icuSources/io/ustdio.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) 1998-2016, International Business Machines
   7  *   Corporation and others.  All Rights Reserved.
   8  *
   9  ******************************************************************************
  10  *
  11  * File ustdio.c
  12  *
  13  * Modification History:
  14  *
  15  *   Date        Name        Description
  16  *   11/18/98    stephen     Creation.
  17  *   03/12/99    stephen     Modified for new C API.
  18  *   07/19/99    stephen     Fixed read() and gets()
  19  ******************************************************************************
  20  */
  21
  22 #include "unicode/ustdio.h"
  23
  24 #if !UCONFIG_NO_CONVERSION
  25
  26 #include "unicode/putil.h"
  27 #include "cmemory.h"
  28 #include "cstring.h"
  29 #include "ufile.h"
  30 #include "ufmt_cmn.h"
  31 #include "unicode/ucnv.h"
  32 #include "unicode/ustring.h"
  33
  34 #include <string.h>
  35
  36 #define DELIM_LF 0x000A
  37 #define DELIM_VT 0x000B
  38 #define DELIM_FF 0x000C
  39 #define DELIM_CR 0x000D
  40 #define DELIM_NEL 0x0085
  41 #define DELIM_LS 0x2028
  42 #define DELIM_PS 0x2029
  43
  44 /* TODO: is this correct for all codepages? Should we just use \n and let the converter handle it? */
  45 #if U_PLATFORM_USES_ONLY_WIN32_API
  46 static const UChar DELIMITERS [] = { DELIM_CR, DELIM_LF, 0x0000 };
  47 static const uint32_t DELIMITERS_LEN = 2;
  48 /* TODO: Default newline writing should be detected based upon the converter being used. */
  49 #else
  50 static const UChar DELIMITERS [] = { DELIM_LF, 0x0000 };
  51 static const uint32_t DELIMITERS_LEN = 1;
  52 #endif
  53
  54 #define IS_FIRST_STRING_DELIMITER(c1) \
  55  (UBool)((DELIM_LF <= (c1) && (c1) <= DELIM_CR) \
  56         || (c1) == DELIM_NEL \
  57         || (c1) == DELIM_LS \
  58         || (c1) == DELIM_PS)
  59 #define CAN_HAVE_COMBINED_STRING_DELIMITER(c1) (UBool)((c1) == DELIM_CR)
  60 #define IS_COMBINED_STRING_DELIMITER(c1, c2) \
  61  (UBool)((c1) == DELIM_CR && (c2) == DELIM_LF)
  62
  63
  64 #if !UCONFIG_NO_TRANSLITERATION
  65
  66 U_CAPI UTransliterator* U_EXPORT2
  67 u_fsettransliterator(UFILE *file, UFileDirection direction,
  68                      UTransliterator *adopt, UErrorCode *status)
  69 {
  70     UTransliterator *old = NULL;
  71
  72     if(U_FAILURE(*status))
  73     {
  74         return adopt;
  75     }
  76
  77     if(!file)
  78     {
  79         *status = U_ILLEGAL_ARGUMENT_ERROR;
  80         return adopt;
  81     }
  82
  83     if(direction & U_READ)
  84     {
  85         /** TODO: implement */
  86         *status = U_UNSUPPORTED_ERROR;
  87         return adopt;
  88     }
  89
  90     if(adopt == NULL) /* they are clearing it */
  91     {
  92         if(file->fTranslit != NULL)
  93         {
  94             /* TODO: Check side */
  95             old = file->fTranslit->translit;
  96             uprv_free(file->fTranslit->buffer);
  97             file->fTranslit->buffer=NULL;
  98             uprv_free(file->fTranslit);
  99             file->fTranslit=NULL;
 100         }
 101     }
 102     else
 103     {
 104         if(file->fTranslit == NULL)
 105         {
 106             file->fTranslit = (UFILETranslitBuffer*) uprv_malloc(sizeof(UFILETranslitBuffer));
 107             if(!file->fTranslit)
 108             {
 109                 *status = U_MEMORY_ALLOCATION_ERROR;
 110                 return adopt;
 111             }
 112             file->fTranslit->capacity = 0;
 113             file->fTranslit->length = 0;
 114             file->fTranslit->pos = 0;
 115             file->fTranslit->buffer = NULL;
 116         }
 117         else
 118         {
 119             old = file->fTranslit->translit;
 120             ufile_flush_translit(file);
 121         }
 122
 123         file->fTranslit->translit = adopt;
 124     }
 125
 126     return old;
 127 }
 128
 129 static const UChar * u_file_translit(UFILE *f, const UChar *src, int32_t *count, UBool flush)
 130 {
 131     int32_t newlen;
 132     int32_t junkCount = 0;
 133     int32_t textLength;
 134     int32_t textLimit;
 135     UTransPosition pos;
 136     UErrorCode status = U_ZERO_ERROR;
 137
 138     if(count == NULL)
 139     {
 140         count = &junkCount;
 141     }
 142
 143     if ((!f)||(!f->fTranslit)||(!f->fTranslit->translit))
 144     {
 145         /* fast path */
 146         return src;
 147     }
 148
 149     /* First: slide over everything */
 150     if(f->fTranslit->length > f->fTranslit->pos)
 151     {
 152         memmove(f->fTranslit->buffer, f->fTranslit->buffer + f->fTranslit->pos,
 153             (f->fTranslit->length - f->fTranslit->pos)*sizeof(UChar));
 154     }
 155     f->fTranslit->length -= f->fTranslit->pos; /* always */
 156     f->fTranslit->pos = 0;
 157
 158     /* Calculate new buffer size needed */
 159     newlen = (*count + f->fTranslit->length) * 4;
 160
 161     if(newlen > f->fTranslit->capacity)
 162     {
 163         if(f->fTranslit->buffer == NULL)
 164         {
 165             f->fTranslit->buffer = (UChar*)uprv_malloc(newlen * sizeof(UChar));
 166         }
 167         else
 168         {
 169             f->fTranslit->buffer = (UChar*)uprv_realloc(f->fTranslit->buffer, newlen * sizeof(UChar));
 170         }
 171         /* Check for malloc/realloc failure. */
 172         if (f->fTranslit->buffer == NULL) {
 173                 return NULL;
 174         }
 175         f->fTranslit->capacity = newlen;
 176     }
 177
 178     /* Now, copy any data over */
 179     u_strncpy(f->fTranslit->buffer + f->fTranslit->length,
 180         src,
 181         *count);
 182     f->fTranslit->length += *count;
 183
 184     /* Now, translit in place as much as we can  */
 185     if(flush == FALSE)
 186     {
 187         textLength = f->fTranslit->length;
 188         pos.contextStart = 0;
 189         pos.contextLimit = textLength;
 190         pos.start        = 0;
 191         pos.limit        = textLength;
 192
 193         utrans_transIncrementalUChars(f->fTranslit->translit,
 194             f->fTranslit->buffer, /* because we shifted */
 195             &textLength,
 196             f->fTranslit->capacity,
 197             &pos,
 198             &status);
 199
 200         /* now: start/limit point to the transliterated text */
 201         /* Transliterated is [buffer..pos.start) */
 202         *count            = pos.start;
 203         f->fTranslit->pos = pos.start;
 204         f->fTranslit->length = pos.limit;
 205
 206         return f->fTranslit->buffer;
 207     }
 208     else
 209     {
 210         textLength = f->fTranslit->length;
 211         textLimit = f->fTranslit->length;
 212
 213         utrans_transUChars(f->fTranslit->translit,
 214             f->fTranslit->buffer,
 215             &textLength,
 216             f->fTranslit->capacity,
 217             0,
 218             &textLimit,
 219             &status);
 220
 221         /* out: converted len */
 222         *count = textLimit;
 223
 224         /* Set pointers to 0 */
 225         f->fTranslit->pos = 0;
 226         f->fTranslit->length = 0;
 227
 228         return f->fTranslit->buffer;
 229     }
 230 }
 231
 232 #endif
 233
 234 void
 235 ufile_flush_translit(UFILE *f)
 236 {
 237 #if !UCONFIG_NO_TRANSLITERATION
 238     if((!f)||(!f->fTranslit))
 239         return;
 240 #endif
 241
 242     u_file_write_flush(NULL, 0, f, FALSE, TRUE);
 243 }
 244
 245
 246 void
 247 ufile_flush_io(UFILE *f)
 248 {
 249   if((!f) || (!f->fFile)) {
 250     return; /* skip if no file */
 251   }
 252
 253   u_file_write_flush(NULL, 0, f, TRUE, FALSE);
 254 }
 255
 256
 257 void
 258 ufile_close_translit(UFILE *f)
 259 {
 260 #if !UCONFIG_NO_TRANSLITERATION
 261     if((!f)||(!f->fTranslit))
 262         return;
 263 #endif
 264
 265     ufile_flush_translit(f);
 266
 267 #if !UCONFIG_NO_TRANSLITERATION
 268     if(f->fTranslit->translit)
 269         utrans_close(f->fTranslit->translit);
 270
 271     if(f->fTranslit->buffer)
 272     {
 273         uprv_free(f->fTranslit->buffer);
 274     }
 275
 276     uprv_free(f->fTranslit);
 277     f->fTranslit = NULL;
 278 #endif
 279 }
 280
 281
 282 /* Input/output */
 283
 284 U_CAPI int32_t U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 285 u_fputs(const UChar    *s,
 286         UFILE        *f)
 287 {
 288     int32_t count = u_file_write(s, u_strlen(s), f);
 289     count += u_file_write(DELIMITERS, DELIMITERS_LEN, f);
 290     return count;
 291 }
 292
 293 U_CAPI UChar32 U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 294 u_fputc(UChar32      uc,
 295         UFILE        *f)
 296 {
 297     UChar buf[2];
 298     int32_t idx = 0;
 299     UBool isError = FALSE;
 300
 301     U16_APPEND(buf, idx, UPRV_LENGTHOF(buf), uc, isError);
 302     if (isError) {
 303         return U_EOF;
 304     }
 305     return u_file_write(buf, idx, f) == idx ? uc : U_EOF;
 306 }
 307
 308
 309 U_CFUNC int32_t U_EXPORT2
 310 u_file_write_flush(const UChar *chars,
 311                    int32_t     count,
 312                    UFILE       *f,
 313                    UBool       flushIO,
 314                    UBool       flushTranslit)
 315 {
 316     /* Set up conversion parameters */
 317     UErrorCode  status       = U_ZERO_ERROR;
 318     const UChar *mySource    = chars;
 319     const UChar *mySourceBegin;
 320     const UChar *mySourceEnd;
 321     char        charBuffer[UFILE_CHARBUFFER_SIZE];
 322     char        *myTarget   = charBuffer;
 323     int32_t     written      = 0;
 324     int32_t     numConverted = 0;
 325
 326     if (count < 0) {
 327         count = u_strlen(chars);
 328     }
 329
 330 #if !UCONFIG_NO_TRANSLITERATION
 331     if((f->fTranslit) && (f->fTranslit->translit))
 332     {
 333         /* Do the transliteration */
 334         mySource = u_file_translit(f, chars, &count, flushTranslit);
 335     }
 336 #endif
 337
 338     /* Write to a string. */
 339     if (!f->fFile) {
 340         int32_t charsLeft = (int32_t)(f->str.fLimit - f->str.fPos);
 341         if (flushIO && charsLeft > count) {
 342             count++;
 343         }
 344         written = ufmt_min(count, charsLeft);
 345         u_strncpy(f->str.fPos, mySource, written);
 346         f->str.fPos += written;
 347         return written;
 348     }
 349
 350     mySourceEnd = mySource + count;
 351
 352     /* Perform the conversion in a loop */
 353     do {
 354         mySourceBegin = mySource; /* beginning location for this loop */
 355         status     = U_ZERO_ERROR;
 356         if(f->fConverter != NULL) { /* We have a valid converter */
 357             ucnv_fromUnicode(f->fConverter,
 358                 &myTarget,
 359                 charBuffer + UFILE_CHARBUFFER_SIZE,
 360                 &mySource,
 361                 mySourceEnd,
 362                 NULL,
 363                 flushIO,
 364                 &status);
 365         } else { /*weiv: do the invariant conversion */
 366             int32_t convertChars = (int32_t) (mySourceEnd - mySource);
 367             if (convertChars > UFILE_CHARBUFFER_SIZE) {
 368                 convertChars = UFILE_CHARBUFFER_SIZE;
 369                 status = U_BUFFER_OVERFLOW_ERROR;
 370             }
 371             u_UCharsToChars(mySource, myTarget, convertChars);
 372             mySource += convertChars;
 373             myTarget += convertChars;
 374         }
 375         numConverted = (int32_t)(myTarget - charBuffer);
 376
 377         if (numConverted > 0) {
 378             /* write the converted bytes */
 379             fwrite(charBuffer,
 380                 sizeof(char),
 381                 numConverted,
 382                 f->fFile);
 383
 384             written     += (int32_t) (mySource - mySourceBegin);
 385         }
 386         myTarget     = charBuffer;
 387     }
 388     while(status == U_BUFFER_OVERFLOW_ERROR);
 389
 390     /* return # of chars written */
 391     return written;
 392 }
 393
 394 U_CAPI int32_t U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 395 u_file_write(    const UChar     *chars,
 396              int32_t        count,
 397              UFILE         *f)
 398 {
 399     return u_file_write_flush(chars,count,f,FALSE,FALSE);
 400 }
 401
 402
 403 /* private function used for buffering input */
 404 void
 405 ufile_fill_uchar_buffer(UFILE *f)
 406 {
 407     UErrorCode  status;
 408     const char  *mySource;
 409     const char  *mySourceEnd;
 410     UChar       *myTarget;
 411     int32_t     bufferSize;
 412     int32_t     maxCPBytes;
 413     int32_t     bytesRead;
 414     int32_t     availLength;
 415     int32_t     dataSize;
 416     char        charBuffer[UFILE_CHARBUFFER_SIZE];
 417     u_localized_string *str;
 418
 419     if (f->fFile == NULL) {
 420         /* There is nothing to do. It's a string. */
 421         return;
 422     }
 423
 424     str = &f->str;
 425     dataSize = (int32_t)(str->fLimit - str->fPos);
 426     if (f->fFileno == 0 && dataSize > 0) {
 427         /* Don't read from stdin too many times. There is still some data. */
 428         return;
 429     }
 430
 431     /* shift the buffer if it isn't empty */
 432     if(dataSize != 0) {
 433         u_memmove(f->fUCBuffer, str->fPos, dataSize); /* not accessing beyond memory */
 434     }
 435
 436
 437     /* record how much buffer space is available */
 438     availLength = UFILE_UCHARBUFFER_SIZE - dataSize;
 439
 440     /* Determine the # of codepage bytes needed to fill our UChar buffer */
 441     /* weiv: if converter is NULL, we use invariant converter with charwidth = 1)*/
 442     maxCPBytes = availLength / (f->fConverter!=NULL?(2*ucnv_getMinCharSize(f->fConverter)):1);
 443
 444     /* Read in the data to convert */
 445     if (f->fFileno == 0) {
 446         /* Special case. Read from stdin one line at a time. */
 447         char *retStr = fgets(charBuffer, ufmt_min(maxCPBytes, UFILE_CHARBUFFER_SIZE), f->fFile);
 448         bytesRead = (int32_t)(retStr ? uprv_strlen(charBuffer) : 0);
 449     }
 450     else {
 451         /* A normal file */
 452         bytesRead = (int32_t)fread(charBuffer,
 453             sizeof(char),
 454             ufmt_min(maxCPBytes, UFILE_CHARBUFFER_SIZE),
 455             f->fFile);
 456     }
 457
 458     /* Set up conversion parameters */
 459     status      = U_ZERO_ERROR;
 460     mySource    = charBuffer;
 461     mySourceEnd = charBuffer + bytesRead;
 462     myTarget    = f->fUCBuffer + dataSize;
 463     bufferSize  = UFILE_UCHARBUFFER_SIZE;
 464
 465     if(f->fConverter != NULL) { /* We have a valid converter */
 466         /* Perform the conversion */
 467         ucnv_toUnicode(f->fConverter,
 468             &myTarget,
 469             f->fUCBuffer + bufferSize,
 470             &mySource,
 471             mySourceEnd,
 472             NULL,
 473             (UBool)(feof(f->fFile) != 0),
 474             &status);
 475
 476     } else { /*weiv: do the invariant conversion */
 477         u_charsToUChars(mySource, myTarget, bytesRead);
 478         myTarget += bytesRead;
 479     }
 480
 481     /* update the pointers into our array */
 482     str->fPos    = str->fBuffer;
 483     str->fLimit  = myTarget;
 484 }
 485
 486 U_CAPI UChar* U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 487 u_fgets(UChar        *s,
 488         int32_t       n,
 489         UFILE        *f)
 490 {
 491     int32_t dataSize;
 492     int32_t count;
 493     UChar *alias;
 494     const UChar *limit;
 495     UChar *sItr;
 496     UChar currDelim = 0;
 497     u_localized_string *str;
 498
 499     if (n <= 0) {
 500         /* Caller screwed up. We need to write the null terminatior. */
 501         return NULL;
 502     }
 503
 504     /* fill the buffer if needed */
 505     str = &f->str;
 506     if (str->fPos >= str->fLimit) {
 507         ufile_fill_uchar_buffer(f);
 508     }
 509
 510     /* subtract 1 from n to compensate for the terminator */
 511     --n;
 512
 513     /* determine the amount of data in the buffer */
 514     dataSize = (int32_t)(str->fLimit - str->fPos);
 515
 516     /* if 0 characters were left, return 0 */
 517     if (dataSize == 0)
 518         return NULL;
 519
 520     /* otherwise, iteratively fill the buffer and copy */
 521     count = 0;
 522     sItr = s;
 523     currDelim = 0;
 524     while (dataSize > 0 && count < n) {
 525         alias = str->fPos;
 526
 527         /* Find how much to copy */
 528         if (dataSize < (n - count)) {
 529             limit = str->fLimit;
 530         }
 531         else {
 532             limit = alias + (n - count);
 533         }
 534
 535         if (!currDelim) {
 536             /* Copy UChars until we find the first occurrence of a delimiter character */
 537             while (alias < limit && !IS_FIRST_STRING_DELIMITER(*alias)) {
 538                 count++;
 539                 *(sItr++) = *(alias++);
 540             }
 541             /* Preserve the newline */
 542             if (alias < limit && IS_FIRST_STRING_DELIMITER(*alias)) {
 543                 if (CAN_HAVE_COMBINED_STRING_DELIMITER(*alias)) {
 544                     currDelim = *alias;
 545                 }
 546                 else {
 547                     currDelim = 1;  /* This isn't a newline, but it's used to say
 548                                     that we should break later. We've checked all
 549                                     possible newline combinations even across buffer
 550                                     boundaries. */
 551                 }
 552                 count++;
 553                 *(sItr++) = *(alias++);
 554             }
 555         }
 556         /* If we have a CRLF combination, preserve that too. */
 557         if (alias < limit) {
 558             if (currDelim && IS_COMBINED_STRING_DELIMITER(currDelim, *alias)) {
 559                 count++;
 560                 *(sItr++) = *(alias++);
 561             }
 562             currDelim = 1;  /* This isn't a newline, but it's used to say
 563                             that we should break later. We've checked all
 564                             possible newline combinations even across buffer
 565                             boundaries. */
 566         }
 567
 568         /* update the current buffer position */
 569         str->fPos = alias;
 570
 571         /* if we found a delimiter */
 572         if (currDelim == 1) {
 573             /* break out */
 574             break;
 575         }
 576
 577         /* refill the buffer */
 578         ufile_fill_uchar_buffer(f);
 579
 580         /* determine the amount of data in the buffer */
 581         dataSize = (int32_t)(str->fLimit - str->fPos);
 582     }
 583
 584     /* add the terminator and return s */
 585     *sItr = 0x0000;
 586     return s;
 587 }
 588
 589 U_CFUNC UBool U_EXPORT2
 590 ufile_getch(UFILE *f, UChar *ch)
 591 {
 592     UBool isValidChar = FALSE;
 593
 594     *ch = U_EOF;
 595     /* if we have an available character in the buffer, return it */
 596     if(f->str.fPos < f->str.fLimit){
 597         *ch = *(f->str.fPos)++;
 598         isValidChar = TRUE;
 599     }
 600     else {
 601         /* otherwise, fill the buffer and return the next character */
 602         if(f->str.fPos >= f->str.fLimit) {
 603             ufile_fill_uchar_buffer(f);
 604         }
 605         if(f->str.fPos < f->str.fLimit) {
 606             *ch = *(f->str.fPos)++;
 607             isValidChar = TRUE;
 608         }
 609     }
 610     return isValidChar;
 611 }
 612
 613 U_CAPI UChar U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 614 u_fgetc(UFILE        *f)
 615 {
 616     UChar ch;
 617     ufile_getch(f, &ch);
 618     return ch;
 619 }
 620
 621 U_CFUNC UBool U_EXPORT2
 622 ufile_getch32(UFILE *f, UChar32 *c32)
 623 {
 624     UBool isValidChar = FALSE;
 625     u_localized_string *str;
 626
 627     *c32 = U_EOF;
 628
 629     /* Fill the buffer if it is empty */
 630     str = &f->str;
 631     if (f && str->fPos + 1 >= str->fLimit) {
 632         ufile_fill_uchar_buffer(f);
 633     }
 634
 635     /* Get the next character in the buffer */
 636     if (str->fPos < str->fLimit) {
 637         *c32 = *(str->fPos)++;
 638         if (U_IS_LEAD(*c32)) {
 639             if (str->fPos < str->fLimit) {
 640                 UChar c16 = *(str->fPos)++;
 641                 *c32 = U16_GET_SUPPLEMENTARY(*c32, c16);
 642                 isValidChar = TRUE;
 643             }
 644             else {
 645                 *c32 = U_EOF;
 646             }
 647         }
 648         else {
 649             isValidChar = TRUE;
 650         }
 651     }
 652
 653     return isValidChar;
 654 }
 655
 656 U_CAPI UChar32 U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 657 u_fgetcx(UFILE        *f)
 658 {
 659     UChar32 ch;
 660     ufile_getch32(f, &ch);
 661     return ch;
 662 }
 663
 664 U_CAPI UChar32 U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 665 u_fungetc(UChar32        ch,
 666     UFILE        *f)
 667 {
 668     u_localized_string *str;
 669
 670     str = &f->str;
 671
 672     /* if we're at the beginning of the buffer, sorry! */
 673     if (str->fPos == str->fBuffer
 674         || (U_IS_LEAD(ch) && (str->fPos - 1) == str->fBuffer))
 675     {
 676         ch = U_EOF;
 677     }
 678     else {
 679         /* otherwise, put the character back */
 680         /* Remember, read them back on in the reverse order. */
 681         if (U_IS_LEAD(ch)) {
 682             if (*--(str->fPos) != U16_TRAIL(ch)
 683                 || *--(str->fPos) != U16_LEAD(ch))
 684             {
 685                 ch = U_EOF;
 686             }
 687         }
 688         else if (*--(str->fPos) != ch) {
 689             ch = U_EOF;
 690         }
 691     }
 692     return ch;
 693 }
 694
 695 U_CAPI int32_t U_EXPORT2 /* U_CAPI ... U_EXPORT2 added by Peter Kirk 17 Nov 2001 */
 696 u_file_read(    UChar        *chars,
 697     int32_t        count,
 698     UFILE         *f)
 699 {
 700     int32_t dataSize;
 701     int32_t read = 0;
 702     u_localized_string *str = &f->str;
 703
 704     do {
 705
 706         /* determine the amount of data in the buffer */
 707         dataSize = (int32_t)(str->fLimit - str->fPos);
 708         if (dataSize <= 0) {
 709             /* fill the buffer */
 710             ufile_fill_uchar_buffer(f);
 711             dataSize = (int32_t)(str->fLimit - str->fPos);
 712         }
 713
 714         /* Make sure that we don't read too much */
 715         if (dataSize > (count - read)) {
 716             dataSize = count - read;
 717         }
 718
 719         /* copy the current data in the buffer */
 720         memcpy(chars + read, str->fPos, dataSize * sizeof(UChar));
 721
 722         /* update number of items read */
 723         read += dataSize;
 724
 725         /* update the current buffer position */
 726         str->fPos += dataSize;
 727     }
 728     while (dataSize != 0 && read < count);
 729
 730     return read;
 731 }
 732 #endif