protoc: do NOT rely on GOBIN & GOPATH

Add public functions

common/common.go

@@ -2,7 +2,16 @@
 // See each sub-package for detail.
 package common
 
-import "v2ray.com/core/common/errors"
+import (
+ "fmt"
+ "go/build"
+ "io/ioutil"
+ "os"
+ "path/filepath"
+ "strings"
+
+ "v2ray.com/core/common/errors"
+)
 
 //go:generate errorgen
 
@@ -28,3 +37,114 @@ func Must2(v interface{}, err error) interface{} {
 func Error2(v interface{}, err error) error {
  return err
 }
+
+// envFile returns the name of the Go environment configuration file.
+// Copy from https://github.com/golang/go/blob/c4f2a9788a7be04daf931ac54382fbe2cb754938/src/cmd/go/internal/cfg/cfg.go#L150-L166
+func envFile() (string, error) {
+ if file := os.Getenv("GOENV"); file != "" {
+ if file == "off" {
+ return "", fmt.Errorf("GOENV=off")
+ }
+ return file, nil
+ }
+ dir, err := os.UserConfigDir()
+ if err != nil {
+ return "", err
+ }
+ if dir == "" {
+ return "", fmt.Errorf("missing user-config dir")
+ }
+ return filepath.Join(dir, "go", "env"), nil
+}
+
+// GetRuntimeEnv returns the value of runtime environment variable,
+// that is set by running following command: `go env -w key=value`.
+func GetRuntimeEnv(key string) (string, error) {
+ file, err := envFile()
+ if err != nil {
+ return "", err
+ }
+ if file == "" {
+ return "", fmt.Errorf("missing runtime env file")
+ }
+ var data []byte
+ var runtimeEnv string
+ data, readErr := ioutil.ReadFile(file)
+ if readErr != nil {
+ return "", readErr
+ }
+ envStrings := strings.Split(string(data), "\n")
+ for _, envItem := range envStrings {
+ envItem = strings.TrimSuffix(envItem, "\r")
+ envKeyValue := strings.Split(envItem, "=")
+ if strings.EqualFold(strings.TrimSpace(envKeyValue[0]), key) {
+ runtimeEnv = strings.TrimSpace(envKeyValue[1])
+ }
+ }
+ return runtimeEnv, nil
+}
+
+// GetGOBIN returns GOBIN environment variable as a string. It will NOT be empty.
+func GetGOBIN() string {
+ // The one set by user explicitly by `export GOBIN=/path` or `env GOBIN=/path command`
+ GOBIN := os.Getenv("GOBIN")
+ if GOBIN == "" {
+ var err error
+ // The one set by user by running `go env -w GOBIN=/path`
+ GOBIN, err = GetRuntimeEnv("GOBIN")
+ if err != nil {
+ // The default one that Golang uses
+ return filepath.Join(build.Default.GOPATH, "bin")
+ }
+ if GOBIN == "" {
+ return filepath.Join(build.Default.GOPATH, "bin")
+ }
+ return GOBIN
+ }
+ return GOBIN
+}
+
+// GetGOPATH returns GOPATH environment variable as a string. It will NOT be empty.
+func GetGOPATH() string {
+ // The one set by user explicitly by `export GOPATH=/path` or `env GOPATH=/path command`
+ GOPATH := os.Getenv("GOPATH")
+ if GOPATH == "" {
+ var err error
+ // The one set by user by running `go env -w GOPATH=/path`
+ GOPATH, err = GetRuntimeEnv("GOPATH")
+ if err != nil {
+ // The default one that Golang uses
+ return build.Default.GOPATH
+ }
+ if GOPATH == "" {
+ return build.Default.GOPATH
+ }
+ return GOPATH
+ }
+ return GOPATH
+}
+
+// GetModuleName returns the value of module in `go.mod` file.
+func GetModuleName(path string) (string, error) {
+ gomodPath := filepath.Join(path, "go.mod")
+ gomodBytes, err := ioutil.ReadFile(gomodPath)
+ if err != nil {
+ return "", err
+ }
+ gomodContent := string(gomodBytes)
+ moduleIdx := strings.Index(gomodContent, "module") + 6
+ newLineIdx := strings.Index(gomodContent, "\n")
+
+ var moduleName string
+ if moduleIdx >= 0 {
+ if newLineIdx >= 0 {
+ moduleName = strings.TrimSpace(gomodContent[moduleIdx:newLineIdx])
+ moduleName = strings.TrimSuffix(moduleName, "\r")
+ } else {
+ moduleName = strings.TrimSpace(gomodContent[moduleIdx:])
+ }
+ } else {
+ return "", fmt.Errorf("can not get the value of `module` in path `%s`", gomodPath)
+ }
+ return moduleName, nil
+}