tools/rbcrun/host.go - platform/build - Git at Google

 // Copyright 2021 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package rbcrun

 import (
 	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"regexp"
 	"strings"

 	"go.starlark.net/starlark"
 	"go.starlark.net/starlarkstruct"
 )

 const callerDirKey = "callerDir"

 var LoadPathRoot = "."
 var shellPath string

 type modentry struct {
 	globals starlark.StringDict
 	err     error
 }

 var moduleCache = make(map[string]*modentry)

 var builtins starlark.StringDict

 func moduleName2AbsPath(moduleName string, callerDir string) (string, error) {
 	path := moduleName
 	if ix := strings.LastIndex(path, ":"); ix >= 0 {
 		path = path[0:ix] + string(os.PathSeparator) + path[ix+1:]
 	}
 	if strings.HasPrefix(path, "//") {
 		return filepath.Abs(filepath.Join(LoadPathRoot, path[2:]))
 	} else if strings.HasPrefix(moduleName, ":") {
 		return filepath.Abs(filepath.Join(callerDir, path[1:]))
 	} else {
 		return filepath.Abs(path)
 	}
 }

 // loader implements load statement. The format of the loaded module URI is
 //  [//path]:base[|symbol]
 // The file path is $ROOT/path/base if path is present, <caller_dir>/base otherwise.
 // The presence of `|symbol` indicates that the loader should return a single 'symbol'
 // bound to None if file is missing.
 func loader(thread *starlark.Thread, module string) (starlark.StringDict, error) {
 	pipePos := strings.LastIndex(module, "|")
 	mustLoad := pipePos < 0
 	var defaultSymbol string
 	if !mustLoad {
 		defaultSymbol = module[pipePos+1:]
 		module = module[:pipePos]
 	}
 	modulePath, err := moduleName2AbsPath(module, thread.Local(callerDirKey).(string))
 	if err != nil {
 		return nil, err
 	}
 	e, ok := moduleCache[modulePath]
 	if e == nil {
 		if ok {
 			return nil, fmt.Errorf("cycle in load graph")
 		}

 		// Add a placeholder to indicate "load in progress".
 		moduleCache[modulePath] = nil

 		// Decide if we should load.
 		if !mustLoad {
 			if _, err := os.Stat(modulePath); err == nil {
 				mustLoad = true
 			}
 		}

 		// Load or return default
 		if mustLoad {
 			childThread := &starlark.Thread{Name: "exec " + module, Load: thread.Load}
 			// Cheating for the sake of testing:
 			// propagate starlarktest's Reporter key, otherwise testing
 			// the load function may cause panic in starlarktest code.
 			const testReporterKey = "Reporter"
 			if v := thread.Local(testReporterKey); v != nil {
 				childThread.SetLocal(testReporterKey, v)
 			}

 			childThread.SetLocal(callerDirKey, filepath.Dir(modulePath))
 			globals, err := starlark.ExecFile(childThread, modulePath, nil, builtins)
 			e = &modentry{globals, err}
 		} else {
 			e = &modentry{starlark.StringDict{defaultSymbol: starlark.None}, nil}
 		}

 		// Update the cache.
 		moduleCache[modulePath] = e
 	}
 	return e.globals, e.err
 }

 // fileExists returns True if file with given name exists.
 func fileExists(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
 	kwargs []starlark.Tuple) (starlark.Value, error) {
 	var path string
 	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &path); err != nil {
 		return starlark.None, err
 	}
 	if stat, err := os.Stat(path); err != nil || stat.IsDir() {
 		return starlark.False, nil
 	}
 	return starlark.True, nil
 }

 // regexMatch(pattern, s) returns True if s matches pattern (a regex)
 func regexMatch(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
 	kwargs []starlark.Tuple) (starlark.Value, error) {
 	var pattern, s string
 	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 2, &pattern, &s); err != nil {
 		return starlark.None, err
 	}
 	match, err := regexp.MatchString(pattern, s)
 	if err != nil {
 		return starlark.None, err
 	}
 	if match {
 		return starlark.True, nil
 	}
 	return starlark.False, nil
 }

 // wildcard(pattern, top=None) expands shell's glob pattern. If 'top' is present,
 // the 'top/pattern' is globbed and then 'top/' prefix is removed.
 func wildcard(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
 	kwargs []starlark.Tuple) (starlark.Value, error) {
 	var pattern string
 	var top string

 	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &pattern, &top); err != nil {
 		return starlark.None, err
 	}

 	var files []string
 	var err error
 	if top == "" {
 		if files, err = filepath.Glob(pattern); err != nil {
 			return starlark.None, err
 		}
 	} else {
 		prefix := top + string(filepath.Separator)
 		if files, err = filepath.Glob(prefix + pattern); err != nil {
 			return starlark.None, err
 		}
 		for i := range files {
 			files[i] = strings.TrimPrefix(files[i], prefix)
 		}
 	}
 	return makeStringList(files), nil
 }

 // shell(command) runs OS shell with given command and returns back
 // its output the same way as Make's $(shell ) function. The end-of-lines
 // ("\n" or "\r\n") are replaced with " " in the result, and the trailing
 // end-of-line is removed.
 func shell(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
 	kwargs []starlark.Tuple) (starlark.Value, error) {
 	var command string
 	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &command); err != nil {
 		return starlark.None, err
 	}
 	if shellPath == "" {
 		return starlark.None,
 			fmt.Errorf("cannot run shell, /bin/sh is missing (running on Windows?)")
 	}
 	cmd := exec.Command(shellPath, "-c", command)
 	// We ignore command's status
 	bytes, _ := cmd.Output()
 	output := string(bytes)
 	if strings.HasSuffix(output, "\n") {
 		output = strings.TrimSuffix(output, "\n")
 	} else {
 		output = strings.TrimSuffix(output, "\r\n")
 	}

 	return starlark.String(
 		strings.ReplaceAll(
 			strings.ReplaceAll(output, "\r\n", " "),
 			"\n", " ")), nil
 }

 func makeStringList(items []string) *starlark.List {
 	elems := make([]starlark.Value, len(items))
 	for i, item := range items {
 		elems[i] = starlark.String(item)
 	}
 	return starlark.NewList(elems)
 }

 // propsetFromEnv constructs a propset from the array of KEY=value strings
 func structFromEnv(env []string) *starlarkstruct.Struct {
 	sd := make(map[string]starlark.Value, len(env))
 	for _, x := range env {
 		kv := strings.SplitN(x, "=", 2)
 		sd[kv[0]] = starlark.String(kv[1])
 	}
 	return starlarkstruct.FromStringDict(starlarkstruct.Default, sd)
 }

 func setup(env []string) {
 	// Create the symbols that aid makefile conversion. See README.md
 	builtins = starlark.StringDict{
 		"struct":   starlark.NewBuiltin("struct", starlarkstruct.Make),
 		"rblf_cli": structFromEnv(env),
 		"rblf_env": structFromEnv(os.Environ()),
 		// To convert makefile's $(wildcard foo)
 		"rblf_file_exists": starlark.NewBuiltin("rblf_file_exists", fileExists),
 		// To convert makefile's $(filter ...)/$(filter-out)
 		"rblf_regex": starlark.NewBuiltin("rblf_regex", regexMatch),
 		// To convert makefile's $(shell cmd)
 		"rblf_shell": starlark.NewBuiltin("rblf_shell", shell),
 		// To convert makefile's $(wildcard foo*)
 		"rblf_wildcard": starlark.NewBuiltin("rblf_wildcard", wildcard),
 	}

 	// NOTE(asmundak): OS-specific. Behave similar to Linux `system` call,
 	// which always uses /bin/sh to run the command
 	shellPath = "/bin/sh"
 	if _, err := os.Stat(shellPath); err != nil {
 		shellPath = ""
 	}
 }

 // Parses, resolves, and executes a Starlark file.
 // filename and src parameters are as for starlark.ExecFile:
 // * filename is the name of the file to execute,
 //   and the name that appears in error messages;
 // * src is an optional source of bytes to use instead of filename
 //   (it can be a string, or a byte array, or an io.Reader instance)
 // * commandVars is an array of "VAR=value" items. They are accessible from
 //   the starlark script as members of the `rblf_cli` propset.
 func Run(filename string, src interface{}, commandVars []string) error {
 	setup(commandVars)

 	mainThread := &starlark.Thread{
 		Name:  "main",
 		Print: func(_ *starlark.Thread, msg string) { fmt.Println(msg) },
 		Load:  loader,
 	}
 	absPath, err := filepath.Abs(filename)
 	if err == nil {
 		mainThread.SetLocal(callerDirKey, filepath.Dir(absPath))
 		_, err = starlark.ExecFile(mainThread, absPath, src, builtins)
 	}
 	return err
 }
	// Copyright 2021 Google LLC
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package rbcrun

	import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"

	"go.starlark.net/starlark"
	"go.starlark.net/starlarkstruct"
	)

	const callerDirKey = "callerDir"

	var LoadPathRoot = "."
	var shellPath string

	type modentry struct {
	globals starlark.StringDict
	err error
	}

	var moduleCache = make(map[string]*modentry)

	var builtins starlark.StringDict

	func moduleName2AbsPath(moduleName string, callerDir string) (string, error) {
	path := moduleName
	if ix := strings.LastIndex(path, ":"); ix >= 0 {
	path = path[0:ix] + string(os.PathSeparator) + path[ix+1:]
	}
	if strings.HasPrefix(path, "//") {
	return filepath.Abs(filepath.Join(LoadPathRoot, path[2:]))
	} else if strings.HasPrefix(moduleName, ":") {
	return filepath.Abs(filepath.Join(callerDir, path[1:]))
	} else {
	return filepath.Abs(path)
	}
	}

	// loader implements load statement. The format of the loaded module URI is
	// [//path]:base[\|symbol]
	// The file path is $ROOT/path/base if path is present, <caller_dir>/base otherwise.
	// The presence of `\|symbol` indicates that the loader should return a single 'symbol'
	// bound to None if file is missing.
	func loader(thread *starlark.Thread, module string) (starlark.StringDict, error) {
	pipePos := strings.LastIndex(module, "\|")
	mustLoad := pipePos < 0
	var defaultSymbol string
	if !mustLoad {
	defaultSymbol = module[pipePos+1:]
	module = module[:pipePos]
	}
	modulePath, err := moduleName2AbsPath(module, thread.Local(callerDirKey).(string))
	if err != nil {
	return nil, err
	}
	e, ok := moduleCache[modulePath]
	if e == nil {
	if ok {
	return nil, fmt.Errorf("cycle in load graph")
	}

	// Add a placeholder to indicate "load in progress".
	moduleCache[modulePath] = nil

	// Decide if we should load.
	if !mustLoad {
	if _, err := os.Stat(modulePath); err == nil {
	mustLoad = true
	}
	}

	// Load or return default
	if mustLoad {
	childThread := &starlark.Thread{Name: "exec " + module, Load: thread.Load}
	// Cheating for the sake of testing:
	// propagate starlarktest's Reporter key, otherwise testing
	// the load function may cause panic in starlarktest code.
	const testReporterKey = "Reporter"
	if v := thread.Local(testReporterKey); v != nil {
	childThread.SetLocal(testReporterKey, v)
	}

	childThread.SetLocal(callerDirKey, filepath.Dir(modulePath))
	globals, err := starlark.ExecFile(childThread, modulePath, nil, builtins)
	e = &modentry{globals, err}
	} else {
	e = &modentry{starlark.StringDict{defaultSymbol: starlark.None}, nil}
	}

	// Update the cache.
	moduleCache[modulePath] = e
	}
	return e.globals, e.err
	}

	// fileExists returns True if file with given name exists.
	func fileExists(_ starlark.Thread, b starlark.Builtin, args starlark.Tuple,
	kwargs []starlark.Tuple) (starlark.Value, error) {
	var path string
	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &path); err != nil {
	return starlark.None, err
	}
	if stat, err := os.Stat(path); err != nil \|\| stat.IsDir() {
	return starlark.False, nil
	}
	return starlark.True, nil
	}

	// regexMatch(pattern, s) returns True if s matches pattern (a regex)
	func regexMatch(_ starlark.Thread, b starlark.Builtin, args starlark.Tuple,
	kwargs []starlark.Tuple) (starlark.Value, error) {
	var pattern, s string
	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 2, &pattern, &s); err != nil {
	return starlark.None, err
	}
	match, err := regexp.MatchString(pattern, s)
	if err != nil {
	return starlark.None, err
	}
	if match {
	return starlark.True, nil
	}
	return starlark.False, nil
	}

	// wildcard(pattern, top=None) expands shell's glob pattern. If 'top' is present,
	// the 'top/pattern' is globbed and then 'top/' prefix is removed.
	func wildcard(_ starlark.Thread, b starlark.Builtin, args starlark.Tuple,
	kwargs []starlark.Tuple) (starlark.Value, error) {
	var pattern string
	var top string

	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &pattern, &top); err != nil {
	return starlark.None, err
	}

	var files []string
	var err error
	if top == "" {
	if files, err = filepath.Glob(pattern); err != nil {
	return starlark.None, err
	}
	} else {
	prefix := top + string(filepath.Separator)
	if files, err = filepath.Glob(prefix + pattern); err != nil {
	return starlark.None, err
	}
	for i := range files {
	files[i] = strings.TrimPrefix(files[i], prefix)
	}
	}
	return makeStringList(files), nil
	}

	// shell(command) runs OS shell with given command and returns back
	// its output the same way as Make's $(shell ) function. The end-of-lines
	// ("\n" or "\r\n") are replaced with " " in the result, and the trailing
	// end-of-line is removed.
	func shell(_ starlark.Thread, b starlark.Builtin, args starlark.Tuple,
	kwargs []starlark.Tuple) (starlark.Value, error) {
	var command string
	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &command); err != nil {
	return starlark.None, err
	}
	if shellPath == "" {
	return starlark.None,
	fmt.Errorf("cannot run shell, /bin/sh is missing (running on Windows?)")
	}
	cmd := exec.Command(shellPath, "-c", command)
	// We ignore command's status
	bytes, _ := cmd.Output()
	output := string(bytes)
	if strings.HasSuffix(output, "\n") {
	output = strings.TrimSuffix(output, "\n")
	} else {
	output = strings.TrimSuffix(output, "\r\n")
	}

	return starlark.String(
	strings.ReplaceAll(
	strings.ReplaceAll(output, "\r\n", " "),
	"\n", " ")), nil
	}

	func makeStringList(items []string) *starlark.List {
	elems := make([]starlark.Value, len(items))
	for i, item := range items {
	elems[i] = starlark.String(item)
	}
	return starlark.NewList(elems)
	}

	// propsetFromEnv constructs a propset from the array of KEY=value strings
	func structFromEnv(env []string) *starlarkstruct.Struct {
	sd := make(map[string]starlark.Value, len(env))
	for _, x := range env {
	kv := strings.SplitN(x, "=", 2)
	sd[kv[0]] = starlark.String(kv[1])
	}
	return starlarkstruct.FromStringDict(starlarkstruct.Default, sd)
	}

	func setup(env []string) {
	// Create the symbols that aid makefile conversion. See README.md
	builtins = starlark.StringDict{
	"struct": starlark.NewBuiltin("struct", starlarkstruct.Make),
	"rblf_cli": structFromEnv(env),
	"rblf_env": structFromEnv(os.Environ()),
	// To convert makefile's $(wildcard foo)
	"rblf_file_exists": starlark.NewBuiltin("rblf_file_exists", fileExists),
	// To convert makefile's $(filter ...)/$(filter-out)
	"rblf_regex": starlark.NewBuiltin("rblf_regex", regexMatch),
	// To convert makefile's $(shell cmd)
	"rblf_shell": starlark.NewBuiltin("rblf_shell", shell),
	// To convert makefile's $(wildcard foo*)
	"rblf_wildcard": starlark.NewBuiltin("rblf_wildcard", wildcard),
	}

	// NOTE(asmundak): OS-specific. Behave similar to Linux `system` call,
	// which always uses /bin/sh to run the command
	shellPath = "/bin/sh"
	if _, err := os.Stat(shellPath); err != nil {
	shellPath = ""
	}
	}

	// Parses, resolves, and executes a Starlark file.
	// filename and src parameters are as for starlark.ExecFile:
	// * filename is the name of the file to execute,
	// and the name that appears in error messages;
	// * src is an optional source of bytes to use instead of filename
	// (it can be a string, or a byte array, or an io.Reader instance)
	// * commandVars is an array of "VAR=value" items. They are accessible from
	// the starlark script as members of the `rblf_cli` propset.
	func Run(filename string, src interface{}, commandVars []string) error {
	setup(commandVars)

	mainThread := &starlark.Thread{
	Name: "main",
	Print: func(_ *starlark.Thread, msg string) { fmt.Println(msg) },
	Load: loader,
	}
	absPath, err := filepath.Abs(filename)
	if err == nil {
	mainThread.SetLocal(callerDirKey, filepath.Dir(absPath))
	_, err = starlark.ExecFile(mainThread, absPath, src, builtins)
	}
	return err
	}