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-rw-r--r--src/go/build/read.go612
1 files changed, 612 insertions, 0 deletions
diff --git a/src/go/build/read.go b/src/go/build/read.go
new file mode 100644
index 0000000..5289197
--- /dev/null
+++ b/src/go/build/read.go
@@ -0,0 +1,612 @@
+// Copyright 2012 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 build
+
+import (
+ "bufio"
+ "bytes"
+ "errors"
+ "fmt"
+ "go/ast"
+ "go/parser"
+ "go/scanner"
+ "go/token"
+ "io"
+ "strconv"
+ "strings"
+ "unicode"
+ "unicode/utf8"
+)
+
+type importReader struct {
+ b *bufio.Reader
+ buf []byte
+ peek byte
+ err error
+ eof bool
+ nerr int
+ pos token.Position
+}
+
+var bom = []byte{0xef, 0xbb, 0xbf}
+
+func newImportReader(name string, r io.Reader) *importReader {
+ b := bufio.NewReader(r)
+ // Remove leading UTF-8 BOM.
+ // Per https://golang.org/ref/spec#Source_code_representation:
+ // a compiler may ignore a UTF-8-encoded byte order mark (U+FEFF)
+ // if it is the first Unicode code point in the source text.
+ if leadingBytes, err := b.Peek(3); err == nil && bytes.Equal(leadingBytes, bom) {
+ b.Discard(3)
+ }
+ return &importReader{
+ b: b,
+ pos: token.Position{
+ Filename: name,
+ Line: 1,
+ Column: 1,
+ },
+ }
+}
+
+func isIdent(c byte) bool {
+ return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '_' || c >= utf8.RuneSelf
+}
+
+var (
+ errSyntax = errors.New("syntax error")
+ errNUL = errors.New("unexpected NUL in input")
+)
+
+// syntaxError records a syntax error, but only if an I/O error has not already been recorded.
+func (r *importReader) syntaxError() {
+ if r.err == nil {
+ r.err = errSyntax
+ }
+}
+
+// readByte reads the next byte from the input, saves it in buf, and returns it.
+// If an error occurs, readByte records the error in r.err and returns 0.
+func (r *importReader) readByte() byte {
+ c, err := r.b.ReadByte()
+ if err == nil {
+ r.buf = append(r.buf, c)
+ if c == 0 {
+ err = errNUL
+ }
+ }
+ if err != nil {
+ if err == io.EOF {
+ r.eof = true
+ } else if r.err == nil {
+ r.err = err
+ }
+ c = 0
+ }
+ return c
+}
+
+// readByteNoBuf is like readByte but doesn't buffer the byte.
+// It exhausts r.buf before reading from r.b.
+func (r *importReader) readByteNoBuf() byte {
+ var c byte
+ var err error
+ if len(r.buf) > 0 {
+ c = r.buf[0]
+ r.buf = r.buf[1:]
+ } else {
+ c, err = r.b.ReadByte()
+ if err == nil && c == 0 {
+ err = errNUL
+ }
+ }
+
+ if err != nil {
+ if err == io.EOF {
+ r.eof = true
+ } else if r.err == nil {
+ r.err = err
+ }
+ return 0
+ }
+ r.pos.Offset++
+ if c == '\n' {
+ r.pos.Line++
+ r.pos.Column = 1
+ } else {
+ r.pos.Column++
+ }
+ return c
+}
+
+// peekByte returns the next byte from the input reader but does not advance beyond it.
+// If skipSpace is set, peekByte skips leading spaces and comments.
+func (r *importReader) peekByte(skipSpace bool) byte {
+ if r.err != nil {
+ if r.nerr++; r.nerr > 10000 {
+ panic("go/build: import reader looping")
+ }
+ return 0
+ }
+
+ // Use r.peek as first input byte.
+ // Don't just return r.peek here: it might have been left by peekByte(false)
+ // and this might be peekByte(true).
+ c := r.peek
+ if c == 0 {
+ c = r.readByte()
+ }
+ for r.err == nil && !r.eof {
+ if skipSpace {
+ // For the purposes of this reader, semicolons are never necessary to
+ // understand the input and are treated as spaces.
+ switch c {
+ case ' ', '\f', '\t', '\r', '\n', ';':
+ c = r.readByte()
+ continue
+
+ case '/':
+ c = r.readByte()
+ if c == '/' {
+ for c != '\n' && r.err == nil && !r.eof {
+ c = r.readByte()
+ }
+ } else if c == '*' {
+ var c1 byte
+ for (c != '*' || c1 != '/') && r.err == nil {
+ if r.eof {
+ r.syntaxError()
+ }
+ c, c1 = c1, r.readByte()
+ }
+ } else {
+ r.syntaxError()
+ }
+ c = r.readByte()
+ continue
+ }
+ }
+ break
+ }
+ r.peek = c
+ return r.peek
+}
+
+// nextByte is like peekByte but advances beyond the returned byte.
+func (r *importReader) nextByte(skipSpace bool) byte {
+ c := r.peekByte(skipSpace)
+ r.peek = 0
+ return c
+}
+
+var goEmbed = []byte("go:embed")
+
+// findEmbed advances the input reader to the next //go:embed comment.
+// It reports whether it found a comment.
+// (Otherwise it found an error or EOF.)
+func (r *importReader) findEmbed(first bool) bool {
+ // The import block scan stopped after a non-space character,
+ // so the reader is not at the start of a line on the first call.
+ // After that, each //go:embed extraction leaves the reader
+ // at the end of a line.
+ startLine := !first
+ var c byte
+ for r.err == nil && !r.eof {
+ c = r.readByteNoBuf()
+ Reswitch:
+ switch c {
+ default:
+ startLine = false
+
+ case '\n':
+ startLine = true
+
+ case ' ', '\t':
+ // leave startLine alone
+
+ case '"':
+ startLine = false
+ for r.err == nil {
+ if r.eof {
+ r.syntaxError()
+ }
+ c = r.readByteNoBuf()
+ if c == '\\' {
+ r.readByteNoBuf()
+ if r.err != nil {
+ r.syntaxError()
+ return false
+ }
+ continue
+ }
+ if c == '"' {
+ c = r.readByteNoBuf()
+ goto Reswitch
+ }
+ }
+ goto Reswitch
+
+ case '`':
+ startLine = false
+ for r.err == nil {
+ if r.eof {
+ r.syntaxError()
+ }
+ c = r.readByteNoBuf()
+ if c == '`' {
+ c = r.readByteNoBuf()
+ goto Reswitch
+ }
+ }
+
+ case '\'':
+ startLine = false
+ for r.err == nil {
+ if r.eof {
+ r.syntaxError()
+ }
+ c = r.readByteNoBuf()
+ if c == '\\' {
+ r.readByteNoBuf()
+ if r.err != nil {
+ r.syntaxError()
+ return false
+ }
+ continue
+ }
+ if c == '\'' {
+ c = r.readByteNoBuf()
+ goto Reswitch
+ }
+ }
+
+ case '/':
+ c = r.readByteNoBuf()
+ switch c {
+ default:
+ startLine = false
+ goto Reswitch
+
+ case '*':
+ var c1 byte
+ for (c != '*' || c1 != '/') && r.err == nil {
+ if r.eof {
+ r.syntaxError()
+ }
+ c, c1 = c1, r.readByteNoBuf()
+ }
+ startLine = false
+
+ case '/':
+ if startLine {
+ // Try to read this as a //go:embed comment.
+ for i := range goEmbed {
+ c = r.readByteNoBuf()
+ if c != goEmbed[i] {
+ goto SkipSlashSlash
+ }
+ }
+ c = r.readByteNoBuf()
+ if c == ' ' || c == '\t' {
+ // Found one!
+ return true
+ }
+ }
+ SkipSlashSlash:
+ for c != '\n' && r.err == nil && !r.eof {
+ c = r.readByteNoBuf()
+ }
+ startLine = true
+ }
+ }
+ }
+ return false
+}
+
+// readKeyword reads the given keyword from the input.
+// If the keyword is not present, readKeyword records a syntax error.
+func (r *importReader) readKeyword(kw string) {
+ r.peekByte(true)
+ for i := 0; i < len(kw); i++ {
+ if r.nextByte(false) != kw[i] {
+ r.syntaxError()
+ return
+ }
+ }
+ if isIdent(r.peekByte(false)) {
+ r.syntaxError()
+ }
+}
+
+// readIdent reads an identifier from the input.
+// If an identifier is not present, readIdent records a syntax error.
+func (r *importReader) readIdent() {
+ c := r.peekByte(true)
+ if !isIdent(c) {
+ r.syntaxError()
+ return
+ }
+ for isIdent(r.peekByte(false)) {
+ r.peek = 0
+ }
+}
+
+// readString reads a quoted string literal from the input.
+// If an identifier is not present, readString records a syntax error.
+func (r *importReader) readString() {
+ switch r.nextByte(true) {
+ case '`':
+ for r.err == nil {
+ if r.nextByte(false) == '`' {
+ break
+ }
+ if r.eof {
+ r.syntaxError()
+ }
+ }
+ case '"':
+ for r.err == nil {
+ c := r.nextByte(false)
+ if c == '"' {
+ break
+ }
+ if r.eof || c == '\n' {
+ r.syntaxError()
+ }
+ if c == '\\' {
+ r.nextByte(false)
+ }
+ }
+ default:
+ r.syntaxError()
+ }
+}
+
+// readImport reads an import clause - optional identifier followed by quoted string -
+// from the input.
+func (r *importReader) readImport() {
+ c := r.peekByte(true)
+ if c == '.' {
+ r.peek = 0
+ } else if isIdent(c) {
+ r.readIdent()
+ }
+ r.readString()
+}
+
+// readComments is like io.ReadAll, except that it only reads the leading
+// block of comments in the file.
+func readComments(f io.Reader) ([]byte, error) {
+ r := newImportReader("", f)
+ r.peekByte(true)
+ if r.err == nil && !r.eof {
+ // Didn't reach EOF, so must have found a non-space byte. Remove it.
+ r.buf = r.buf[:len(r.buf)-1]
+ }
+ return r.buf, r.err
+}
+
+// readGoInfo expects a Go file as input and reads the file up to and including the import section.
+// It records what it learned in *info.
+// If info.fset is non-nil, readGoInfo parses the file and sets info.parsed, info.parseErr,
+// info.imports and info.embeds.
+//
+// It only returns an error if there are problems reading the file,
+// not for syntax errors in the file itself.
+func readGoInfo(f io.Reader, info *fileInfo) error {
+ r := newImportReader(info.name, f)
+
+ r.readKeyword("package")
+ r.readIdent()
+ for r.peekByte(true) == 'i' {
+ r.readKeyword("import")
+ if r.peekByte(true) == '(' {
+ r.nextByte(false)
+ for r.peekByte(true) != ')' && r.err == nil {
+ r.readImport()
+ }
+ r.nextByte(false)
+ } else {
+ r.readImport()
+ }
+ }
+
+ info.header = r.buf
+
+ // If we stopped successfully before EOF, we read a byte that told us we were done.
+ // Return all but that last byte, which would cause a syntax error if we let it through.
+ if r.err == nil && !r.eof {
+ info.header = r.buf[:len(r.buf)-1]
+ }
+
+ // If we stopped for a syntax error, consume the whole file so that
+ // we are sure we don't change the errors that go/parser returns.
+ if r.err == errSyntax {
+ r.err = nil
+ for r.err == nil && !r.eof {
+ r.readByte()
+ }
+ info.header = r.buf
+ }
+ if r.err != nil {
+ return r.err
+ }
+
+ if info.fset == nil {
+ return nil
+ }
+
+ // Parse file header & record imports.
+ info.parsed, info.parseErr = parser.ParseFile(info.fset, info.name, info.header, parser.ImportsOnly|parser.ParseComments)
+ if info.parseErr != nil {
+ return nil
+ }
+
+ hasEmbed := false
+ for _, decl := range info.parsed.Decls {
+ d, ok := decl.(*ast.GenDecl)
+ if !ok {
+ continue
+ }
+ for _, dspec := range d.Specs {
+ spec, ok := dspec.(*ast.ImportSpec)
+ if !ok {
+ continue
+ }
+ quoted := spec.Path.Value
+ path, err := strconv.Unquote(quoted)
+ if err != nil {
+ return fmt.Errorf("parser returned invalid quoted string: <%s>", quoted)
+ }
+ if !isValidImport(path) {
+ // The parser used to return a parse error for invalid import paths, but
+ // no longer does, so check for and create the error here instead.
+ info.parseErr = scanner.Error{Pos: info.fset.Position(spec.Pos()), Msg: "invalid import path: " + path}
+ info.imports = nil
+ return nil
+ }
+ if path == "embed" {
+ hasEmbed = true
+ }
+
+ doc := spec.Doc
+ if doc == nil && len(d.Specs) == 1 {
+ doc = d.Doc
+ }
+ info.imports = append(info.imports, fileImport{path, spec.Pos(), doc})
+ }
+ }
+
+ // Extract directives.
+ for _, group := range info.parsed.Comments {
+ if group.Pos() >= info.parsed.Package {
+ break
+ }
+ for _, c := range group.List {
+ if strings.HasPrefix(c.Text, "//go:") {
+ info.directives = append(info.directives, Directive{c.Text, info.fset.Position(c.Slash)})
+ }
+ }
+ }
+
+ // If the file imports "embed",
+ // we have to look for //go:embed comments
+ // in the remainder of the file.
+ // The compiler will enforce the mapping of comments to
+ // declared variables. We just need to know the patterns.
+ // If there were //go:embed comments earlier in the file
+ // (near the package statement or imports), the compiler
+ // will reject them. They can be (and have already been) ignored.
+ if hasEmbed {
+ var line []byte
+ for first := true; r.findEmbed(first); first = false {
+ line = line[:0]
+ pos := r.pos
+ for {
+ c := r.readByteNoBuf()
+ if c == '\n' || r.err != nil || r.eof {
+ break
+ }
+ line = append(line, c)
+ }
+ // Add args if line is well-formed.
+ // Ignore badly-formed lines - the compiler will report them when it finds them,
+ // and we can pretend they are not there to help go list succeed with what it knows.
+ embs, err := parseGoEmbed(string(line), pos)
+ if err == nil {
+ info.embeds = append(info.embeds, embs...)
+ }
+ }
+ }
+
+ return nil
+}
+
+// isValidImport checks if the import is a valid import using the more strict
+// checks allowed by the implementation restriction in https://go.dev/ref/spec#Import_declarations.
+// It was ported from the function of the same name that was removed from the
+// parser in CL 424855, when the parser stopped doing these checks.
+func isValidImport(s string) bool {
+ const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
+ for _, r := range s {
+ if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
+ return false
+ }
+ }
+ return s != ""
+}
+
+// parseGoEmbed parses the text following "//go:embed" to extract the glob patterns.
+// It accepts unquoted space-separated patterns as well as double-quoted and back-quoted Go strings.
+// This is based on a similar function in cmd/compile/internal/gc/noder.go;
+// this version calculates position information as well.
+func parseGoEmbed(args string, pos token.Position) ([]fileEmbed, error) {
+ trimBytes := func(n int) {
+ pos.Offset += n
+ pos.Column += utf8.RuneCountInString(args[:n])
+ args = args[n:]
+ }
+ trimSpace := func() {
+ trim := strings.TrimLeftFunc(args, unicode.IsSpace)
+ trimBytes(len(args) - len(trim))
+ }
+
+ var list []fileEmbed
+ for trimSpace(); args != ""; trimSpace() {
+ var path string
+ pathPos := pos
+ Switch:
+ switch args[0] {
+ default:
+ i := len(args)
+ for j, c := range args {
+ if unicode.IsSpace(c) {
+ i = j
+ break
+ }
+ }
+ path = args[:i]
+ trimBytes(i)
+
+ case '`':
+ var ok bool
+ path, _, ok = strings.Cut(args[1:], "`")
+ if !ok {
+ return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
+ }
+ trimBytes(1 + len(path) + 1)
+
+ case '"':
+ i := 1
+ for ; i < len(args); i++ {
+ if args[i] == '\\' {
+ i++
+ continue
+ }
+ if args[i] == '"' {
+ q, err := strconv.Unquote(args[:i+1])
+ if err != nil {
+ return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args[:i+1])
+ }
+ path = q
+ trimBytes(i + 1)
+ break Switch
+ }
+ }
+ if i >= len(args) {
+ return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
+ }
+ }
+
+ if args != "" {
+ r, _ := utf8.DecodeRuneInString(args)
+ if !unicode.IsSpace(r) {
+ return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
+ }
+ }
+ list = append(list, fileEmbed{path, pathPos})
+ }
+ return list, nil
+}
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