xmlwf - Determines if an XML document is well-formed
xmlwf
[OPTIONS] [FILE ...]
xmlwf
-h
xmlwf
-v
xmlwf uses the Expat library to determine if an XML document is
  well-formed. It is non-validating.
If you do not specify any files on the command-line, and you have
    a recent version of xmlwf, the input file will be read from standard
    input.
A well-formed document must adhere to the following rules:
  - •
- The file begins with an XML declaration. For instance, <?xml
      version="1.0" standalone="yes"?>. NOTE:
      xmlwf does not currently check for a valid XML declaration.
- •
- Every start tag is either empty (<tag/>) or has a corresponding end
      tag.
- •
- There is exactly one root element. This element must contain all other
      elements in the document. Only comments, white space, and processing
      instructions may come after the close of the root element.
- •
- All elements nest properly.
- •
- All attribute values are enclosed in quotes (either single or
    double).
If the document has a DTD, and it strictly complies with that DTD,
    then the document is also considered valid. xmlwf is a
    non-validating parser -- it does not check the DTD. However, it does support
    external entities (see the -x option).
When an option includes an argument, you may specify the argument either
  separately ("-d output") or concatenated with the
  option ("-doutput"). xmlwf supports both.
  - -a factor
- Sets the maximum tolerated amplification factor for protection against
      billion laughs attacks (default: 100.0). The amplification factor is
      calculated as ..
    
    
            amplification := (direct + indirect) / direct
          
    .. while parsing, whereas <direct> is the number of
        bytes read from the primary document in parsing and <indirect> is
        the number of bytes added by expanding entities and reading of external
        DTD files, combined. NOTE: If you ever need to increase this value for
        non-attack payload, please file a bug report. 
- -b bytes
- Sets the number of output bytes (including amplification) needed to
      activate protection against billion laughs attacks (default: 8 MiB). This
      can be thought of as an "activation threshold".
    NOTE: If you ever need to increase this value for
        non-attack payload, please file a bug report. 
- -c
- If the input file is well-formed and xmlwf doesn't encounter any
      errors, the input file is simply copied to the output directory unchanged.
      This implies no namespaces (turns off -n) and requires -d to
      specify an output directory.
- -d output-dir
- Specifies a directory to contain transformed representations of the input
      files. By default, -d outputs a canonical representation (described
      below). You can select different output formats using -c, -m
      and -N.
    The output filenames will be exactly the same as the input
        filenames or "STDIN" if the input is coming from standard
        input. Therefore, you must be careful that the output file does not go
        into the same directory as the input file. Otherwise, xmlwf will
        delete the input file before it generates the output file (just like
        running cat < file > file in most shells). Two structurally equivalent XML documents have a byte-for-byte
        identical canonical XML representation. Note that ignorable white space
        is considered significant and is treated equivalently to data. More on
        canonical XML can be found at http://www.jclark.com/xml/canonxml.html
      . 
- -e encoding
- Specifies the character encoding for the document, overriding any document
      encoding declaration. xmlwf supports four built-in encodings:
      US-ASCII, UTF-8, UTF-16, and ISO-8859-1. Also see the -w
    option.
- -k
- When processing multiple files, xmlwf by default halts after the
      the first file with an error. This tells xmlwf to report the error
      but to keep processing. This can be useful, for example, when testing a
      filter that converts many files to XML and you want to quickly find out
      which conversions failed.
- -m
- Outputs some strange sort of XML file that completely describes the input
      file, including character positions. Requires -d to specify an
      output file.
- -n
- Turns on namespace processing. (describe namespaces) -c disables
      namespaces.
- -N
- Adds a doctype and notation declarations to canonical XML output. This
      matches the example output used by the formal XML test cases. Requires
      -d to specify an output file.
- -p
- Tells xmlwf to process external DTDs and parameter entities.
    Normally xmlwf never parses parameter entities.
        -p tells it to always parse them. -p implies
      -x. 
- -r
- Normally xmlwf memory-maps the XML file before parsing; this can
      result in faster parsing on many platforms. -r turns off
      memory-mapping and uses normal file IO calls instead. Of course,
      memory-mapping is automatically turned off when reading from standard
      input.
    Use of memory-mapping can cause some platforms to report
        substantially higher memory usage for xmlwf, but this appears to
        be a matter of the operating system reporting memory in a strange way;
        there is not a leak in xmlwf. 
- -s
- Prints an error if the document is not standalone. A document is
      standalone if it has no external subset and no references to parameter
      entities.
- -t
- Turns on timings. This tells Expat to parse the entire file, but not
      perform any processing. This gives a fairly accurate idea of the raw speed
      of Expat itself without client overhead. -t turns off most of the
      output options (-d, -m, -c, ...).
- -v
- Prints the version of the Expat library being used, including some
      information on the compile-time configuration of the library, and then
      exits.
- -w
- Enables support for Windows code pages. Normally, xmlwf will throw
      an error if it runs across an encoding that it is not equipped to handle
      itself. With -w, xmlwf will try to use a Windows code page.
      See also -e.
- -x
- Turns on parsing external entities.
    Non-validating parsers are not required to resolve external
        entities, or even expand entities at all. Expat always expands internal
        entities (?), but external entity parsing must be enabled
      explicitly. External entities are simply entities that obtain their data
        from outside the XML file currently being parsed. This is an example of an internal entity: 
<!ENTITY vers '1.0.2'>
    And here are some examples of external entities: 
<!ENTITY header SYSTEM "header-&vers;.xml">  (parsed)
<!ENTITY logo SYSTEM "logo.png" PNG>         (unparsed)
    
- --
- (Two hyphens.) Terminates the list of options. This is only needed if a
      filename starts with a hyphen. For example:
    
    
xmlwf -- -myfile.xml
    will run xmlwf on the file -myfile.xml. 
Older versions of xmlwf do not support reading from
    standard input.
xmlwf outputs nothing for files which are problem-free. If any input file
  is not well-formed, or if the output for any input file cannot be opened,
  xmlwf prints a single line describing the problem to standard output.
If the -k option is not provided, xmlwf halts upon
    encountering a well-formedness or output-file error. If -k is
    provided, xmlwf continues processing the remaining input files,
    describing problems found with any of them.
For option -v or -h, xmlwf always exits with status code 0.
  For other cases, the following exit status codes are returned:
  - 0
- The input files are well-formed and the output (if requested) was written
      successfully.
- 1
- An internal error occurred.
- 2
- One or more input files were not well-formed or could not be parsed.
- 3
- If using the -d option, an error occurred opening an output
    file.
- 4
- There was a command-line argument error in how xmlwf was
    invoked.
The errors should go to standard error, not standard output.There should be a way to get -d to send its output to
    standard output rather than forcing the user to send it to a file.
I have no idea why anyone would want to use the -d,
    -c, and -m options. If someone could explain it to me, I'd
    like to add this information to this manpage.
The Expat home page:                            https://libexpat.github.io/
The W3 XML 1.0 specification (fourth edition):  https://www.w3.org/TR/2006/REC-xml-20060816/
Billion laughs attack:                          https://en.wikipedia.org/wiki/Billion_laughs_attack
This manual page was originally written by Scott Bronson
  <bronson@rinspin.com> in December 2001 for the Debian GNU/Linux system
  (but may be used by others). Permission is granted to copy, distribute and/or
  modify this document under the terms of the GNU Free Documentation License,
  Version 1.1.