1 files changed, 493 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 0000000000..a39be9864b
--- /dev/null
+++ b/src/cmd/compile/internal/noder/import.go
@@ -0,0 +1,493 @@
+// 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.
+
+//go:generate go run mkbuiltin.go
+
+package noder
+
+import (
+	"fmt"
+	"go/constant"
+	"os"
+	"path"
+	"runtime"
+	"sort"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/archive"
+	"cmd/internal/bio"
+	"cmd/internal/goobj"
+	"cmd/internal/objabi"
+	"cmd/internal/src"
+)
+
+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 findpkg(name string) (file string, ok bool) {
+	if islocalname(name) {
+		if base.Flag.NoLocalImports {
+			return "", false
+		}
+
+		if base.Flag.Cfg.PackageFile != nil {
+			file, ok = base.Flag.Cfg.PackageFile[name]
+			return file, ok
+		}
+
+		// try .a before .6.  important for building libraries:
+		// if there is an array.6 in the array.a library,
+		// want to find all of array.a, not just array.6.
+		file = fmt.Sprintf("%s.a", name)
+		if _, err := os.Stat(file); err == nil {
+			return file, true
+		}
+		file = fmt.Sprintf("%s.o", name)
+		if _, err := os.Stat(file); err == nil {
+			return file, true
+		}
+		return "", false
+	}
+
+	// local imports should be canonicalized already.
+	// don't want to see "encoding/../encoding/base64"
+	// as different from "encoding/base64".
+	if q := path.Clean(name); q != name {
+		base.Errorf("non-canonical import path %q (should be %q)", name, q)
+		return "", false
+	}
+
+	if base.Flag.Cfg.PackageFile != nil {
+		file, ok = base.Flag.Cfg.PackageFile[name]
+		return file, ok
+	}
+
+	for _, dir := range base.Flag.Cfg.ImportDirs {
+		file = fmt.Sprintf("%s/%s.a", dir, name)
+		if _, err := os.Stat(file); err == nil {
+			return file, true
+		}
+		file = fmt.Sprintf("%s/%s.o", dir, name)
+		if _, err := os.Stat(file); err == nil {
+			return file, true
+		}
+	}
+
+	if objabi.GOROOT != "" {
+		suffix := ""
+		suffixsep := ""
+		if base.Flag.InstallSuffix != "" {
+			suffixsep = "_"
+			suffix = base.Flag.InstallSuffix
+		} else if base.Flag.Race {
+			suffixsep = "_"
+			suffix = "race"
+		} else if base.Flag.MSan {
+			suffixsep = "_"
+			suffix = "msan"
+		}
+
+		file = fmt.Sprintf("%s/pkg/%s_%s%s%s/%s.a", objabi.GOROOT, objabi.GOOS, objabi.GOARCH, suffixsep, suffix, name)
+		if _, err := os.Stat(file); err == nil {
+			return file, true
+		}
+		file = fmt.Sprintf("%s/pkg/%s_%s%s%s/%s.o", objabi.GOROOT, objabi.GOOS, objabi.GOARCH, suffixsep, suffix, name)
+		if _, err := os.Stat(file); err == nil {
+			return file, true
+		}
+	}
+
+	return "", false
+}
+
+// myheight tracks the local package's height based on packages
+// imported so far.
+var myheight int
+
+func importfile(f constant.Value) *types.Pkg {
+	if f.Kind() != constant.String {
+		base.Errorf("import path must be a string")
+		return nil
+	}
+
+	path_ := constant.StringVal(f)
+	if len(path_) == 0 {
+		base.Errorf("import path is empty")
+		return nil
+	}
+
+	if isbadimport(path_, false) {
+		return nil
+	}
+
+	// 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" {
+		base.Errorf("cannot import \"main\"")
+		base.ErrorExit()
+	}
+
+	if base.Ctxt.Pkgpath != "" && path_ == base.Ctxt.Pkgpath {
+		base.Errorf("import %q while compiling that package (import cycle)", path_)
+		base.ErrorExit()
+	}
+
+	if mapped, ok := base.Flag.Cfg.ImportMap[path_]; ok {
+		path_ = mapped
+	}
+
+	if path_ == "unsafe" {
+		return ir.Pkgs.Unsafe
+	}
+
+	if islocalname(path_) {
+		if path_[0] == '/' {
+			base.Errorf("import path cannot be absolute path")
+			return nil
+		}
+
+		prefix := base.Ctxt.Pathname
+		if base.Flag.D != "" {
+			prefix = base.Flag.D
+		}
+		path_ = path.Join(prefix, path_)
+
+		if isbadimport(path_, true) {
+			return nil
+		}
+	}
+
+	file, found := findpkg(path_)
+	if !found {
+		base.Errorf("can't find import: %q", path_)
+		base.ErrorExit()
+	}
+
+	importpkg := types.NewPkg(path_, "")
+	if importpkg.Imported {
+		return importpkg
+	}
+
+	importpkg.Imported = true
+
+	imp, err := bio.Open(file)
+	if err != nil {
+		base.Errorf("can't open import: %q: %v", path_, err)
+		base.ErrorExit()
+	}
+	defer imp.Close()
+
+	// check object header
+	p, err := imp.ReadString('\n')
+	if err != nil {
+		base.Errorf("import %s: reading input: %v", file, err)
+		base.ErrorExit()
+	}
+
+	if p == "!<arch>\n" { // package archive
+		// package export block should be first
+		sz := archive.ReadHeader(imp.Reader, "__.PKGDEF")
+		if sz <= 0 {
+			base.Errorf("import %s: not a package file", file)
+			base.ErrorExit()
+		}
+		p, err = imp.ReadString('\n')
+		if err != nil {
+			base.Errorf("import %s: reading input: %v", file, err)
+			base.ErrorExit()
+		}
+	}
+
+	if !strings.HasPrefix(p, "go object ") {
+		base.Errorf("import %s: not a go object file: %s", file, p)
+		base.ErrorExit()
+	}
+	q := fmt.Sprintf("%s %s %s %s\n", objabi.GOOS, objabi.GOARCH, objabi.Version, objabi.Expstring())
+	if p[10:] != q {
+		base.Errorf("import %s: object is [%s] expected [%s]", file, p[10:], q)
+		base.ErrorExit()
+	}
+
+	// process header lines
+	for {
+		p, err = imp.ReadString('\n')
+		if err != nil {
+			base.Errorf("import %s: reading input: %v", file, err)
+			base.ErrorExit()
+		}
+		if p == "\n" {
+			break // header ends with blank line
+		}
+	}
+
+	// Expect $$B\n to signal binary import format.
+
+	// look for $$
+	var c byte
+	for {
+		c, err = imp.ReadByte()
+		if err != nil {
+			break
+		}
+		if c == '$' {
+			c, err = imp.ReadByte()
+			if c == '$' || err != nil {
+				break
+			}
+		}
+	}
+
+	// get character after $$
+	if err == nil {
+		c, _ = imp.ReadByte()
+	}
+
+	var fingerprint goobj.FingerprintType
+	switch c {
+	case '\n':
+		base.Errorf("cannot import %s: old export format no longer supported (recompile library)", path_)
+		return nil
+
+	case 'B':
+		if base.Debug.Export != 0 {
+			fmt.Printf("importing %s (%s)\n", path_, file)
+		}
+		imp.ReadByte() // skip \n after $$B
+
+		c, err = imp.ReadByte()
+		if err != nil {
+			base.Errorf("import %s: reading input: %v", file, err)
+			base.ErrorExit()
+		}
+
+		// Indexed format is distinguished by an 'i' byte,
+		// whereas previous export formats started with 'c', 'd', or 'v'.
+		if c != 'i' {
+			base.Errorf("import %s: unexpected package format byte: %v", file, c)
+			base.ErrorExit()
+		}
+		fingerprint = typecheck.ReadImports(importpkg, imp)
+
+	default:
+		base.Errorf("no import in %q", path_)
+		base.ErrorExit()
+	}
+
+	// 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".
+		base.Ctxt.AddImport(file[len(file)-len(path_)-len(".a"):], fingerprint)
+	}
+
+	if importpkg.Height >= myheight {
+		myheight = importpkg.Height + 1
+	}
+
+	return importpkg
+}
+
+// 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 isbadimport(path string, allowSpace bool) bool {
+	if strings.Contains(path, "\x00") {
+		base.Errorf("import path contains NUL")
+		return true
+	}
+
+	for _, ri := range reservedimports {
+		if path == ri {
+			base.Errorf("import path %q is reserved and cannot be used", path)
+			return true
+		}
+	}
+
+	for _, r := range path {
+		if r == utf8.RuneError {
+			base.Errorf("import path contains invalid UTF-8 sequence: %q", path)
+			return true
+		}
+
+		if r < 0x20 || r == 0x7f {
+			base.Errorf("import path contains control character: %q", path)
+			return true
+		}
+
+		if r == '\\' {
+			base.Errorf("import path contains backslash; use slash: %q", path)
+			return true
+		}
+
+		if !allowSpace && unicode.IsSpace(r) {
+			base.Errorf("import path contains space character: %q", path)
+			return true
+		}
+
+		if strings.ContainsRune("!\"#$%&'()*,:;<=>?[]^`{|}", r) {
+			base.Errorf("import path contains invalid character '%c': %q", r, path)
+			return true
+		}
+	}
+
+	return false
+}
+
+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 types.IsDotAlias(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
+}