1XMLWF(1) [FIXME: manual] XMLWF(1)
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6 xmlwf - Determines if an XML document is well-formed
7
9 xmlwf [OPTIONS] [FILE ...]
10 xmlwf -h
12 xmlwf -v
14
16 xmlwf uses the Expat library to determine if an XML document is
17 well-formed. It is non-validating.
18 If you do not specify any files on the command-line, and you have a
20 recent version of xmlwf, the input file will be read from standard
21 input.
22
24 A well-formed document must adhere to the following rules:
25 • The file begins with an XML declaration. For instance, <?xml
27 version="1.0" standalone="yes"?>. NOTE: xmlwf does not currently
28 check for a valid XML declaration.
29 • Every start tag is either empty (<tag/>) or has a corresponding end
31 tag.
32 • There is exactly one root element. This element must contain all
34 other elements in the document. Only comments, white space, and
35 processing instructions may come after the close of the root
36 element.
37 • All elements nest properly.
39 • All attribute values are enclosed in quotes (either single or
41 double).
42 If the document has a DTD, and it strictly complies with that DTD, then
44 the document is also considered valid. xmlwf is a non-validating
45 parser -- it does not check the DTD. However, it does support external
46 entities (see the -x option).
47
49 When an option includes an argument, you may specify the argument
50 either separately ("-d output") or concatenated with the option
51 ("-doutput"). xmlwf supports both.
52 -a factor
54 Sets the maximum tolerated amplification factor for protection
55 against billion laughs attacks (default: 100.0). The amplification
56 factor is calculated as ..
57 amplification := (direct + indirect) / direct
59 .. while parsing, whereas <direct> is the number of bytes read from
62 the primary document in parsing and <indirect> is the number of
63 bytes added by expanding entities and reading of external DTD
64 files, combined.
65 NOTE: If you ever need to increase this value for non-attack
67 payload, please file a bug report.
68 -b bytes
70 Sets the number of output bytes (including amplification) needed to
71 activate protection against billion laughs attacks (default: 8
72 MiB). This can be thought of as an "activation threshold".
73 NOTE: If you ever need to increase this value for non-attack
75 payload, please file a bug report.
76 -c
78 If the input file is well-formed and xmlwf doesn't encounter any
79 errors, the input file is simply copied to the output directory
80 unchanged. This implies no namespaces (turns off -n) and requires
81 -d to specify an output directory.
82 -d output-dir
84 Specifies a directory to contain transformed representations of the
85 input files. By default, -d outputs a canonical representation
86 (described below). You can select different output formats using
87 -c, -m and -N.
88 The output filenames will be exactly the same as the input
90 filenames or "STDIN" if the input is coming from standard input.
91 Therefore, you must be careful that the output file does not go
92 into the same directory as the input file. Otherwise, xmlwf will
93 delete the input file before it generates the output file (just
94 like running cat < file > file in most shells).
95 Two structurally equivalent XML documents have a byte-for-byte
97 identical canonical XML representation. Note that ignorable white
98 space is considered significant and is treated equivalently to
99 data. More on canonical XML can be found at
100 http://www.jclark.com/xml/canonxml.html .
101 -e encoding
103 Specifies the character encoding for the document, overriding any
104 document encoding declaration. xmlwf supports four built-in
105 encodings: US-ASCII, UTF-8, UTF-16, and ISO-8859-1. Also see the -w
106 option.
107 -k
109 When processing multiple files, xmlwf by default halts after the
110 the first file with an error. This tells xmlwf to report the error
111 but to keep processing. This can be useful, for example, when
112 testing a filter that converts many files to XML and you want to
113 quickly find out which conversions failed.
114 -m
116 Outputs some strange sort of XML file that completely describes the
117 input file, including character positions. Requires -d to specify
118 an output file.
119 -n
121 Turns on namespace processing. (describe namespaces) -c disables
122 namespaces.
123 -N
125 Adds a doctype and notation declarations to canonical XML output.
126 This matches the example output used by the formal XML test cases.
127 Requires -d to specify an output file.
128 -p
130 Tells xmlwf to process external DTDs and parameter entities.
131 Normally xmlwf never parses parameter entities. -p tells it to
133 always parse them. -p implies -x.
134 -r
136 Normally xmlwf memory-maps the XML file before parsing; this can
137 result in faster parsing on many platforms. -r turns off
138 memory-mapping and uses normal file IO calls instead. Of course,
139 memory-mapping is automatically turned off when reading from
140 standard input.
141 Use of memory-mapping can cause some platforms to report
143 substantially higher memory usage for xmlwf, but this appears to be
144 a matter of the operating system reporting memory in a strange way;
145 there is not a leak in xmlwf.
146 -s
148 Prints an error if the document is not standalone. A document is
149 standalone if it has no external subset and no references to
150 parameter entities.
151 -t
153 Turns on timings. This tells Expat to parse the entire file, but
154 not perform any processing. This gives a fairly accurate idea of
155 the raw speed of Expat itself without client overhead. -t turns
156 off most of the output options (-d, -m, -c, ...).
157 -v
159 Prints the version of the Expat library being used, including some
160 information on the compile-time configuration of the library, and
161 then exits.
162 -w
164 Enables support for Windows code pages. Normally, xmlwf will throw
165 an error if it runs across an encoding that it is not equipped to
166 handle itself. With -w, xmlwf will try to use a Windows code page.
167 See also -e.
168 -x
170 Turns on parsing external entities.
171 Non-validating parsers are not required to resolve external
173 entities, or even expand entities at all. Expat always expands
174 internal entities (?), but external entity parsing must be enabled
175 explicitly.
176 External entities are simply entities that obtain their data from
178 outside the XML file currently being parsed.
179 This is an example of an internal entity:
181 <!ENTITY vers '1.0.2'>
183 And here are some examples of external entities:
185 <!ENTITY header SYSTEM "header-&vers;.xml"> (parsed)
187 <!ENTITY logo SYSTEM "logo.png" PNG> (unparsed)
188 --
191 (Two hyphens.) Terminates the list of options. This is only needed
192 if a filename starts with a hyphen. For example:
193 xmlwf -- -myfile.xml
195 will run xmlwf on the file -myfile.xml.
197 Older versions of xmlwf do not support reading from standard input.
199
201 xmlwf outputs nothing for files which are problem-free. If any input
202 file is not well-formed, or if the output for any input file cannot be
203 opened, xmlwf prints a single line describing the problem to standard
204 output.
205 If the -k option is not provided, xmlwf halts upon encountering a
207 well-formedness or output-file error. If -k is provided, xmlwf
208 continues processing the remaining input files, describing problems
209 found with any of them.
210
212 For option -v or -h, xmlwf always exits with status code 0. For other
213 cases, the following exit status codes are returned:
214 0
216 The input files are well-formed and the output (if requested) was
217 written successfully.
218 1
220 An internal error occurred.
221 2
223 One or more input files were not well-formed or could not be
224 parsed.
225 3
227 If using the -d option, an error occurred opening an output file.
228 4
230 There was a command-line argument error in how xmlwf was invoked.
231
233 The errors should go to standard error, not standard output.
234 There should be a way to get -d to send its output to standard output
236 rather than forcing the user to send it to a file.
237 I have no idea why anyone would want to use the -d, -c, and -m options.
239 If someone could explain it to me, I'd like to add this information to
240 this manpage.
241
243 The Expat home page: https://libexpat.github.io/
244 The W3 XML 1.0 specification (fourth edition): https://www.w3.org/TR/2006/REC-xml-20060816/
245 Billion laughs attack: https://en.wikipedia.org/wiki/Billion_laughs_attack
246
249 This manual page was originally written by Scott Bronson
250 <bronson@rinspin.com> in December 2001 for the Debian GNU/Linux(TM)
251 system (but may be used by others). Permission is granted to copy,
252 distribute and/or modify this document under the terms of the GNU Free
253 Documentation License, Version 1.1.
254
256 Scott Bronson
257 Author.
258
260 Copyright © 2001 Scott Bronson
261[FIXME: source] March 4, 2022 XMLWF(1)