blob: 5f484e4999291a7719013a0e7c01a4d2e42e4295 [file] [log] [blame]
package parser
// line parsers are dispatch calls that parse a single unit of text into a
// Node object which contains the whole statement. Dockerfiles have varied
// (but not usually unique, see ONBUILD for a unique example) parsing rules
// per-command, and these unify the processing in a way that makes it
// manageable.
import (
"encoding/json"
"errors"
"fmt"
"strings"
"unicode"
"unicode/utf8"
)
var (
errDockerfileNotStringArray = errors.New("When using JSON array syntax, arrays must be comprised of strings only.")
)
// ignore the current argument. This will still leave a command parsed, but
// will not incorporate the arguments into the ast.
func parseIgnore(rest string) (*Node, map[string]bool, error) {
return &Node{}, nil, nil
}
// used for onbuild. Could potentially be used for anything that represents a
// statement with sub-statements.
//
// ONBUILD RUN foo bar -> (onbuild (run foo bar))
//
func parseSubCommand(rest string) (*Node, map[string]bool, error) {
if rest == "" {
return nil, nil, nil
}
_, child, err := ParseLine(rest)
if err != nil {
return nil, nil, err
}
return &Node{Children: []*Node{child}}, nil, nil
}
// helper to parse words (i.e space delimited or quoted strings) in a statement.
// The quotes are preserved as part of this function and they are stripped later
// as part of processWords().
func parseWords(rest string) []string {
const (
inSpaces = iota // looking for start of a word
inWord
inQuote
)
words := []string{}
phase := inSpaces
word := ""
quote := '\000'
blankOK := false
var ch rune
var chWidth int
for pos := 0; pos <= len(rest); pos += chWidth {
if pos != len(rest) {
ch, chWidth = utf8.DecodeRuneInString(rest[pos:])
}
if phase == inSpaces { // Looking for start of word
if pos == len(rest) { // end of input
break
}
if unicode.IsSpace(ch) { // skip spaces
continue
}
phase = inWord // found it, fall through
}
if (phase == inWord || phase == inQuote) && (pos == len(rest)) {
if blankOK || len(word) > 0 {
words = append(words, word)
}
break
}
if phase == inWord {
if unicode.IsSpace(ch) {
phase = inSpaces
if blankOK || len(word) > 0 {
words = append(words, word)
}
word = ""
blankOK = false
continue
}
if ch == '\'' || ch == '"' {
quote = ch
blankOK = true
phase = inQuote
}
if ch == tokenEscape {
if pos+chWidth == len(rest) {
continue // just skip an escape token at end of line
}
// If we're not quoted and we see an escape token, then always just
// add the escape token plus the char to the word, even if the char
// is a quote.
word += string(ch)
pos += chWidth
ch, chWidth = utf8.DecodeRuneInString(rest[pos:])
}
word += string(ch)
continue
}
if phase == inQuote {
if ch == quote {
phase = inWord
}
// The escape token is special except for ' quotes - can't escape anything for '
if ch == tokenEscape && quote != '\'' {
if pos+chWidth == len(rest) {
phase = inWord
continue // just skip the escape token at end
}
pos += chWidth
word += string(ch)
ch, chWidth = utf8.DecodeRuneInString(rest[pos:])
}
word += string(ch)
}
}
return words
}
// parse environment like statements. Note that this does *not* handle
// variable interpolation, which will be handled in the evaluator.
func parseNameVal(rest string, key string) (*Node, map[string]bool, error) {
// This is kind of tricky because we need to support the old
// variant: KEY name value
// as well as the new one: KEY name=value ...
// The trigger to know which one is being used will be whether we hit
// a space or = first. space ==> old, "=" ==> new
words := parseWords(rest)
if len(words) == 0 {
return nil, nil, nil
}
var rootnode *Node
// Old format (KEY name value)
if !strings.Contains(words[0], "=") {
node := &Node{}
rootnode = node
strs := tokenWhitespace.Split(rest, 2)
if len(strs) < 2 {
return nil, nil, fmt.Errorf(key + " must have two arguments")
}
node.Value = strs[0]
node.Next = &Node{}
node.Next.Value = strs[1]
} else {
var prevNode *Node
for i, word := range words {
if !strings.Contains(word, "=") {
return nil, nil, fmt.Errorf("Syntax error - can't find = in %q. Must be of the form: name=value", word)
}
parts := strings.SplitN(word, "=", 2)
name := &Node{}
value := &Node{}
name.Next = value
name.Value = parts[0]
value.Value = parts[1]
if i == 0 {
rootnode = name
} else {
prevNode.Next = name
}
prevNode = value
}
}
return rootnode, nil, nil
}
func parseEnv(rest string) (*Node, map[string]bool, error) {
return parseNameVal(rest, "ENV")
}
func parseLabel(rest string) (*Node, map[string]bool, error) {
return parseNameVal(rest, "LABEL")
}
// parses a statement containing one or more keyword definition(s) and/or
// value assignments, like `name1 name2= name3="" name4=value`.
// Note that this is a stricter format than the old format of assignment,
// allowed by parseNameVal(), in a way that this only allows assignment of the
// form `keyword=[<value>]` like `name2=`, `name3=""`, and `name4=value` above.
// In addition, a keyword definition alone is of the form `keyword` like `name1`
// above. And the assignments `name2=` and `name3=""` are equivalent and
// assign an empty value to the respective keywords.
func parseNameOrNameVal(rest string) (*Node, map[string]bool, error) {
words := parseWords(rest)
if len(words) == 0 {
return nil, nil, nil
}
var (
rootnode *Node
prevNode *Node
)
for i, word := range words {
node := &Node{}
node.Value = word
if i == 0 {
rootnode = node
} else {
prevNode.Next = node
}
prevNode = node
}
return rootnode, nil, nil
}
// parses a whitespace-delimited set of arguments. The result is effectively a
// linked list of string arguments.
func parseStringsWhitespaceDelimited(rest string) (*Node, map[string]bool, error) {
if rest == "" {
return nil, nil, nil
}
node := &Node{}
rootnode := node
prevnode := node
for _, str := range tokenWhitespace.Split(rest, -1) { // use regexp
prevnode = node
node.Value = str
node.Next = &Node{}
node = node.Next
}
// XXX to get around regexp.Split *always* providing an empty string at the
// end due to how our loop is constructed, nil out the last node in the
// chain.
prevnode.Next = nil
return rootnode, nil, nil
}
// parsestring just wraps the string in quotes and returns a working node.
func parseString(rest string) (*Node, map[string]bool, error) {
if rest == "" {
return nil, nil, nil
}
n := &Node{}
n.Value = rest
return n, nil, nil
}
// parseJSON converts JSON arrays to an AST.
func parseJSON(rest string) (*Node, map[string]bool, error) {
rest = strings.TrimLeftFunc(rest, unicode.IsSpace)
if !strings.HasPrefix(rest, "[") {
return nil, nil, fmt.Errorf(`Error parsing "%s" as a JSON array`, rest)
}
var myJSON []interface{}
if err := json.NewDecoder(strings.NewReader(rest)).Decode(&myJSON); err != nil {
return nil, nil, err
}
var top, prev *Node
for _, str := range myJSON {
s, ok := str.(string)
if !ok {
return nil, nil, errDockerfileNotStringArray
}
node := &Node{Value: s}
if prev == nil {
top = node
} else {
prev.Next = node
}
prev = node
}
return top, map[string]bool{"json": true}, nil
}
// parseMaybeJSON determines if the argument appears to be a JSON array. If
// so, passes to parseJSON; if not, quotes the result and returns a single
// node.
func parseMaybeJSON(rest string) (*Node, map[string]bool, error) {
if rest == "" {
return nil, nil, nil
}
node, attrs, err := parseJSON(rest)
if err == nil {
return node, attrs, nil
}
if err == errDockerfileNotStringArray {
return nil, nil, err
}
node = &Node{}
node.Value = rest
return node, nil, nil
}
// parseMaybeJSONToList determines if the argument appears to be a JSON array. If
// so, passes to parseJSON; if not, attempts to parse it as a whitespace
// delimited string.
func parseMaybeJSONToList(rest string) (*Node, map[string]bool, error) {
node, attrs, err := parseJSON(rest)
if err == nil {
return node, attrs, nil
}
if err == errDockerfileNotStringArray {
return nil, nil, err
}
return parseStringsWhitespaceDelimited(rest)
}
// The HEALTHCHECK command is like parseMaybeJSON, but has an extra type argument.
func parseHealthConfig(rest string) (*Node, map[string]bool, error) {
// Find end of first argument
var sep int
for ; sep < len(rest); sep++ {
if unicode.IsSpace(rune(rest[sep])) {
break
}
}
next := sep
for ; next < len(rest); next++ {
if !unicode.IsSpace(rune(rest[next])) {
break
}
}
if sep == 0 {
return nil, nil, nil
}
typ := rest[:sep]
cmd, attrs, err := parseMaybeJSON(rest[next:])
if err != nil {
return nil, nil, err
}
return &Node{Value: typ, Next: cmd, Attributes: attrs}, nil, err
}