ref: 2536a35b68aa37d3a6d57305ae12b50b99c51f42
dir: /config/config.go/
// Package config provides configuration parsing.
package config
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"math"
"strconv"
"strings"
)
// Config holds all parsed configuration entries from a Git config file.
//
// A Config preserves the ordering of entries as they appeared in the source.
//
// Lookups are matched case-insensitively for section and key names, and
// subsections must match exactly.
//
// Includes aren't supported yet; they will be supported in a later revision.
type Config struct {
entries []ConfigEntry
}
// ValueKind describes the presence and form of a config value.
type ValueKind uint8
const (
// ValueMissing means the queried key does not exist.
ValueMissing ValueKind = iota
// ValueValueless means the key exists but has no "= <value>" part.
ValueValueless
// ValueString means the key exists and has an explicit value (possibly "").
ValueString
)
// LookupResult is a value returned by Lookup/LookupAll.
type LookupResult struct {
Kind ValueKind
Value string
}
// String returns the explicit string value.
func (r LookupResult) String() (string, error) {
switch r.Kind {
case ValueMissing:
return "", errors.New("missing config value")
case ValueValueless:
return "", errors.New("valueless config key")
case ValueString:
return r.Value, nil
default:
return "", fmt.Errorf("unknown value kind %d", r.Kind)
}
}
// Bool interprets this lookup result using Git config boolean rules.
func (r LookupResult) Bool() (bool, error) {
switch r.Kind {
case ValueMissing:
return false, errors.New("missing config value")
case ValueValueless:
return true, nil
case ValueString:
return parseBool(r.Value)
default:
return false, fmt.Errorf("unknown value kind %d", r.Kind)
}
}
// Int interprets this lookup result as a Git integer value.
func (r LookupResult) Int() (int, error) {
switch r.Kind {
case ValueMissing:
return 0, errors.New("missing config value")
case ValueValueless:
return 0, errors.New("valueless config key")
case ValueString:
return parseInt(r.Value)
default:
return 0, fmt.Errorf("unknown value kind %d", r.Kind)
}
}
// Int64 interprets this lookup result as a Git int64 value.
func (r LookupResult) Int64() (int64, error) {
switch r.Kind {
case ValueMissing:
return 0, errors.New("missing config value")
case ValueValueless:
return 0, errors.New("valueless config key")
case ValueString:
return parseInt64(r.Value)
default:
return 0, fmt.Errorf("unknown value kind %d", r.Kind)
}
}
// ConfigEntry represents a single parsed configuration directive.
type ConfigEntry struct {
// The section name in canonical lowercase form.
Section string
// The subsection name, retaining the exact form parsed from the input.
Subsection string
// The key name in canonical lowercase form.
Key string
// Kind records whether this entry has no value or an explicit value.
Kind ValueKind
// The interpreted value of the configuration entry, including unescaped
// characters where appropriate.
Value string
}
// ParseConfig reads and parses Git configuration entries from r.
func ParseConfig(r io.Reader) (*Config, error) {
parser := &configParser{
reader: bufio.NewReader(r),
lineNum: 1,
}
return parser.parse()
}
// Lookup retrieves the first value for a given section, optional subsection,
// and key.
func (c *Config) Lookup(section, subsection, key string) LookupResult {
section = strings.ToLower(section)
key = strings.ToLower(key)
for _, entry := range c.entries {
if strings.EqualFold(entry.Section, section) &&
entry.Subsection == subsection &&
strings.EqualFold(entry.Key, key) {
return LookupResult{
Kind: entry.Kind,
Value: entry.Value,
}
}
}
return LookupResult{Kind: ValueMissing}
}
// LookupAll retrieves all values for a given section, optional subsection,
// and key.
func (c *Config) LookupAll(section, subsection, key string) []LookupResult {
section = strings.ToLower(section)
key = strings.ToLower(key)
var values []LookupResult
for _, entry := range c.entries {
if strings.EqualFold(entry.Section, section) &&
entry.Subsection == subsection &&
strings.EqualFold(entry.Key, key) {
values = append(values, LookupResult{
Kind: entry.Kind,
Value: entry.Value,
})
}
}
return values
}
// Entries returns a copy of all parsed configuration entries in the order they
// appeared. Modifying the returned slice does not affect the Config.
func (c *Config) Entries() []ConfigEntry {
result := make([]ConfigEntry, len(c.entries))
copy(result, c.entries)
return result
}
type configParser struct {
reader *bufio.Reader
lineNum int
currentSection string
currentSubsec string
peeked byte
hasPeeked bool
}
func (p *configParser) parse() (*Config, error) {
cfg := &Config{}
if err := p.skipBOM(); err != nil {
return nil, err
}
for {
ch, err := p.nextChar()
if errors.Is(err, io.EOF) {
break
}
if err != nil {
return nil, err
}
// Skip leading whitespace between entries.
if isWhitespace(ch) {
continue
}
// Comments
if ch == '#' || ch == ';' {
if err := p.skipToEOL(); err != nil && !errors.Is(err, io.EOF) {
return nil, err
}
continue
}
// Section header
if ch == '[' {
if err := p.parseSection(); err != nil {
return nil, fmt.Errorf("furgit: config: line %d: %w", p.lineNum, err)
}
continue
}
// Key-value pair
if isLetter(ch) {
p.unreadChar(ch)
if err := p.parseKeyValue(cfg); err != nil {
return nil, fmt.Errorf("furgit: config: line %d: %w", p.lineNum, err)
}
continue
}
return nil, fmt.Errorf("furgit: config: line %d: unexpected character %q", p.lineNum, ch)
}
return cfg, nil
}
func (p *configParser) nextChar() (byte, error) {
if p.hasPeeked {
p.hasPeeked = false
return p.peeked, nil
}
ch, err := p.reader.ReadByte()
if err != nil {
return 0, err
}
if ch == '\r' {
next, err := p.reader.ReadByte()
if err == nil && next == '\n' {
ch = '\n'
} else if err == nil {
// Weird but ok
_ = p.reader.UnreadByte()
}
}
if ch == '\n' {
p.lineNum++
}
return ch, nil
}
func (p *configParser) unreadChar(ch byte) {
p.peeked = ch
p.hasPeeked = true
if ch == '\n' && p.lineNum > 1 {
p.lineNum--
}
}
func (p *configParser) skipBOM() error {
first, err := p.reader.ReadByte()
if errors.Is(err, io.EOF) {
return nil
}
if err != nil {
return err
}
if first != 0xef {
_ = p.reader.UnreadByte()
return nil
}
second, err := p.reader.ReadByte()
if err != nil {
if errors.Is(err, io.EOF) {
_ = p.reader.UnreadByte()
return nil
}
return err
}
third, err := p.reader.ReadByte()
if err != nil {
if errors.Is(err, io.EOF) {
_ = p.reader.UnreadByte()
_ = p.reader.UnreadByte()
return nil
}
return err
}
if second == 0xbb && third == 0xbf {
return nil
}
_ = p.reader.UnreadByte()
_ = p.reader.UnreadByte()
_ = p.reader.UnreadByte()
return nil
}
func (p *configParser) skipToEOL() error {
for {
ch, err := p.nextChar()
if err != nil {
return err
}
if ch == '\n' {
return nil
}
}
}
func (p *configParser) parseSection() error {
var name bytes.Buffer
for {
ch, err := p.nextChar()
if err != nil {
return errors.New("unexpected EOF in section header")
}
if ch == ']' {
section := name.String()
if !isValidSection(section) {
return fmt.Errorf("invalid section name: %q", section)
}
p.currentSection = strings.ToLower(section)
p.currentSubsec = ""
return nil
}
if isWhitespace(ch) {
return p.parseExtendedSection(&name)
}
if !isKeyChar(ch) && ch != '.' {
return fmt.Errorf("invalid character in section name: %q", ch)
}
name.WriteByte(toLower(ch))
}
}
func (p *configParser) parseExtendedSection(sectionName *bytes.Buffer) error {
for {
ch, err := p.nextChar()
if err != nil {
return errors.New("unexpected EOF in section header")
}
if !isWhitespace(ch) {
if ch != '"' {
return errors.New("expected quote after section name")
}
break
}
}
var subsec bytes.Buffer
for {
ch, err := p.nextChar()
if err != nil {
return errors.New("unexpected EOF in subsection")
}
if ch == '\n' {
return errors.New("newline in subsection")
}
if ch == '"' {
break
}
if ch == '\\' {
next, err := p.nextChar()
if err != nil {
return errors.New("unexpected EOF after backslash in subsection")
}
if next == '\n' {
return errors.New("newline after backslash in subsection")
}
subsec.WriteByte(next)
} else {
subsec.WriteByte(ch)
}
}
ch, err := p.nextChar()
if err != nil {
return errors.New("unexpected EOF after subsection")
}
if ch != ']' {
return fmt.Errorf("expected ']' after subsection, got %q", ch)
}
section := sectionName.String()
if !isValidSection(section) {
return fmt.Errorf("invalid section name: %q", section)
}
p.currentSection = strings.ToLower(section)
p.currentSubsec = subsec.String()
return nil
}
func (p *configParser) parseKeyValue(cfg *Config) error {
if p.currentSection == "" {
return errors.New("key-value pair before any section header")
}
var key bytes.Buffer
for {
ch, err := p.nextChar()
if errors.Is(err, io.EOF) {
break
}
if err != nil {
return err
}
if ch == '=' || ch == '\n' || isSpace(ch) {
p.unreadChar(ch)
break
}
if !isKeyChar(ch) {
return fmt.Errorf("invalid character in key: %q", ch)
}
key.WriteByte(toLower(ch))
}
keyStr := key.String()
if len(keyStr) == 0 {
return errors.New("empty key name")
}
if !isLetter(keyStr[0]) {
return errors.New("key must start with a letter")
}
for {
ch, err := p.nextChar()
if errors.Is(err, io.EOF) {
cfg.entries = append(cfg.entries, ConfigEntry{
Section: p.currentSection,
Subsection: p.currentSubsec,
Key: keyStr,
Kind: ValueValueless,
Value: "",
})
return nil
}
if err != nil {
return err
}
if ch == '\n' {
cfg.entries = append(cfg.entries, ConfigEntry{
Section: p.currentSection,
Subsection: p.currentSubsec,
Key: keyStr,
Kind: ValueValueless,
Value: "",
})
return nil
}
if ch == '#' || ch == ';' {
if err := p.skipToEOL(); err != nil && !errors.Is(err, io.EOF) {
return err
}
cfg.entries = append(cfg.entries, ConfigEntry{
Section: p.currentSection,
Subsection: p.currentSubsec,
Key: keyStr,
Kind: ValueValueless,
Value: "",
})
return nil
}
if ch == '=' {
break
}
if !isSpace(ch) {
return fmt.Errorf("unexpected character after key: %q", ch)
}
}
value, err := p.parseValue()
if err != nil {
return err
}
cfg.entries = append(cfg.entries, ConfigEntry{
Section: p.currentSection,
Subsection: p.currentSubsec,
Key: keyStr,
Kind: ValueString,
Value: value,
})
return nil
}
func (p *configParser) parseValue() (string, error) {
var value bytes.Buffer
var inQuote bool
var inComment bool
trimLen := 0
for {
ch, err := p.nextChar()
if errors.Is(err, io.EOF) {
if inQuote {
return "", errors.New("unexpected EOF in quoted value")
}
if trimLen > 0 {
return truncateAtNUL(value.String()[:trimLen]), nil
}
return truncateAtNUL(value.String()), nil
}
if err != nil {
return "", err
}
if ch == '\n' {
if inQuote {
return "", errors.New("newline in quoted value")
}
if trimLen > 0 {
return truncateAtNUL(value.String()[:trimLen]), nil
}
return truncateAtNUL(value.String()), nil
}
if inComment {
continue
}
if isWhitespace(ch) && !inQuote {
if trimLen == 0 && value.Len() > 0 {
trimLen = value.Len()
}
if value.Len() > 0 {
value.WriteByte(ch)
}
continue
}
if !inQuote && (ch == '#' || ch == ';') {
inComment = true
continue
}
if trimLen > 0 {
trimLen = 0
}
if ch == '\\' {
next, err := p.nextChar()
if errors.Is(err, io.EOF) {
return "", errors.New("unexpected EOF after backslash")
}
if err != nil {
return "", err
}
switch next {
case '\n':
continue
case 'n':
value.WriteByte('\n')
case 't':
value.WriteByte('\t')
case 'b':
value.WriteByte('\b')
case '\\', '"':
value.WriteByte(next)
default:
return "", fmt.Errorf("invalid escape sequence: \\%c", next)
}
continue
}
if ch == '"' {
inQuote = !inQuote
continue
}
value.WriteByte(ch)
}
}
func isValidSection(s string) bool {
if len(s) == 0 {
return false
}
for i := 0; i < len(s); i++ {
ch := s[i]
if !isLetter(ch) && !isDigit(ch) && ch != '-' && ch != '.' {
return false
}
}
return true
}
func isKeyChar(ch byte) bool {
return isLetter(ch) || isDigit(ch) || ch == '-'
}
func parseBool(value string) (bool, error) {
switch {
case strings.EqualFold(value, "true"),
strings.EqualFold(value, "yes"),
strings.EqualFold(value, "on"):
return true, nil
case strings.EqualFold(value, "false"),
strings.EqualFold(value, "no"),
strings.EqualFold(value, "off"),
value == "":
return false, nil
}
n, err := parseInt32(value)
if err != nil {
return false, fmt.Errorf("invalid boolean value %q", value)
}
return n != 0, nil
}
func parseInt32(value string) (int32, error) {
n64, err := parseInt64WithMax(value, math.MaxInt32)
if err != nil {
return 0, err
}
return int32(n64), nil
}
func parseInt(value string) (int, error) {
n64, err := parseInt64WithMax(value, int64(int(^uint(0)>>1)))
if err != nil {
return 0, err
}
return int(n64), nil
}
func parseInt64(value string) (int64, error) {
return parseInt64WithMax(value, int64(^uint64(0)>>1))
}
func parseInt64WithMax(value string, max int64) (int64, error) {
if value == "" {
return 0, errors.New("empty value")
}
trimmed := strings.TrimLeft(value, " \t\n\r\f\v")
if trimmed == "" {
return 0, errors.New("empty value")
}
numPart := trimmed
factor := int64(1)
if last := trimmed[len(trimmed)-1]; last == 'k' || last == 'K' || last == 'm' || last == 'M' || last == 'g' || last == 'G' {
switch toLower(last) {
case 'k':
factor = 1024
case 'm':
factor = 1024 * 1024
case 'g':
factor = 1024 * 1024 * 1024
}
numPart = trimmed[:len(trimmed)-1]
}
if numPart == "" {
return 0, errors.New("missing integer value")
}
n, err := strconv.ParseInt(numPart, 0, 64)
if err != nil {
return 0, err
}
intMax := max
intMin := -max - 1
if n > 0 && n > intMax/factor {
return 0, errors.New("integer overflow")
}
if n < 0 && n < intMin/factor {
return 0, errors.New("integer overflow")
}
n *= factor
return n, nil
}
func truncateAtNUL(value string) string {
for i := 0; i < len(value); i++ {
if value[i] == 0 {
return value[:i]
}
}
return value
}
func isSpace(ch byte) bool {
return ch == ' ' || ch == '\t'
}
func isWhitespace(ch byte) bool {
return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r' || ch == '\v' || ch == '\f'
}
func isLetter(ch byte) bool {
return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')
}
func isDigit(ch byte) bool {
return ch >= '0' && ch <= '9'
}
func toLower(ch byte) byte {
if ch >= 'A' && ch <= 'Z' {
return ch + ('a' - 'A')
}
return ch
}