cmd/micro/shellwords/shellwords.go

   1 package shellwords
   2
   3 import (
   4         "bytes"
   5         "errors"
   6         "os"
   7         "regexp"
   8 )
   9
  10 var envRe = regexp.MustCompile(`\$({[a-zA-Z0-9_]+}|[a-zA-Z0-9_]+)`)
  11
  12 func isSpace(r rune) bool {
  13         switch r {
  14         case ' ', '\t', '\r', '\n':
  15                 return true
  16         }
  17         return false
  18 }
  19
  20 func replaceEnv(s string) string {
  21         return envRe.ReplaceAllStringFunc(s, func(s string) string {
  22                 s = s[1:]
  23                 if s[0] == '{' {
  24                         s = s[1 : len(s)-1]
  25                 }
  26                 return os.Getenv(s)
  27         })
  28 }
  29
  30 type Parser struct {
  31         Position int
  32 }
  33
  34 func NewParser() *Parser {
  35         return &Parser{0}
  36 }
  37
  38 func (p *Parser) Parse(line string) ([]string, error) {
  39         args := []string{}
  40         buf := ""
  41         var escaped, doubleQuoted, singleQuoted, backQuote, dollarQuote bool
  42         backtick := ""
  43
  44         pos := -1
  45         got := false
  46
  47 loop:
  48         for i, r := range line {
  49                 if escaped {
  50                         buf += string(r)
  51                         escaped = false
  52                         continue
  53                 }
  54
  55                 if r == '\\' {
  56                         if singleQuoted {
  57                                 buf += string(r)
  58                         } else {
  59                                 escaped = true
  60                         }
  61                         continue
  62                 }
  63
  64                 if isSpace(r) {
  65                         if singleQuoted || doubleQuoted || backQuote || dollarQuote {
  66                                 buf += string(r)
  67                                 backtick += string(r)
  68                         } else if got {
  69                                 buf = replaceEnv(buf)
  70                                 args = append(args, buf)
  71                                 buf = ""
  72                                 got = false
  73                         }
  74                         continue
  75                 }
  76
  77                 switch r {
  78                 case '`':
  79                         if !singleQuoted && !doubleQuoted && !dollarQuote {
  80                                 if backQuote {
  81                                         out, err := shellRun(backtick)
  82                                         if err != nil {
  83                                                 return nil, err
  84                                         }
  85                                         buf = out
  86                                 }
  87                                 backtick = ""
  88                                 backQuote = !backQuote
  89                                 continue
  90                                 backtick = ""
  91                                 backQuote = !backQuote
  92                         }
  93                 case ')':
  94                         if !singleQuoted && !doubleQuoted && !backQuote {
  95                                 if dollarQuote {
  96                                         out, err := shellRun(backtick)
  97                                         if err != nil {
  98                                                 return nil, err
  99                                         }
 100                                         buf = out
 101                                 }
 102                                 backtick = ""
 103                                 dollarQuote = !dollarQuote
 104                                 continue
 105                                 backtick = ""
 106                                 dollarQuote = !dollarQuote
 107                         }
 108                 case '(':
 109                         if !singleQuoted && !doubleQuoted && !backQuote {
 110                                 if !dollarQuote && len(buf) > 0 && buf == "$" {
 111                                         dollarQuote = true
 112                                         buf += "("
 113                                         continue
 114                                 } else {
 115                                         return nil, errors.New("invalid command line string")
 116                                 }
 117                         }
 118                 case '"':
 119                         if !singleQuoted && !dollarQuote {
 120                                 doubleQuoted = !doubleQuoted
 121                                 continue
 122                         }
 123                 case '\'':
 124                         if !doubleQuoted && !dollarQuote {
 125                                 singleQuoted = !singleQuoted
 126                                 continue
 127                         }
 128                 case ';', '&', '|', '<', '>':
 129                         if !(escaped || singleQuoted || doubleQuoted || backQuote) {
 130                                 pos = i
 131                                 break loop
 132                         }
 133                 }
 134
 135                 got = true
 136                 buf += string(r)
 137                 if backQuote || dollarQuote {
 138                         backtick += string(r)
 139                 }
 140         }
 141
 142         buf = replaceEnv(buf)
 143         args = append(args, buf)
 144
 145         if escaped || singleQuoted || doubleQuoted || backQuote || dollarQuote {
 146                 return nil, errors.New("invalid command line string")
 147         }
 148
 149         p.Position = pos
 150
 151         return args, nil
 152 }
 153
 154 func Split(line string) ([]string, error) {
 155         return NewParser().Parse(line)
 156 }
 157
 158 func Join(args ...string) string {
 159         var buf bytes.Buffer
 160         for i, w := range args {
 161                 if i != 0 {
 162                         buf.WriteByte(' ')
 163                 }
 164                 if w == "" {
 165                         buf.WriteString("''")
 166                         continue
 167                 }
 168
 169                 for _, b := range w {
 170                         switch b {
 171                         case ' ', '\t', '\r', '\n':
 172                                 buf.WriteByte('\\')
 173                                 buf.WriteString(string(b))
 174                         default:
 175                                 buf.WriteString(string(b))
 176                         }
 177                 }
 178         }
 179         return buf.String()
 180 }