icuSources/common/ucnvsel.cpp

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 *******************************************************************************
   5 *
   6 *   Copyright (C) 2008-2011, International Business Machines
   7 *   Corporation, Google and others.  All Rights Reserved.
   8 *
   9 *******************************************************************************
  10 */
  11 // Author : eldawy@google.com (Mohamed Eldawy)
  12 // ucnvsel.cpp
  13 //
  14 // Purpose: To generate a list of encodings capable of handling
  15 // a given Unicode text
  16 //
  17 // Started 09-April-2008
  18
  19 /**
  20  * \file
  21  *
  22  * This is an implementation of an encoding selector.
  23  * The goal is, given a unicode string, find the encodings
  24  * this string can be mapped to. To make processing faster
  25  * a trie is built when you call ucnvsel_open() that
  26  * stores all encodings a codepoint can map to
  27  */
  28
  29 #include "unicode/ucnvsel.h"
  30
  31 #if !UCONFIG_NO_CONVERSION
  32
  33 #include <string.h>
  34
  35 #include "unicode/uchar.h"
  36 #include "unicode/uniset.h"
  37 #include "unicode/ucnv.h"
  38 #include "unicode/ustring.h"
  39 #include "unicode/uchriter.h"
  40 #include "utrie2.h"
  41 #include "propsvec.h"
  42 #include "uassert.h"
  43 #include "ucmndata.h"
  44 #include "uenumimp.h"
  45 #include "cmemory.h"
  46 #include "cstring.h"
  47
  48 U_NAMESPACE_USE
  49
  50 struct UConverterSelector {
  51   UTrie2 *trie;              // 16 bit trie containing offsets into pv
  52   uint32_t* pv;              // table of bits!
  53   int32_t pvCount;
  54   char** encodings;          // which encodings did user ask to use?
  55   int32_t encodingsCount;
  56   int32_t encodingStrLength;
  57   uint8_t* swapped;
  58   UBool ownPv, ownEncodingStrings;
  59 };
  60
  61 static void generateSelectorData(UConverterSelector* result,
  62                                  UPropsVectors *upvec,
  63                                  const USet* excludedCodePoints,
  64                                  const UConverterUnicodeSet whichSet,
  65                                  UErrorCode* status) {
  66   if (U_FAILURE(*status)) {
  67     return;
  68   }
  69
  70   int32_t columns = (result->encodingsCount+31)/32;
  71
  72   // set errorValue to all-ones
  73   for (int32_t col = 0; col < columns; col++) {
  74     upvec_setValue(upvec, UPVEC_ERROR_VALUE_CP, UPVEC_ERROR_VALUE_CP,
  75                    col, ~0, ~0, status);
  76   }
  77
  78   for (int32_t i = 0; i < result->encodingsCount; ++i) {
  79     uint32_t mask;
  80     uint32_t column;
  81     int32_t item_count;
  82     int32_t j;
  83     UConverter* test_converter = ucnv_open(result->encodings[i], status);
  84     if (U_FAILURE(*status)) {
  85       return;
  86     }
  87     USet* unicode_point_set;
  88     unicode_point_set = uset_open(1, 0);  // empty set
  89
  90     ucnv_getUnicodeSet(test_converter, unicode_point_set,
  91                        whichSet, status);
  92     if (U_FAILURE(*status)) {
  93       ucnv_close(test_converter);
  94       return;
  95     }
  96
  97     column = i / 32;
  98     mask = 1 << (i%32);
  99     // now iterate over intervals on set i!
 100     item_count = uset_getItemCount(unicode_point_set);
 101
 102     for (j = 0; j < item_count; ++j) {
 103       UChar32 start_char;
 104       UChar32 end_char;
 105       UErrorCode smallStatus = U_ZERO_ERROR;
 106       uset_getItem(unicode_point_set, j, &start_char, &end_char, NULL, 0,
 107                    &smallStatus);
 108       if (U_FAILURE(smallStatus)) {
 109         // this will be reached for the converters that fill the set with
 110         // strings. Those should be ignored by our system
 111       } else {
 112         upvec_setValue(upvec, start_char, end_char, column, ~0, mask,
 113                        status);
 114       }
 115     }
 116     ucnv_close(test_converter);
 117     uset_close(unicode_point_set);
 118     if (U_FAILURE(*status)) {
 119       return;
 120     }
 121   }
 122
 123   // handle excluded encodings! Simply set their values to all 1's in the upvec
 124   if (excludedCodePoints) {
 125     int32_t item_count = uset_getItemCount(excludedCodePoints);
 126     for (int32_t j = 0; j < item_count; ++j) {
 127       UChar32 start_char;
 128       UChar32 end_char;
 129
 130       uset_getItem(excludedCodePoints, j, &start_char, &end_char, NULL, 0,
 131                    status);
 132       for (int32_t col = 0; col < columns; col++) {
 133         upvec_setValue(upvec, start_char, end_char, col, ~0, ~0,
 134                       status);
 135       }
 136     }
 137   }
 138
 139   // alright. Now, let's put things in the same exact form you'd get when you
 140   // unserialize things.
 141   result->trie = upvec_compactToUTrie2WithRowIndexes(upvec, status);
 142   result->pv = upvec_cloneArray(upvec, &result->pvCount, NULL, status);
 143   result->pvCount *= columns;  // number of uint32_t = rows * columns
 144   result->ownPv = TRUE;
 145 }
 146
 147 /* open a selector. If converterListSize is 0, build for all converters.
 148    If excludedCodePoints is NULL, don't exclude any codepoints */
 149 U_CAPI UConverterSelector* U_EXPORT2
 150 ucnvsel_open(const char* const*  converterList, int32_t converterListSize,
 151              const USet* excludedCodePoints,
 152              const UConverterUnicodeSet whichSet, UErrorCode* status) {
 153   // check if already failed
 154   if (U_FAILURE(*status)) {
 155     return NULL;
 156   }
 157   // ensure args make sense!
 158   if (converterListSize < 0 || (converterList == NULL && converterListSize != 0)) {
 159     *status = U_ILLEGAL_ARGUMENT_ERROR;
 160     return NULL;
 161   }
 162
 163   // allocate a new converter
 164   LocalUConverterSelectorPointer newSelector(
 165     (UConverterSelector*)uprv_malloc(sizeof(UConverterSelector)));
 166   if (newSelector.isNull()) {
 167     *status = U_MEMORY_ALLOCATION_ERROR;
 168     return NULL;
 169   }
 170   uprv_memset(newSelector.getAlias(), 0, sizeof(UConverterSelector));
 171
 172   if (converterListSize == 0) {
 173     converterList = NULL;
 174     converterListSize = ucnv_countAvailable();
 175   }
 176   newSelector->encodings =
 177     (char**)uprv_malloc(converterListSize * sizeof(char*));
 178   if (!newSelector->encodings) {
 179     *status = U_MEMORY_ALLOCATION_ERROR;
 180     return NULL;
 181   }
 182   newSelector->encodings[0] = NULL;  // now we can call ucnvsel_close()
 183
 184   // make a backup copy of the list of converters
 185   int32_t totalSize = 0;
 186   int32_t i;
 187   for (i = 0; i < converterListSize; i++) {
 188     totalSize +=
 189       (int32_t)uprv_strlen(converterList != NULL ? converterList[i] : ucnv_getAvailableName(i)) + 1;
 190   }
 191   // 4-align the totalSize to 4-align the size of the serialized form
 192   int32_t encodingStrPadding = totalSize & 3;
 193   if (encodingStrPadding != 0) {
 194     encodingStrPadding = 4 - encodingStrPadding;
 195   }
 196   newSelector->encodingStrLength = totalSize += encodingStrPadding;
 197   char* allStrings = (char*) uprv_malloc(totalSize);
 198   if (!allStrings) {
 199     *status = U_MEMORY_ALLOCATION_ERROR;
 200     return NULL;
 201   }
 202
 203   for (i = 0; i < converterListSize; i++) {
 204     newSelector->encodings[i] = allStrings;
 205     uprv_strcpy(newSelector->encodings[i],
 206                 converterList != NULL ? converterList[i] : ucnv_getAvailableName(i));
 207     allStrings += uprv_strlen(newSelector->encodings[i]) + 1;
 208   }
 209   while (encodingStrPadding > 0) {
 210     *allStrings++ = 0;
 211     --encodingStrPadding;
 212   }
 213
 214   newSelector->ownEncodingStrings = TRUE;
 215   newSelector->encodingsCount = converterListSize;
 216   UPropsVectors *upvec = upvec_open((converterListSize+31)/32, status);
 217   generateSelectorData(newSelector.getAlias(), upvec, excludedCodePoints, whichSet, status);
 218   upvec_close(upvec);
 219
 220   if (U_FAILURE(*status)) {
 221     return NULL;
 222   }
 223
 224   return newSelector.orphan();
 225 }
 226
 227 /* close opened selector */
 228 U_CAPI void U_EXPORT2
 229 ucnvsel_close(UConverterSelector *sel) {
 230   if (!sel) {
 231     return;
 232   }
 233   if (sel->ownEncodingStrings) {
 234     uprv_free(sel->encodings[0]);
 235   }
 236   uprv_free(sel->encodings);
 237   if (sel->ownPv) {
 238     uprv_free(sel->pv);
 239   }
 240   utrie2_close(sel->trie);
 241   uprv_free(sel->swapped);
 242   uprv_free(sel);
 243 }
 244
 245 static const UDataInfo dataInfo = {
 246   sizeof(UDataInfo),
 247   0,
 248
 249   U_IS_BIG_ENDIAN,
 250   U_CHARSET_FAMILY,
 251   U_SIZEOF_UCHAR,
 252   0,
 253
 254   { 0x43, 0x53, 0x65, 0x6c },   /* dataFormat="CSel" */
 255   { 1, 0, 0, 0 },               /* formatVersion */
 256   { 0, 0, 0, 0 }                /* dataVersion */
 257 };
 258
 259 enum {
 260   UCNVSEL_INDEX_TRIE_SIZE,      // trie size in bytes
 261   UCNVSEL_INDEX_PV_COUNT,       // number of uint32_t in the bit vectors
 262   UCNVSEL_INDEX_NAMES_COUNT,    // number of encoding names
 263   UCNVSEL_INDEX_NAMES_LENGTH,   // number of encoding name bytes including padding
 264   UCNVSEL_INDEX_SIZE = 15,      // bytes following the DataHeader
 265   UCNVSEL_INDEX_COUNT = 16
 266 };
 267
 268 /*
 269  * Serialized form of a UConverterSelector, formatVersion 1:
 270  *
 271  * The serialized form begins with a standard ICU DataHeader with a UDataInfo
 272  * as the template above.
 273  * This is followed by:
 274  *   int32_t indexes[UCNVSEL_INDEX_COUNT];          // see index entry constants above
 275  *   serialized UTrie2;                             // indexes[UCNVSEL_INDEX_TRIE_SIZE] bytes
 276  *   uint32_t pv[indexes[UCNVSEL_INDEX_PV_COUNT]];  // bit vectors
 277  *   char* encodingNames[indexes[UCNVSEL_INDEX_NAMES_LENGTH]];  // NUL-terminated strings + padding
 278  */
 279
 280 /* serialize a selector */
 281 U_CAPI int32_t U_EXPORT2
 282 ucnvsel_serialize(const UConverterSelector* sel,
 283                   void* buffer, int32_t bufferCapacity, UErrorCode* status) {
 284   // check if already failed
 285   if (U_FAILURE(*status)) {
 286     return 0;
 287   }
 288   // ensure args make sense!
 289   uint8_t *p = (uint8_t *)buffer;
 290   if (bufferCapacity < 0 ||
 291       (bufferCapacity > 0 && (p == NULL || (U_POINTER_MASK_LSB(p, 3) != 0)))
 292   ) {
 293     *status = U_ILLEGAL_ARGUMENT_ERROR;
 294     return 0;
 295   }
 296   // add up the size of the serialized form
 297   int32_t serializedTrieSize = utrie2_serialize(sel->trie, NULL, 0, status);
 298   if (*status != U_BUFFER_OVERFLOW_ERROR && U_FAILURE(*status)) {
 299     return 0;
 300   }
 301   *status = U_ZERO_ERROR;
 302
 303   DataHeader header;
 304   uprv_memset(&header, 0, sizeof(header));
 305   header.dataHeader.headerSize = (uint16_t)((sizeof(header) + 15) & ~15);
 306   header.dataHeader.magic1 = 0xda;
 307   header.dataHeader.magic2 = 0x27;
 308   uprv_memcpy(&header.info, &dataInfo, sizeof(dataInfo));
 309
 310   int32_t indexes[UCNVSEL_INDEX_COUNT] = {
 311     serializedTrieSize,
 312     sel->pvCount,
 313     sel->encodingsCount,
 314     sel->encodingStrLength
 315   };
 316
 317   int32_t totalSize =
 318     header.dataHeader.headerSize +
 319     (int32_t)sizeof(indexes) +
 320     serializedTrieSize +
 321     sel->pvCount * 4 +
 322     sel->encodingStrLength;
 323   indexes[UCNVSEL_INDEX_SIZE] = totalSize - header.dataHeader.headerSize;
 324   if (totalSize > bufferCapacity) {
 325     *status = U_BUFFER_OVERFLOW_ERROR;
 326     return totalSize;
 327   }
 328   // ok, save!
 329   int32_t length = header.dataHeader.headerSize;
 330   uprv_memcpy(p, &header, sizeof(header));
 331   uprv_memset(p + sizeof(header), 0, length - sizeof(header));
 332   p += length;
 333
 334   length = (int32_t)sizeof(indexes);
 335   uprv_memcpy(p, indexes, length);
 336   p += length;
 337
 338   utrie2_serialize(sel->trie, p, serializedTrieSize, status);
 339   p += serializedTrieSize;
 340
 341   length = sel->pvCount * 4;
 342   uprv_memcpy(p, sel->pv, length);
 343   p += length;
 344
 345   uprv_memcpy(p, sel->encodings[0], sel->encodingStrLength);
 346   p += sel->encodingStrLength;
 347
 348   return totalSize;
 349 }
 350
 351 /**
 352  * swap a selector into the desired Endianness and Asciiness of
 353  * the system. Just as FYI, selectors are always saved in the format
 354  * of the system that created them. They are only converted if used
 355  * on another system. In other words, selectors created on different
 356  * system can be different even if the params are identical (endianness
 357  * and Asciiness differences only)
 358  *
 359  * @param ds pointer to data swapper containing swapping info
 360  * @param inData pointer to incoming data
 361  * @param length length of inData in bytes
 362  * @param outData pointer to output data. Capacity should
 363  *                be at least equal to capacity of inData
 364  * @param status an in/out ICU UErrorCode
 365  * @return 0 on failure, number of bytes swapped on success
 366  *         number of bytes swapped can be smaller than length
 367  */
 368 static int32_t
 369 ucnvsel_swap(const UDataSwapper *ds,
 370              const void *inData, int32_t length,
 371              void *outData, UErrorCode *status) {
 372   /* udata_swapDataHeader checks the arguments */
 373   int32_t headerSize = udata_swapDataHeader(ds, inData, length, outData, status);
 374   if(U_FAILURE(*status)) {
 375     return 0;
 376   }
 377
 378   /* check data format and format version */
 379   const UDataInfo *pInfo = (const UDataInfo *)((const char *)inData + 4);
 380   if(!(
 381     pInfo->dataFormat[0] == 0x43 &&  /* dataFormat="CSel" */
 382     pInfo->dataFormat[1] == 0x53 &&
 383     pInfo->dataFormat[2] == 0x65 &&
 384     pInfo->dataFormat[3] == 0x6c
 385   )) {
 386     udata_printError(ds, "ucnvsel_swap(): data format %02x.%02x.%02x.%02x is not recognized as UConverterSelector data\n",
 387                      pInfo->dataFormat[0], pInfo->dataFormat[1],
 388                      pInfo->dataFormat[2], pInfo->dataFormat[3]);
 389     *status = U_INVALID_FORMAT_ERROR;
 390     return 0;
 391   }
 392   if(pInfo->formatVersion[0] != 1) {
 393     udata_printError(ds, "ucnvsel_swap(): format version %02x is not supported\n",
 394                      pInfo->formatVersion[0]);
 395     *status = U_UNSUPPORTED_ERROR;
 396     return 0;
 397   }
 398
 399   if(length >= 0) {
 400     length -= headerSize;
 401     if(length < 16*4) {
 402       udata_printError(ds, "ucnvsel_swap(): too few bytes (%d after header) for UConverterSelector data\n",
 403                        length);
 404       *status = U_INDEX_OUTOFBOUNDS_ERROR;
 405       return 0;
 406     }
 407   }
 408
 409   const uint8_t *inBytes = (const uint8_t *)inData + headerSize;
 410   uint8_t *outBytes = (uint8_t *)outData + headerSize;
 411
 412   /* read the indexes */
 413   const int32_t *inIndexes = (const int32_t *)inBytes;
 414   int32_t indexes[16];
 415   int32_t i;
 416   for(i = 0; i < 16; ++i) {
 417     indexes[i] = udata_readInt32(ds, inIndexes[i]);
 418   }
 419
 420   /* get the total length of the data */
 421   int32_t size = indexes[UCNVSEL_INDEX_SIZE];
 422   if(length >= 0) {
 423     if(length < size) {
 424       udata_printError(ds, "ucnvsel_swap(): too few bytes (%d after header) for all of UConverterSelector data\n",
 425                        length);
 426       *status = U_INDEX_OUTOFBOUNDS_ERROR;
 427       return 0;
 428     }
 429
 430     /* copy the data for inaccessible bytes */
 431     if(inBytes != outBytes) {
 432       uprv_memcpy(outBytes, inBytes, size);
 433     }
 434
 435     int32_t offset = 0, count;
 436
 437     /* swap the int32_t indexes[] */
 438     count = UCNVSEL_INDEX_COUNT*4;
 439     ds->swapArray32(ds, inBytes, count, outBytes, status);
 440     offset += count;
 441
 442     /* swap the UTrie2 */
 443     count = indexes[UCNVSEL_INDEX_TRIE_SIZE];
 444     utrie2_swap(ds, inBytes + offset, count, outBytes + offset, status);
 445     offset += count;
 446
 447     /* swap the uint32_t pv[] */
 448     count = indexes[UCNVSEL_INDEX_PV_COUNT]*4;
 449     ds->swapArray32(ds, inBytes + offset, count, outBytes + offset, status);
 450     offset += count;
 451
 452     /* swap the encoding names */
 453     count = indexes[UCNVSEL_INDEX_NAMES_LENGTH];
 454     ds->swapInvChars(ds, inBytes + offset, count, outBytes + offset, status);
 455     offset += count;
 456
 457     U_ASSERT(offset == size);
 458   }
 459
 460   return headerSize + size;
 461 }
 462
 463 /* unserialize a selector */
 464 U_CAPI UConverterSelector* U_EXPORT2
 465 ucnvsel_openFromSerialized(const void* buffer, int32_t length, UErrorCode* status) {
 466   // check if already failed
 467   if (U_FAILURE(*status)) {
 468     return NULL;
 469   }
 470   // ensure args make sense!
 471   const uint8_t *p = (const uint8_t *)buffer;
 472   if (length <= 0 ||
 473       (length > 0 && (p == NULL || (U_POINTER_MASK_LSB(p, 3) != 0)))
 474   ) {
 475     *status = U_ILLEGAL_ARGUMENT_ERROR;
 476     return NULL;
 477   }
 478   // header
 479   if (length < 32) {
 480     // not even enough space for a minimal header
 481     *status = U_INDEX_OUTOFBOUNDS_ERROR;
 482     return NULL;
 483   }
 484   const DataHeader *pHeader = (const DataHeader *)p;
 485   if (!(
 486     pHeader->dataHeader.magic1==0xda &&
 487     pHeader->dataHeader.magic2==0x27 &&
 488     pHeader->info.dataFormat[0] == 0x43 &&
 489     pHeader->info.dataFormat[1] == 0x53 &&
 490     pHeader->info.dataFormat[2] == 0x65 &&
 491     pHeader->info.dataFormat[3] == 0x6c
 492   )) {
 493     /* header not valid or dataFormat not recognized */
 494     *status = U_INVALID_FORMAT_ERROR;
 495     return NULL;
 496   }
 497   if (pHeader->info.formatVersion[0] != 1) {
 498     *status = U_UNSUPPORTED_ERROR;
 499     return NULL;
 500   }
 501   uint8_t* swapped = NULL;
 502   if (pHeader->info.isBigEndian != U_IS_BIG_ENDIAN ||
 503       pHeader->info.charsetFamily != U_CHARSET_FAMILY
 504   ) {
 505     // swap the data
 506     UDataSwapper *ds =
 507       udata_openSwapperForInputData(p, length, U_IS_BIG_ENDIAN, U_CHARSET_FAMILY, status);
 508     int32_t totalSize = ucnvsel_swap(ds, p, -1, NULL, status);
 509     if (U_FAILURE(*status)) {
 510       udata_closeSwapper(ds);
 511       return NULL;
 512     }
 513     if (length < totalSize) {
 514       udata_closeSwapper(ds);
 515       *status = U_INDEX_OUTOFBOUNDS_ERROR;
 516       return NULL;
 517     }
 518     swapped = (uint8_t*)uprv_malloc(totalSize);
 519     if (swapped == NULL) {
 520       udata_closeSwapper(ds);
 521       *status = U_MEMORY_ALLOCATION_ERROR;
 522       return NULL;
 523     }
 524     ucnvsel_swap(ds, p, length, swapped, status);
 525     udata_closeSwapper(ds);
 526     if (U_FAILURE(*status)) {
 527       uprv_free(swapped);
 528       return NULL;
 529     }
 530     p = swapped;
 531     pHeader = (const DataHeader *)p;
 532   }
 533   if (length < (pHeader->dataHeader.headerSize + 16 * 4)) {
 534     // not even enough space for the header and the indexes
 535     uprv_free(swapped);
 536     *status = U_INDEX_OUTOFBOUNDS_ERROR;
 537     return NULL;
 538   }
 539   p += pHeader->dataHeader.headerSize;
 540   length -= pHeader->dataHeader.headerSize;
 541   // indexes
 542   const int32_t *indexes = (const int32_t *)p;
 543   if (length < indexes[UCNVSEL_INDEX_SIZE]) {
 544     uprv_free(swapped);
 545     *status = U_INDEX_OUTOFBOUNDS_ERROR;
 546     return NULL;
 547   }
 548   p += UCNVSEL_INDEX_COUNT * 4;
 549   // create and populate the selector object
 550   UConverterSelector* sel = (UConverterSelector*)uprv_malloc(sizeof(UConverterSelector));
 551   char **encodings =
 552     (char **)uprv_malloc(
 553       indexes[UCNVSEL_INDEX_NAMES_COUNT] * sizeof(char *));
 554   if (sel == NULL || encodings == NULL) {
 555     uprv_free(swapped);
 556     uprv_free(sel);
 557     uprv_free(encodings);
 558     *status = U_MEMORY_ALLOCATION_ERROR;
 559     return NULL;
 560   }
 561   uprv_memset(sel, 0, sizeof(UConverterSelector));
 562   sel->pvCount = indexes[UCNVSEL_INDEX_PV_COUNT];
 563   sel->encodings = encodings;
 564   sel->encodingsCount = indexes[UCNVSEL_INDEX_NAMES_COUNT];
 565   sel->encodingStrLength = indexes[UCNVSEL_INDEX_NAMES_LENGTH];
 566   sel->swapped = swapped;
 567   // trie
 568   sel->trie = utrie2_openFromSerialized(UTRIE2_16_VALUE_BITS,
 569                                         p, indexes[UCNVSEL_INDEX_TRIE_SIZE], NULL,
 570                                         status);
 571   p += indexes[UCNVSEL_INDEX_TRIE_SIZE];
 572   if (U_FAILURE(*status)) {
 573     ucnvsel_close(sel);
 574     return NULL;
 575   }
 576   // bit vectors
 577   sel->pv = (uint32_t *)p;
 578   p += sel->pvCount * 4;
 579   // encoding names
 580   char* s = (char*)p;
 581   for (int32_t i = 0; i < sel->encodingsCount; ++i) {
 582     sel->encodings[i] = s;
 583     s += uprv_strlen(s) + 1;
 584   }
 585   p += sel->encodingStrLength;
 586
 587   return sel;
 588 }
 589
 590 // a bunch of functions for the enumeration thingie! Nothing fancy here. Just
 591 // iterate over the selected encodings
 592 struct Enumerator {
 593   int16_t* index;
 594   int16_t length;
 595   int16_t cur;
 596   const UConverterSelector* sel;
 597 };
 598
 599 U_CDECL_BEGIN
 600
 601 static void U_CALLCONV
 602 ucnvsel_close_selector_iterator(UEnumeration *enumerator) {
 603   uprv_free(((Enumerator*)(enumerator->context))->index);
 604   uprv_free(enumerator->context);
 605   uprv_free(enumerator);
 606 }
 607
 608
 609 static int32_t U_CALLCONV
 610 ucnvsel_count_encodings(UEnumeration *enumerator, UErrorCode *status) {
 611   // check if already failed
 612   if (U_FAILURE(*status)) {
 613     return 0;
 614   }
 615   return ((Enumerator*)(enumerator->context))->length;
 616 }
 617
 618
 619 static const char* U_CALLCONV ucnvsel_next_encoding(UEnumeration* enumerator,
 620                                                  int32_t* resultLength,
 621                                                  UErrorCode* status) {
 622   // check if already failed
 623   if (U_FAILURE(*status)) {
 624     return NULL;
 625   }
 626
 627   int16_t cur = ((Enumerator*)(enumerator->context))->cur;
 628   const UConverterSelector* sel;
 629   const char* result;
 630   if (cur >= ((Enumerator*)(enumerator->context))->length) {
 631     return NULL;
 632   }
 633   sel = ((Enumerator*)(enumerator->context))->sel;
 634   result = sel->encodings[((Enumerator*)(enumerator->context))->index[cur] ];
 635   ((Enumerator*)(enumerator->context))->cur++;
 636   if (resultLength) {
 637     *resultLength = (int32_t)uprv_strlen(result);
 638   }
 639   return result;
 640 }
 641
 642 static void U_CALLCONV ucnvsel_reset_iterator(UEnumeration* enumerator,
 643                                            UErrorCode* status) {
 644   // check if already failed
 645   if (U_FAILURE(*status)) {
 646     return ;
 647   }
 648   ((Enumerator*)(enumerator->context))->cur = 0;
 649 }
 650
 651 U_CDECL_END
 652
 653
 654 static const UEnumeration defaultEncodings = {
 655   NULL,
 656     NULL,
 657     ucnvsel_close_selector_iterator,
 658     ucnvsel_count_encodings,
 659     uenum_unextDefault,
 660     ucnvsel_next_encoding,
 661     ucnvsel_reset_iterator
 662 };
 663
 664
 665 // internal fn to intersect two sets of masks
 666 // returns whether the mask has reduced to all zeros
 667 static UBool intersectMasks(uint32_t* dest, const uint32_t* source1, int32_t len) {
 668   int32_t i;
 669   uint32_t oredDest = 0;
 670   for (i = 0 ; i < len ; ++i) {
 671     oredDest |= (dest[i] &= source1[i]);
 672   }
 673   return oredDest == 0;
 674 }
 675
 676 // internal fn to count how many 1's are there in a mask
 677 // algorithm taken from  http://graphics.stanford.edu/~seander/bithacks.html
 678 static int16_t countOnes(uint32_t* mask, int32_t len) {
 679   int32_t i, totalOnes = 0;
 680   for (i = 0 ; i < len ; ++i) {
 681     uint32_t ent = mask[i];
 682     for (; ent; totalOnes++)
 683     {
 684       ent &= ent - 1; // clear the least significant bit set
 685     }
 686   }
 687   return totalOnes;
 688 }
 689
 690
 691 /* internal function! */
 692 static UEnumeration *selectForMask(const UConverterSelector* sel,
 693                                    uint32_t *mask, UErrorCode *status) {
 694   // this is the context we will use. Store a table of indices to which
 695   // encodings are legit.
 696   struct Enumerator* result = (Enumerator*)uprv_malloc(sizeof(Enumerator));
 697   if (result == NULL) {
 698     uprv_free(mask);
 699     *status = U_MEMORY_ALLOCATION_ERROR;
 700     return NULL;
 701   }
 702   result->index = NULL;  // this will be allocated later!
 703   result->length = result->cur = 0;
 704   result->sel = sel;
 705
 706   UEnumeration *en = (UEnumeration *)uprv_malloc(sizeof(UEnumeration));
 707   if (en == NULL) {
 708     // TODO(markus): Combine Enumerator and UEnumeration into one struct.
 709     uprv_free(mask);
 710     uprv_free(result);
 711     *status = U_MEMORY_ALLOCATION_ERROR;
 712     return NULL;
 713   }
 714   memcpy(en, &defaultEncodings, sizeof(UEnumeration));
 715   en->context = result;
 716
 717   int32_t columns = (sel->encodingsCount+31)/32;
 718   int16_t numOnes = countOnes(mask, columns);
 719   // now, we know the exact space we need for index
 720   if (numOnes > 0) {
 721     result->index = (int16_t*) uprv_malloc(numOnes * sizeof(int16_t));
 722
 723     int32_t i, j;
 724     int16_t k = 0;
 725     for (j = 0 ; j < columns; j++) {
 726       uint32_t v = mask[j];
 727       for (i = 0 ; i < 32 && k < sel->encodingsCount; i++, k++) {
 728         if ((v & 1) != 0) {
 729           result->index[result->length++] = k;
 730         }
 731         v >>= 1;
 732       }
 733     }
 734   } //otherwise, index will remain NULL (and will never be touched by
 735     //the enumerator code anyway)
 736   uprv_free(mask);
 737   return en;
 738 }
 739
 740 /* check a string against the selector - UTF16 version */
 741 U_CAPI UEnumeration * U_EXPORT2
 742 ucnvsel_selectForString(const UConverterSelector* sel,
 743                         const UChar *s, int32_t length, UErrorCode *status) {
 744   // check if already failed
 745   if (U_FAILURE(*status)) {
 746     return NULL;
 747   }
 748   // ensure args make sense!
 749   if (sel == NULL || (s == NULL && length != 0)) {
 750     *status = U_ILLEGAL_ARGUMENT_ERROR;
 751     return NULL;
 752   }
 753
 754   int32_t columns = (sel->encodingsCount+31)/32;
 755   uint32_t* mask = (uint32_t*) uprv_malloc(columns * 4);
 756   if (mask == NULL) {
 757     *status = U_MEMORY_ALLOCATION_ERROR;
 758     return NULL;
 759   }
 760   uprv_memset(mask, ~0, columns *4);
 761
 762   if(s!=NULL) {
 763     const UChar *limit;
 764     if (length >= 0) {
 765       limit = s + length;
 766     } else {
 767       limit = NULL;
 768     }
 769
 770     while (limit == NULL ? *s != 0 : s != limit) {
 771       UChar32 c;
 772       uint16_t pvIndex;
 773       UTRIE2_U16_NEXT16(sel->trie, s, limit, c, pvIndex);
 774       if (intersectMasks(mask, sel->pv+pvIndex, columns)) {
 775         break;
 776       }
 777     }
 778   }
 779   return selectForMask(sel, mask, status);
 780 }
 781
 782 /* check a string against the selector - UTF8 version */
 783 U_CAPI UEnumeration * U_EXPORT2
 784 ucnvsel_selectForUTF8(const UConverterSelector* sel,
 785                       const char *s, int32_t length, UErrorCode *status) {
 786   // check if already failed
 787   if (U_FAILURE(*status)) {
 788     return NULL;
 789   }
 790   // ensure args make sense!
 791   if (sel == NULL || (s == NULL && length != 0)) {
 792     *status = U_ILLEGAL_ARGUMENT_ERROR;
 793     return NULL;
 794   }
 795
 796   int32_t columns = (sel->encodingsCount+31)/32;
 797   uint32_t* mask = (uint32_t*) uprv_malloc(columns * 4);
 798   if (mask == NULL) {
 799     *status = U_MEMORY_ALLOCATION_ERROR;
 800     return NULL;
 801   }
 802   uprv_memset(mask, ~0, columns *4);
 803
 804   if (length < 0) {
 805     length = (int32_t)uprv_strlen(s);
 806   }
 807
 808   if(s!=NULL) {
 809     const char *limit = s + length;
 810
 811     while (s != limit) {
 812       uint16_t pvIndex;
 813       UTRIE2_U8_NEXT16(sel->trie, s, limit, pvIndex);
 814       if (intersectMasks(mask, sel->pv+pvIndex, columns)) {
 815         break;
 816       }
 817     }
 818   }
 819   return selectForMask(sel, mask, status);
 820 }
 821
 822 #endif  // !UCONFIG_NO_CONVERSION