[Bug 221113] New: readline function in perl does not correctly set $!

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https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=221113

           Summary: readline function in perl does not correctly set $!
           Product: Fedora Core
           Version: fc6
          Platform: i386
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: normal
         Component: perl
        AssignedTo: rnorwood at redhat.com
        ReportedBy: wpilorz at gmail.com
         QAContact: dkl at redhat.com
                CC: fedora-perl-devel-list at redhat.com


Description of problem:

perldoc -f readline

displays example code how do check for errors with readline:
for (;;) {
    undef $!;
    unless (defined( $line = <> )) {
        die $! if $!;
        last; # reached EOF
    }
    # ...
}

Unfortunately this method no longer works as described in current perl version.

I am including a short perl script readline_test.pl attempting to use that
method and bash script readline_test.bash calling that perl script 16 times;
input is either "1234" or "1234\n",
PERLIO environment variable is set to perlio or stdio,
(PERLIO=perlio is equivalent to PERLIO not set in FC6)
$/ is set to undef, not modified, \2, \1024.

$/ is set to a reference to value specified in environment variable CHUNKSIZE,
unless it is 0 ($/ not set in this case) or negative ($/ set to undef).

In correct perl implementation all 16 tests should run successfully (no die).

The results included show that PERLIO=stdio is better (4 tests fail for stdio, 6
tests fail for perlio)

Version-Release number of selected component (if applicable):
perl-5.8.8-10

How reproducible:
always

Steps to Reproduce:
1. save readline_test.pl and readline_test.bash files from attachemnts into
current directory
2. run the following command in the current directory
  bash readline_test.bash
you could prefer to run 
  bash -vx readline_test.bash
to see exactly what is being run

  
Actual results:

$ bash readline_test.bash
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=-1,PERLIO=perlio...
 INFO: $/ will be set to undef
Bad file descriptor at readline_test.pl line 30, <F> chunk 1.
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=-1,PERLIO=stdio...
 INFO: $/ will be set to undef
Bad file descriptor at readline_test.pl line 30, <F> chunk 1.
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=0,PERLIO=perlio...
 INFO: $/ will not be set
Bad file descriptor at readline_test.pl line 30, <F> line 1.
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=0,PERLIO=stdio...
 INFO: $/ will not be set
Bad file descriptor at readline_test.pl line 30, <F> line 1.
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=2,PERLIO=perlio...
 INFO: $/ will be set to 2
 INFO: File /dev/stdin has been read, nbytes = 4
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=2,PERLIO=stdio...
 INFO: $/ will be set to 2
 INFO: File /dev/stdin has been read, nbytes = 4
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=1k,PERLIO=perlio...
 INFO: $/ will be set to 1024
Bad file descriptor at readline_test.pl line 30, <F> chunk 1.
 __ running readline_test.pl for stdin=1234,CHUNKSIZE=1k,PERLIO=stdio...
 INFO: $/ will be set to 1024
 INFO: File /dev/stdin has been read, nbytes = 4
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=-1,PERLIO=perlio...
 INFO: $/ will be set to undef
Bad file descriptor at readline_test.pl line 30, <F> chunk 1.
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=-1,PERLIO=stdio...
 INFO: $/ will be set to undef
Bad file descriptor at readline_test.pl line 30, <F> chunk 1.
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=0,PERLIO=perlio...
 INFO: $/ will not be set
 INFO: File /dev/stdin has been read, nbytes = 5
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=0,PERLIO=stdio...
 INFO: $/ will not be set
Bad file descriptor at readline_test.pl line 30, <F> line 1.
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=2,PERLIO=perlio...
 INFO: $/ will be set to 2
Bad file descriptor at readline_test.pl line 30, <F> chunk 3.
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=2,PERLIO=stdio...
 INFO: $/ will be set to 2
 INFO: File /dev/stdin has been read, nbytes = 5
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=1k,PERLIO=perlio...
 INFO: $/ will be set to 1024
Bad file descriptor at readline_test.pl line 30, <F> chunk 1.
 __ running readline_test.pl for stdin=1234\n,CHUNKSIZE=1k,PERLIO=stdio...
 INFO: $/ will be set to 1024
 INFO: File /dev/stdin has been read, nbytes = 5



Expected results:
each run of perl should complete without die and show number of bytes on input
(4 for first 8 tests, 5 for remaining tests) 

Additional info:
if PERLIO=perlio is used and there is actual I/O error in data file, the
readline_test.pl dies with inappropriate error message 
'Bad file descriptor' rather than 'Input/output error'
im most cases.

This can be easily shown with truncated ISO-9660 image file, loop mounted.
Should I also include test cases for this?

------- Additional Comments From wpilorz at gmail.com  2007-01-01 18:46 EST -------
Created an attachment (id=144615)
 --> (https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=144615&action=view)
readline_test.pl test script


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