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feature(helm): add --set-literal flag for literal string interpretation
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The current family of '--set' methods interprets some special characters
in values (e.g. commas, square brackets, points, backslashes). With the
typical shell escaping rules, this can increase the difficulty of overwriting
values in some cases.

In contrast to '--set-string' or similar methods, '--set-literal' does
not interpret those special characters. It interprets given values as
literal strings.

Example:

    --set-literal outer.inner='so\me,values'

    outer:
      inner: so\me,values

Closes #4030

Signed-off-by: Patrick Scheid <p.scheid92@gmail.com>
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pscheid92 committed Sep 23, 2022
1 parent a48b87f commit 4516039
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Showing 4 changed files with 665 additions and 5 deletions.
1 change: 1 addition & 0 deletions cmd/helm/flags.go
Expand Up @@ -48,6 +48,7 @@ func addValueOptionsFlags(f *pflag.FlagSet, v *values.Options) {
f.StringArrayVar(&v.StringValues, "set-string", []string{}, "set STRING values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)")
f.StringArrayVar(&v.FileValues, "set-file", []string{}, "set values from respective files specified via the command line (can specify multiple or separate values with commas: key1=path1,key2=path2)")
f.StringArrayVar(&v.JSONValues, "set-json", []string{}, "set JSON values on the command line (can specify multiple or separate values with commas: key1=jsonval1,key2=jsonval2)")
f.StringArrayVar(&v.LiteralValues, "set-literal", []string{}, "set a literal STRING value on the command line")
}

func addChartPathOptionsFlags(f *pflag.FlagSet, c *action.ChartPathOptions) {
Expand Down
18 changes: 13 additions & 5 deletions pkg/cli/values/options.go
Expand Up @@ -30,11 +30,12 @@ import (
)

type Options struct {
ValueFiles []string
StringValues []string
Values []string
FileValues []string
JSONValues []string
ValueFiles []string
StringValues []string
Values []string
FileValues []string
JSONValues []string
LiteralValues []string
}

// MergeValues merges values from files specified via -f/--values and directly
Expand Down Expand Up @@ -93,6 +94,13 @@ func (opts *Options) MergeValues(p getter.Providers) (map[string]interface{}, er
}
}

// User specified a value via --set-literal
for _, value := range opts.LiteralValues {
if err := strvals.ParseLiteralInto(value, base); err != nil {
return nil, errors.Wrap(err, "failed parsing --set-literal data")
}
}

return base, nil
}

Expand Down
236 changes: 236 additions & 0 deletions pkg/strvals/literal_parser.go
@@ -0,0 +1,236 @@
/*
Copyright The Helm Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package strvals

import (
"bytes"
"fmt"
"io"
"strconv"

"github.com/pkg/errors"
)

// ParseLiteral parses a set line interpreting the value as a literal string.
//
// A set line is of the form name1=value1
func ParseLiteral(s string) (map[string]interface{}, error) {
vals := map[string]interface{}{}
scanner := bytes.NewBufferString(s)
t := newLiteralParser(scanner, vals)
err := t.parse()
return vals, err
}

// ParseLiteralInto parses a strvals line and merges the result into dest.
// The value is interpreted as a literal string.
//
// If the strval string has a key that exists in dest, it overwrites the
// dest version.
func ParseLiteralInto(s string, dest map[string]interface{}) error {
scanner := bytes.NewBufferString(s)
t := newLiteralParser(scanner, dest)
return t.parse()
}

// literalParser is a simple parser that takes a strvals line and parses
// it into a map representation.
//
// Values are interpreted as a literal string.
//
// where sc is the source of the original data being parsed
// where data is the final parsed data from the parses with correct types
type literalParser struct {
sc *bytes.Buffer
data map[string]interface{}
}

func newLiteralParser(sc *bytes.Buffer, data map[string]interface{}) *literalParser {
return &literalParser{sc: sc, data: data}
}

func (t *literalParser) parse() error {
for {
err := t.key(t.data)
if err == nil {
continue
}
if err == io.EOF {
return nil
}
return err
}
}

func runesUntilLiteral(in io.RuneReader, stop map[rune]bool) ([]rune, rune, error) {
v := []rune{}
for {
switch r, _, e := in.ReadRune(); {
case e != nil:
return v, r, e
case inMap(r, stop):
return v, r, nil
default:
v = append(v, r)
}
}
}

func (t *literalParser) key(data map[string]interface{}) (reterr error) {
defer func() {
if r := recover(); r != nil {
reterr = fmt.Errorf("unable to parse key: %s", r)
}
}()
stop := runeSet([]rune{'=', '[', '.'})
for {
switch key, lastRune, err := runesUntilLiteral(t.sc, stop); {
case err != nil:
if len(key) == 0 {
return err
}
return errors.Errorf("key %q has no value", string(key))

case lastRune == '=':
// found end of key: swallow the '=' and get the value
value, err := t.val()
if err == nil && err != io.EOF {
return err
}
set(data, string(key), string(value))
return nil

case lastRune == '.':
// first, create or find the target map in the given data
inner := map[string]interface{}{}
if _, ok := data[string(key)]; ok {
inner = data[string(key)].(map[string]interface{})
}

// recurse on sub-tree with remaining data
err := t.key(inner)
if len(inner) == 0 {
return errors.Errorf("key map %q has no value", string(key))
}
set(data, string(key), inner)
return err

case lastRune == '[':
// We are in a list index context, so we need to set an index.
i, err := t.keyIndex()
if err != nil {
return errors.Wrap(err, "error parsing index")
}
kk := string(key)

// find or create target list
list := []interface{}{}
if _, ok := data[kk]; ok {
list = data[kk].([]interface{})
}

// now we need to get the value after the ]
list, err = t.listItem(list, i)
set(data, kk, list)
return err
}
}
}

func (t *literalParser) keyIndex() (int, error) {
// First, get the key.
stop := runeSet([]rune{']'})
v, _, err := runesUntilLiteral(t.sc, stop)
if err != nil {
return 0, err
}

// v should be the index
return strconv.Atoi(string(v))
}

func (t *literalParser) listItem(list []interface{}, i int) ([]interface{}, error) {
if i < 0 {
return list, fmt.Errorf("negative %d index not allowed", i)
}
stop := runeSet([]rune{'[', '.', '='})

switch key, lastRune, err := runesUntilLiteral(t.sc, stop); {
case len(key) > 0:
return list, errors.Errorf("unexpected data at end of array index: %q", key)

case err != nil:
return list, err

case lastRune == '=':
value, err := t.val()
if err != nil && err != io.EOF {
return list, err
}
return setIndex(list, i, string(value))

case lastRune == '.':
// we have a nested object. Send to t.key
inner := map[string]interface{}{}
if len(list) > i {
var ok bool
inner, ok = list[i].(map[string]interface{})
if !ok {
// We have indices out of order. Initialize empty value.
list[i] = map[string]interface{}{}
inner = list[i].(map[string]interface{})
}
}

// recurse
err := t.key(inner)
if err != nil {
return list, err
}
return setIndex(list, i, inner)

case lastRune == '[':
// now we have a nested list. Read the index and handle.
nextI, err := t.keyIndex()
if err != nil {
return list, errors.Wrap(err, "error parsing index")
}
var crtList []interface{}
if len(list) > i {
// If nested list already exists, take the value of list to next cycle.
existed := list[i]
if existed != nil {
crtList = list[i].([]interface{})
}
}

// Now we need to get the value after the ].
list2, err := t.listItem(crtList, nextI)
if err != nil {
return list, err
}
return setIndex(list, i, list2)

default:
return nil, errors.Errorf("parse error: unexpected token %v", lastRune)
}
}

func (t *literalParser) val() ([]rune, error) {
stop := runeSet([]rune{})
v, _, err := runesUntilLiteral(t.sc, stop)
return v, err
}

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