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Postings from February 2004
On Wed, Oct 29, 2003 at 09:56:53AM +0000, Graham Barr wrote:
> It gets worse
>
> #! /usr/bin/perl -w
> $a="abcdefg";
> for (substr($a,0, 4)) {
> print "a=$a\n";
> print "$_\n";
> $_="12";
> print "$_\n";
> print "a=$a\n";
> $_=".";
> print "$_\n";
> print "a=$a\n";
> }
>
> prints:
>
> a=abcdefg
> abcd
> 12ef
> a=12efg
> .g
> a=.g
>
> So multiple assigns to the LV with strings that are shorter than the
> original LV length will result in the string being nibbled away. Below
> is a patch that makes it output what I think is expected
>
> a=abcdefg
> abcd
> 12
> a=12efg
> .
> a=.efg
>
> All tests still pass, so if there are no objections to this patch I
> shall add some tests to t/op/substr.t to test for this specifically
Thanks, applied to bleed as change #22414.
Are you still intending to write those tests? ;-)
>
> --- mg.c.orig Wed Oct 29 08:28:52 2003
> +++ mg.c Wed Oct 29 09:20:31 2003
> @@ -1744,16 +1744,20 @@
> sv_utf8_upgrade(lsv);
> sv_pos_u2b(lsv, &lvoff, &lvlen);
> sv_insert(lsv, lvoff, lvlen, tmps, len);
> + LvTARGLEN(sv) = sv_len_utf8(sv);
> SvUTF8_on(lsv);
> }
> else if (lsv && SvUTF8(lsv)) {
> sv_pos_u2b(lsv, &lvoff, &lvlen);
> + LvTARGLEN(sv) = len;
> tmps = (char*)bytes_to_utf8((U8*)tmps, &len);
> sv_insert(lsv, lvoff, lvlen, tmps, len);
> Safefree(tmps);
> }
> - else
> - sv_insert(lsv, lvoff, lvlen, tmps, len);
> + else {
> + sv_insert(lsv, lvoff, lvlen, tmps, len);
> + LvTARGLEN(sv) = len;
> + }
>
> return 0;
> }
>
> Graham.
--
Technology is dominated by two types of people: those who understand what
they do not manage, and those who manage what they do not understand.
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