/[Biblio-Isis]/trunk/lib/Biblio/Isis.pm
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revision 8 by dpavlin, Wed Dec 29 15:17:59 2004 UTC revision 35 by dpavlin, Thu Jan 6 16:27:07 2005 UTC
# Line 2  package IsisDB; Line 2  package IsisDB;
2  use strict;  use strict;
3    
4  use Carp;  use Carp;
5    use File::Glob qw(:globally :nocase);
6    
7  use Data::Dumper;  use Data::Dumper;
8    
9  BEGIN {  BEGIN {
10          use Exporter ();          use Exporter ();
11          use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);          use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
12          $VERSION     = 0.02;          $VERSION     = 0.09;
13          @ISA         = qw (Exporter);          @ISA         = qw (Exporter);
14          #Give a hoot don't pollute, do not export more than needed by default          #Give a hoot don't pollute, do not export more than needed by default
15          @EXPORT      = qw ();          @EXPORT      = qw ();
# Line 18  BEGIN { Line 20  BEGIN {
20    
21  =head1 NAME  =head1 NAME
22    
23  IsisDB - Read CDS/ISIS database  IsisDB - Read CDS/ISIS, WinISIS and IsisMarc database
24    
25  =head1 SYNOPSIS  =head1 SYNOPSIS
26    
27    use IsisDB    use IsisDB;
28    
29    my $isis = new IsisDB(    my $isis = new IsisDB(
30          isisdb => './cds/cds',          isisdb => './cds/cds',
31    );    );
32    
33      for(my $mfn = 1; $mfn <= $isis->count; $mfn++) {
34            print $isis->to_ascii($mfn),"\n";
35      }
36    
37  =head1 DESCRIPTION  =head1 DESCRIPTION
38    
39  This module will read CDS/ISIS databases and create hash values out of it.  This module will read ISIS databases created by DOS CDS/ISIS, WinIsis or
40  It can be used as perl-only alternative to OpenIsis module.  IsisMarc. It can be used as perl-only alternative to OpenIsis module which
41    seems to depriciate it's old C<XS> bindings for perl.
42    
43    It can create hash values from data in ISIS database (using C<to_hash>),
44    ASCII dump (using C<to_ascii>) or just hash with field names and packed
45    values (like C<^asomething^belse>).
46    
47    Unique feature of this module is ability to C<include_deleted> records.
48    It will also skip zero sized fields (OpenIsis has a bug in XS bindings, so
49    fields which are zero sized will be filled with random junk from memory).
50    
51    It also has support for identifiers (only if ISIS database is created by
52    IsisMarc), see C<to_hash>.
53    
54    This module will always be slower than OpenIsis module which use C
55    library. However, since it's written in perl, it's platform independent (so
56    you don't need C compiler), and can be easily modified. I hope that it
57    creates data structures which are easier to use than ones created by
58    OpenIsis, so reduced time in other parts of the code should compensate for
59    slower performance of this module (speed of reading ISIS database is
60    rarely an issue).
61    
62  =head1 METHODS  =head1 METHODS
63    
# Line 50  It can be used as perl-only alternative Line 77  It can be used as perl-only alternative
77  # some binary reads  # some binary reads
78  #  #
79    
 sub Read32 {  
         my $self = shift;  
   
         my $f = shift || die "Read32 needs file handle";  
         read($$f,$b,4) || die "can't read 4 bytes from $$f from position ".tell($f);  
         return unpack("l",$b);  
 }  
   
80  =head2 new  =head2 new
81    
82  Open CDS/ISIS database  Open ISIS database
83    
84   my $isis = new IsisDB(   my $isis = new IsisDB(
85          isisdb => './cds/cds',          isisdb => './cds/cds',
86          read_fdt => 1,          read_fdt => 1,
87            include_deleted => 1,
88            hash_filter => sub {
89                    my $v = shift;
90                    $v =~ s#foo#bar#g;
91            },
92          debug => 1,          debug => 1,
93   );   );
94    
# Line 74  Options are described below: Line 98  Options are described below:
98    
99  =item isisdb  =item isisdb
100    
101  Prefix path to CDS/ISIS. It should contain full or relative path to database  This is full or relative path to ISIS database files which include
102  and common prefix of C<.FDT>, C<.MST>, C<.CNT>, C<.XRF> and C<.MST> files.  common prefix of C<.MST>, and C<.XRF> and optionally C<.FDT> (if using
103    C<read_fdt> option) files.
104    
105    In this example it uses C<./cds/cds.MST> and related files.
106    
107  =item read_fdt  =item read_fdt
108    
109  Boolean flag to specify if field definition table should be read. It's off  Boolean flag to specify if field definition table should be read. It's off
110  by default.  by default.
111    
112    =item include_deleted
113    
114    Don't skip logically deleted records in ISIS.
115    
116    =item hash_filter
117    
118    Filter code ref which will be used before data is converted to hash.
119    
120  =item debug  =item debug
121    
122  Dump a C<lot> of debugging output.  Dump a B<lot> of debugging output.
123    
124  =back  =back
125    
 It will also set C<$isis-E<gt>{'maxmfn'}> which is maximum MFN stored in database.  
   
126  =cut  =cut
127    
128  sub new {  sub new {
# Line 97  sub new { Line 130  sub new {
130          my $self = {};          my $self = {};
131          bless($self, $class);          bless($self, $class);
132    
133          $self->{isisdb} = {@_}->{isisdb} || croak "new needs database name as argument!";          croak "new needs database name (isisdb) as argument!" unless ({@_}->{isisdb});
134    
135          $self->{debug} = {@_}->{debug};          foreach my $v (qw{isisdb debug include_deleted hash_filter}) {
136                    $self->{$v} = {@_}->{$v};
137            }
138    
139            my @isis_files = grep(/\.(FDT|MST|XRF|CNT)$/i,glob($self->{isisdb}."*"));
140    
141            foreach my $f (@isis_files) {
142                    my $ext = $1 if ($f =~ m/\.(\w\w\w)$/);
143                    $self->{lc($ext)."_file"} = $f;
144            }
145    
146            my @must_exist = qw(mst xrf);
147            push @must_exist, "fdt" if ($self->{read_fdt});
148    
149            foreach my $ext (@must_exist) {
150                    croak "missing ",uc($ext)," file in ",$self->{isisdb} unless ($self->{$ext."_file"});
151            }
152    
153            print STDERR "## using files: ",join(" ",@isis_files),"\n" if ($self->{debug});
154    
155          # if you want to read .FDT file use read_fdt argument when creating class!          # if you want to read .FDT file use read_fdt argument when creating class!
156          if ({@_}->{read_fdt} && -e $self->{isisdb}.".FDT") {          if ($self->{read_fdt} && -e $self->{fdt_file}) {
157    
158                  # read the $db.FDT file for tags                  # read the $db.FDT file for tags
159                  my $fieldzone=0;                  my $fieldzone=0;
160    
161                  open(fileFDT, $self->{isisdb}.".FDT") || croak "can't read '$self->{isisdb}.FDT': $!";                  open(my $fileFDT, $self->{fdt_file}) || croak "can't read '$self->{fdt_file}': $!";
162                    binmode($fileFDT);
163    
164                  while (<fileFDT>) {                  while (<$fileFDT>) {
165                          chomp;                          chomp;
166                          if ($fieldzone) {                          if ($fieldzone) {
167                                  my $name=substr($_,0,30);                                  my $name=substr($_,0,30);
# Line 126  sub new { Line 178  sub new {
178                          }                          }
179                  }                  }
180                                    
181                  close(fileFDT);                  close($fileFDT);
182          }          }
183    
184          # Get the Maximum MFN from $db.MST          # Get the Maximum MFN from $db.MST
185    
186          open(fileMST,$self->{isisdb}.".MST") || croak "can't read '$self->{isisdb}.MST': $!";          open($self->{'fileMST'}, $self->{mst_file}) || croak "can't open '$self->{mst_file}': $!";
187            binmode($self->{'fileMST'});
188    
189          # MST format:   (* = 32 bit signed)          # MST format:   (* = 32 bit signed)
190          # CTLMFN*       always 0          # CTLMFN*       always 0
# Line 139  sub new { Line 192  sub new {
192          # NXTMFB*       last block allocated to master file          # NXTMFB*       last block allocated to master file
193          # NXTMFP        offset to next available position in last block          # NXTMFP        offset to next available position in last block
194          # MFTYPE        always 0 for user db file (1 for system)          # MFTYPE        always 0 for user db file (1 for system)
195          seek(fileMST,4,0);          seek($self->{'fileMST'},4,0) || croak "can't seek to offset 0 in MST: $!";
         $self->{'NXTMFN'}=$self->Read32(\*fileMST) || carp "NXTNFN is zero";  
   
         # save maximum MFN  
         $self->{'maxmfn'} = $self->{'NXTMFN'} - 1;  
   
         close(fileMST);  
   
         # Get the index information from $db.CNT  
     
         open(fileCNT, $self->{isisdb}.".CNT") || croak "can't read '$self->{isisdb}.CNT': $!";  
196    
197          # There is two 26 Bytes fixed lenght records          my $buff;
198    
199          #  0: IDTYPE    BTree type                              16          read($self->{'fileMST'}, $buff, 4) || croak "can't read NXTMFN from MST: $!";
200          #  2: ORDN      Nodes Order                             16          $self->{'NXTMFN'}=unpack("V",$buff) || croak "NXTNFN is zero";
         #  4: ORDF      Leafs Order                             16  
         #  6: N         Number of Memory buffers for nodes      16  
         #  8: K         Number of buffers for first level index 16  
         # 10: LIV       Current number of Index Levels          16  
         # 12: POSRX*    Pointer to Root Record in N0x           32  
         # 16: NMAXPOS*  Next Available position in N0x          32  
         # 20: FMAXPOS*  Next available position in L0x          32  
         # 24: ABNORMAL  Formal BTree normality indicator        16  
         # length: 26 bytes  
   
         sub unpack_cnt {  
                 my $self = shift;  
   
                 my @flds = qw(ORDN ORDF N K LIV POSRX NMAXPOS FMAXPOS ABNORMAL);  
   
                 my $buff = shift || return;  
                 my @arr = unpack("ssssssllls", $buff);  
   
                 my $IDTYPE = shift @arr;  
                 foreach (@flds) {  
                         $self->{$IDTYPE}->{$_} = abs(shift @arr);  
                 }  
         }  
201    
202          my $buff;          print STDERR Dumper($self),"\n" if ($self->{debug});
         read(fileCNT, $buff, 26);  
         $self->unpack_cnt($buff);  
203    
204          read(fileCNT, $buff, 26);          # open files for later
205          $self->unpack_cnt($buff);          open($self->{'fileXRF'}, $self->{xrf_file}) || croak "can't open '$self->{xrf_file}': $!";
206            binmode($self->{'fileXRF'});
207    
208            $self ? return $self : return undef;
209    }
210    
211          close(fileCNT);  =head2 count
212    
213          print Dumper($self) if ($self->{debug});  Return number of records in database
214    
215          # open files for later    print $isis->count;
         open($self->{'fileXRF'}, $self->{isisdb}.".XRF") || croak "can't open '$self->{isisdb}.XRF': $!";  
216    
217          open($self->{'fileMST'}, $self->{isisdb}.".MST") || croak "can't open '$self->{isisdb}.MST': $!";  =cut
218    
219          $self ? return $self : return undef;  sub count {
220            my $self = shift;
221            return $self->{'NXTMFN'} - 1;
222  }  }
223    
224  =head2 fetch  =head2 fetch
# Line 206  Read record with selected MFN Line 228  Read record with selected MFN
228    my $rec = $isis->fetch(55);    my $rec = $isis->fetch(55);
229    
230  Returns hash with keys which are field names and values are unpacked values  Returns hash with keys which are field names and values are unpacked values
231  for that field.  for that field like this:
232    
233      $rec = {
234        '210' => [ '^aNew York^cNew York University press^dcop. 1988' ],
235        '990' => [ '2140', '88', 'HAY' ],
236      };
237    
238  =cut  =cut
239    
# Line 215  sub fetch { Line 242  sub fetch {
242    
243          my $mfn = shift || croak "fetch needs MFN as argument!";          my $mfn = shift || croak "fetch needs MFN as argument!";
244    
245          print "fetch: $mfn\n" if ($self->{debug});          # is mfn allready in memory?
246            my $old_mfn = $self->{'current_mfn'} || -1;
247            return $self->{record} if ($mfn == $old_mfn);
248    
249            print STDERR "## fetch: $mfn\n" if ($self->{debug});
250    
251          # XXX check this?          # XXX check this?
252          my $mfnpos=($mfn+int(($mfn-1)/127))*4;          my $mfnpos=($mfn+int(($mfn-1)/127))*4;
253    
254          print "seeking to $mfnpos in file '$self->{isisdb}.XRF'\n" if ($self->{debug});          print STDERR "## seeking to $mfnpos in file '$self->{xrf_file}'\n" if ($self->{debug});
255          seek($self->{'fileXRF'},$mfnpos,0);          seek($self->{'fileXRF'},$mfnpos,0);
256    
257            my $buff;
258    
259            # delete old record
260            delete $self->{record};
261    
262          # read XRFMFB abd XRFMFP          # read XRFMFB abd XRFMFP
263          my $pointer=$self->Read32(\*{$self->{'fileXRF'}});          read($self->{'fileXRF'}, $buff, 4);
264            my $pointer=unpack("V",$buff) || croak "pointer is null";
265    
266            # check for logically deleted record
267            if ($pointer & 0x80000000) {
268                    print STDERR "## record $mfn is logically deleted\n" if ($self->{debug});
269                    $self->{deleted} = $mfn;
270    
271                    return unless $self->{include_deleted};
272    
273                    # abs
274                    $pointer = ($pointer ^ 0xffffffff) + 1;
275            }
276    
277          my $XRFMFB = int($pointer/2048);          my $XRFMFB = int($pointer/2048);
278          my $XRFMFP = $pointer - ($XRFMFB*2048);          my $XRFMFP = $pointer - ($XRFMFB*2048);
279    
280          print "XRFMFB: $XRFMFB XRFMFP: $XRFMFP\n" if ($self->{debug});          # (XRFMFB - 1) * 512 + XRFMFP
281            # why do i have to do XRFMFP % 1024 ?
282    
283          # XXX fix this to be more readable!!          my $blk_off = (($XRFMFB - 1) * 512) + ($XRFMFP % 512);
         # e.g. (XRFMFB - 1) * 512 + XRFMFP  
284    
285          my $offset = $pointer;          print STDERR "## pointer: $pointer XRFMFB: $XRFMFB XRFMFP: $XRFMFP offset: $blk_off\n" if ($self->{'debug'});
         my $offset2=int($offset/2048)-1;  
         my $offset22=int($offset/4096);  
         my $offset3=$offset-($offset22*4096);  
         if ($offset3>512) {  
                 $offset3=$offset3-2048;  
         }  
         my $offset4=($offset2*512)+$offset3;  
   
         print "$offset - $offset2 - $offset3 - $offset4\n" if ($self->{debug});  
286    
287          # Get Record Information          # Get Record Information
288    
289          seek($self->{'fileMST'},$offset4,0);          seek($self->{'fileMST'},$blk_off,0) || croak "can't seek to $blk_off: $!";
290    
291            read($self->{'fileMST'}, $buff, 4) || croak "can't read 4 bytes at offset $blk_off from MST file: $!";
292            my $value=unpack("V",$buff);
293    
294          my $value=$self->Read32(\*{$self->{'fileMST'}});          print STDERR "## offset for rowid $value is $blk_off (blk $XRFMFB off $XRFMFP)\n" if ($self->{debug});
295    
296          if ($value!=$mfn) {          if ($value!=$mfn) {
297  print ("Error: The MFN:".$mfn." is not found in MST(".$value.")");                      if ($value == 0) {
298                  return -1;      # XXX deleted record?                          print STDERR "## record $mfn is physically deleted\n" if ($self->{debug});
299          }                          $self->{deleted} = $mfn;
300                            return;
301                    }
302    
303  #       $MFRL=$self->Read16($fileMST);                  carp "Error: MFN ".$mfn." not found in MST file, found $value";    
304  #       $MFBWB=$self->Read32($fileMST);                  return;
305  #       $MFBWP=$self->Read16($fileMST);          }
 #       $BASE=$self->Read16($fileMST);  
 #       $NVF=$self->Read16($fileMST);  
 #       $STATUS=$self->Read16($fileMST);  
306    
         my $buff;  
307          read($self->{'fileMST'}, $buff, 14);          read($self->{'fileMST'}, $buff, 14);
308    
309          my ($MFRL,$MFBWB,$MFBWP,$BASE,$NVF,$STATUS) = unpack("slssss", $buff);          my ($MFRL,$MFBWB,$MFBWP,$BASE,$NVF,$STATUS) = unpack("vVvvvv", $buff);
310    
311            print STDERR "## MFRL: $MFRL MFBWB: $MFBWB MFBWP: $MFBWP BASE: $BASE NVF: $NVF STATUS: $STATUS\n" if ($self->{debug});
312    
313            warn "MFRL $MFRL is not even number" unless ($MFRL % 2 == 0);
314    
315          print "MFRL: $MFRL MFBWB: $MFBWB MFBWP: $MFBWP BASE: $BASE NVF: $NVF STATUS: $STATUS\n" if ($self->{debug});          warn "BASE is not 18+6*NVF" unless ($BASE == 18 + 6 * $NVF);
316    
317          # Get Directory Format          # Get Directory Format
318    
# Line 278  print ("Error: The MFN:".$mfn." is not f Line 322  print ("Error: The MFN:".$mfn." is not f
322    
323          read($self->{'fileMST'}, $buff, 6 * $NVF);          read($self->{'fileMST'}, $buff, 6 * $NVF);
324    
325          my $fld_len = 0;          my $rec_len = 0;
326    
327          for (my $i = 0 ; $i < $NVF ; $i++) {          for (my $i = 0 ; $i < $NVF ; $i++) {
328    
329  #               $TAG=$self->Read16($fileMST);                  my ($TAG,$POS,$LEN) = unpack("vvv", substr($buff,$i * 6, 6));
 #               $POS=$self->Read16($fileMST);  
 #               $LEN=$self->Read16($fileMST);  
330    
331                  my ($TAG,$POS,$LEN) = unpack("sss", substr($buff,$i * 6, 6));                  print STDERR "## TAG: $TAG POS: $POS LEN: $LEN\n" if ($self->{debug});
   
                 print "TAG: $TAG POS: $POS LEN: $LEN\n" if ($self->{debug});  
332    
333                  # The TAG does not exists in .FDT so we set it to 0.                  # The TAG does not exists in .FDT so we set it to 0.
334                  #                  #
# Line 304  print ("Error: The MFN:".$mfn." is not f Line 344  print ("Error: The MFN:".$mfn." is not f
344                  push @FieldPOS,$POS;                  push @FieldPOS,$POS;
345                  push @FieldLEN,$LEN;                  push @FieldLEN,$LEN;
346    
347                  $fld_len += $LEN;                  $rec_len += $LEN;
348          }          }
349    
350          # Get Variable Fields          # Get Variable Fields
351    
352          delete $self->{record};          read($self->{'fileMST'},$buff,$rec_len);
353    
354          read($self->{'fileMST'},$buff,$fld_len);          print STDERR "## rec_len: $rec_len poc: ",tell($self->{'fileMST'})."\n" if ($self->{debug});
355    
356          for (my $i = 0 ; $i < $NVF ; $i++) {          for (my $i = 0 ; $i < $NVF ; $i++) {
357                    # skip zero-sized fields
358                    next if ($FieldLEN[$i] == 0);
359    
360                  push @{$self->{record}->{$FieldTAG[$i]}}, substr($buff,$FieldPOS[$i],$FieldLEN[$i]);                  push @{$self->{record}->{$FieldTAG[$i]}}, substr($buff,$FieldPOS[$i],$FieldLEN[$i]);
361          }          }
         close(fileMST);  
362    
363          # The record is marked for deletion          $self->{'current_mfn'} = $mfn;
         if ($STATUS==1) {  
                 return -1;  
         }  
364    
365          print Dumper($self) if ($self->{debug});          print STDERR Dumper($self),"\n" if ($self->{debug});
366    
367          return $self->{'record'};          return $self->{'record'};
368  }  }
369    
370  =head2 to_ascii  =head2 to_ascii
371    
372  Dump ascii output of selected MFN  Returns ASCII output of record with specified MFN
373    
374    print $isis->to_ascii(55);    print $isis->to_ascii(42);
375    
376    This outputs something like this:
377    
378      210   ^aNew York^cNew York University press^dcop. 1988
379      990   2140
380      990   88
381      990   HAY
382    
383    If C<read_fdt> is specified when calling C<new> it will display field names
384    from C<.FDT> file instead of numeric tags.
385    
386  =cut  =cut
387    
# Line 346  sub to_ascii { Line 395  sub to_ascii {
395          my $out = "0\t$mfn";          my $out = "0\t$mfn";
396    
397          foreach my $f (sort keys %{$rec}) {          foreach my $f (sort keys %{$rec}) {
398                  $out .= "\n$f\t".join("\n$f\t",@{$self->{record}->{$f}});                  my $fn = $self->tag_name($f);
399                    $out .= "\n$fn\t".join("\n$fn\t",@{$self->{record}->{$f}});
400          }          }
401    
402          $out .= "\n";          $out .= "\n";
# Line 354  sub to_ascii { Line 404  sub to_ascii {
404          return $out;          return $out;
405  }  }
406    
407  #  =head2 to_hash
408  # XXX porting from php left-over:  
409  #  Read record with specified MFN and convert it to hash
410  # do I *REALLY* need those methods, or should I use  
411  # $self->{something} directly?    my $hash = $isis->to_hash($mfn);
412  #  
413  # Probably direct usage is better!  It has ability to convert characters (using C<hash_filter>) from ISIS
414  #  database before creating structures enabling character re-mapping or quick
415    fix-up of data.
416    
417    This function returns hash which is like this:
418    
419      $hash = {
420        '210' => [
421                   {
422                     'c' => 'New York University press',
423                     'a' => 'New York',
424                     'd' => 'cop. 1988'
425                   }
426                 ],
427        '990' => [
428                   '2140',
429                   '88',
430                   'HAY'
431                 ],
432      };
433    
434    You can later use that hash to produce any output from ISIS data.
435    
436    If database is created using IsisMarc, it will also have to special fields
437    which will be used for identifiers, C<i1> and C<i2> like this:
438    
439      '200' => [
440                 {
441                   'i1' => '1',
442                   'i2' => ' '
443                   'a' => 'Goa',
444                   'f' => 'Valdo D\'Arienzo',
445                   'e' => 'tipografie e tipografi nel XVI secolo',
446                 }
447               ],
448    
449    This method will also create additional field C<000> with MFN.
450    
451    =cut
452    
453  sub TagName {  sub to_hash {
454          my $self = shift;          my $self = shift;
455          return $self->{TagName};  
456            my $mfn = shift || confess "need mfn!";
457    
458            # init record to include MFN as field 000
459            my $rec = { '000' => [ $mfn ] };
460    
461            my $row = $self->fetch($mfn);
462    
463            foreach my $k (keys %{$row}) {
464                    foreach my $l (@{$row->{$k}}) {
465    
466                            # filter output
467                            $l = $self->{'hash_filter'}->($l) if ($self->{'hash_filter'});
468    
469                            my $val;
470    
471                            # has identifiers?
472                            ($val->{'i1'},$val->{'i2'}) = ($1,$2) if ($l =~ s/^([01 #])([01 #])\^/\^/);
473    
474                            # has subfields?
475                            if ($l =~ m/\^/) {
476                                    foreach my $t (split(/\^/,$l)) {
477                                            next if (! $t);
478                                            $val->{substr($t,0,1)} = substr($t,1);
479                                    }
480                            } else {
481                                    $val = $l;
482                            }
483    
484                            push @{$rec->{$k}}, $val;
485                    }
486            }
487    
488            return $rec;
489  }  }
490    
491  sub NextMFN {  =head2 tag_name
492    
493    Return name of selected tag
494    
495     print $isis->tag_name('200');
496    
497    =cut
498    
499    sub tag_name {
500          my $self = shift;          my $self = shift;
501          return $self->{NXTMFN};          my $tag = shift || return;
502            return $self->{'TagName'}->{$tag} || $tag;
503    }
504    
505    
506    =head2 read_cnt
507    
508    Read content of C<.CNT> file and return hash containing it.
509    
510      print Dumper($isis->read_cnt);
511    
512    This function is not used by module (C<.CNT> files are not required for this
513    module to work), but it can be useful to examine your index (while debugging
514    for example).
515    
516    =cut
517    
518    sub read_cnt  {
519            my $self = shift;
520    
521            croak "missing CNT file in ",$self->{isisdb} unless ($self->{cnt_file});
522    
523            # Get the index information from $db.CNT
524      
525            open(my $fileCNT, $self->{cnt_file}) || croak "can't read '$self->{cnt_file}': $!";
526            binmode($fileCNT);
527    
528            my $buff;
529    
530            read($fileCNT, $buff, 26) || croak "can't read first table from CNT: $!";
531            $self->unpack_cnt($buff);
532    
533            read($fileCNT, $buff, 26) || croak "can't read second table from CNT: $!";
534            $self->unpack_cnt($buff);
535    
536            close($fileCNT);
537    
538            return $self->{cnt};
539    }
540    
541    =head2 unpack_cnt
542    
543    Unpack one of two 26 bytes fixed length record in C<.CNT> file.
544    
545    Here is definition of record:
546    
547     off key        description                             size
548      0: IDTYPE     BTree type                              s
549      2: ORDN       Nodes Order                             s
550      4: ORDF       Leafs Order                             s
551      6: N          Number of Memory buffers for nodes      s
552      8: K          Number of buffers for first level index s
553     10: LIV        Current number of Index Levels          s
554     12: POSRX      Pointer to Root Record in N0x           l
555     16: NMAXPOS    Next Available position in N0x          l
556     20: FMAXPOS    Next available position in L0x          l
557     24: ABNORMAL   Formal BTree normality indicator        s
558     length: 26 bytes
559    
560    This will fill C<$self> object under C<cnt> with hash. It's used by C<read_cnt>.
561    
562    =cut
563    
564    sub unpack_cnt {
565            my $self = shift;
566    
567            my @flds = qw(ORDN ORDF N K LIV POSRX NMAXPOS FMAXPOS ABNORMAL);
568    
569            my $buff = shift || return;
570            my @arr = unpack("vvvvvvVVVv", $buff);
571    
572            print STDERR "unpack_cnt: ",join(" ",@arr),"\n" if ($self->{'debug'});
573    
574            my $IDTYPE = shift @arr;
575            foreach (@flds) {
576                    $self->{cnt}->{$IDTYPE}->{$_} = abs(shift @arr);
577            }
578  }  }
579    
580  1;  1;
581    
582  =head1 BUGS  =head1 BUGS
583    
584  This module has been very lightly tested. Use with caution and report bugs.  Some parts of CDS/ISIS documentation are not detailed enough to exmplain
585    some variations in input databases which has been tested with this module.
586    When I was in doubt, I assumed that OpenIsis's implementation was right
587    (except for obvious bugs).
588    
589    However, every effort has been made to test this module with as much
590    databases (and programs that create them) as possible.
591    
592    I would be very greatful for success or failure reports about usage of this
593    module with databases from programs other than WinIsis and IsisMarc. I had
594    tested this against ouput of one C<isis.dll>-based application, but I don't
595    know any details about it's version.
596    
597  =head1 AUTHOR  =head1 AUTHOR
598    
# Line 386  This module has been very lightly tested Line 601  This module has been very lightly tested
601          dpavlin@rot13.org          dpavlin@rot13.org
602          http://www.rot13.org/~dpavlin/          http://www.rot13.org/~dpavlin/
603    
604  This module is based heavily on code from LIBISIS.PHP - Library to read ISIS files V0.1.1  This module is based heavily on code from C<LIBISIS.PHP> library to read ISIS files V0.1.1
605  written in php and (c) 2000 Franck Martin - <franck@sopac.org> released under LGPL.  written in php and (c) 2000 Franck Martin <franck@sopac.org> and released under LGPL.
606    
607  =head1 COPYRIGHT  =head1 COPYRIGHT
608    
# Line 400  LICENSE file included with this module. Line 615  LICENSE file included with this module.
615    
616  =head1 SEE ALSO  =head1 SEE ALSO
617    
618  L<http://www.openisis.org|OpenIsis>, perl(1).  OpenIsis web site L<http://www.openisis.org>
619    
620    perl4lib site L<http://perl4lib.perl.org>
621    
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