зеркало из https://github.com/microsoft/docker.git
244 строки
4.8 KiB
Go
244 строки
4.8 KiB
Go
package builder
|
|
|
|
// This will take a single word and an array of env variables and
|
|
// process all quotes (" and ') as well as $xxx and ${xxx} env variable
|
|
// tokens. Tries to mimic bash shell process.
|
|
// It doesn't support all flavors of ${xx:...} formats but new ones can
|
|
// be added by adding code to the "special ${} format processing" section
|
|
|
|
import (
|
|
"fmt"
|
|
"strings"
|
|
"unicode"
|
|
)
|
|
|
|
type shellWord struct {
|
|
word string
|
|
envs []string
|
|
pos int
|
|
}
|
|
|
|
// ProcessWord will use the 'env' list of environment variables,
|
|
// and replace any env var references in 'word'.
|
|
func ProcessWord(word string, env []string) (string, error) {
|
|
sw := &shellWord{
|
|
word: word,
|
|
envs: env,
|
|
pos: 0,
|
|
}
|
|
return sw.process()
|
|
}
|
|
|
|
func (sw *shellWord) process() (string, error) {
|
|
return sw.processStopOn('\000')
|
|
}
|
|
|
|
// Process the word, starting at 'pos', and stop when we get to the
|
|
// end of the word or the 'stopChar' character
|
|
func (sw *shellWord) processStopOn(stopChar rune) (string, error) {
|
|
var result string
|
|
var charFuncMapping = map[rune]func() (string, error){
|
|
'\'': sw.processSingleQuote,
|
|
'"': sw.processDoubleQuote,
|
|
'$': sw.processDollar,
|
|
}
|
|
|
|
for sw.pos < len(sw.word) {
|
|
ch := sw.peek()
|
|
if stopChar != '\000' && ch == stopChar {
|
|
sw.next()
|
|
break
|
|
}
|
|
if fn, ok := charFuncMapping[ch]; ok {
|
|
// Call special processing func for certain chars
|
|
tmp, err := fn()
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
result += tmp
|
|
} else {
|
|
// Not special, just add it to the result
|
|
ch = sw.next()
|
|
if ch == '\\' {
|
|
// '\' escapes, except end of line
|
|
ch = sw.next()
|
|
if ch == '\000' {
|
|
continue
|
|
}
|
|
}
|
|
result += string(ch)
|
|
}
|
|
}
|
|
|
|
return result, nil
|
|
}
|
|
|
|
func (sw *shellWord) peek() rune {
|
|
if sw.pos == len(sw.word) {
|
|
return '\000'
|
|
}
|
|
return rune(sw.word[sw.pos])
|
|
}
|
|
|
|
func (sw *shellWord) next() rune {
|
|
if sw.pos == len(sw.word) {
|
|
return '\000'
|
|
}
|
|
ch := rune(sw.word[sw.pos])
|
|
sw.pos++
|
|
return ch
|
|
}
|
|
|
|
func (sw *shellWord) processSingleQuote() (string, error) {
|
|
// All chars between single quotes are taken as-is
|
|
// Note, you can't escape '
|
|
var result string
|
|
|
|
sw.next()
|
|
|
|
for {
|
|
ch := sw.next()
|
|
if ch == '\000' || ch == '\'' {
|
|
break
|
|
}
|
|
result += string(ch)
|
|
}
|
|
return result, nil
|
|
}
|
|
|
|
func (sw *shellWord) processDoubleQuote() (string, error) {
|
|
// All chars up to the next " are taken as-is, even ', except any $ chars
|
|
// But you can escape " with a \
|
|
var result string
|
|
|
|
sw.next()
|
|
|
|
for sw.pos < len(sw.word) {
|
|
ch := sw.peek()
|
|
if ch == '"' {
|
|
sw.next()
|
|
break
|
|
}
|
|
if ch == '$' {
|
|
tmp, err := sw.processDollar()
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
result += tmp
|
|
} else {
|
|
ch = sw.next()
|
|
if ch == '\\' {
|
|
chNext := sw.peek()
|
|
|
|
if chNext == '\000' {
|
|
// Ignore \ at end of word
|
|
continue
|
|
}
|
|
|
|
if chNext == '"' || chNext == '$' {
|
|
// \" and \$ can be escaped, all other \'s are left as-is
|
|
ch = sw.next()
|
|
}
|
|
}
|
|
result += string(ch)
|
|
}
|
|
}
|
|
|
|
return result, nil
|
|
}
|
|
|
|
func (sw *shellWord) processDollar() (string, error) {
|
|
sw.next()
|
|
ch := sw.peek()
|
|
if ch == '{' {
|
|
sw.next()
|
|
name := sw.processName()
|
|
ch = sw.peek()
|
|
if ch == '}' {
|
|
// Normal ${xx} case
|
|
sw.next()
|
|
return sw.getEnv(name), nil
|
|
}
|
|
if ch == ':' {
|
|
// Special ${xx:...} format processing
|
|
// Yes it allows for recursive $'s in the ... spot
|
|
|
|
sw.next() // skip over :
|
|
modifier := sw.next()
|
|
|
|
word, err := sw.processStopOn('}')
|
|
if err != nil {
|
|
return "", err
|
|
}
|
|
|
|
// Grab the current value of the variable in question so we
|
|
// can use to to determine what to do based on the modifier
|
|
newValue := sw.getEnv(name)
|
|
|
|
switch modifier {
|
|
case '+':
|
|
if newValue != "" {
|
|
newValue = word
|
|
}
|
|
return newValue, nil
|
|
|
|
case '-':
|
|
if newValue == "" {
|
|
newValue = word
|
|
}
|
|
return newValue, nil
|
|
|
|
default:
|
|
return "", fmt.Errorf("Unsupported modifier (%c) in substitution: %s", modifier, sw.word)
|
|
}
|
|
}
|
|
return "", fmt.Errorf("Missing ':' in substitution: %s", sw.word)
|
|
}
|
|
// $xxx case
|
|
name := sw.processName()
|
|
if name == "" {
|
|
return "$", nil
|
|
}
|
|
return sw.getEnv(name), nil
|
|
}
|
|
|
|
func (sw *shellWord) processName() string {
|
|
// Read in a name (alphanumeric or _)
|
|
// If it starts with a numeric then just return $#
|
|
var name string
|
|
|
|
for sw.pos < len(sw.word) {
|
|
ch := sw.peek()
|
|
if len(name) == 0 && unicode.IsDigit(ch) {
|
|
ch = sw.next()
|
|
return string(ch)
|
|
}
|
|
if !unicode.IsLetter(ch) && !unicode.IsDigit(ch) && ch != '_' {
|
|
break
|
|
}
|
|
ch = sw.next()
|
|
name += string(ch)
|
|
}
|
|
|
|
return name
|
|
}
|
|
|
|
func (sw *shellWord) getEnv(name string) string {
|
|
for _, env := range sw.envs {
|
|
i := strings.Index(env, "=")
|
|
if i < 0 {
|
|
if name == env {
|
|
// Should probably never get here, but just in case treat
|
|
// it like "var" and "var=" are the same
|
|
return ""
|
|
}
|
|
continue
|
|
}
|
|
if name != env[:i] {
|
|
continue
|
|
}
|
|
return env[i+1:]
|
|
}
|
|
return ""
|
|
}
|