github.com/endophage/docker@v1.4.2-0.20161027011718-242853499895/runconfig/opts/envfile.go (about)

     1  package opts
     2  
     3  import (
     4  	"bufio"
     5  	"bytes"
     6  	"fmt"
     7  	"os"
     8  	"strings"
     9  	"unicode"
    10  	"unicode/utf8"
    11  )
    12  
    13  // ParseEnvFile reads a file with environment variables enumerated by lines
    14  //
    15  // ``Environment variable names used by the utilities in the Shell and
    16  // Utilities volume of IEEE Std 1003.1-2001 consist solely of uppercase
    17  // letters, digits, and the '_' (underscore) from the characters defined in
    18  // Portable Character Set and do not begin with a digit. *But*, other
    19  // characters may be permitted by an implementation; applications shall
    20  // tolerate the presence of such names.''
    21  // -- http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html
    22  //
    23  // As of #16585, it's up to application inside docker to validate or not
    24  // environment variables, that's why we just strip leading whitespace and
    25  // nothing more.
    26  func ParseEnvFile(filename string) ([]string, error) {
    27  	fh, err := os.Open(filename)
    28  	if err != nil {
    29  		return []string{}, err
    30  	}
    31  	defer fh.Close()
    32  
    33  	lines := []string{}
    34  	scanner := bufio.NewScanner(fh)
    35  	currentLine := 0
    36  	utf8bom := []byte{0xEF, 0xBB, 0xBF}
    37  	for scanner.Scan() {
    38  		scannedBytes := scanner.Bytes()
    39  		if !utf8.Valid(scannedBytes) {
    40  			return []string{}, fmt.Errorf("env file %s contains invalid utf8 bytes at line %d: %v", filename, currentLine+1, scannedBytes)
    41  		}
    42  		// We trim UTF8 BOM
    43  		if currentLine == 0 {
    44  			scannedBytes = bytes.TrimPrefix(scannedBytes, utf8bom)
    45  		}
    46  		// trim the line from all leading whitespace first
    47  		line := strings.TrimLeftFunc(string(scannedBytes), unicode.IsSpace)
    48  		currentLine++
    49  		// line is not empty, and not starting with '#'
    50  		if len(line) > 0 && !strings.HasPrefix(line, "#") {
    51  			data := strings.SplitN(line, "=", 2)
    52  
    53  			// trim the front of a variable, but nothing else
    54  			variable := strings.TrimLeft(data[0], whiteSpaces)
    55  			if strings.ContainsAny(variable, whiteSpaces) {
    56  				return []string{}, ErrBadEnvVariable{fmt.Sprintf("variable '%s' has white spaces", variable)}
    57  			}
    58  
    59  			if len(data) > 1 {
    60  
    61  				// pass the value through, no trimming
    62  				lines = append(lines, fmt.Sprintf("%s=%s", variable, data[1]))
    63  			} else {
    64  				// if only a pass-through variable is given, clean it up.
    65  				lines = append(lines, fmt.Sprintf("%s=%s", strings.TrimSpace(line), os.Getenv(line)))
    66  			}
    67  		}
    68  	}
    69  	return lines, scanner.Err()
    70  }
    71  
    72  var whiteSpaces = " \t"
    73  
    74  // ErrBadEnvVariable typed error for bad environment variable
    75  type ErrBadEnvVariable struct {
    76  	msg string
    77  }
    78  
    79  func (e ErrBadEnvVariable) Error() string {
    80  	return fmt.Sprintf("poorly formatted environment: %s", e.msg)
    81  }