1 files changed, 371 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..b7008ac
--- /dev/null
+++ b/src/cmd/compile/internal/noder/import.go
@@ -0,0 +1,371 @@
+// 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"
+	"internal/pkgbits"
+	"os"
+	pathpkg "path"
+	"runtime"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/importer"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/compile/internal/types2"
+	"cmd/internal/archive"
+	"cmd/internal/bio"
+	"cmd/internal/goobj"
+	"cmd/internal/objabi"
+)
+
+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")
+}
+
+// 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
+}
+
+// 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, err := findExportData(f)
+	if err != nil {
+		return
+	}
+
+	if base.Debug.Export != 0 {
+		fmt.Printf("importing %s (%s)\n", path, f.Name())
+	}
+
+	c, err := r.ReadByte()
+	if err != nil {
+		return
+	}
+
+	pos := r.Offset()
+
+	// Map export 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
+	}
+
+	switch c {
+	case 'u':
+		// TODO(mdempsky): This seems a bit clunky.
+		data = strings.TrimSuffix(data, "\n$$\n")
+
+		pr := pkgbits.NewPkgDecoder(pkg1.Path, data)
+
+		// Read package descriptors for both types2 and compiler backend.
+		readPackage(newPkgReader(pr), pkg1, false)
+		pkg2 = importer.ReadPackage(env, packages, pr)
+
+	default:
+		// Indexed format is distinguished by an 'i' byte,
+		// whereas previous export formats started with 'c', 'd', or 'v'.
+		err = fmt.Errorf("unexpected package format byte: %v", c)
+		return
+	}
+
+	err = addFingerprint(path, f, end)
+	return
+}
+
+// findExportData returns a *bio.Reader positioned at the start of the
+// binary export data section, and a file offset for where to stop
+// reading.
+func findExportData(f *os.File) (r *bio.Reader, end int64, err error) {
+	r = bio.NewReader(f)
+
+	// check object header
+	line, err := r.ReadString('\n')
+	if err != nil {
+		return
+	}
+
+	if line == "!<arch>\n" { // package archive
+		// package export block should be first
+		sz := int64(archive.ReadHeader(r.Reader, "__.PKGDEF"))
+		if sz <= 0 {
+			err = errors.New("not a package file")
+			return
+		}
+		end = r.Offset() + sz
+		line, err = r.ReadString('\n')
+		if err != nil {
+			return
+		}
+	} else {
+		// Not an archive; provide end of file instead.
+		// TODO(mdempsky): I don't think this happens anymore.
+		var fi os.FileInfo
+		fi, err = f.Stat()
+		if err != nil {
+			return
+		}
+		end = fi.Size()
+	}
+
+	if !strings.HasPrefix(line, "go object ") {
+		err = fmt.Errorf("not a go object file: %s", line)
+		return
+	}
+	if expect := objabi.HeaderString(); line != expect {
+		err = fmt.Errorf("object is [%s] expected [%s]", line, expect)
+		return
+	}
+
+	// process header lines
+	for !strings.HasPrefix(line, "$$") {
+		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[:])
+	base.Ctxt.AddImport(path, fingerprint)
+
+	return nil
+}
+
+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 base.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
+}