in redo question ( part 'catching segfaults' ) i tried to figure out where an app was segfaulting, and why. i found the where and the why, i think.

running a job as root, attempting to overwrite files owned by nobody, did weird stuff ... i can't explain it. i put in a lot of extra  -e $filename checks to avoid overwriting the files ... and now the script runs just fine.

so why would this segfault?

note: more code added for completeness:

calling CGI script:

    my $mainImg = $self->query->param('propImg');

    my $id = $self->query->param('pId')
      || $self->param('DBH')->{mysql_insertid};

    if ($mainImg) {

        warn " ( $id ) directory ... " . FINALDIR if DEBUG;

        my $utils  = MLSUtils->new();
        my $fsName =
          $utils->save_to_filesystem( $self->query, FINALDIR, 'propImg
+' );

        my ( $base, $dir, $suffix ) = fileparse( $fsName, qr{\..*} );
        my $newImgName = FINALDIR . "/LG${id}_0" . $suffix;
        warn "passing $newImgName to resizeImg " if DEBUG;

        $utils->resizeImg( $fsName, $newImgName, 1 )
          or die "Resizing images failed! ";

        $sth = $self->param('DBH')->prepare(
"UPDATE jbg_managed_props SET NumPhotos = 1 WHERE jbgPropertyID = ? "
          );
        $sth->execute($id) if ( !$self->query->param('pId') );
    }

    warn "back from images " if DEBUG;
[download]

MLSUtils.pm

sub resizeImg {

    my ( $self, $imageName, $newImageName, $mkThumb ) = @_;

    die("Cannot resize null image value") unless ($imageName);

    warn "before regex: imageName -->  $imageName "       if DEBUG;
    warn "before regex: newImageName -->  $newImageName " if DEBUG;

    my ( $base,  $dir,  $suffix )  = fileparse( $imageName,    qr{\..*
+} );
    my ( $base2, $dir2, $suffix2 ) = fileparse( $newImageName, qr{\..*
+} );
    $base2 =~ s/LG/TH/;

    my $tmpName = IMAGEDIR . '/' . $imageName;

    my $fileName = $newImageName;

    my $large = Image::Magick->new() or die "NO IMAGE READ!!!: $!";

    my $filesRead = $large->Read($imageName);
    my $thumb     = $large->Clone();

    my ( $height, $width ) = $large->Get( 'height', 'width' );

    my $reduceWlg = LG_MAX_WIDTH / $width;

    my $reducePercent = $reduceWlg;
    my $newH          = $height * $reducePercent;
    my $newW          = $width * $reducePercent;

    warn "new IMG:  $fileName " if DEBUG;

    my $attempts;
  FILEWRITE: {

        $attempts++;

        eval {
            open( NEWIMG, ">$fileName" )
              or die "Can't open new imagefile: ($fileName) $! \n";
            binmode(NEWIMG);

            warn "after OPEN and BINMODE" if DEBUG;

            ###3 don't forget!  Image::Magick functions don't have ret
+urn values
            $large->Resize( height => $newH, width => $newW )
              ;    # or die "Resizing error: $! \n";
            warn "RESIZE worked! " if DEBUG;

            $large->Write( file => \*NEWIMG );    # or die "Write erro
+r:  $!\n";
            warn "WRITE  worked! " if DEBUG;
            close(NEWIMG);
        };

        warn "trying to write the new file ( $fileName ) failed: $@ " 
+if ($@);
        redo FILEWRITE if ( $@ and $attempts < 3 );
    }

    #undef $large;

    warn "New LG image written" if DEBUG;

    if ($mkThumb) {

        my $thumbName = "${dir2}/${base2}${suffix2}";

        warn "thumb : $thumbName " if DEBUG;

        my $reduceWth = TH_MAX_WIDTH / $width;
        $reducePercent = $reduceWth;
        $newH          = $height * $reducePercent;
        $newW          = $width * $reducePercent;

        $thumb->Resize( height => $newH, width => $newW );
        open( NEWIMG, ">$thumbName" )
          or die "Can't open new imagefile: ($thumbName)  $! \n";
        $thumb->Write( file => \*NEWIMG );
        close(NEWIMG);

        warn "New TH image written" if DEBUG;

    }

    warn "exiting sub resizeImg()" if DEBUG;

    return 1;

}
[download]

output in error_log

[Wed Jul 14 19:10:13 2004] admin.cgi: passing /home/httpd/jbgoodwin.co
+m/html/image/LG6_6.jpg to resize img at /home/httpd/jbgoodwin.com/lib
+s/AdminFunctions.pm line 394.
[Wed Jul 14 19:10:13 2004] admin.cgi: before regex: imageName -->  /ho
+me/httpd/jbgoodwin.com/html/image/Provance Model living 6.jpg  at /ho
+me/httpd/jbgoodwin.com/libs/MLSUtils.pm line 84.
[Wed Jul 14 19:10:13 2004] admin.cgi: before regex: newImageName -->  
+/home/httpd/jbgoodwin.com/html/image/LG6_6.jpg  at /home/httpd/jbgood
+win.com/libs/MLSUtils.pm line 85.
[Wed Jul 14 19:10:13 2004] admin.cgi: new IMG:  /home/httpd/jbgoodwin.
+com/html/image/LG6_6.jpg  at /home/httpd/jbgoodwin.com/libs/MLSUtils.
+pm line 108.
[Wed Jul 14 19:10:13 2004] admin.cgi: after OPEN and BINMODE at /home/
+httpd/jbgoodwin.com/libs/MLSUtils.pm line 119.
[Wed Jul 14 19:10:13 2004] admin.cgi: RESIZE worked!  at /home/httpd/j
+bgoodwin.com/libs/MLSUtils.pm line 123.
[Wed Jul 14 19:10:13 2004] admin.cgi: WRITE  worked!  at /home/httpd/j
+bgoodwin.com/libs/MLSUtils.pm line 126.
[Wed Jul 14 19:10:13 2004] admin.cgi: New LG image written at /home/ht
+tpd/jbgoodwin.com/libs/MLSUtils.pm line 136.
[Wed Jul 14 19:10:13 2004] admin.cgi: exiting sub resizeImg() at /home
+/httpd/jbgoodwin.com/libs/MLSUtils.pm line 158.
[Wed Jul 14 19:10:13 2004] [error] [client 24.173.210.82] Premature en
+d of script headers: /home/httpd/jbgoodwin.com/html/admin/admin.cgi
[download]

no reason for dying, just death. i have another smaller cron-based script which uses the same ImageUtils lib, and it shows the the segfault ( when run via commandline )

i see the "existing sub resizeImg()" warn, but never the "back from images" warn ...