[pcre-dev] [Bug 1600] Issue with Regex

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Autor: Philip Hazel
Datum:  
To: pcre-dev
Betreff: [pcre-dev] [Bug 1600] Issue with Regex
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http://bugs.exim.org/show_bug.cgi?id=1600




--- Comment #6 from Philip Hazel <ph10@???> 2015-03-19 15:59:45 ---
On Thu, 19 Mar 2015, Prashant Joshi wrote:

> Regex 1:
> " /Letzter Messwert.*</th><td class="ActualDataTableBody"
> align="center">([^<].*)</td><td class="ActualDataTableBody"
> align="center">([^<].*)</td><td class="ActualDataTableBody"
> align="center">([^<].*)</td></tr><tr><th scope="row"
> class="ActualDataTableRowLabel">Mittelwert/"
>
> Attached text on which we tried to find above regex.


What program are you using to handle that regex? PCRE is just a library,
so it has to be called by another program. That program may well be
pre-processing the regex before passing it to PCRE.

> When I changed this regex to below regex it worked with 8.34:
> Regex 2:
> /Letzter Messwert[\s]+<\/th><td
> class="ActualDataTableBody".*>[-+]?([0-9]*\.[0-9]+|[0-9]+)<\/td><td
> class="ActualDataTableBody".*>[-+]?([0-9]*\.[0-9]+|[0-9]+)<\/td><td
> class="ActualDataTableBody".*>[-+]?([0-9]*\.[0-9]+|[0-9]+)<\/td><\/tr><tr><th
> scope="row" class="ActualDataTableRowLabel">Mittelwert/
>
> Regex 1 is working with PCRE 0.2 but not with 8.34.
> Regex 2 is working with PCRE 8.34.


There never was a PCRE release 0.2, so I do not know what software you
were using. The first release of PCRE was 0.91 (10-Sep-97).

> Please let me know why is above behavior? Also Are there any other regex
> changes which do not work with PCRE 8.34.


It seems to me that whatever program you fed Regex 1 into was somehow
processing it to allow for pairs of "" within the overall quotes, and
was also handling the / delimiters within the pattern. I do not know
what program might do that.

Regex 2 looks like a regex delimited by / that is handled by a program
that needs escaping internal / characters as \/ as you have done. The
pcretest program will do this.

So I ask again: what program are you actually passing your input to?

Philip


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