1 files changed, 601 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/noder/import.go b/src/cmd/compile/internal/noder/import.go
new file mode 100644
index 0000000..58dffba
--- /dev/null
+++ b/src/cmd/compile/internal/noder/import.go
@@ -0,0 +1,601 @@
+// Copyright 2009 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 noder
+
+import (
+	"errors"
+	"fmt"
+	"internal/buildcfg"
+	"os"
+	pathpkg "path"
+	"runtime"
+	"sort"
+	"strconv"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/importer"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/compile/internal/types2"
+	"cmd/internal/archive"
+	"cmd/internal/bio"
+	"cmd/internal/goobj"
+	"cmd/internal/objabi"
+	"cmd/internal/src"
+)
+
+// haveLegacyImports records whether we've imported any packages
+// without a new export data section. This is useful for experimenting
+// with new export data format designs, when you need to support
+// existing tests that manually compile files with inconsistent
+// compiler flags.
+var haveLegacyImports = false
+
+// newReadImportFunc is an extension hook for experimenting with new
+// export data formats. If a new export data payload was written out
+// for an imported package by overloading writeNewExportFunc, then
+// that payload will be mapped into memory and passed to
+// newReadImportFunc.
+var newReadImportFunc = func(data string, pkg1 *types.Pkg, env *types2.Context, packages map[string]*types2.Package) (pkg2 *types2.Package, err error) {
+	panic("unexpected new export data payload")
+}
+
+type gcimports struct {
+	ctxt     *types2.Context
+	packages map[string]*types2.Package
+}
+
+func (m *gcimports) Import(path string) (*types2.Package, error) {
+	return m.ImportFrom(path, "" /* no vendoring */, 0)
+}
+
+func (m *gcimports) ImportFrom(path, srcDir string, mode types2.ImportMode) (*types2.Package, error) {
+	if mode != 0 {
+		panic("mode must be 0")
+	}
+
+	_, pkg, err := readImportFile(path, typecheck.Target, m.ctxt, m.packages)
+	return pkg, err
+}
+
+func isDriveLetter(b byte) bool {
+	return 'a' <= b && b <= 'z' || 'A' <= b && b <= 'Z'
+}
+
+// is this path a local name? begins with ./ or ../ or /
+func islocalname(name string) bool {
+	return strings.HasPrefix(name, "/") ||
+		runtime.GOOS == "windows" && len(name) >= 3 && isDriveLetter(name[0]) && name[1] == ':' && name[2] == '/' ||
+		strings.HasPrefix(name, "./") || name == "." ||
+		strings.HasPrefix(name, "../") || name == ".."
+}
+
+func openPackage(path string) (*os.File, error) {
+	if islocalname(path) {
+		if base.Flag.NoLocalImports {
+			return nil, errors.New("local imports disallowed")
+		}
+
+		if base.Flag.Cfg.PackageFile != nil {
+			return os.Open(base.Flag.Cfg.PackageFile[path])
+		}
+
+		// try .a before .o.  important for building libraries:
+		// if there is an array.o in the array.a library,
+		// want to find all of array.a, not just array.o.
+		if file, err := os.Open(fmt.Sprintf("%s.a", path)); err == nil {
+			return file, nil
+		}
+		if file, err := os.Open(fmt.Sprintf("%s.o", path)); err == nil {
+			return file, nil
+		}
+		return nil, errors.New("file not found")
+	}
+
+	// local imports should be canonicalized already.
+	// don't want to see "encoding/../encoding/base64"
+	// as different from "encoding/base64".
+	if q := pathpkg.Clean(path); q != path {
+		return nil, fmt.Errorf("non-canonical import path %q (should be %q)", path, q)
+	}
+
+	if base.Flag.Cfg.PackageFile != nil {
+		return os.Open(base.Flag.Cfg.PackageFile[path])
+	}
+
+	for _, dir := range base.Flag.Cfg.ImportDirs {
+		if file, err := os.Open(fmt.Sprintf("%s/%s.a", dir, path)); err == nil {
+			return file, nil
+		}
+		if file, err := os.Open(fmt.Sprintf("%s/%s.o", dir, path)); err == nil {
+			return file, nil
+		}
+	}
+
+	if buildcfg.GOROOT != "" {
+		suffix := ""
+		if base.Flag.InstallSuffix != "" {
+			suffix = "_" + base.Flag.InstallSuffix
+		} else if base.Flag.Race {
+			suffix = "_race"
+		} else if base.Flag.MSan {
+			suffix = "_msan"
+		} else if base.Flag.ASan {
+			suffix = "_asan"
+		}
+
+		if file, err := os.Open(fmt.Sprintf("%s/pkg/%s_%s%s/%s.a", buildcfg.GOROOT, buildcfg.GOOS, buildcfg.GOARCH, suffix, path)); err == nil {
+			return file, nil
+		}
+		if file, err := os.Open(fmt.Sprintf("%s/pkg/%s_%s%s/%s.o", buildcfg.GOROOT, buildcfg.GOOS, buildcfg.GOARCH, suffix, path)); err == nil {
+			return file, nil
+		}
+	}
+	return nil, errors.New("file not found")
+}
+
+// myheight tracks the local package's height based on packages
+// imported so far.
+var myheight int
+
+// resolveImportPath resolves an import path as it appears in a Go
+// source file to the package's full path.
+func resolveImportPath(path string) (string, error) {
+	// The package name main is no longer reserved,
+	// but we reserve the import path "main" to identify
+	// the main package, just as we reserve the import
+	// path "math" to identify the standard math package.
+	if path == "main" {
+		return "", errors.New("cannot import \"main\"")
+	}
+
+	if base.Ctxt.Pkgpath != "" && path == base.Ctxt.Pkgpath {
+		return "", fmt.Errorf("import %q while compiling that package (import cycle)", path)
+	}
+
+	if mapped, ok := base.Flag.Cfg.ImportMap[path]; ok {
+		path = mapped
+	}
+
+	if islocalname(path) {
+		if path[0] == '/' {
+			return "", errors.New("import path cannot be absolute path")
+		}
+
+		prefix := base.Flag.D
+		if prefix == "" {
+			// Questionable, but when -D isn't specified, historically we
+			// resolve local import paths relative to the directory the
+			// compiler's current directory, not the respective source
+			// file's directory.
+			prefix = base.Ctxt.Pathname
+		}
+		path = pathpkg.Join(prefix, path)
+
+		if err := checkImportPath(path, true); err != nil {
+			return "", err
+		}
+	}
+
+	return path, nil
+}
+
+func importfile(decl *syntax.ImportDecl) *types.Pkg {
+	path, err := parseImportPath(decl.Path)
+	if err != nil {
+		base.Errorf("%s", err)
+		return nil
+	}
+
+	pkg, _, err := readImportFile(path, typecheck.Target, nil, nil)
+	if err != nil {
+		base.Errorf("%s", err)
+		return nil
+	}
+
+	if pkg != types.UnsafePkg && pkg.Height >= myheight {
+		myheight = pkg.Height + 1
+	}
+	return pkg
+}
+
+func parseImportPath(pathLit *syntax.BasicLit) (string, error) {
+	if pathLit.Kind != syntax.StringLit {
+		return "", errors.New("import path must be a string")
+	}
+
+	path, err := strconv.Unquote(pathLit.Value)
+	if err != nil {
+		return "", errors.New("import path must be a string")
+	}
+
+	if err := checkImportPath(path, false); err != nil {
+		return "", err
+	}
+
+	return path, err
+}
+
+// readImportFile reads the import file for the given package path and
+// returns its types.Pkg representation. If packages is non-nil, the
+// types2.Package representation is also returned.
+func readImportFile(path string, target *ir.Package, env *types2.Context, packages map[string]*types2.Package) (pkg1 *types.Pkg, pkg2 *types2.Package, err error) {
+	path, err = resolveImportPath(path)
+	if err != nil {
+		return
+	}
+
+	if path == "unsafe" {
+		pkg1, pkg2 = types.UnsafePkg, types2.Unsafe
+
+		// TODO(mdempsky): Investigate if this actually matters. Why would
+		// the linker or runtime care whether a package imported unsafe?
+		if !pkg1.Direct {
+			pkg1.Direct = true
+			target.Imports = append(target.Imports, pkg1)
+		}
+
+		return
+	}
+
+	pkg1 = types.NewPkg(path, "")
+	if packages != nil {
+		pkg2 = packages[path]
+		assert(pkg1.Direct == (pkg2 != nil && pkg2.Complete()))
+	}
+
+	if pkg1.Direct {
+		return
+	}
+	pkg1.Direct = true
+	target.Imports = append(target.Imports, pkg1)
+
+	f, err := openPackage(path)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+
+	r, end, newsize, err := findExportData(f)
+	if err != nil {
+		return
+	}
+
+	if base.Debug.Export != 0 {
+		fmt.Printf("importing %s (%s)\n", path, f.Name())
+	}
+
+	if newsize != 0 {
+		// We have unified IR data. Map it, and feed to the importers.
+		end -= newsize
+		var data string
+		data, err = base.MapFile(r.File(), end, newsize)
+		if err != nil {
+			return
+		}
+
+		pkg2, err = newReadImportFunc(data, pkg1, env, packages)
+	} else {
+		// We only have old data. Oh well, fall back to the legacy importers.
+		haveLegacyImports = true
+
+		var c byte
+		switch c, err = r.ReadByte(); {
+		case err != nil:
+			return
+
+		case c != 'i':
+			// Indexed format is distinguished by an 'i' byte,
+			// whereas previous export formats started with 'c', 'd', or 'v'.
+			err = fmt.Errorf("unexpected package format byte: %v", c)
+			return
+		}
+
+		pos := r.Offset()
+
+		// Map string (and data) section into memory as a single large
+		// string. This reduces heap fragmentation and allows
+		// returning individual substrings very efficiently.
+		var data string
+		data, err = base.MapFile(r.File(), pos, end-pos)
+		if err != nil {
+			return
+		}
+
+		typecheck.ReadImports(pkg1, data)
+
+		if packages != nil {
+			pkg2, err = importer.ImportData(packages, data, path)
+			if err != nil {
+				return
+			}
+		}
+	}
+
+	err = addFingerprint(path, f, end)
+	return
+}
+
+// findExportData returns a *bio.Reader positioned at the start of the
+// binary export data section, and a file offset for where to stop
+// reading.
+func findExportData(f *os.File) (r *bio.Reader, end, newsize int64, err error) {
+	r = bio.NewReader(f)
+
+	// check object header
+	line, err := r.ReadString('\n')
+	if err != nil {
+		return
+	}
+
+	if line == "!<arch>\n" { // package archive
+		// package export block should be first
+		sz := int64(archive.ReadHeader(r.Reader, "__.PKGDEF"))
+		if sz <= 0 {
+			err = errors.New("not a package file")
+			return
+		}
+		end = r.Offset() + sz
+		line, err = r.ReadString('\n')
+		if err != nil {
+			return
+		}
+	} else {
+		// Not an archive; provide end of file instead.
+		// TODO(mdempsky): I don't think this happens anymore.
+		var fi os.FileInfo
+		fi, err = f.Stat()
+		if err != nil {
+			return
+		}
+		end = fi.Size()
+	}
+
+	if !strings.HasPrefix(line, "go object ") {
+		err = fmt.Errorf("not a go object file: %s", line)
+		return
+	}
+	if expect := objabi.HeaderString(); line != expect {
+		err = fmt.Errorf("object is [%s] expected [%s]", line, expect)
+		return
+	}
+
+	// process header lines
+	for !strings.HasPrefix(line, "$$") {
+		if strings.HasPrefix(line, "newexportsize ") {
+			fields := strings.Fields(line)
+			newsize, err = strconv.ParseInt(fields[1], 10, 64)
+			if err != nil {
+				return
+			}
+		}
+
+		line, err = r.ReadString('\n')
+		if err != nil {
+			return
+		}
+	}
+
+	// Expect $$B\n to signal binary import format.
+	if line != "$$B\n" {
+		err = errors.New("old export format no longer supported (recompile library)")
+		return
+	}
+
+	return
+}
+
+// addFingerprint reads the linker fingerprint included at the end of
+// the exportdata.
+func addFingerprint(path string, f *os.File, end int64) error {
+	const eom = "\n$$\n"
+	var fingerprint goobj.FingerprintType
+
+	var buf [len(fingerprint) + len(eom)]byte
+	if _, err := f.ReadAt(buf[:], end-int64(len(buf))); err != nil {
+		return err
+	}
+
+	// Caller should have given us the end position of the export data,
+	// which should end with the "\n$$\n" marker. As a consistency check
+	// to make sure we're reading at the right offset, make sure we
+	// found the marker.
+	if s := string(buf[len(fingerprint):]); s != eom {
+		return fmt.Errorf("expected $$ marker, but found %q", s)
+	}
+
+	copy(fingerprint[:], buf[:])
+
+	// assume files move (get installed) so don't record the full path
+	if base.Flag.Cfg.PackageFile != nil {
+		// If using a packageFile map, assume path_ can be recorded directly.
+		base.Ctxt.AddImport(path, fingerprint)
+	} else {
+		// For file "/Users/foo/go/pkg/darwin_amd64/math.a" record "math.a".
+		file := f.Name()
+		base.Ctxt.AddImport(file[len(file)-len(path)-len(".a"):], fingerprint)
+	}
+	return nil
+}
+
+// The linker uses the magic symbol prefixes "go." and "type."
+// Avoid potential confusion between import paths and symbols
+// by rejecting these reserved imports for now. Also, people
+// "can do weird things in GOPATH and we'd prefer they didn't
+// do _that_ weird thing" (per rsc). See also #4257.
+var reservedimports = []string{
+	"go",
+	"type",
+}
+
+func checkImportPath(path string, allowSpace bool) error {
+	if path == "" {
+		return errors.New("import path is empty")
+	}
+
+	if strings.Contains(path, "\x00") {
+		return errors.New("import path contains NUL")
+	}
+
+	for _, ri := range reservedimports {
+		if path == ri {
+			return fmt.Errorf("import path %q is reserved and cannot be used", path)
+		}
+	}
+
+	for _, r := range path {
+		switch {
+		case r == utf8.RuneError:
+			return fmt.Errorf("import path contains invalid UTF-8 sequence: %q", path)
+		case r < 0x20 || r == 0x7f:
+			return fmt.Errorf("import path contains control character: %q", path)
+		case r == '\\':
+			return fmt.Errorf("import path contains backslash; use slash: %q", path)
+		case !allowSpace && unicode.IsSpace(r):
+			return fmt.Errorf("import path contains space character: %q", path)
+		case strings.ContainsRune("!\"#$%&'()*,:;<=>?[]^`{|}", r):
+			return fmt.Errorf("import path contains invalid character '%c': %q", r, path)
+		}
+	}
+
+	return nil
+}
+
+func pkgnotused(lineno src.XPos, path string, name string) {
+	// If the package was imported with a name other than the final
+	// import path element, show it explicitly in the error message.
+	// Note that this handles both renamed imports and imports of
+	// packages containing unconventional package declarations.
+	// Note that this uses / always, even on Windows, because Go import
+	// paths always use forward slashes.
+	elem := path
+	if i := strings.LastIndex(elem, "/"); i >= 0 {
+		elem = elem[i+1:]
+	}
+	if name == "" || elem == name {
+		base.ErrorfAt(lineno, "imported and not used: %q", path)
+	} else {
+		base.ErrorfAt(lineno, "imported and not used: %q as %s", path, name)
+	}
+}
+
+func mkpackage(pkgname string) {
+	if types.LocalPkg.Name == "" {
+		if pkgname == "_" {
+			base.Errorf("invalid package name _")
+		}
+		types.LocalPkg.Name = pkgname
+	} else {
+		if pkgname != types.LocalPkg.Name {
+			base.Errorf("package %s; expected %s", pkgname, types.LocalPkg.Name)
+		}
+	}
+}
+
+func clearImports() {
+	type importedPkg struct {
+		pos  src.XPos
+		path string
+		name string
+	}
+	var unused []importedPkg
+
+	for _, s := range types.LocalPkg.Syms {
+		n := ir.AsNode(s.Def)
+		if n == nil {
+			continue
+		}
+		if n.Op() == ir.OPACK {
+			// throw away top-level package name left over
+			// from previous file.
+			// leave s->block set to cause redeclaration
+			// errors if a conflicting top-level name is
+			// introduced by a different file.
+			p := n.(*ir.PkgName)
+			if !p.Used && base.SyntaxErrors() == 0 {
+				unused = append(unused, importedPkg{p.Pos(), p.Pkg.Path, s.Name})
+			}
+			s.Def = nil
+			continue
+		}
+		if s.Def != nil && s.Def.Sym() != s {
+			// throw away top-level name left over
+			// from previous import . "x"
+			// We'll report errors after type checking in CheckDotImports.
+			s.Def = nil
+			continue
+		}
+	}
+
+	sort.Slice(unused, func(i, j int) bool { return unused[i].pos.Before(unused[j].pos) })
+	for _, pkg := range unused {
+		pkgnotused(pkg.pos, pkg.path, pkg.name)
+	}
+}
+
+// CheckDotImports reports errors for any unused dot imports.
+func CheckDotImports() {
+	for _, pack := range dotImports {
+		if !pack.Used {
+			base.ErrorfAt(pack.Pos(), "imported and not used: %q", pack.Pkg.Path)
+		}
+	}
+
+	// No longer needed; release memory.
+	dotImports = nil
+	typecheck.DotImportRefs = nil
+}
+
+// dotImports tracks all PkgNames that have been dot-imported.
+var dotImports []*ir.PkgName
+
+// find all the exported symbols in package referenced by PkgName,
+// and make them available in the current package
+func importDot(pack *ir.PkgName) {
+	if typecheck.DotImportRefs == nil {
+		typecheck.DotImportRefs = make(map[*ir.Ident]*ir.PkgName)
+	}
+
+	opkg := pack.Pkg
+	for _, s := range opkg.Syms {
+		if s.Def == nil {
+			if _, ok := typecheck.DeclImporter[s]; !ok {
+				continue
+			}
+		}
+		if !types.IsExported(s.Name) || strings.ContainsRune(s.Name, 0xb7) { // 0xb7 = center dot
+			continue
+		}
+		s1 := typecheck.Lookup(s.Name)
+		if s1.Def != nil {
+			pkgerror := fmt.Sprintf("during import %q", opkg.Path)
+			typecheck.Redeclared(base.Pos, s1, pkgerror)
+			continue
+		}
+
+		id := ir.NewIdent(src.NoXPos, s)
+		typecheck.DotImportRefs[id] = pack
+		s1.Def = id
+		s1.Block = 1
+	}
+
+	dotImports = append(dotImports, pack)
+}
+
+// importName is like oldname,
+// but it reports an error if sym is from another package and not exported.
+func importName(sym *types.Sym) ir.Node {
+	n := oldname(sym)
+	if !types.IsExported(sym.Name) && sym.Pkg != types.LocalPkg {
+		n.SetDiag(true)
+		base.Errorf("cannot refer to unexported name %s.%s", sym.Pkg.Name, sym.Name)
+	}
+	return n
+}