bug#7172: emacs 23.2; xml.el: xml-parse-file hangs when DOCTYPE element names contain _ (underscore)

[Glenn Morris]

Jose Marino wrote:

> Attaching strace to the running emacs process prints:
> brk(0x267b000)                          = 0x267b000

A much more useful thing to do in such cases is to
M-x toggle-debug-on-quit
beforehand, then interrupt Emacs with C-g when it hangs. Resulting backtrace:

Debugger entered--Lisp error: (quit)
  looking-at("<!ATTLIST[        \n
]*\\([[:alpha:]:_][-[:digit:].[:alpha:]:_]*\\)[         \n
]*\\(\\(?:[     \n
]*[[:alpha:]:_][-[:digit:].[:alpha:]:_]*[       \n
]*\\(?:CDATA\\|\\(?:ID\\|IDREF\\|IDREFS\\|ENTITY\\|ENTITIES\\|NMTOKEN\\|NMTOKENS\\)\\|\\(?:NOTATION[
    \n
]([     \n
]*[[:alpha:]:_][-[:digit:].[:alpha:]:_]*\\(?:[  \n
]*|[    \n
]*[[:alpha:]:_][-[:digit:].[:alpha:]:_]*\\)*[   \n
]*)\\)\\|\\(?:\\(?:NOTATION[    \n
]([     \n
]*[[:alpha:]:_][-[:digit:].[:alpha:]:_]*\\(?:[  \n
]*|[    \n
]*[[:alpha:]:_][-[:digit:].[:alpha:]:_]*\\)*[   \n
]*)\\)\\|\\(?:([        \n
]*[-[:digit:].[:alpha:]:_]+\\(?:[       \n
]*|[    \n
]*[-[:digit:].[:alpha:]:_]+\\)*[        \n
])\\)\\)\\)[    \n
]*\\(?:#REQUIRED\\|#IMPLIED\\|\\(?:#FIXED[      \n
]\\)*\\(?:\"\\(?:[^&\"]\\|\\(?:&[[:alpha:]:_][-[:digit:].[:alpha:]:_]*;\\|\\(?:&#[0-9]+;\\|&#x[0-9a-fA-F]+;\\)\\)\\)*\"\\|'\\(?:[^&']\\|\\(?:&[[:alpha:]:_][-[:digit:].[:alpha:]:_]*;\\|\\(?:&#[0-9]+;\\|&#x[0-9a-fA-F]+;\\)\\)\\)*'\\)\\)\\)\\)*[
      \n
]*>")
  xml-parse-dtd(nil)
  xml-parse-tag(nil nil)
  xml-parse-tag(nil nil)
  xml-parse-region(1 116 #<buffer  *temp*> nil nil)
  xml-parse-file("example-bad.xml")


That certainly is a regexp.