[stas - Mon Jan 05 15:15:57 2004]:
This is a bug report for perl from [EMAIL PROTECTED], generated with the help of perlbug 1.34 running under perl v5.8.1.
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Consider the following short program:
# using Symbol to support older perls use Symbol; for (1..2) { my $dup = Symbol::gensym(); open $dup, "<&DATA" or die "Can't dup DATA: $!"; print "DATA: " . tell(DATA) . "\n"; print "dup : " . tell($dup) . "\n"; #seek $dup, tell(DATA), 0; # rewind to the beginning <$dup>; }
__DATA__ foo bar
w/o perlio we get:
DATA: 309 dup : 309 DATA: 318 dup : 318
the DATA fh pointer is correctly moved along with 'dup' as per dup(2).
w/ perlio we get:
DATA: 309 dup : 309 DATA: 309 dup : 313
the DATA fh pointer is frozen and doesn't get moved to the same pointer as the 'dup' fh.
as rgs quoted on irc:
<rgs> that's what my dup(2) manpage says <rgs> "After successful return of dup or dup2, the old and new descriptors may be used interchangeably."
and Nicolas has followed up:
<Nicholas> problem (presumably) is that duping by file number means that the original file handle has buffered data, while the new one does not. so underlying Unix fh is not at the same file offset as the return from ftell might lead you to think
This is observed with any perl 5.8.x
I wondering if either case you have above is correct. On Linux, I see the following...
[EMAIL PROTECTED]:~$ PERLIO=:stdio perl rt_24818.pl DATA: 279 dup : 287 DATA: 279 dup : 287
I get the same with PERLIO=:stdio as you do, Steve. The w/o perlio test was with perl that had no perlio enabed. Here it is again:
/tmp> env PERLIO=:perlio perl-5.8.6-ithread xxx DATA: 277 dup : 277 DATA: 277 dup : 281 /tmp> env PERLIO=:stdio perl-5.8.6-ithread xxx DATA: 277 dup : 285 DATA: 277 dup : 285 /tmp> perl-5.8.6-nouseperlio xxx DATA: 277 dup : 277 DATA: 285 dup : 285
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