context)(&bctxt)
p = &build.Package{}
p.ImportPath = "."
p.Dir = filepath.Join(mi.modroot, rp.dir)
var pkgerr error
switch ctxt.Compiler {
case "gccgo", "gc":
default:
// Save error for end of function.
pkgerr = fmt.Errorf("import %q: unknown compiler %q", p.Dir, ctxt.Compiler)
}
if p.Dir == "" {
return p, fmt.Errorf("import %q: import of unknown directory", p.Dir)
}
// goroot and gopath
inTestdata := func(sub string) bool {
return strings.Contains(sub, "/testdata/") || strings.HasSuffix(sub, "/testdata") || str.HasPathPrefix(sub, "testdata")
}
if !inTestdata(relpath) {
// In build.go, p.Root should only be set in the non-local-import case, or in
// GOROOT or GOPATH. Since module mode only calls Import with path set to "."
// and the module index doesn't apply outside modules, the GOROOT case is
// the only case where GOROOT needs to be set.
// But: p.Root is actually set in the local-import case outside GOROOT, if
// the directory is contained in GOPATH/src
// TODO(#37015): fix that behavior in go/build and remove the gopath case
// below.
if ctxt.GOROOT != "" && str.HasFilePathPrefix(p.Dir, cfg.GOROOTsrc) && p.Dir != cfg.GOROOTsrc {
p.Root = ctxt.GOROOT
p.Goroot = true
modprefix := str.TrimFilePathPrefix(mi.modroot, cfg.GOROOTsrc)
p.ImportPath = relpath
if modprefix != "" {
p.ImportPath = filepath.Join(modprefix, p.ImportPath)
}
}
for _, root := range ctxt.gopath() {
// TODO(matloob): do we need to reimplement the conflictdir logic?
// TODO(matloob): ctxt.hasSubdir evaluates symlinks, so it
// can be slower than we'd like. Find out if we can drop this
// logic before the release.
if sub, ok := ctxt.hasSubdir(filepath.Join(root, "src"), p.Dir); ok {
p.ImportPath = sub
p.Root = root
}
}
}
if p.Root != "" {
// Set GOROOT-specific fields (sometimes for modules in a GOPATH directory).
// The fields set below (SrcRoot, PkgRoot, BinDir, PkgTargetRoot, and PkgObj)
// are only set in build.Import if p.Root != "". As noted in the comment
// on setting p.Root above, p.Root should only be set in the GOROOT case for the
// set of packages we care about, but is also set for modules in a GOPATH src
// directory.
var pkgtargetroot string
var pkga string
suffix := ""
if ctxt.InstallSuffix != "" {
suffix = "_" + ctxt.InstallSuffix
}
switch ctxt.Compiler {
case "gccgo":
pkgtargetroot = "pkg/gccgo_" + ctxt.GOOS + "_" + ctxt.GOARCH + suffix
dir, elem := path.Split(p.ImportPath)
pkga = pkgtargetroot + "/" + dir + "lib" + elem + ".a"
case "gc":
pkgtargetroot = "pkg/" + ctxt.GOOS + "_" + ctxt.GOARCH + suffix
pkga = pkgtargetroot + "/" + p.ImportPath + ".a"
}
p.SrcRoot = ctxt.joinPath(p.Root, "src")
p.PkgRoot = ctxt.joinPath(p.Root, "pkg")
p.BinDir = ctxt.joinPath(p.Root, "bin")
if pkga != "" {
p.PkgTargetRoot = ctxt.joinPath(p.Root, pkgtargetroot)
p.PkgObj = ctxt.joinPath(p.Root, pkga)
}
}
if rp.error != nil {
if errors.Is(rp.error, errCannotFindPackage) && ctxt.Compiler == "gccgo" && p.Goroot {
return p, nil
}
return p, rp.error
}
if mode&build.FindOnly != 0 {
return p, pkgerr
}
// We need to do a second round of bad file processing.
var badGoError error
badFiles := make(map[string]bool)
badFile := func(name string, err error) {
if badGoError == nil {
badGoError = err
}
if !badFiles[name] {
p.InvalidGoFiles = append(p.InvalidGoFiles, name)
badFiles[name] = true
}
}
var Sfiles []string // files with ".S"(capital S)/.sx(capital s equivalent for case insensitive filesystems)
var firstFile string
embedPos := make(map[string][]token.Position)
testEmbedPos := make(map[string][]token.Position)
xTestEmbedPos := make(map[string][]token.Position)
importPos := make(map[string][]token.Position)
testImportPos := make(map[string][]token.Position)
xTestImportPos := make(map[string][]token.Position)
allTags := make(map[string]bool)
for _, tf := range rp.sourceFiles {
name := tf.name()
if error := tf.error(); error != "" {
badFile(name, errors.New(tf.error()))
continue
} else if parseError := tf.parseError(); parseError != "" {
badFile(name, parseErrorFromString(tf.parseError()))
// Fall through: we still want to list files with parse errors.
}
var shouldBuild = true
if !ctxt.goodOSArchFile(name, allTags) && !ctxt.UseAllFiles {
shouldBuild = false
} else if goBuildConstraint := tf.goBuildConstraint(); goBuildConstraint != "" {
x, err := constraint.Parse(goBuildConstraint)
if err != nil {
return p, fmt.Errorf("%s: parsing //go:build line: %v", name, err)
}
shouldBuild = ctxt.eval(x, allTags)
} else if plusBuildConstraints := tf.plusBuildConstraints(); len(plusBuildConstraints) > 0 {
for _, text := range plusBuildConstraints {
if x, err := constraint.Parse(text); err == nil {
if !ctxt.eval(x, allTags) {
shouldBuild = false
}
}
}
}
ext := nameExt(name)
if !shouldBuild || tf.ignoreFile() {
if ext == ".go" {
p.IgnoredGoFiles = append(p.IgnoredGoFiles, name)
} else if fileListForExt((*Package)(p), ext) != nil {
p.IgnoredOtherFiles = append(p.IgnoredOtherFiles, name)
}
continue
}
// Going to save the file. For non-Go files, can stop here.
switch ext {
case ".go":
// keep going
case ".S", ".sx":
// special case for cgo, handled at end
Sfiles = append(Sfiles, name)
continue
default:
if list := fileListForExt((*Package)(p), ext); list != nil {
*list = append(*list, name)
}
continue
}
pkg := tf.pkgName()
if pkg == "documentation" {
p.IgnoredGoFiles = append(p.IgnoredGoFiles, name)
continue
}
isTest := strings.HasSuffix(name, "_test.go")
isXTest := false
if isTest && strings.HasSuffix(tf.pkgName(), "_test") && p.Name != tf.pkgName() {
isXTest = true
pkg = pkg[:len(pkg)-len("_test")]
}
if !isTest && tf.binaryOnly() {
p.BinaryOnly = true
}
if p.Name == "" {
p.Name = pkg
firstFile = name
} else if pkg != p.Name {
// TODO(#45999): The choice of p.Name is arbitrary based on file iteration
// order. Instead of resolving p.Name arbitrarily, we should clear out the
// existing Name and mark the existing files as also invalid.
badFile(name, &MultiplePackageError{
Dir: p.Dir,
Packages: []string{p.Name, pkg},
Files: []string{firstFile, name},
})
}
// Grab the first package comment as docs, provided it is not from a test file.
if p.Doc == "" && !isTest && !isXTest {
if synopsis := tf.synopsis(); synopsis != "" {
p.Doc = synopsis
}
}
// Record Imports and information about cgo.
isCgo := false
imports := tf.imports()
for _, imp := range imports {
if imp.path == "C" {
if isTest {
badFile(name, fmt.Errorf("use of cgo in test %s not supported", name))
continue
}
isCgo = true
}
}
if directives := tf.cgoDirectives(); directives != "" {
if err := ctxt.saveCgo(name, (*Package)(p), directives); err != nil {
badFile(name, err)
}
}
var fileList *[]string
var importMap, embedMap map[string][]token.Position
switch {
case isCgo:
allTags["cgo"] = true
if ctxt.CgoEnabled {
fileList = &p.CgoFiles
importMap = importPos
embedMap = embedPos
} else {
// Ignore Imports and Embeds from cgo files if cgo is disabled.
fileList = &p.IgnoredGoFiles
}
case isXTest:
fileList = &p.XTestGoFiles
importMap = xTestImportPos
embedMap = xTestEmbedPos
case isTest:
fileList = &p.TestGoFiles
importMap = testImportPos
embedMap = testEmbedPos
default:
fileList = &p.GoFiles
importMap = importPos
embedMap = embedPos
}
*fileList = append(*fileList, name)
if importMap != nil {
for _, imp := range imports {
importMap[imp.path] = append(importMap[imp.path], imp.position)
}
}
if embedMap != nil {
for _, e := range tf.embeds() {
embedMap[e.pattern] = append(embedMap[e.pattern], e.position)
}
}
}
p.EmbedPatterns, p.EmbedPatternPos = cleanDecls(embedPos)
p.TestEmbedPatterns, p.TestEmbedPatternPos = cleanDecls(testEmbedPos)
p.XTestEmbedPatterns, p.XTestEmbedPatternPos = cleanDecls(xTestEmbedPos)
p.Imports, p.ImportPos = cleanDecls(importPos)
p.TestImports, p.TestImportPos = cleanDecls(testImportPos)
p.XTestImports, p.XTestImportPos = cleanDecls(xTestImportPos)
for tag := range allTags {
p.AllTags = append(p.AllTags, tag)
}
sort.Strings(p.AllTags)
if len(p.CgoFiles) > 0 {
p.SFiles = append(p.SFiles, Sfiles...)
sort.Strings(p.SFiles)
} else {
p.IgnoredOtherFiles = append(p.IgnoredOtherFiles, Sfiles...)
sort.Strings(p.IgnoredOtherFiles)
}
if badGoError != nil {
return p, badGoError
}
if len(p.GoFiles)+len(p.CgoFiles)+len(p.TestGoFiles)+len(p.XTestGoFiles) == 0 {
return p, &build.NoGoError{Dir: p.Dir}
}
return p, pkgerr
}
// IsStandardPackage reports whether path is a standard package
// for the goroot and compiler using the module index if possible,
// and otherwise falling back to internal/goroot.IsStandardPackage
func IsStandardPackage(goroot_, compiler, path string) bool {
if !enabled || compiler != "gc" {
return goroot.IsStandardPackage(goroot_, compiler, path)
}
reldir := filepath.FromSlash(path) // relative dir path in module index for package
modroot := filepath.Join(goroot_, "src")
if str.HasFilePathPrefix(reldir, "cmd") {
reldir = str.TrimFilePathPrefix(reldir, "cmd")
modroot = filepath.Join(modroot, "cmd")
}
mod, err := Get(modroot)
if err != nil {
return goroot.IsStandardPackage(goroot_, compiler, path)
}
pkgs := mod.Packages()
i := sort.SearchStrings(pkgs, reldir)
return i != len(pkgs) && pkgs[i] == reldir
}
// IsDirWithGoFiles is the equivalent of fsys.IsDirWithGoFiles using the information in the index.
func (mi *ModuleIndex) IsDirWithGoFiles(relpath string) (_ bool, err error) {
rp := mi.indexPackage(relpath)
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("error reading module index: %v", e)
}
}()
for _, sf := range rp.sourceFiles {
if strings.HasSuffix(sf.name(), ".go") {
return true, nil
}
}
return false, nil
}
// ScanDir implements imports.ScanDir using the information in the index.
func (mi *ModuleIndex) ScanDir(path string, tags map[string]bool) (sortedImports []string, sortedTestImports []string, err error) {
rp := mi.indexPackage(path)
// TODO(matloob) dir should eventually be relative to indexed directory
// TODO(matloob): skip reading raw package and jump straight to data we need?
defer func() {
if e := recover(); e != nil {
err = fmt.Errorf("error reading module index: %v", e)
}
}()
imports_ := make(map[string]bool)
testImports := make(map[string]bool)
numFiles := 0
Files:
for _, sf := range rp.sourceFiles {
name := sf.name()
if strings.HasPrefix(name, "_") || strings.HasPrefix(name, ".") || !strings.HasSuffix(name, ".go") || !imports.MatchFile(name, tags) {
continue
}
// The following section exists for backwards compatibility reasons:
// scanDir ignores files with import "C" when collecting the list
// of imports unless the "cgo" tag is provided. The following comment
// is copied from the original.
//
// import "C" is implicit requirement of cgo tag.
// When listing files on the command line (explicitFiles=true)
// we do not apply build tag filtering but we still do apply
// cgo filtering, so no explicitFiles check here.
// Why? Because we always have, and it's not worth breaking
// that behavior now.
imps := sf.imports() // TODO(matloob): directly read import paths to avoid the extra strings?
for _, imp := range imps {
if imp.path == "C" && !tags["cgo"] && !tags["*"] {
continue Files
}
}
if !shouldBuild(sf, tags) {
continue
}
numFiles++
m := imports_
if strings.HasSuffix(name, "_test.go") {
m = testImports
}
for _, p := range imps {
m[p.path] = true
}
}
if numFiles == 0 {
return nil, nil, imports.ErrNoGo
}
return keys(imports_), keys(testImports), nil
}
func keys(m map[string]bool) []string {
list := make([]string, 0, len(m))
for k := range m {
list = append(list, k)
}
sort.Strings(list)
return list
}
// implements imports.ShouldBuild in terms of an index sourcefile.
func shouldBuild(sf *sourceFile, tags map[string]bool) bool {
if goBuildConstraint := sf.goBuildConstraint(); goBuildConstraint != "" {
x, err := constraint.Parse(goBuildConstraint)
if err != nil {
return false
}
return imports.Eval(x, tags, true)
}
plusBuildConstraints := sf.plusBuildConstraints()
for _, text := range plusBuildConstraints {
if x, err := constraint.Parse(text); err == nil {
if imports.Eval(x, tags, true) == false {
return false
}
}
}
return true
}
// index package holds the information needed to access information in the
// index about a package.
type indexPackage struct {
error error
dir string // directory of the package relative to the modroot
// Source files
sourceFiles []*sourceFile
}
var errCannotFindPackage = errors.New("cannot find package")
// indexPackage returns an indexPackage constructed using the information in the ModuleIndex.
func (mi *ModuleIndex) indexPackage(path string) *indexPackage {
defer func() {
if e := recover(); e != nil {
base.Fatalf("error reading module index: %v", e)
}
}()
offset, ok := mi.packages[path]
if !ok {
return &indexPackage{error: fmt.Errorf("%w %q in:\n\t%s", errCannotFindPackage, path, filepath.Join(mi.modroot, path))}
}
// TODO(matloob): do we want to lock on the module index?
d := mi.od.decoderAt(offset)
rp := new(indexPackage)
if errstr := d.string(); errstr != "" {
rp.error = errors.New(errstr)
}
rp.dir = d.string()
numSourceFiles := d.uint32()
rp.sourceFiles = make([]*sourceFile, numSourceFiles)
for i := uint32(0); i < numSourceFiles; i++ {
offset := d.uint32()
rp.sourceFiles[i] = &sourceFile{
od: mi.od.offsetDecoderAt(offset),
}
}
return rp
}
// sourceFile represents the information of a given source file in the module index.
type sourceFile struct {
od offsetDecoder // od interprets all offsets relative to the start of the source file's data
onceReadImports sync.Once
savedImports []rawImport // saved imports so that they're only read once
}
// Offsets for fields in the sourceFile.
const (
sourceFileError = 4 * iota
sourceFileParseError
sourceFileSynopsis
sourceFileName
sourceFilePkgName
sourceFileIgnoreFile
sourceFileBinaryOnly
sourceFileCgoDirectives
sourceFileGoBuildConstraint
sourceFileNumPlusBuildConstraints
)
func (sf *sourceFile) error() string {
return sf.od.stringAt(sourceFileError)
}
func (sf *sourceFile) parseError() string {
return sf.od.stringAt(sourceFileParseError)
}
func (sf *sourceFile) name() string {
return sf.od.stringAt(sourceFileName)
}
func (sf *sourceFile) synopsis() string {
return sf.od.stringAt(sourceFileSynopsis)
}
func (sf *sourceFile) pkgName() string {
return sf.od.stringAt(sourceFilePkgName)
}
func (sf *sourceFile) ignoreFile() bool {
return sf.od.boolAt(sourceFileIgnoreFile)
}
func (sf *sourceFile) binaryOnly() bool {
return sf.od.boolAt(sourceFileBinaryOnly)
}
func (sf *sourceFile) cgoDirectives() string {
return sf.od.stringAt(sourceFileCgoDirectives)
}
func (sf *sourceFile) goBuildConstraint() string {
return sf.od.stringAt(sourceFileGoBuildConstraint)
}
func (sf *sourceFile) plusBuildConstraints() []string {
d := sf.od.decoderAt(sourceFileNumPlusBuildConstraints)
n := d.int()
ret := make([]string, n)
for i := 0; i < n; i++ {
ret[i] = d.string()
}
return ret
}
func importsOffset(numPlusBuildConstraints int) int {
// 4 bytes per uin32, add one to advance past numPlusBuildConstraints itself
return sourceFileNumPlusBuildConstraints + 4*(numPlusBuildConstraints+1)
}
func (sf *sourceFile) importsOffset() int {
numPlusBuildConstraints := sf.od.intAt(sourceFileNumPlusBuildConstraints)
return importsOffset(numPlusBuildConstraints)
}
func embedsOffset(importsOffset, numImports int) int {
// 4 bytes per uint32; 1 to advance past numImports itself, and 5 uint32s per import
return importsOffset + 4*(1+(5*numImports))
}
func (sf *sourceFile) embedsOffset() int {
importsOffset := sf.importsOffset()
numImports := sf.od.intAt(importsOffset)
return embedsOffset(importsOffset, numImports)
}
func (sf *sourceFile) imports() []rawImport {
sf.onceReadImports.Do(func() {
importsOffset := sf.importsOffset()
d := sf.od.decoderAt(importsOffset)
numImports := d.int()
ret := make([]rawImport, numImports)
for i := 0; i < numImports; i++ {
ret[i].path = d.string()
ret[i].position = d.tokpos()
}
sf.savedImports = ret
})
return sf.savedImports
}
func (sf *sourceFile) embeds() []embed {
embedsOffset := sf.embedsOffset()
d := sf.od.decoderAt(embedsOffset)
numEmbeds := d.int()
ret := make([]embed, numEmbeds)
for i := range ret {
pattern := d.string()
pos := d.tokpos()
ret[i] = embed{pattern, pos}
}
return ret
}
// A decoder reads from the current position of the file and advances its position as it
// reads.
type decoder struct {
b []byte
st *stringTable
}
func (d *decoder) uint32() uint32 {
n := binary.LittleEndian.Uint32(d.b[:4])
d.b = d.b[4:]
return n
}
func (d *decoder) int() int {
n := d.uint32()
if int64(n) > math.MaxInt {
base.Fatalf("go: attempting to read a uint32 from the index that overflows int")
}
return int(n)
}
func (d *decoder) tokpos() token.Position {
file := d.string()
offset := d.int()
line := d.int()
column := d.int()
return token.Position{
Filename: file,
Offset: offset,
Line: line,
Column: column,
}
}
func (d *decoder) string() string {
return d.st.string(d.int())
}
// And offset decoder reads information offset from its position in the file.
// It's either offset from the beginning of the index, or the beginning of a sourceFile's data.
type offsetDecoder struct {
b []byte
st *stringTable
}
func (od *offsetDecoder) uint32At(offset int) uint32 {
if offset > len(od.b) {
base.Fatalf("go: trying to read from index file at offset higher than file length. This indicates a corrupt offset file in the cache.")
}
return binary.LittleEndian.Uint32(od.b[offset:])
}
func (od *offsetDecoder) intAt(offset int) int {
n := od.uint32At(offset)
if int64(n) > math.MaxInt {
base.Fatalf("go: attempting to read a uint32 from the index that overflows int")
}
return int(n)
}
func (od *offsetDecoder) boolAt(offset int) bool {
switch v := od.uint32At(offset); v {
case 0:
return false
case 1:
return true
default:
base.Fatalf("go: invalid bool value in index file encoding: %v", v)
}
panic("unreachable")
}
func (od *offsetDecoder) stringAt(offset int) string {
return od.st.string(od.intAt(offset))
}
func (od *offsetDecoder) decoderAt(offset int) *decoder {
return &decoder{od.b[offset:], od.st}
}
func (od *offsetDecoder) offsetDecoderAt(offset uint32) offsetDecoder {
return offsetDecoder{od.b[offset:], od.st}
}
type stringTable struct {
b []byte
}
func newStringTable(b []byte) *stringTable {
return &stringTable{b: b}
}
func (st *stringTable) string(pos int) string {
if pos == 0 {
return ""
}
bb := st.b[pos:]
i := bytes.IndexByte(bb, 0)
if i == -1 {
panic("reached end of string table trying to read string")
}
s := asString(bb[:i])
return s
}
func asString(b []byte) string {
p := (*unsafeheader.Slice)(unsafe.Pointer(&b)).Data
var s string
hdr := (*unsafeheader.String)(unsafe.Pointer(&s))
hdr.Data = p
hdr.Len = len(b)
return s
}