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// 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 == "" {
panic("missing pkgpath")
}
if 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
}