package opts import ( "bufio" "bytes" "fmt" "os" "strings" "unicode" "unicode/utf8" ) // ParseEnvFile reads a file with environment variables enumerated by lines // // ``Environment variable names used by the utilities in the Shell and // Utilities volume of IEEE Std 1003.1-2001 consist solely of uppercase // letters, digits, and the '_' (underscore) from the characters defined in // Portable Character Set and do not begin with a digit. *But*, other // characters may be permitted by an implementation; applications shall // tolerate the presence of such names.'' // -- http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html // // As of #16585, it's up to application inside docker to validate or not // environment variables, that's why we just strip leading whitespace and // nothing more. func ParseEnvFile(filename string) ([]string, error) { fh, err := os.Open(filename) if err != nil { return []string{}, err } defer fh.Close() lines := []string{} scanner := bufio.NewScanner(fh) currentLine := 0 utf8bom := []byte{0xEF, 0xBB, 0xBF} for scanner.Scan() { scannedBytes := scanner.Bytes() if !utf8.Valid(scannedBytes) { return []string{}, fmt.Errorf("env file %s contains invalid utf8 bytes at line %d: %v", filename, currentLine+1, scannedBytes) } // We trim UTF8 BOM if currentLine == 0 { scannedBytes = bytes.TrimPrefix(scannedBytes, utf8bom) } // trim the line from all leading whitespace first line := strings.TrimLeftFunc(string(scannedBytes), unicode.IsSpace) currentLine++ // line is not empty, and not starting with '#' if len(line) > 0 && !strings.HasPrefix(line, "#") { data := strings.SplitN(line, "=", 2) // trim the front of a variable, but nothing else variable := strings.TrimLeft(data[0], whiteSpaces) if strings.ContainsAny(variable, whiteSpaces) { return []string{}, ErrBadEnvVariable{fmt.Sprintf("variable '%s' has white spaces", variable)} } if len(data) > 1 { // pass the value through, no trimming lines = append(lines, fmt.Sprintf("%s=%s", variable, data[1])) } else { // if only a pass-through variable is given, clean it up. lines = append(lines, fmt.Sprintf("%s=%s", strings.TrimSpace(line), os.Getenv(line))) } } } return lines, scanner.Err() } var whiteSpaces = " \t" // ErrBadEnvVariable typed error for bad environment variable type ErrBadEnvVariable struct { msg string } func (e ErrBadEnvVariable) Error() string { return fmt.Sprintf("poorly formatted environment: %s", e.msg) }