TOMOYO Linux Cross Reference
Linux/lib/build_OID_registry

   #!/usr/bin/perl -w
   # SPDX-License-Identifier: GPL-2.0-or-later
   #
   # Build a static ASN.1 Object Identified (OID) registry
   #
   # Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   # Written by David Howells (dhowells@redhat.com)
   #
   
  use strict;
  use Cwd qw(abs_path);
  
  my @names = ();
  my @oids = ();
  
  if ($#ARGV != 1) {
      print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
      exit(2);
  }
  
  my $abs_srctree = abs_path($ENV{'srctree'});
  
  #
  # Open the file to read from
  #
  open IN_FILE, "<$ARGV[0]" || die;
  while (<IN_FILE>) {
      chomp;
      if (m!\s+OID_([a-zA-z][a-zA-Z0-9_]+),\s+/[*]\s+([012][.0-9]*)\s+[*]/!) {
          push @names, $1;
          push @oids, $2;
      }
  }
  close IN_FILE || die;
  
  #
  # Open the files to write into
  #
  open C_FILE, ">$ARGV[1]" or die;
  print C_FILE "/*\n";
  my $scriptname = $0;
  $scriptname =~ s#^\Q$abs_srctree/\E##;
  print C_FILE " * Automatically generated by ", $scriptname, ".  Do not edit\n";
  print C_FILE " */\n";
  
  #
  # Split the data up into separate lists and also determine the lengths of the
  # encoded data arrays.
  #
  my @indices = ();
  my @lengths = ();
  my $total_length = 0;
  
  for (my $i = 0; $i <= $#names; $i++) {
      my $name = $names[$i];
      my $oid = $oids[$i];
  
      my @components = split(/[.]/, $oid);
  
      # Determine the encoded length of this OID
      my $size = $#components;
      for (my $loop = 2; $loop <= $#components; $loop++) {
          my $c = $components[$loop];
  
          # We will base128 encode the number
          my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
          $tmp = int($tmp / 7);
          $size += $tmp;
      }
      push @lengths, $size;
      push @indices, $total_length;
      $total_length += $size;
  }
  
  #
  # Emit the look-up-by-OID index table
  #
  print C_FILE "\n";
  if ($total_length <= 255) {
      print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n";
  } else {
      print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n";
  }
  for (my $i = 0; $i <= $#names; $i++) {
      print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
  }
  print C_FILE "\t[OID__NR] = ", $total_length, "\n";
  print C_FILE "};\n";
  
  #
  # Encode the OIDs
  #
  my @encoded_oids = ();
  
  for (my $i = 0; $i <= $#names; $i++) {
      my @octets = ();
  
      my @components = split(/[.]/, $oids[$i]);
  
     push @octets, $components[0] * 40 + $components[1];
 
     for (my $loop = 2; $loop <= $#components; $loop++) {
         my $c = $components[$loop];
 
         # Base128 encode the number
         my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
         $tmp = int($tmp / 7);
 
         for (; $tmp > 0; $tmp--) {
             push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
         }
         push @octets, $c & 0x7f;
     }
 
     push @encoded_oids, \@octets;
 }
 
 #
 # Create a hash value for each OID
 #
 my @hash_values = ();
 for (my $i = 0; $i <= $#names; $i++) {
     my @octets = @{$encoded_oids[$i]};
 
     my $hash = $#octets;
     foreach (@octets) {
         $hash += $_ * 33;
     }
 
     $hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);
 
     push @hash_values, $hash & 0xff;
 }
 
 #
 # Emit the OID data
 #
 print C_FILE "\n";
 print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
 for (my $i = 0; $i <= $#names; $i++) {
     my @octets = @{$encoded_oids[$i]};
     print C_FILE "\t";
     print C_FILE $_, ", " foreach (@octets);
     print C_FILE "\t// ", $names[$i];
     print C_FILE "\n";
 }
 print C_FILE "};\n";
 
 #
 # Build the search index table (ordered by length then hash then content)
 #
 my @index_table = ( 0 .. $#names );
 
 @index_table = sort {
     my @octets_a = @{$encoded_oids[$a]};
     my @octets_b = @{$encoded_oids[$b]};
 
     return $hash_values[$a] <=> $hash_values[$b]
         if ($hash_values[$a] != $hash_values[$b]);
     return $#octets_a <=> $#octets_b
         if ($#octets_a != $#octets_b);
     for (my $i = $#octets_a; $i >= 0; $i--) {
         return $octets_a[$i] <=> $octets_b[$i]
             if ($octets_a[$i] != $octets_b[$i]);
     }
     return 0;
 
 } @index_table;
 
 #
 # Emit the search index and hash value table
 #
 print C_FILE "\n";
 print C_FILE "static const struct {\n";
 print C_FILE "\tunsigned char hash;\n";
 if ($#names <= 255) {
     print C_FILE "\tenum OID oid : 8;\n";
 } else {
     print C_FILE "\tenum OID oid : 16;\n";
 }
 print C_FILE "} oid_search_table[OID__NR] = {\n";
 for (my $i = 0; $i <= $#names; $i++) {
     my @octets = @{$encoded_oids[$index_table[$i]]};
     printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ",
            $i,
            $hash_values[$index_table[$i]],
            $names[$index_table[$i]]);
     printf C_FILE "%02x", $_ foreach (@octets);
     print C_FILE "\n";
 }
 print C_FILE "};\n";
 
 #
 # Emit the OID debugging name table
 #
 #print C_FILE "\n";
 #print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";
 #
 #for (my $i = 0; $i <= $#names; $i++) {
 #    print C_FILE "\t\"", $names[$i], "\",\n"
 #}
 #print C_FILE "\t\"Unknown-OID\"\n";
 #print C_FILE "};\n";
 
 #
 # Polish off
 #
 close C_FILE or die;

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