includes/utils/CdbPHP.php

   1 <?php
   2 /**
   3  * This is a port of D.J. Bernstein's CDB to PHP. It's based on the copy that
   4  * appears in PHP 5.3. Changes are:
   5  *    * Error returns replaced with exceptions
   6  *    * Exception thrown if sizes or offsets are between 2GB and 4GB
   7  *    * Some variables renamed
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  */
  26
  27 /**
  28  * Common functions for readers and writers
  29  */
  30 class CdbFunctions {
  31         /**
  32          * Take a modulo of a signed integer as if it were an unsigned integer.
  33          * $b must be less than 0x40000000 and greater than 0
  34          *
  35          * @param $a
  36          * @param $b
  37          *
  38          * @return int
  39          */
  40         public static function unsignedMod( $a, $b ) {
  41                 if ( $a & 0x80000000 ) {
  42                         $m = ( $a & 0x7fffffff ) % $b + 2 * ( 0x40000000 % $b );
  43
  44                         return $m % $b;
  45                 } else {
  46                         return $a % $b;
  47                 }
  48         }
  49
  50         /**
  51          * Shift a signed integer right as if it were unsigned
  52          * @param $a
  53          * @param $b
  54          * @return int
  55          */
  56         public static function unsignedShiftRight( $a, $b ) {
  57                 if ( $b == 0 ) {
  58                         return $a;
  59                 }
  60                 if ( $a & 0x80000000 ) {
  61                         return ( ( $a & 0x7fffffff ) >> $b ) | ( 0x40000000 >> ( $b - 1 ) );
  62                 } else {
  63                         return $a >> $b;
  64                 }
  65         }
  66
  67         /**
  68          * The CDB hash function.
  69          *
  70          * @param $s string
  71          *
  72          * @return int
  73          */
  74         public static function hash( $s ) {
  75                 $h = 5381;
  76                 $len = strlen( $s );
  77                 for ( $i = 0; $i < $len; $i++ ) {
  78                         $h5 = ( $h << 5 ) & 0xffffffff;
  79                         // Do a 32-bit sum
  80                         // Inlined here for speed
  81                         $sum = ( $h & 0x3fffffff ) + ( $h5 & 0x3fffffff );
  82                         $h =
  83                                 (
  84                                         ( $sum & 0x40000000 ? 1 : 0 )
  85                                         + ( $h & 0x80000000 ? 2 : 0 )
  86                                         + ( $h & 0x40000000 ? 1 : 0 )
  87                                         + ( $h5 & 0x80000000 ? 2 : 0 )
  88                                         + ( $h5 & 0x40000000 ? 1 : 0 )
  89                                 ) << 30
  90                                 | ( $sum & 0x3fffffff );
  91                         $h ^= ord( $s[$i] );
  92                         $h &= 0xffffffff;
  93                 }
  94
  95                 return $h;
  96         }
  97 }
  98
  99 /**
 100  * CDB reader class
 101  */
 102 class CdbReaderPHP extends CdbReader {
 103         /** The filename */
 104         protected $fileName;
 105
 106         /* number of hash slots searched under this key */
 107         protected $loop;
 108
 109         /* initialized if loop is nonzero */
 110         protected $khash;
 111
 112         /* initialized if loop is nonzero */
 113         protected $kpos;
 114
 115         /* initialized if loop is nonzero */
 116         protected $hpos;
 117
 118         /* initialized if loop is nonzero */
 119         protected $hslots;
 120
 121         /* initialized if findNext() returns true */
 122         protected $dpos;
 123
 124         /* initialized if cdb_findnext() returns 1 */
 125         protected $dlen;
 126
 127         /**
 128          * @param $fileName string
 129          * @throws CdbException
 130          */
 131         public function __construct( $fileName ) {
 132                 $this->fileName = $fileName;
 133                 $this->handle = fopen( $fileName, 'rb' );
 134                 if ( !$this->handle ) {
 135                         throw new CdbException( 'Unable to open CDB file "' . $this->fileName . '".' );
 136                 }
 137                 $this->findStart();
 138         }
 139
 140         public function close() {
 141                 if ( isset( $this->handle ) ) {
 142                         fclose( $this->handle );
 143                 }
 144                 unset( $this->handle );
 145         }
 146
 147         /**
 148          * @param $key
 149          * @return bool|string
 150          */
 151         public function get( $key ) {
 152                 // strval is required
 153                 if ( $this->find( strval( $key ) ) ) {
 154                         return $this->read( $this->dlen, $this->dpos );
 155                 } else {
 156                         return false;
 157                 }
 158         }
 159
 160         /**
 161          * @param $key
 162          * @param $pos
 163          * @return bool
 164          */
 165         protected function match( $key, $pos ) {
 166                 $buf = $this->read( strlen( $key ), $pos );
 167
 168                 return $buf === $key;
 169         }
 170
 171         protected function findStart() {
 172                 $this->loop = 0;
 173         }
 174
 175         /**
 176          * @throws CdbException
 177          * @param $length
 178          * @param $pos
 179          * @return string
 180          */
 181         protected function read( $length, $pos ) {
 182                 if ( fseek( $this->handle, $pos ) == -1 ) {
 183                         // This can easily happen if the internal pointers are incorrect
 184                         throw new CdbException(
 185                                 'Seek failed, file "' . $this->fileName . '" may be corrupted.' );
 186                 }
 187
 188                 if ( $length == 0 ) {
 189                         return '';
 190                 }
 191
 192                 $buf = fread( $this->handle, $length );
 193                 if ( $buf === false || strlen( $buf ) !== $length ) {
 194                         throw new CdbException(
 195                                 'Read from CDB file failed, file "' . $this->fileName . '" may be corrupted.' );
 196                 }
 197
 198                 return $buf;
 199         }
 200
 201         /**
 202          * Unpack an unsigned integer and throw an exception if it needs more than 31 bits
 203          * @param $s
 204          * @throws CdbException
 205          * @return mixed
 206          */
 207         protected function unpack31( $s ) {
 208                 $data = unpack( 'V', $s );
 209                 if ( $data[1] > 0x7fffffff ) {
 210                         throw new CdbException(
 211                                 'Error in CDB file "' . $this->fileName . '", integer too big.' );
 212                 }
 213
 214                 return $data[1];
 215         }
 216
 217         /**
 218          * Unpack a 32-bit signed integer
 219          * @param $s
 220          * @return int
 221          */
 222         protected function unpackSigned( $s ) {
 223                 $data = unpack( 'va/vb', $s );
 224
 225                 return $data['a'] | ( $data['b'] << 16 );
 226         }
 227
 228         /**
 229          * @param $key
 230          * @return bool
 231          */
 232         protected function findNext( $key ) {
 233                 if ( !$this->loop ) {
 234                         $u = CdbFunctions::hash( $key );
 235                         $buf = $this->read( 8, ( $u << 3 ) & 2047 );
 236                         $this->hslots = $this->unpack31( substr( $buf, 4 ) );
 237                         if ( !$this->hslots ) {
 238                                 return false;
 239                         }
 240                         $this->hpos = $this->unpack31( substr( $buf, 0, 4 ) );
 241                         $this->khash = $u;
 242                         $u = CdbFunctions::unsignedShiftRight( $u, 8 );
 243                         $u = CdbFunctions::unsignedMod( $u, $this->hslots );
 244                         $u <<= 3;
 245                         $this->kpos = $this->hpos + $u;
 246                 }
 247
 248                 while ( $this->loop < $this->hslots ) {
 249                         $buf = $this->read( 8, $this->kpos );
 250                         $pos = $this->unpack31( substr( $buf, 4 ) );
 251                         if ( !$pos ) {
 252                                 return false;
 253                         }
 254                         $this->loop += 1;
 255                         $this->kpos += 8;
 256                         if ( $this->kpos == $this->hpos + ( $this->hslots << 3 ) ) {
 257                                 $this->kpos = $this->hpos;
 258                         }
 259                         $u = $this->unpackSigned( substr( $buf, 0, 4 ) );
 260                         if ( $u === $this->khash ) {
 261                                 $buf = $this->read( 8, $pos );
 262                                 $keyLen = $this->unpack31( substr( $buf, 0, 4 ) );
 263                                 if ( $keyLen == strlen( $key ) && $this->match( $key, $pos + 8 ) ) {
 264                                         // Found
 265                                         $this->dlen = $this->unpack31( substr( $buf, 4 ) );
 266                                         $this->dpos = $pos + 8 + $keyLen;
 267
 268                                         return true;
 269                                 }
 270                         }
 271                 }
 272
 273                 return false;
 274         }
 275
 276         /**
 277          * @param $key
 278          * @return bool
 279          */
 280         protected function find( $key ) {
 281                 $this->findStart();
 282
 283                 return $this->findNext( $key );
 284         }
 285 }
 286
 287 /**
 288  * CDB writer class
 289  */
 290 class CdbWriterPHP extends CdbWriter {
 291         protected $hplist;
 292
 293         protected $numentries;
 294
 295         protected $pos;
 296
 297         /**
 298          * @param $fileName string
 299          */
 300         public function __construct( $fileName ) {
 301                 $this->realFileName = $fileName;
 302                 $this->tmpFileName = $fileName . '.tmp.' . mt_rand( 0, 0x7fffffff );
 303                 $this->handle = fopen( $this->tmpFileName, 'wb' );
 304                 if ( !$this->handle ) {
 305                         $this->throwException(
 306                                 'Unable to open CDB file "' . $this->tmpFileName . '" for write.' );
 307                 }
 308                 $this->hplist = array();
 309                 $this->numentries = 0;
 310                 $this->pos = 2048; // leaving space for the pointer array, 256 * 8
 311                 if ( fseek( $this->handle, $this->pos ) == -1 ) {
 312                         $this->throwException( 'fseek failed in file "' . $this->tmpFileName . '".' );
 313                 }
 314         }
 315
 316         /**
 317          * @param string $key
 318          * @param string $value
 319          */
 320         public function set( $key, $value ) {
 321                 if ( strval( $key ) === '' ) {
 322                         // DBA cross-check hack
 323                         return;
 324                 }
 325                 $this->addbegin( strlen( $key ), strlen( $value ) );
 326                 $this->write( $key );
 327                 $this->write( $value );
 328                 $this->addend( strlen( $key ), strlen( $value ), CdbFunctions::hash( $key ) );
 329         }
 330
 331         /**
 332          * @throws CdbException
 333          */
 334         public function close() {
 335                 $this->finish();
 336                 if ( isset( $this->handle ) ) {
 337                         fclose( $this->handle );
 338                 }
 339                 if ( $this->isWindows() && file_exists( $this->realFileName ) ) {
 340                         unlink( $this->realFileName );
 341                 }
 342                 if ( !rename( $this->tmpFileName, $this->realFileName ) ) {
 343                         $this->throwException( 'Unable to move the new CDB file into place.' );
 344                 }
 345                 unset( $this->handle );
 346         }
 347
 348         /**
 349          * @throws CdbException
 350          * @param $buf
 351          */
 352         protected function write( $buf ) {
 353                 $len = fwrite( $this->handle, $buf );
 354                 if ( $len !== strlen( $buf ) ) {
 355                         $this->throwException( 'Error writing to CDB file "' . $this->tmpFileName . '".' );
 356                 }
 357         }
 358
 359         /**
 360          * @throws CdbException
 361          * @param $len
 362          */
 363         protected function posplus( $len ) {
 364                 $newpos = $this->pos + $len;
 365                 if ( $newpos > 0x7fffffff ) {
 366                         $this->throwException(
 367                                 'A value in the CDB file "' . $this->tmpFileName . '" is too large.' );
 368                 }
 369                 $this->pos = $newpos;
 370         }
 371
 372         /**
 373          * @param $keylen
 374          * @param $datalen
 375          * @param $h
 376          */
 377         protected function addend( $keylen, $datalen, $h ) {
 378                 $this->hplist[] = array(
 379                         'h' => $h,
 380                         'p' => $this->pos
 381                 );
 382
 383                 $this->numentries++;
 384                 $this->posplus( 8 );
 385                 $this->posplus( $keylen );
 386                 $this->posplus( $datalen );
 387         }
 388
 389         /**
 390          * @throws CdbException
 391          * @param $keylen
 392          * @param $datalen
 393          */
 394         protected function addbegin( $keylen, $datalen ) {
 395                 if ( $keylen > 0x7fffffff ) {
 396                         $this->throwException( 'Key length too long in file "' . $this->tmpFileName . '".' );
 397                 }
 398                 if ( $datalen > 0x7fffffff ) {
 399                         $this->throwException( 'Data length too long in file "' . $this->tmpFileName . '".' );
 400                 }
 401                 $buf = pack( 'VV', $keylen, $datalen );
 402                 $this->write( $buf );
 403         }
 404
 405         /**
 406          * @throws CdbException
 407          */
 408         protected function finish() {
 409                 // Hack for DBA cross-check
 410                 $this->hplist = array_reverse( $this->hplist );
 411
 412                 // Calculate the number of items that will be in each hashtable
 413                 $counts = array_fill( 0, 256, 0 );
 414                 foreach ( $this->hplist as $item ) {
 415                         ++$counts[255 & $item['h']];
 416                 }
 417
 418                 // Fill in $starts with the *end* indexes
 419                 $starts = array();
 420                 $pos = 0;
 421                 for ( $i = 0; $i < 256; ++$i ) {
 422                         $pos += $counts[$i];
 423                         $starts[$i] = $pos;
 424                 }
 425
 426                 // Excessively clever and indulgent code to simultaneously fill $packedTables
 427                 // with the packed hashtables, and adjust the elements of $starts
 428                 // to actually point to the starts instead of the ends.
 429                 $packedTables = array_fill( 0, $this->numentries, false );
 430                 foreach ( $this->hplist as $item ) {
 431                         $packedTables[--$starts[255 & $item['h']]] = $item;
 432                 }
 433
 434                 $final = '';
 435                 for ( $i = 0; $i < 256; ++$i ) {
 436                         $count = $counts[$i];
 437
 438                         // The size of the hashtable will be double the item count.
 439                         // The rest of the slots will be empty.
 440                         $len = $count + $count;
 441                         $final .= pack( 'VV', $this->pos, $len );
 442
 443                         $hashtable = array();
 444                         for ( $u = 0; $u < $len; ++$u ) {
 445                                 $hashtable[$u] = array( 'h' => 0, 'p' => 0 );
 446                         }
 447
 448                         // Fill the hashtable, using the next empty slot if the hashed slot
 449                         // is taken.
 450                         for ( $u = 0; $u < $count; ++$u ) {
 451                                 $hp = $packedTables[$starts[$i] + $u];
 452                                 $where = CdbFunctions::unsignedMod(
 453                                         CdbFunctions::unsignedShiftRight( $hp['h'], 8 ), $len );
 454                                 while ( $hashtable[$where]['p'] ) {
 455                                         if ( ++$where == $len ) {
 456                                                 $where = 0;
 457                                         }
 458                                 }
 459                                 $hashtable[$where] = $hp;
 460                         }
 461
 462                         // Write the hashtable
 463                         for ( $u = 0; $u < $len; ++$u ) {
 464                                 $buf = pack( 'vvV',
 465                                         $hashtable[$u]['h'] & 0xffff,
 466                                         CdbFunctions::unsignedShiftRight( $hashtable[$u]['h'], 16 ),
 467                                         $hashtable[$u]['p'] );
 468                                 $this->write( $buf );
 469                                 $this->posplus( 8 );
 470                         }
 471                 }
 472
 473                 // Write the pointer array at the start of the file
 474                 rewind( $this->handle );
 475                 if ( ftell( $this->handle ) != 0 ) {
 476                         $this->throwException( 'Error rewinding to start of file "' . $this->tmpFileName . '".' );
 477                 }
 478                 $this->write( $final );
 479         }
 480
 481         /**
 482          * Clean up the temp file and throw an exception
 483          *
 484          * @param $msg string
 485          * @throws CdbException
 486          */
 487         protected function throwException( $msg ) {
 488                 if ( $this->handle ) {
 489                         fclose( $this->handle );
 490                         unlink( $this->tmpFileName );
 491                 }
 492                 throw new CdbException( $msg );
 493         }
 494 }