github.com/knieriem/gointernal@v0.2.0-pre2/cmd/go/envcmd/env.go

// Copyright 2012 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 envcmd implements the ``go env'' command.
package envcmd

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"unicode/utf8"

	"github.com/knieriem/gointernal/cmd/go/base"
	"github.com/knieriem/gointernal/cmd/go/cfg"
)

var CmdEnv = &base.Command{
	UsageLine: "<prog> env [-json] [-u] [-w] [var ...]",
	Short:     "print environment information",
	Long: `
Env prints environment information.

By default env prints information as a shell script
(on Windows, a batch file). If one or more variable
names is given as arguments, env prints the value of
each named variable on its own line.

The -json flag prints the environment in JSON format
instead of as a shell script.

The -u flag requires one or more arguments and unsets
the default setting for the named environment variables,
if one has been set with '<prog> env -w'.

The -w flag requires one or more arguments of the
form NAME=VALUE and changes the default settings
of the named environment variables to the given values.

For more about environment variables, see 'go help environment'.
	`,
}

func init() {
	CmdEnv.Run = runEnv // break init cycle
}

var (
	envJson = CmdEnv.Flag.Bool("json", false, "")
	envU    = CmdEnv.Flag.Bool("u", false, "")
	envW    = CmdEnv.Flag.Bool("w", false, "")
)

func findEnv(env []cfg.EnvVar, name string) string {
	for _, e := range env {
		if e.Name == name {
			return e.Value
		}
	}
	return ""
}

// ExtraEnvVars returns environment variables that should not leak into child processes.
func ExtraEnvVars() []cfg.EnvVar {
	return nil
}

// ExtraEnvVarsCostly returns environment variables that should not leak into child processes
// but are costly to evaluate.
func ExtraEnvVarsCostly() []cfg.EnvVar {
	return nil
}

// argKey returns the KEY part of the arg KEY=VAL, or else arg itself.
func argKey(arg string) string {
	i := strings.Index(arg, "=")
	if i < 0 {
		return arg
	}
	return arg[:i]
}

func runEnv(ctx context.Context, cmd *base.Command, args []string) {
	if *envJson && *envU {
		base.Fatalf("go: cannot use -json with -u")
	}
	if *envJson && *envW {
		base.Fatalf("go: cannot use -json with -w")
	}
	if *envU && *envW {
		base.Fatalf("go: cannot use -u with -w")
	}

	// Handle 'go env -w' and 'go env -u' before calling buildcfg.Check,
	// so they can be used to recover from an invalid configuration.
	if *envW {
		runEnvW(args)
		return
	}

	if *envU {
		runEnvU(args)
		return
	}

	env := cfg.CmdEnv
	env = append(env, ExtraEnvVars()...)

	// Do we need to call ExtraEnvVarsCostly, which is a bit expensive?
	needCostly := false
	if len(args) == 0 {
		// We're listing all environment variables ("go env"),
		// including the expensive ones.
		needCostly = true
	} else {
		needCostly = false
	checkCostly:
		for _, arg := range args {
			switch argKey(arg) {
			case "CGO_CFLAGS",
				"CGO_CPPFLAGS",
				"CGO_CXXFLAGS",
				"CGO_FFLAGS",
				"CGO_LDFLAGS",
				"PKG_CONFIG",
				"GOGCCFLAGS":
				needCostly = true
				break checkCostly
			}
		}
	}
	if needCostly {
		env = append(env, ExtraEnvVarsCostly()...)
	}

	if len(args) > 0 {
		if *envJson {
			var es []cfg.EnvVar
			for _, name := range args {
				e := cfg.EnvVar{Name: name, Value: findEnv(env, name)}
				es = append(es, e)
			}
			printEnvAsJSON(es)
		} else {
			for _, name := range args {
				fmt.Printf("%s\n", findEnv(env, name))
			}
		}
		return
	}

	if *envJson {
		printEnvAsJSON(env)
		return
	}

	PrintEnv(os.Stdout, env)
}

func runEnvW(args []string) {
	// Process and sanity-check command line.
	if len(args) == 0 {
		base.Fatalf("go: no KEY=VALUE arguments given")
	}
	osEnv := make(map[string]string)
	for _, e := range cfg.OrigEnv {
		if i := strings.Index(e, "="); i >= 0 {
			osEnv[e[:i]] = e[i+1:]
		}
	}
	add := make(map[string]string)
	for _, arg := range args {
		i := strings.Index(arg, "=")
		if i < 0 {
			base.Fatalf("go: arguments must be KEY=VALUE: invalid argument: %s", arg)
		}
		key, val := arg[:i], arg[i+1:]
		if err := checkEnvWrite(key, val); err != nil {
			base.Fatalf("go: %v", err)
		}
		if _, ok := add[key]; ok {
			base.Fatalf("go: multiple values for key: %s", key)
		}
		add[key] = val
		if osVal := osEnv[key]; osVal != "" && osVal != val {
			fmt.Fprintf(os.Stderr, "warning: go env -w %s=... does not override conflicting OS environment variable\n", key)
		}
	}

	gotmp, okGOTMP := add["GOTMPDIR"]
	if okGOTMP {
		if !filepath.IsAbs(gotmp) && gotmp != "" {
			base.Fatalf("go: GOTMPDIR must be an absolute path")
		}
	}

	updateEnvFile(add, nil)
}

func runEnvU(args []string) {
	// Process and sanity-check command line.
	if len(args) == 0 {
		base.Fatalf("go: 'go env -u' requires an argument")
	}
	del := make(map[string]bool)
	for _, arg := range args {
		if err := checkEnvWrite(arg, ""); err != nil {
			base.Fatalf("go: %v", err)
		}
		del[arg] = true
	}

	updateEnvFile(nil, del)
}

// PrintEnv prints the environment variables to w.
func PrintEnv(w io.Writer, env []cfg.EnvVar) {
	for _, e := range env {
		if e.Name != "TERM" {
			switch runtime.GOOS {
			default:
				fmt.Fprintf(w, "%s=\"%s\"\n", e.Name, e.Value)
			case "plan9":
				if strings.IndexByte(e.Value, '\x00') < 0 {
					fmt.Fprintf(w, "%s='%s'\n", e.Name, strings.ReplaceAll(e.Value, "'", "''"))
				} else {
					v := strings.Split(e.Value, "\x00")
					fmt.Fprintf(w, "%s=(", e.Name)
					for x, s := range v {
						if x > 0 {
							fmt.Fprintf(w, " ")
						}
						fmt.Fprintf(w, "%s", s)
					}
					fmt.Fprintf(w, ")\n")
				}
			case "windows":
				fmt.Fprintf(w, "set %s=%s\n", e.Name, e.Value)
			}
		}
	}
}

func printEnvAsJSON(env []cfg.EnvVar) {
	m := make(map[string]string)
	for _, e := range env {
		if e.Name == "TERM" {
			continue
		}
		m[e.Name] = e.Value
	}
	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "\t")
	if err := enc.Encode(m); err != nil {
		base.Fatalf("go: %s", err)
	}
}

func getOrigEnv(key string) string {
	for _, v := range cfg.OrigEnv {
		if strings.HasPrefix(v, key+"=") {
			return strings.TrimPrefix(v, key+"=")
		}
	}
	return ""
}

func checkEnvWrite(key, val string) error {
	// To catch typos and the like, check that we know the variable.
	if !cfg.CanGetenv(key) {
		return fmt.Errorf("unknown go command variable %s", key)
	}

	// Some variables can only have one of a few valid values. If set to an
	// invalid value, the next cmd/go invocation might fail immediately,
	// even 'go env -w' itself.
	switch key {
	}

	if !utf8.ValidString(val) {
		return fmt.Errorf("invalid UTF-8 in %s=... value", key)
	}
	if strings.Contains(val, "\x00") {
		return fmt.Errorf("invalid NUL in %s=... value", key)
	}
	if strings.ContainsAny(val, "\v\r\n") {
		return fmt.Errorf("invalid newline in %s=... value", key)
	}
	return nil
}

func updateEnvFile(add map[string]string, del map[string]bool) {
	file, err := cfg.EnvFile()
	if file == "" {
		base.Fatalf("go: cannot find go env config: %v", err)
	}
	data, err := os.ReadFile(file)
	if err != nil && (!os.IsNotExist(err) || len(add) == 0) {
		base.Fatalf("go: reading go env config: %v", err)
	}

	lines := strings.SplitAfter(string(data), "\n")
	if lines[len(lines)-1] == "" {
		lines = lines[:len(lines)-1]
	} else {
		lines[len(lines)-1] += "\n"
	}

	// Delete all but last copy of any duplicated variables,
	// since the last copy is the one that takes effect.
	prev := make(map[string]int)
	for l, line := range lines {
		if key := lineToKey(line); key != "" {
			if p, ok := prev[key]; ok {
				lines[p] = ""
			}
			prev[key] = l
		}
	}

	// Add variables (go env -w). Update existing lines in file if present, add to end otherwise.
	for key, val := range add {
		if p, ok := prev[key]; ok {
			lines[p] = key + "=" + val + "\n"
			delete(add, key)
		}
	}
	for key, val := range add {
		lines = append(lines, key+"="+val+"\n")
	}

	// Delete requested variables (go env -u).
	for key := range del {
		if p, ok := prev[key]; ok {
			lines[p] = ""
		}
	}

	// Sort runs of KEY=VALUE lines
	// (that is, blocks of lines where blocks are separated
	// by comments, blank lines, or invalid lines).
	start := 0
	for i := 0; i <= len(lines); i++ {
		if i == len(lines) || lineToKey(lines[i]) == "" {
			sortKeyValues(lines[start:i])
			start = i + 1
		}
	}

	data = []byte(strings.Join(lines, ""))
	err = os.WriteFile(file, data, 0666)
	if err != nil {
		// Try creating directory.
		os.MkdirAll(filepath.Dir(file), 0777)
		err = os.WriteFile(file, data, 0666)
		if err != nil {
			base.Fatalf("go: writing go env config: %v", err)
		}
	}
}

// lineToKey returns the KEY part of the line KEY=VALUE or else an empty string.
func lineToKey(line string) string {
	i := strings.Index(line, "=")
	if i < 0 || strings.Contains(line[:i], "#") {
		return ""
	}
	return line[:i]
}

// sortKeyValues sorts a sequence of lines by key.
// It differs from sort.Strings in that keys which are GOx where x is an ASCII
// character smaller than = sort after GO=.
// (There are no such keys currently. It used to matter for GO386 which was
// removed in Go 1.16.)
func sortKeyValues(lines []string) {
	sort.Slice(lines, func(i, j int) bool {
		return lineToKey(lines[i]) < lineToKey(lines[j])
	})
}