[SR-12219] XML DTDs are completely broken

[karwa]

Previous ID	SR-12219
Radar	rdar://problem/59655370
Original Reporter	@karwa
Type	Bug

Environment

Swift-corelibs-foundation:

97bfd79

Darwin Foundation:

macOS 10.15.2 (19C57)

Xcode 11.3.1 (11C504)

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	None
Priority	Medium

md5: c60cd4ad2b138e7548d0599e363d1c2a

Issue Description:

The swift-corelibs-foundation version of XML DTDs are just entirely broken.

1. Root document not set

let typedefs = XMLDTD()
let document = XMLDocument(rootElement: nil)
document.dtd = typedefs
print(typedefs.rootDocument) // nil -- huh?

This is the same on both Darwin and SCF, but it definitely looks like a bug.

2. Children not set

This means that basic entity substitutions (`&author;` -> "Robert Thompson") also do not work on SCF.

let typedefs = XMLDTD()
let ent = XMLNode.dtdNode(withXMLString:"<!ENTITY author 'Robert Thompson'>") as! XMLDTDNode
typedefs.addChild(ent)
        
let document = XMLDocument(rootElement: nil)
document.dtd = typedefs
print(typedefs.childCount)
print(typedefs.children?.count)
print("-----")
print(document)

SCF output (note that childCount != children.count):

0
Optional(1)
-----
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE  PUBLIC "" "">

Darwin output:

1
Optional(1)
-----
<!DOCTYPE  [
    <!ENTITY author "Robert Thompson">
]>

3. Adding copies of nodes crashes

let typedefs = XMLDTD()
let ent = XMLNode.dtdNode(withXMLString:"<!ENTITY author 'Robert Thompson'>") as! XMLDTDNode
typedefs.addChild(ent)
typedefs.addChild(ent.copy() as! XMLNode)
print(typedefs)

SCF output:

Crash in CFXMLInterface.c:_CFXMLNodeGetPrivateData (node is a null pointer)

Darwin output (no crash):

<!ENTITY author "Robert Thompson">
<!ENTITY (null) "Robert Thompson">

4. Makes a copy of the DTD node when it shouldn't

(note: we're using children.count rather than childCount to work around #2)

let document = XMLDocument(rootElement: nil)

let typedefs = XMLDTD()
document.dtd = typedefs

let ent = XMLNode.dtdNode(withXMLString:"<!ENTITY author 'Robert Thompson'>") as! XMLDTDNode
typedefs.addChild(ent)
print(document.dtd)
print(document.dtd?.children?.count)

SCF output:

Optional(<!DOCTYPE  PUBLIC "" "">)
Optional(0)

Darwin output:

Optional(    <!ENTITY author "Robert Thompson">
)
Optional(1)

[hborla]

@swift-ci create