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// Copyright 2014 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 buildutil
import (
"fmt"
"go/ast"
"go/build"
"go/parser"
"go/token"
"io"
"io/ioutil"
"os"
"path"
"path/filepath"
"strings"
)
// ParseFile behaves like parser.ParseFile,
// but uses the build context's file system interface, if any.
//
// If file is not absolute (as defined by IsAbsPath), the (dir, file)
// components are joined using JoinPath; dir must be absolute.
//
// The displayPath function, if provided, is used to transform the
// filename that will be attached to the ASTs.
//
// TODO(adonovan): call this from go/loader.parseFiles when the tree thaws.
func ParseFile(fset *token.FileSet, ctxt *build.Context, displayPath func(string) string, dir string, file string, mode parser.Mode) (*ast.File, error) {
if !IsAbsPath(ctxt, file) {
file = JoinPath(ctxt, dir, file)
}
rd, err := OpenFile(ctxt, file)
if err != nil {
return nil, err
}
defer rd.Close() // ignore error
if displayPath != nil {
file = displayPath(file)
}
return parser.ParseFile(fset, file, rd, mode)
}
// ContainingPackage returns the package containing filename.
//
// If filename is not absolute, it is interpreted relative to working directory dir.
// All I/O is via the build context's file system interface, if any.
//
// The '...Files []string' fields of the resulting build.Package are not
// populated (build.FindOnly mode).
func ContainingPackage(ctxt *build.Context, dir, filename string) (*build.Package, error) {
if !IsAbsPath(ctxt, filename) {
filename = JoinPath(ctxt, dir, filename)
}
// We must not assume the file tree uses
// "/" always,
// `\` always,
// or os.PathSeparator (which varies by platform),
// but to make any progress, we are forced to assume that
// paths will not use `\` unless the PathSeparator
// is also `\`, thus we can rely on filepath.ToSlash for some sanity.
dirSlash := path.Dir(filepath.ToSlash(filename)) + "/"
// We assume that no source root (GOPATH[i] or GOROOT) contains any other.
for _, srcdir := range ctxt.SrcDirs() {
srcdirSlash := filepath.ToSlash(srcdir) + "/"
if importPath, ok := HasSubdir(ctxt, srcdirSlash, dirSlash); ok {
return ctxt.Import(importPath, dir, build.FindOnly)
}
}
return nil, fmt.Errorf("can't find package containing %s", filename)
}
// -- Effective methods of file system interface -------------------------
// (go/build.Context defines these as methods, but does not export them.)
// HasSubdir calls ctxt.HasSubdir (if not nil) or else uses
// the local file system to answer the question.
func HasSubdir(ctxt *build.Context, root, dir string) (rel string, ok bool) {
if f := ctxt.HasSubdir; f != nil {
return f(root, dir)
}
// Try using paths we received.
if rel, ok = hasSubdir(root, dir); ok {
return
}
// Try expanding symlinks and comparing
// expanded against unexpanded and
// expanded against expanded.
rootSym, _ := filepath.EvalSymlinks(root)
dirSym, _ := filepath.EvalSymlinks(dir)
if rel, ok = hasSubdir(rootSym, dir); ok {
return
}
if rel, ok = hasSubdir(root, dirSym); ok {
return
}
return hasSubdir(rootSym, dirSym)
}
func hasSubdir(root, dir string) (rel string, ok bool) {
const sep = string(filepath.Separator)
root = filepath.Clean(root)
if !strings.HasSuffix(root, sep) {
root += sep
}
dir = filepath.Clean(dir)
if !strings.HasPrefix(dir, root) {
return "", false
}
return filepath.ToSlash(dir[len(root):]), true
}
// FileExists returns true if the specified file exists,
// using the build context's file system interface.
func FileExists(ctxt *build.Context, path string) bool {
if ctxt.OpenFile != nil {
r, err := ctxt.OpenFile(path)
if err != nil {
return false
}
r.Close() // ignore error
return true
}
_, err := os.Stat(path)
return err == nil
}
// OpenFile behaves like os.Open,
// but uses the build context's file system interface, if any.
func OpenFile(ctxt *build.Context, path string) (io.ReadCloser, error) {
if ctxt.OpenFile != nil {
return ctxt.OpenFile(path)
}
return os.Open(path)
}
// IsAbsPath behaves like filepath.IsAbs,
// but uses the build context's file system interface, if any.
func IsAbsPath(ctxt *build.Context, path string) bool {
if ctxt.IsAbsPath != nil {
return ctxt.IsAbsPath(path)
}
return filepath.IsAbs(path)
}
// JoinPath behaves like filepath.Join,
// but uses the build context's file system interface, if any.
func JoinPath(ctxt *build.Context, path ...string) string {
if ctxt.JoinPath != nil {
return ctxt.JoinPath(path...)
}
return filepath.Join(path...)
}
// IsDir behaves like os.Stat plus IsDir,
// but uses the build context's file system interface, if any.
func IsDir(ctxt *build.Context, path string) bool {
if ctxt.IsDir != nil {
return ctxt.IsDir(path)
}
fi, err := os.Stat(path)
return err == nil && fi.IsDir()
}
// ReadDir behaves like ioutil.ReadDir,
// but uses the build context's file system interface, if any.
func ReadDir(ctxt *build.Context, path string) ([]os.FileInfo, error) {
if ctxt.ReadDir != nil {
return ctxt.ReadDir(path)
}
return ioutil.ReadDir(path)
}
// SplitPathList behaves like filepath.SplitList,
// but uses the build context's file system interface, if any.
func SplitPathList(ctxt *build.Context, s string) []string {
if ctxt.SplitPathList != nil {
return ctxt.SplitPathList(s)
}
return filepath.SplitList(s)
}
// sameFile returns true if x and y have the same basename and denote
// the same file.
func sameFile(x, y string) bool {
if path.Clean(x) == path.Clean(y) {
return true
}
if filepath.Base(x) == filepath.Base(y) { // (optimisation)
if xi, err := os.Stat(x); err == nil {
if yi, err := os.Stat(y); err == nil {
return os.SameFile(xi, yi)
}
}
}
return false
}
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