Mihaela Mihaljevic
497e2460a3
A general entity whose replacement text contains markup (directly or transitively) is reparsed as content at the reference (4.4.2 Included): the replacement is WFC-validated, cycle-checked, and budgeted, then pushed back into the reader stream, so its elements become elements in the tree and the pull-event stream rather than escaped character data. Character references in internal entity literals now expand at declaration time for general entities too (4.4.5), making char-ref markup splice and the Appendix D double escape render as a literal ampersand; the reference-time WFC validates remaining references instead of re-expanding. Text-only entities keep the coalescing single-pass path. Sun valid is 28/28. Closes #133
278 lines
13 KiB
Swift
278 lines
13 KiB
Swift
/// The strict XML 1.0 grammar for `<!ENTITY>` declarations, external
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/// identifiers, and public-identifier literals, split from the scanner body to
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/// keep it under the length caps. The scan is one well-formedness gate: any
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/// deviation throws a located `ParseError`.
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extension DTDScanner {
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mutating func scanEntityDeclaration(_ reader: inout Reader) throws {
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let mark = reader.mark
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reader.consume("<!ENTITY")
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guard reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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let isParameter = reader.consume("%")
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if isParameter {
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guard reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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}
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let name = try scanStrictName(&reader, at: mark)
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guard reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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if let value = scanLiteral(&reader) {
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try scanInternalEntityTail(&reader, name: name, value: value, isParameter: isParameter, at: mark)
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return
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}
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try scanExternalEntityTail(&reader, name: name, isParameter: isParameter, at: mark)
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}
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/// The tail of an internal entity: the literal already read, then `S? '>'`.
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private mutating func scanInternalEntityTail(_ reader: inout Reader, name: String, value: String, isParameter: Bool, at mark: Mark) throws {
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try validateEntityLiteral(value, at: mark)
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reader.skipSpace()
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guard reader.peek() == ">" else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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skip(&reader, until: ">")
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// Character references in an entity literal are expanded when the
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// declaration is parsed (4.4.5): `%zz;` stores a usable `%zz;`,
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// `<foo>` stores markup that content splicing reparses, and the
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// Appendix D double escape `&#38;` stores `&`, which the
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// content reparse turns into a literal ampersand. The replacement-text
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// well-formedness constraint still binds at reference time (an
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// unreferenced entity may carry a bad value).
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guard let replacement = PureXML.Parsing.EntityReplacementGrammar.expandCharacterReferences(value) else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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storeEntity(name: name, value: expandParameterReferences(replacement), isParameter: isParameter)
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}
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/// The tail of an external entity: the identifier, an optional `S NDATA Name`
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/// (general entities only), then `S? '>'`.
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private mutating func scanExternalEntityTail(_ reader: inout Reader, name: String, isParameter: Bool, at mark: Mark) throws {
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guard let id = try parseStrictExternalID(&reader, requireSystem: true, at: mark) else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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var notation: String?
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if reader.peek()?.isWhitespace == true {
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reader.skipSpace()
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if reader.consume("NDATA") {
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// NDATA is for unparsed general entities only, and `S Name`
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// must follow (production 76).
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guard !isParameter, reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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notation = try scanStrictName(&reader, at: mark)
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}
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} else if reader.peek() != ">" {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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guard reader.peek() == ">" else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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skip(&reader, until: ">")
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storeExternalEntity(name: name, id: id, isParameter: isParameter, notation: notation)
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}
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/// Validates an entity value literal: every character must be an XML Char,
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/// every `&` must begin a complete reference (`&name;` or a character
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/// reference), and every `%` must begin a complete parameter-entity
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/// reference (production 9 admits no bare `%` or `&` in an EntityValue).
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func validateEntityLiteral(_ value: String, at mark: Mark) throws {
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let characters = Array(value)
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var index = 0
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while index < characters.count {
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let character = characters[index]
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guard character.unicodeScalars.allSatisfy(PureXML.Parsing.XMLCharacter.isChar) else {
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throw ParseError.invalidCharacter(mark)
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}
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if character == "&" || character == "%" {
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var probe = index + 1
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if character == "&", probe < characters.count, characters[probe] == "#" { probe += 1 }
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let bodyStart = probe
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let stops: Set<Character> = [";", "&", "%"]
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while probe < characters.count, !stops.contains(characters[probe]), !characters[probe].isWhitespace {
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probe += 1
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}
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guard probe > bodyStart, probe < characters.count, characters[probe] == ";" else {
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throw ParseError.invalidReference(String(character), mark)
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}
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index = probe
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}
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index += 1
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}
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}
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/// Scans a Name strictly: the first character must satisfy NameStartChar
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/// and the rest NameChar, so `-ge` or `.pe` is rejected where the lenient
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/// continuation-character scan would accept it.
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mutating func scanStrictName(_ reader: inout Reader, at mark: Mark) throws -> String {
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guard let first = reader.peek(), first.unicodeScalars.allSatisfy(PureXML.Parsing.XMLCharacter.isNameStart) else {
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throw ParseError.expectedName(mark)
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}
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return scanName(&reader)
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}
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/// Removes a leading text declaration from an external entity's resolved
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/// text (4.3.1): the declaration is not part of the replacement text. Text
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/// without one passes through unchanged, including text whose `<?xml` is
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/// not actually a text declaration.
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func strippingTextDeclaration(_ text: String) -> String {
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guard text.hasPrefix("<?xml") else { return text }
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// Foundation-free search for the closing '?>'.
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var close = text.index(text.startIndex, offsetBy: 5)
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while close < text.endIndex {
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if text[close] == "?", text.index(after: close) < text.endIndex, text[text.index(after: close)] == ">" {
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break
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}
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close = text.index(after: close)
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}
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guard close < text.endIndex else { return text }
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let declaration = String(text[text.index(text.startIndex, offsetBy: 5) ..< close])
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guard declaration.first?.isWhitespace == true,
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PureXML.Parsing.XMLDeclaration.parseTextDeclaration(declaration) != nil
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else { return text }
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return String(text[text.index(close, offsetBy: 2)...])
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}
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/// Consumes the external subset's optional text declaration
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/// `<?xml VersionInfo? EncodingDecl S? ?>` (production 77): unlike the
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/// document's XML declaration, the version is optional, the encoding is
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/// required, and `standalone` is not allowed.
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mutating func scanTextDeclaration(_ reader: inout Reader, at mark: Mark) throws {
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// Reader copies share their pull source, so look ahead in place: only
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// '<?xml' followed by whitespace opens a text declaration ('<?xml-…'
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// is an ordinary PI target and '<?xml?>' falls through to the
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// reserved-target check).
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guard reader.matches("<?xml"), reader.peek(5)?.isWhitespace == true else {
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return
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}
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reader.consume("<?xml")
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var text = ""
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while !reader.matches("?>") {
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guard let character = reader.advance() else {
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throw ParseError.malformedDeclaration(mark)
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}
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text.append(character)
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}
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reader.consume("?>")
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guard PureXML.Parsing.XMLDeclaration.parseTextDeclaration(text) != nil else {
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throw ParseError.malformedDeclaration(mark)
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}
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}
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/// Parses an external identifier strictly: `SYSTEM S literal`, or
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/// `PUBLIC S pubid-literal S system-literal` (the system literal is required
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/// when `requireSystem` is true, as for entities and the DOCTYPE itself).
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/// Public identifiers are checked against the `PubidChar` set.
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func parseStrictExternalID(_ reader: inout Reader, requireSystem: Bool, at mark: Mark) throws -> ExternalID? {
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if reader.consume("SYSTEM") {
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guard reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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guard let systemID = scanLiteral(&reader) else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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return ExternalID(systemID: systemID)
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}
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if reader.consume("PUBLIC") {
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return try parsePublicID(&reader, requireSystem: requireSystem, at: mark)
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}
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return nil
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}
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/// `PUBLIC S PubidLiteral (S SystemLiteral)` with the system literal
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/// required for entities and the DOCTYPE, optional for notations.
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private func parsePublicID(_ reader: inout Reader, requireSystem: Bool, at mark: Mark) throws -> ExternalID {
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guard reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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guard let publicID = scanLiteral(&reader) else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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try validatePublicID(publicID, at: mark)
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if requireSystem {
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guard reader.peek()?.isWhitespace == true else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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reader.skipSpace()
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guard let systemID = scanLiteral(&reader) else {
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throw ParseError.invalidEntityDeclaration(mark)
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}
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return ExternalID(publicID: publicID, systemID: systemID)
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}
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// Notations may carry a public identifier alone.
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var systemID = ""
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if reader.peek()?.isWhitespace == true {
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reader.skipSpace()
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if let literal = scanLiteral(&reader) { systemID = literal }
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}
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return ExternalID(publicID: publicID, systemID: systemID)
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}
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/// `PubidChar ::= #x20 | #xD | #xA | [a-zA-Z0-9] | [-'()+,./:=?;!*#@$_%]`
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func validatePublicID(_ publicID: String, at mark: Mark) throws {
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let allowed = Set("-'()+,./:=?;!*#@$_%")
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for character in publicID {
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let valid = character == " " || character == "\r" || character == "\n"
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|| (character.isASCII && (character.isLetter || character.isNumber))
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|| allowed.contains(character)
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guard valid else {
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throw ParseError.invalidPublicIdentifier(mark)
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}
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}
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}
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/// A default attribute value may reference only general entities that are
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/// already declared and internal: an undeclared, forward-declared, external,
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/// or unparsed entity in a default is not well-formed, and the referenced
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/// chain must not recurse.
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func validateDefaultValueReferences(_ value: String, at mark: Mark) throws {
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try walkDefaultReferences(value, visiting: [], at: mark)
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}
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func walkDefaultReferences(_ value: String, visiting: Set<String>, at mark: Mark) throws {
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let predefined: Set = ["amp", "lt", "gt", "quot", "apos"]
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let characters = Array(value)
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var index = 0
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while index < characters.count {
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guard characters[index] == "&" else {
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index += 1
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continue
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}
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var probe = index + 1
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if probe < characters.count, characters[probe] == "#" {
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while probe < characters.count, characters[probe] != ";" {
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probe += 1
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}
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index = probe + 1
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continue
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}
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var name = ""
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while probe < characters.count, characters[probe] != ";" {
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name.append(characters[probe])
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probe += 1
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}
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index = probe + 1
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guard !predefined.contains(name) else { continue }
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guard !visiting.contains(name) else {
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throw ParseError.recursiveEntity(name: name, mark)
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}
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guard doctype.unparsedEntities[name] == nil, doctype.externalEntities[name] == nil else {
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throw ParseError.invalidAttributeListDeclaration(mark)
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}
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guard let replacement = doctype.entities[name] else {
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throw ParseError.undefinedEntity(name: name, mark)
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}
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try walkDefaultReferences(replacement, visiting: visiting.union([name]), at: mark)
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}
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}
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}
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