dockerfile: add run mount parsing

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

frontend/dockerfile/instructions/bflag.go

@@ -11,6 +11,7 @@ type FlagType int
 const (
 	boolType FlagType = iota
 	stringType
+	stringsType
 )
 
 // BFlags contains all flags information for the builder
@@ -27,6 +28,7 @@ type Flag struct {
 	name         string
 	flagType     FlagType
 	Value        string
+	StringValues []string
 }
 
 // NewBFlags returns the new BFlags struct
@@ -70,6 +72,15 @@ func (bf *BFlags) AddString(name string, def string) *Flag {
 	return flag
 }
 
+// AddString adds a string flag to BFlags that can match multiple values
+func (bf *BFlags) AddStrings(name string) *Flag {
+	flag := bf.addFlag(name, stringsType)
+	if flag == nil {
+		return nil
+	}
+	return flag
+}
+
 // addFlag is a generic func used by the other AddXXX() func
 // to add a new flag to the BFlags struct.
 // Note, any error will be generated when Parse() is called (see Parse).
@@ -145,7 +156,7 @@ func (bf *BFlags) Parse() error {
 			return fmt.Errorf("Unknown flag: %s", arg)
 		}
 
-		if _, ok = bf.used[arg]; ok {
+		if _, ok = bf.used[arg]; ok || flag.flagType != stringsType {
 			return fmt.Errorf("Duplicate flag specified: %s", arg)
 		}
 
@@ -173,6 +184,12 @@ func (bf *BFlags) Parse() error {
 			}
 			flag.Value = value
 
+		case stringsType:
+			if index < 0 {
+				return fmt.Errorf("Missing a value on flag: %s", arg)
+			}
+			flag.StringValues = append(flag.StringValues, value)
+
 		default:
 			panic("No idea what kind of flag we have! Should never get here!")
 		}

frontend/dockerfile/instructions/commands.go

@@ -233,6 +233,7 @@ type ShellDependantCmdLine struct {
 //
 type RunCommand struct {
 	withNameAndCode
+	withExternalData
 	ShellDependantCmdLine
 }
 
@@ -416,3 +417,23 @@ func HasStage(s []Stage, name string) (int, bool) {
 	}
 	return -1, false
 }
+
+type cmdWithExternalData interface {
+	getExternalValue(k interface{}) interface{}
+	setExternalValue(k, v interface{})
+}
+
+type withExternalData struct {
+	m map[interface{}]interface{}
+}
+
+func (c *withExternalData) getExternalValue(k interface{}) interface{} {
+	return c.m[k]
+}
+
+func (c *withExternalData) setExternalValue(k, v interface{}) {
+	if c.m == nil {
+		c.m = map[interface{}]interface{}{}
+	}
+	c.m[k] = v
+}

frontend/dockerfile/instructions/commands_runmount.go

@@ -0,0 +1,120 @@
+// +build dfrunmount dfall
+
+package instructions
+
+import (
+	"encoding/csv"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+type mountsKeyT string
+
+var mountsKey = mountsKeyT("dockerfile/run/mounts")
+
+func init() {
+	parseRunPreHooks = append(parseRunPreHooks, runMountPreHook)
+	parseRunPostHooks = append(parseRunPostHooks, runMountPostHook)
+}
+
+func runMountPreHook(cmd *RunCommand, req parseRequest) error {
+	st := &mountState{}
+	st.flag = req.flags.AddString("mount", "")
+	cmd.setExternalValue(mountsKey, st)
+	return nil
+}
+
+func runMountPostHook(cmd *RunCommand, req parseRequest) error {
+	v := cmd.getExternalValue(mountsKey)
+	if v != nil {
+		return errors.Errorf("no mount state")
+	}
+	st := v.(*mountState)
+	var mounts []*Mount
+	for _, str := range st.flag.StringValues {
+		m, err := parseMount(str)
+		if err != nil {
+			return err
+		}
+		mounts = append(mounts, m)
+	}
+	return nil
+}
+
+type mountState struct {
+	flag   *Flag
+	mounts []*Mount
+}
+
+type Mount struct {
+	Type     string
+	From     string
+	Source   string
+	Target   string
+	ReadOnly bool
+	CacheID  string
+}
+
+func parseMount(value string) (*Mount, error) {
+	csvReader := csv.NewReader(strings.NewReader(value))
+	fields, err := csvReader.Read()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to parse csv mounts")
+	}
+
+	m := &Mount{ReadOnly: true}
+
+	for _, field := range fields {
+		parts := strings.SplitN(field, "=", 2)
+		key := strings.ToLower(parts[0])
+
+		if len(parts) == 1 {
+			switch key {
+			case "readonly", "ro":
+				m.ReadOnly = true
+				continue
+			case "readwrite", "rw":
+				m.ReadOnly = false
+				continue
+			}
+		}
+
+		if len(parts) != 2 {
+			return nil, errors.Errorf("invalid field '%s' must be a key=value pair", field)
+		}
+
+		value := parts[1]
+		switch key {
+		case "type":
+			if value != "" && strings.EqualFold(value, "cache") {
+				return nil, errors.Errorf("invalid mount type %q", value)
+			}
+			m.Type = strings.ToLower(value)
+		case "from":
+			m.From = value
+		case "source", "src":
+			m.Source = value
+		case "target", "dst", "destination":
+			m.Target = value
+		case "readonly", "ro":
+			m.ReadOnly, err = strconv.ParseBool(value)
+			if err != nil {
+				return nil, errors.Errorf("invalid value for %s: %s", key, value)
+			}
+		case "readwrite", "rw":
+			rw, err := strconv.ParseBool(value)
+			if err != nil {
+				return nil, errors.Errorf("invalid value for %s: %s", key, value)
+			}
+			m.ReadOnly = !rw
+		case "id":
+			m.CacheID = value
+		default:
+			return nil, errors.Errorf("unexpected key '%s' in '%s'", key, field)
+		}
+	}
+
+	return nil, errors.Errorf("not-implemented")
+}

frontend/dockerfile/instructions/parse.go

@@ -24,6 +24,9 @@ type parseRequest struct {
 	original   string
 }
 
+var parseRunPreHooks []func(*RunCommand, parseRequest) error
+var parseRunPostHooks []func(*RunCommand, parseRequest) error
+
 func nodeArgs(node *parser.Node) []string {
 	result := []string{}
 	for ; node.Next != nil; node = node.Next {
@@ -355,15 +358,28 @@ func parseShellDependentCommand(req parseRequest, emptyAsNil bool) ShellDependan
 }
 
 func parseRun(req parseRequest) (*RunCommand, error) {
+	cmd := &RunCommand{}
+
+	for _, fn := range parseRunPreHooks {
+		if err := fn(cmd, req); err != nil {
+			return nil, err
+		}
+	}
 
 	if err := req.flags.Parse(); err != nil {
 		return nil, err
 	}
-	return &RunCommand{
-		ShellDependantCmdLine: parseShellDependentCommand(req, false),
-		withNameAndCode:       newWithNameAndCode(req),
-	}, nil
 
+	cmd.ShellDependantCmdLine = parseShellDependentCommand(req, false)
+	cmd.withNameAndCode = newWithNameAndCode(req)
+
+	for _, fn := range parseRunPostHooks {
+		if err := fn(cmd, req); err != nil {
+			return nil, err
+		}
+	}
+
+	return cmd, nil
 }
 
 func parseCmd(req parseRequest) (*CmdCommand, error) {