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https://issues.apache.org/jira/browse/TIKA-2955?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16946270#comment-16946270
]
Luke Butters commented on TIKA-2955:
------------------------------------
So [wikipedia
Valid_characters_in_XML|https://en.wikipedia.org/wiki/Valid_characters_in_XML]
has this to says for XML 1.0 this range is valid:
{quote}
U+0020–U+D7FF, U+E000–U+FFFD: this excludes some (not all) non-characters
in the BMP (all surrogates, U+FFFE and U+FFFF are forbidden);
{quote}
it goes on to say:
{quote}
The preceding code points ranges contain the following controls which are only
valid in certain contexts in XML 1.0 documents, and whose usage is restricted
and highly discouraged:
U+007F–U+0084, U+0086–U+009F: this includes a C0 control character and all
but one C1 control.
{quote}
I think most of that range is allowed in XML, although discouraged.
Going over to
https://www.w3.org/TR/2011/WD-html5-20110525/syntax.html#character-references
it says:
{quote}
The numeric character reference forms described above are allowed to reference
any Unicode code point other than U+0000, U+000D, permanently undefined Unicode
characters (noncharacters), and control characters other than space characters.
{quote}
I think it is trying to say it exclude control characters from those encodings.
Looking at: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt
{code}
007F;<control>;Cc;0;BN;;;;;N;DELETE;;;;
0080;<control>;Cc;0;BN;;;;;N;;;;;
0081;<control>;Cc;0;BN;;;;;N;;;;;
0082;<control>;Cc;0;BN;;;;;N;BREAK PERMITTED HERE;;;;
0083;<control>;Cc;0;BN;;;;;N;NO BREAK HERE;;;;
0084;<control>;Cc;0;BN;;;;;N;;;;;
0085;<control>;Cc;0;B;;;;;N;NEXT LINE (NEL);;;;
0086;<control>;Cc;0;BN;;;;;N;START OF SELECTED AREA;;;;
0087;<control>;Cc;0;BN;;;;;N;END OF SELECTED AREA;;;;
0088;<control>;Cc;0;BN;;;;;N;CHARACTER TABULATION SET;;;;
0089;<control>;Cc;0;BN;;;;;N;CHARACTER TABULATION WITH JUSTIFICATION;;;;
008A;<control>;Cc;0;BN;;;;;N;LINE TABULATION SET;;;;
008B;<control>;Cc;0;BN;;;;;N;PARTIAL LINE FORWARD;;;;
008C;<control>;Cc;0;BN;;;;;N;PARTIAL LINE BACKWARD;;;;
008D;<control>;Cc;0;BN;;;;;N;REVERSE LINE FEED;;;;
008E;<control>;Cc;0;BN;;;;;N;SINGLE SHIFT TWO;;;;
008F;<control>;Cc;0;BN;;;;;N;SINGLE SHIFT THREE;;;;
0090;<control>;Cc;0;BN;;;;;N;DEVICE CONTROL STRING;;;;
0091;<control>;Cc;0;BN;;;;;N;PRIVATE USE ONE;;;;
0092;<control>;Cc;0;BN;;;;;N;PRIVATE USE TWO;;;;
0093;<control>;Cc;0;BN;;;;;N;SET TRANSMIT STATE;;;;
0094;<control>;Cc;0;BN;;;;;N;CANCEL CHARACTER;;;;
0095;<control>;Cc;0;BN;;;;;N;MESSAGE WAITING;;;;
0096;<control>;Cc;0;BN;;;;;N;START OF GUARDED AREA;;;;
0097;<control>;Cc;0;BN;;;;;N;END OF GUARDED AREA;;;;
0098;<control>;Cc;0;BN;;;;;N;START OF STRING;;;;
0099;<control>;Cc;0;BN;;;;;N;;;;;
009A;<control>;Cc;0;BN;;;;;N;SINGLE CHARACTER INTRODUCER;;;;
009B;<control>;Cc;0;BN;;;;;N;CONTROL SEQUENCE INTRODUCER;;;;
009C;<control>;Cc;0;BN;;;;;N;STRING TERMINATOR;;;;
009D;<control>;Cc;0;BN;;;;;N;OPERATING SYSTEM COMMAND;;;;
009E;<control>;Cc;0;BN;;;;;N;PRIVACY MESSAGE;;;;
009F;<control>;Cc;0;BN;;;;;N;APPLICATION PROGRAM COMMAND;;;;
{code}
I then remembered https://validator.w3.org/nu/#textarea exists and tried out
{{}} the validator did not like that and said:
{code}
Character reference expands to a control character (U+007f).
{code}
So I think it is invalid only in HTML but ok in XML.
> PDF parsing to XHTML results in tika attempting to write invalid HTML
> characters.
> ---------------------------------------------------------------------------------
>
> Key: TIKA-2955
> URL: https://issues.apache.org/jira/browse/TIKA-2955
> Project: Tika
> Issue Type: Bug
> Reporter: Luke Butters
> Priority: Major
> Attachments: 314.pdf
>
>
> Hi, I am trying to parse: [^314.pdf]
> what is happening when I try to convert it to XHTML is my XML parser fails
> because:
> {code}
> 14:35:12.876 [main] ERROR com.funnelback.common.filter.TikaFilterProvider -
> Unable to filter stream with document type '.pdf'
> org.xml.sax.SAXException: net.sf.saxon.trans.XPathException: Illegal HTML
> character: decimal 147
> at
> net.sf.saxon.event.ReceivingContentHandler.endElement(ReceivingContentHandler.java:538)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at
> org.apache.tika.sax.ContentHandlerDecorator.endElement(ContentHandlerDecorator.java:136)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.sax.SecureContentHandler.endElement(SecureContentHandler.java:256)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.sax.ContentHandlerDecorator.endElement(ContentHandlerDecorator.java:136)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.sax.ContentHandlerDecorator.endElement(ContentHandlerDecorator.java:136)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.sax.ContentHandlerDecorator.endElement(ContentHandlerDecorator.java:136)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.sax.SafeContentHandler.endElement(SafeContentHandler.java:274)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.sax.XHTMLContentHandler.endDocument(XHTMLContentHandler.java:229)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> org.apache.tika.parser.pdf.AbstractPDF2XHTML.endDocument(AbstractPDF2XHTML.java:556)
> ~[tika-parsers-1.19.1.jar:1.19.1]
> at
> org.apache.pdfbox.text.PDFTextStripper.writeText(PDFTextStripper.java:267)
> ~[pdfbox-2.0.12.jar:2.0.12]
> at org.apache.tika.parser.pdf.PDF2XHTML.process(PDF2XHTML.java:117)
> ~[tika-parsers-1.19.1.jar:1.19.1]
> at org.apache.tika.parser.pdf.PDFParser.parse(PDFParser.java:172)
> ~[tika-parsers-1.19.1.jar:1.19.1]
> at org.apache.tika.parser.CompositeParser.parse(CompositeParser.java:280)
> ~[tika-core-1.19.1.jar:1.19.1]
> at org.apache.tika.parser.CompositeParser.parse(CompositeParser.java:280)
> ~[tika-core-1.19.1.jar:1.19.1]
> at org.apache.tika.parser.AutoDetectParser.parse(AutoDetectParser.java:143)
> ~[tika-core-1.19.1.jar:1.19.1]
> at
> [removed section of trace]
> Caused by: net.sf.saxon.trans.XPathException: Illegal HTML character: decimal
> 147
> at net.sf.saxon.serialize.HTMLEmitter.writeEscape(HTMLEmitter.java:379)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at net.sf.saxon.serialize.XMLEmitter.characters(XMLEmitter.java:662)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at net.sf.saxon.serialize.HTMLEmitter.characters(HTMLEmitter.java:441)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at net.sf.saxon.serialize.HTMLIndenter.characters(HTMLIndenter.java:216)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at net.sf.saxon.event.ProxyReceiver.characters(ProxyReceiver.java:193)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at net.sf.saxon.event.ProxyReceiver.characters(ProxyReceiver.java:193)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at net.sf.saxon.event.ProxyReceiver.characters(ProxyReceiver.java:193)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at
> net.sf.saxon.event.SequenceNormalizer.characters(SequenceNormalizer.java:183)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at
> net.sf.saxon.event.ReceivingContentHandler.flush(ReceivingContentHandler.java:646)
> ~[Saxon-HE-9.9.0-2.jar:?]
> at
> net.sf.saxon.event.ReceivingContentHandler.endElement(ReceivingContentHandler.java:526)
> ~[Saxon-HE-9.9.0-2.jar:?]
> ... 43 more
> {code}
> It looks like tika is asking the XML library to handle chracter 147 ie 0x93
> which is not allowed in HTML.
> This saxon XML library is not happy with that, I think the default java one
> doesn't complain when given the invalid character though, however tika is
> probably wrong to write out that character when writing XHTML.
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