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Date: Fri, 7 Sep 2018 11:33:02 -0400
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Cc: Steffen Nurpmeso <steffen@...oden.eu>
Subject: Re: Regex: behaviour of ? after () atom
On Fri, Sep 07, 2018 at 05:25:17PM +0200, Steffen Nurpmeso wrote:
> Rich Felker wrote in <20180907151821.GL1878@...ghtrain.aerifal.cx>:
> |On Fri, Sep 07, 2018 at 03:38:05PM +0200, Steffen Nurpmeso wrote:
> |> Hello.
> |>
> |> In perl this is
> |>
> |> $x="print 1 2";
> |> if($x =~ /^(:[[:space:]]+)?([^[:space:]]+)(.*)$/){
> |> print "<$0> -> <$1> <$2> <$3>\n"
> |>}
> |>
> |> and the result is
> |>
> |> </tmp/t.pl> -> <> <print> < 1 2>
> |>
> |> Now the same on AlpineLinux edge and musl-1.1.19-r10 with the MUA
> |> i maintain, which uses the normal regex stuff and calls it via
> |>
> |> echo eins=$3
> |> vput vexpr i regex "${3}" \
> |> '^(:[[:space:]]+)?([^[:space:]]+)(.*)$' \
> |> '<\$0> -> <\$1> <\$2> <\$3>'
> |> echo i=$i
> |>
> |> which in C code does
> |>
> |> if((reflrv = regcomp(&re, argv[2], reflrv))){
> |> ...
> |> goto jestr;
> |>}
> |> fprintf(stderr, "GOING for <%s> -> <%s> %u\n",
> |> argv[1],argv[2],n_NELEM(rema));
> |> reflrv = regexec(&re, argv[1], n_NELEM(rema), rema, 0);
> |>
> |> and overall prints
> |>
> |> eins=print 1 2
> |> GOING for <print 1 2> -> <^(:[[:space:]]+)?([^[:space:]]+)(.*)$> 17
> |> i=<print 1 2> -> <> <> <>
> |>
> |> It works correctly if i remove the ()? atom, so i thought i should
> |> report that.
> |
> |What is the value of the flags argument you passed to regcomp?
> |
>
> REG_EXTENDED, optional REG_ICASE:
>
> reflrv = REG_EXTENDED;
> if(f & a_ICASE)
> reflrv |= REG_ICASE;
> if((reflrv = regcomp(&re, argv[2], reflrv))){
OK, it looks like that should work, and seemed to work here when I
passed the regex to grep -E linked with musl's regex. Can you provide
a minimal self-contained C program to demonstrate the issue you're
having?
BTW which "()?" are you talking about? The whole first parenthesized
subsexpression and the ? after it? I wouldn't call that an atom, but
nothing seems wrong with it.
Rich
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