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268 lines
8.3 KiB
268 lines
8.3 KiB
// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package rbcrun
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import (
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"fmt"
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"os"
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"os/exec"
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"path/filepath"
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"regexp"
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"strings"
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"go.starlark.net/starlark"
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"go.starlark.net/starlarkstruct"
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)
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const callerDirKey = "callerDir"
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var LoadPathRoot = "."
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var shellPath string
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type modentry struct {
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globals starlark.StringDict
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err error
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}
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var moduleCache = make(map[string]*modentry)
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var builtins starlark.StringDict
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func moduleName2AbsPath(moduleName string, callerDir string) (string, error) {
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path := moduleName
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if ix := strings.LastIndex(path, ":"); ix >= 0 {
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path = path[0:ix] + string(os.PathSeparator) + path[ix+1:]
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}
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if strings.HasPrefix(path, "//") {
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return filepath.Abs(filepath.Join(LoadPathRoot, path[2:]))
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} else if strings.HasPrefix(moduleName, ":") {
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return filepath.Abs(filepath.Join(callerDir, path[1:]))
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} else {
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return filepath.Abs(path)
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}
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}
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// loader implements load statement. The format of the loaded module URI is
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// [//path]:base[|symbol]
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// The file path is $ROOT/path/base if path is present, <caller_dir>/base otherwise.
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// The presence of `|symbol` indicates that the loader should return a single 'symbol'
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// bound to None if file is missing.
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func loader(thread *starlark.Thread, module string) (starlark.StringDict, error) {
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pipePos := strings.LastIndex(module, "|")
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mustLoad := pipePos < 0
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var defaultSymbol string
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if !mustLoad {
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defaultSymbol = module[pipePos+1:]
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module = module[:pipePos]
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}
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modulePath, err := moduleName2AbsPath(module, thread.Local(callerDirKey).(string))
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if err != nil {
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return nil, err
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}
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e, ok := moduleCache[modulePath]
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if e == nil {
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if ok {
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return nil, fmt.Errorf("cycle in load graph")
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}
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// Add a placeholder to indicate "load in progress".
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moduleCache[modulePath] = nil
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// Decide if we should load.
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if !mustLoad {
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if _, err := os.Stat(modulePath); err == nil {
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mustLoad = true
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}
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}
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// Load or return default
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if mustLoad {
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childThread := &starlark.Thread{Name: "exec " + module, Load: thread.Load}
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// Cheating for the sake of testing:
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// propagate starlarktest's Reporter key, otherwise testing
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// the load function may cause panic in starlarktest code.
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const testReporterKey = "Reporter"
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if v := thread.Local(testReporterKey); v != nil {
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childThread.SetLocal(testReporterKey, v)
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}
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childThread.SetLocal(callerDirKey, filepath.Dir(modulePath))
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globals, err := starlark.ExecFile(childThread, modulePath, nil, builtins)
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e = &modentry{globals, err}
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} else {
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e = &modentry{starlark.StringDict{defaultSymbol: starlark.None}, nil}
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}
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// Update the cache.
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moduleCache[modulePath] = e
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}
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return e.globals, e.err
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}
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// fileExists returns True if file with given name exists.
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func fileExists(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
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kwargs []starlark.Tuple) (starlark.Value, error) {
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var path string
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if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &path); err != nil {
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return starlark.None, err
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}
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if stat, err := os.Stat(path); err != nil || stat.IsDir() {
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return starlark.False, nil
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}
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return starlark.True, nil
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}
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// regexMatch(pattern, s) returns True if s matches pattern (a regex)
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func regexMatch(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
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kwargs []starlark.Tuple) (starlark.Value, error) {
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var pattern, s string
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if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 2, &pattern, &s); err != nil {
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return starlark.None, err
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}
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match, err := regexp.MatchString(pattern, s)
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if err != nil {
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return starlark.None, err
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}
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if match {
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return starlark.True, nil
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}
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return starlark.False, nil
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}
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// wildcard(pattern, top=None) expands shell's glob pattern. If 'top' is present,
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// the 'top/pattern' is globbed and then 'top/' prefix is removed.
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func wildcard(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
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kwargs []starlark.Tuple) (starlark.Value, error) {
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var pattern string
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var top string
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if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &pattern, &top); err != nil {
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return starlark.None, err
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}
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var files []string
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var err error
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if top == "" {
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if files, err = filepath.Glob(pattern); err != nil {
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return starlark.None, err
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}
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} else {
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prefix := top + string(filepath.Separator)
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if files, err = filepath.Glob(prefix + pattern); err != nil {
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return starlark.None, err
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}
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for i := range files {
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files[i] = strings.TrimPrefix(files[i], prefix)
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}
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}
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return makeStringList(files), nil
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}
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// shell(command) runs OS shell with given command and returns back
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// its output the same way as Make's $(shell ) function. The end-of-lines
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// ("\n" or "\r\n") are replaced with " " in the result, and the trailing
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// end-of-line is removed.
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func shell(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
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kwargs []starlark.Tuple) (starlark.Value, error) {
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var command string
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if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &command); err != nil {
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return starlark.None, err
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}
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if shellPath == "" {
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return starlark.None,
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fmt.Errorf("cannot run shell, /bin/sh is missing (running on Windows?)")
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}
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cmd := exec.Command(shellPath, "-c", command)
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// We ignore command's status
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bytes, _ := cmd.Output()
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output := string(bytes)
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if strings.HasSuffix(output, "\n") {
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output = strings.TrimSuffix(output, "\n")
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} else {
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output = strings.TrimSuffix(output, "\r\n")
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}
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return starlark.String(
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strings.ReplaceAll(
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strings.ReplaceAll(output, "\r\n", " "),
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"\n", " ")), nil
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}
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func makeStringList(items []string) *starlark.List {
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elems := make([]starlark.Value, len(items))
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for i, item := range items {
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elems[i] = starlark.String(item)
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}
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return starlark.NewList(elems)
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}
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// propsetFromEnv constructs a propset from the array of KEY=value strings
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func structFromEnv(env []string) *starlarkstruct.Struct {
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sd := make(map[string]starlark.Value, len(env))
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for _, x := range env {
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kv := strings.SplitN(x, "=", 2)
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sd[kv[0]] = starlark.String(kv[1])
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}
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return starlarkstruct.FromStringDict(starlarkstruct.Default, sd)
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}
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func setup(env []string) {
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// Create the symbols that aid makefile conversion. See README.md
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builtins = starlark.StringDict{
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"struct": starlark.NewBuiltin("struct", starlarkstruct.Make),
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"rblf_cli": structFromEnv(env),
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"rblf_env": structFromEnv(os.Environ()),
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// To convert makefile's $(wildcard foo)
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"rblf_file_exists": starlark.NewBuiltin("rblf_file_exists", fileExists),
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// To convert makefile's $(filter ...)/$(filter-out)
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"rblf_regex": starlark.NewBuiltin("rblf_regex", regexMatch),
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// To convert makefile's $(shell cmd)
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"rblf_shell": starlark.NewBuiltin("rblf_shell", shell),
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// To convert makefile's $(wildcard foo*)
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"rblf_wildcard": starlark.NewBuiltin("rblf_wildcard", wildcard),
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}
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// NOTE(asmundak): OS-specific. Behave similar to Linux `system` call,
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// which always uses /bin/sh to run the command
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shellPath = "/bin/sh"
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if _, err := os.Stat(shellPath); err != nil {
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shellPath = ""
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}
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}
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// Parses, resolves, and executes a Starlark file.
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// filename and src parameters are as for starlark.ExecFile:
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// * filename is the name of the file to execute,
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// and the name that appears in error messages;
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// * src is an optional source of bytes to use instead of filename
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// (it can be a string, or a byte array, or an io.Reader instance)
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// * commandVars is an array of "VAR=value" items. They are accessible from
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// the starlark script as members of the `rblf_cli` propset.
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func Run(filename string, src interface{}, commandVars []string) error {
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setup(commandVars)
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mainThread := &starlark.Thread{
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Name: "main",
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Print: func(_ *starlark.Thread, msg string) { fmt.Println(msg) },
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Load: loader,
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}
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absPath, err := filepath.Abs(filename)
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if err == nil {
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mainThread.SetLocal(callerDirKey, filepath.Dir(absPath))
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_, err = starlark.ExecFile(mainThread, absPath, src, builtins)
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}
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return err
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}
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