iconv/loop.c

   1 /* Conversion loop frame work.
   2    Copyright (C) 1998-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 /* This file provides a frame for the reader loop in all conversion modules.
  21    The actual code must (of course) be provided in the actual module source
  22    code but certain actions can be written down generically, with some
  23    customization options which are these:
  24
  25      MIN_NEEDED_INPUT   minimal number of input bytes needed for the next
  26                         conversion.
  27      MIN_NEEDED_OUTPUT  minimal number of bytes produced by the next round
  28                         of conversion.
  29
  30      MAX_NEEDED_INPUT   you guess it, this is the maximal number of input
  31                         bytes needed.  It defaults to MIN_NEEDED_INPUT
  32      MAX_NEEDED_OUTPUT  likewise for output bytes.
  33
  34      LOOPFCT            name of the function created.  If not specified
  35                         the name is `loop' but this prevents the use
  36                         of multiple functions in the same file.
  37
  38      BODY               this is supposed to expand to the body of the loop.
  39                         The user must provide this.
  40
  41      EXTRA_LOOP_DECLS   extra arguments passed from conversion loop call.
  42
  43      INIT_PARAMS        code to define and initialize variables from params.
  44      UPDATE_PARAMS      code to store result in params.
  45
  46      ONEBYTE_BODY       body of the specialized conversion function for a
  47                         single byte from the current character set to INTERNAL.
  48 */
  49
  50 #include <assert.h>
  51 #include <endian.h>
  52 #include <iconv/gconv_int.h>
  53 #include <stdint.h>
  54 #include <string.h>
  55 #include <wchar.h>
  56 #include <sys/param.h>          /* For MIN.  */
  57 #define __need_size_t
  58 #include <stddef.h>
  59 #include <libc-diag.h>
  60
  61 /* We have to provide support for machines which are not able to handled
  62    unaligned memory accesses.  Some of the character encodings have
  63    representations with a fixed width of 2 or 4 bytes.  But if we cannot
  64    access unaligned memory we still have to read byte-wise.  */
  65 #undef FCTNAME2
  66 #if _STRING_ARCH_unaligned || !defined DEFINE_UNALIGNED
  67 /* We can handle unaligned memory access.  */
  68 # define get16(addr) *((const uint16_t *) (addr))
  69 # define get32(addr) *((const uint32_t *) (addr))
  70
  71 /* We need no special support for writing values either.  */
  72 # define put16(addr, val) *((uint16_t *) (addr)) = (val)
  73 # define put32(addr, val) *((uint32_t *) (addr)) = (val)
  74
  75 # define FCTNAME2(name) name
  76 #else
  77 /* Distinguish between big endian and little endian.  */
  78 # if __BYTE_ORDER == __LITTLE_ENDIAN
  79 #  define get16(addr) \
  80      (((const unsigned char *) (addr))[1] << 8                                \
  81       | ((const unsigned char *) (addr))[0])
  82 #  define get32(addr) \
  83      (((((const unsigned char *) (addr))[3] << 8                              \
  84         | ((const unsigned char *) (addr))[2]) << 8                           \
  85        | ((const unsigned char *) (addr))[1]) << 8                            \
  86       | ((const unsigned char *) (addr))[0])
  87
  88 #  define put16(addr, val) \
  89      ({ uint16_t __val = (val);                                               \
  90         ((unsigned char *) (addr))[0] = __val;                                \
  91         ((unsigned char *) (addr))[1] = __val >> 8;                           \
  92         (void) 0; })
  93 #  define put32(addr, val) \
  94      ({ uint32_t __val = (val);                                               \
  95         ((unsigned char *) (addr))[0] = __val;                                \
  96         __val >>= 8;                                                          \
  97         ((unsigned char *) (addr))[1] = __val;                                \
  98         __val >>= 8;                                                          \
  99         ((unsigned char *) (addr))[2] = __val;                                \
 100         __val >>= 8;                                                          \
 101         ((unsigned char *) (addr))[3] = __val;                                \
 102         (void) 0; })
 103 # else
 104 #  define get16(addr) \
 105      (((const unsigned char *) (addr))[0] << 8                                \
 106       | ((const unsigned char *) (addr))[1])
 107 #  define get32(addr) \
 108      (((((const unsigned char *) (addr))[0] << 8                              \
 109         | ((const unsigned char *) (addr))[1]) << 8                           \
 110        | ((const unsigned char *) (addr))[2]) << 8                            \
 111       | ((const unsigned char *) (addr))[3])
 112
 113 #  define put16(addr, val) \
 114      ({ uint16_t __val = (val);                                               \
 115         ((unsigned char *) (addr))[1] = __val;                                \
 116         ((unsigned char *) (addr))[0] = __val >> 8;                           \
 117         (void) 0; })
 118 #  define put32(addr, val) \
 119      ({ uint32_t __val = (val);                                               \
 120         ((unsigned char *) (addr))[3] = __val;                                \
 121         __val >>= 8;                                                          \
 122         ((unsigned char *) (addr))[2] = __val;                                \
 123         __val >>= 8;                                                          \
 124         ((unsigned char *) (addr))[1] = __val;                                \
 125         __val >>= 8;                                                          \
 126         ((unsigned char *) (addr))[0] = __val;                                \
 127         (void) 0; })
 128 # endif
 129
 130 # define FCTNAME2(name) name##_unaligned
 131 #endif
 132 #define FCTNAME(name) FCTNAME2(name)
 133
 134
 135 /* We need at least one byte for the next round.  */
 136 #ifndef MIN_NEEDED_INPUT
 137 # error "MIN_NEEDED_INPUT definition missing"
 138 #elif MIN_NEEDED_INPUT < 1
 139 # error "MIN_NEEDED_INPUT must be >= 1"
 140 #endif
 141
 142 /* Let's see how many bytes we produce.  */
 143 #ifndef MAX_NEEDED_INPUT
 144 # define MAX_NEEDED_INPUT       MIN_NEEDED_INPUT
 145 #endif
 146
 147 /* We produce at least one byte in the next round.  */
 148 #ifndef MIN_NEEDED_OUTPUT
 149 # error "MIN_NEEDED_OUTPUT definition missing"
 150 #elif MIN_NEEDED_OUTPUT < 1
 151 # error "MIN_NEEDED_OUTPUT must be >= 1"
 152 #endif
 153
 154 /* Let's see how many bytes we produce.  */
 155 #ifndef MAX_NEEDED_OUTPUT
 156 # define MAX_NEEDED_OUTPUT      MIN_NEEDED_OUTPUT
 157 #endif
 158
 159 /* Default name for the function.  */
 160 #ifndef LOOPFCT
 161 # define LOOPFCT                loop
 162 #endif
 163
 164 /* Make sure we have a loop body.  */
 165 #ifndef BODY
 166 # error "Definition of BODY missing for function" LOOPFCT
 167 #endif
 168
 169
 170 /* If no arguments have to passed to the loop function define the macro
 171    as empty.  */
 172 #ifndef EXTRA_LOOP_DECLS
 173 # define EXTRA_LOOP_DECLS
 174 #endif
 175
 176 /* Allow using UPDATE_PARAMS in macros where #ifdef UPDATE_PARAMS test
 177    isn't possible.  */
 178 #ifndef UPDATE_PARAMS
 179 # define UPDATE_PARAMS do { } while (0)
 180 #endif
 181 #ifndef REINIT_PARAMS
 182 # define REINIT_PARAMS do { } while (0)
 183 #endif
 184
 185
 186 /* To make it easier for the writers of the modules, we define a macro
 187    to test whether we have to ignore errors.  */
 188 #define ignore_errors_p() \
 189   (irreversible != NULL && (flags & __GCONV_IGNORE_ERRORS))
 190
 191
 192 /* Error handling for the FROM_LOOP direction, with ignoring of errors.
 193    Note that we cannot use the do while (0) trick since `break' and
 194    `continue' must reach certain points.  */
 195 #define STANDARD_FROM_LOOP_ERR_HANDLER(Incr) \
 196   {                                                                           \
 197     result = __GCONV_ILLEGAL_INPUT;                                           \
 198                                                                               \
 199     if (! ignore_errors_p ())                                                 \
 200       break;                                                                  \
 201                                                                               \
 202     /* We ignore the invalid input byte sequence.  */                         \
 203     inptr += (Incr);                                                          \
 204     ++*irreversible;                                                          \
 205     /* But we keep result == __GCONV_ILLEGAL_INPUT, because of the constraint \
 206        that "iconv -c" must give the same exitcode as "iconv".  */            \
 207     continue;                                                                 \
 208   }
 209
 210 /* Error handling for the TO_LOOP direction, with use of transliteration/
 211    transcription functions and ignoring of errors.  Note that we cannot use
 212    the do while (0) trick since `break' and `continue' must reach certain
 213    points.  */
 214 #define STANDARD_TO_LOOP_ERR_HANDLER(Incr) \
 215   {                                                                           \
 216     result = __GCONV_ILLEGAL_INPUT;                                           \
 217                                                                               \
 218     if (irreversible == NULL)                                                 \
 219       /* This means we are in call from __gconv_transliterate.  In this       \
 220          case we are not doing any error recovery outself.  */                \
 221       break;                                                                  \
 222                                                                               \
 223     /* If needed, flush any conversion state, so that __gconv_transliterate   \
 224        starts with current shift state.  */                                   \
 225     UPDATE_PARAMS;                                                            \
 226                                                                               \
 227     /* First try the transliteration methods.  */                             \
 228     if ((step_data->__flags & __GCONV_TRANSLIT) != 0)                         \
 229       result = __gconv_transliterate                                          \
 230         (step, step_data, *inptrp,                                            \
 231          &inptr, inend, &outptr, irreversible);                       \
 232                                                                               \
 233     REINIT_PARAMS;                                                            \
 234                                                                               \
 235     /* If any of them recognized the input continue with the loop.  */        \
 236     if (result != __GCONV_ILLEGAL_INPUT)                                      \
 237       {                                                                       \
 238         if (__glibc_unlikely (result == __GCONV_FULL_OUTPUT))                 \
 239           break;                                                              \
 240                                                                               \
 241         continue;                                                             \
 242       }                                                                       \
 243                                                                               \
 244     /* Next see whether we have to ignore the error.  If not, stop.  */       \
 245     if (! ignore_errors_p ())                                                 \
 246       break;                                                                  \
 247                                                                               \
 248     /* When we come here it means we ignore the character.  */                \
 249     ++*irreversible;                                                          \
 250     inptr += Incr;                                                            \
 251     /* But we keep result == __GCONV_ILLEGAL_INPUT, because of the constraint \
 252        that "iconv -c" must give the same exitcode as "iconv".  */            \
 253     continue;                                                                 \
 254   }
 255
 256
 257 /* With GCC 7 when compiling with -Os for 32-bit s390 the compiler
 258    warns that the variable 'ch', in the definition of BODY in
 259    sysdeps/s390/multiarch/8bit-generic.c, may be used uninitialized in
 260    the call to UNICODE_TAG_HANDLER in that macro.  This variable is
 261    actually always initialized before use, in the prior loop if INDEX
 262    is nonzero and in the following 'if' if INDEX is zero.  That code
 263    has a comment referencing this diagnostic disabling; updates in one
 264    place may require updates in the other.  */
 265 DIAG_PUSH_NEEDS_COMMENT;
 266 DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
 267 /* Handling of Unicode 3.1 TAG characters.  Unicode recommends
 268    "If language codes are not relevant to the particular processing
 269     operation, then they should be ignored."  This macro is usually
 270    called right before  STANDARD_TO_LOOP_ERR_HANDLER (Incr).  */
 271 #define UNICODE_TAG_HANDLER(Character, Incr) \
 272   {                                                                           \
 273     /* TAG characters are those in the range U+E0000..U+E007F.  */            \
 274     if (((Character) >> 7) == (0xe0000 >> 7))                                 \
 275       {                                                                       \
 276         inptr += Incr;                                                        \
 277         continue;                                                             \
 278       }                                                                       \
 279   }
 280 DIAG_POP_NEEDS_COMMENT;
 281
 282
 283 /* The function returns the status, as defined in gconv.h.  */
 284 static inline int
 285 __attribute ((always_inline))
 286 FCTNAME (LOOPFCT) (struct __gconv_step *step,
 287                    struct __gconv_step_data *step_data,
 288                    const unsigned char **inptrp, const unsigned char *inend,
 289                    unsigned char **outptrp, const unsigned char *outend,
 290                    size_t *irreversible EXTRA_LOOP_DECLS)
 291 {
 292 #ifdef LOOP_NEED_STATE
 293   mbstate_t *state = step_data->__statep;
 294 #endif
 295 #ifdef LOOP_NEED_FLAGS
 296   int flags = step_data->__flags;
 297 #endif
 298 #ifdef LOOP_NEED_DATA
 299   void *data = step->__data;
 300 #endif
 301   int result = __GCONV_EMPTY_INPUT;
 302   const unsigned char *inptr = *inptrp;
 303   unsigned char *outptr = *outptrp;
 304
 305 #ifdef INIT_PARAMS
 306   INIT_PARAMS;
 307 #endif
 308
 309   while (inptr != inend)
 310     {
 311       /* `if' cases for MIN_NEEDED_OUTPUT ==/!= 1 is made to help the
 312          compiler generating better code.  They will be optimized away
 313          since MIN_NEEDED_OUTPUT is always a constant.  */
 314       if (MIN_NEEDED_INPUT > 1
 315           && __builtin_expect (inptr + MIN_NEEDED_INPUT > inend, 0))
 316         {
 317           /* We don't have enough input for another complete input
 318              character.  */
 319           result = __GCONV_INCOMPLETE_INPUT;
 320           break;
 321         }
 322       if ((MIN_NEEDED_OUTPUT != 1
 323            && __builtin_expect (outptr + MIN_NEEDED_OUTPUT > outend, 0))
 324           || (MIN_NEEDED_OUTPUT == 1
 325               && __builtin_expect (outptr >= outend, 0)))
 326         {
 327           /* Overflow in the output buffer.  */
 328           result = __GCONV_FULL_OUTPUT;
 329           break;
 330         }
 331
 332       /* Here comes the body the user provides.  It can stop with
 333          RESULT set to GCONV_INCOMPLETE_INPUT (if the size of the
 334          input characters vary in size), GCONV_ILLEGAL_INPUT, or
 335          GCONV_FULL_OUTPUT (if the output characters vary in size).  */
 336       BODY
 337     }
 338
 339   /* Update the pointers pointed to by the parameters.  */
 340   *inptrp = inptr;
 341   *outptrp = outptr;
 342   UPDATE_PARAMS;
 343
 344   return result;
 345 }
 346
 347
 348 /* Include the file a second time to define the function to handle
 349    unaligned access.  */
 350 #if !defined DEFINE_UNALIGNED && !_STRING_ARCH_unaligned \
 351     && MIN_NEEDED_INPUT != 1 && MAX_NEEDED_INPUT % MIN_NEEDED_INPUT == 0 \
 352     && MIN_NEEDED_OUTPUT != 1 && MAX_NEEDED_OUTPUT % MIN_NEEDED_OUTPUT == 0
 353 # undef get16
 354 # undef get32
 355 # undef put16
 356 # undef put32
 357 # undef unaligned
 358
 359 # define DEFINE_UNALIGNED
 360 # include "loop.c"
 361 # undef DEFINE_UNALIGNED
 362 #else
 363 # if MAX_NEEDED_INPUT > 1
 364 #  define SINGLE(fct) SINGLE2 (fct)
 365 #  define SINGLE2(fct) fct##_single
 366 static inline int
 367 __attribute ((always_inline))
 368 SINGLE(LOOPFCT) (struct __gconv_step *step,
 369                  struct __gconv_step_data *step_data,
 370                  const unsigned char **inptrp, const unsigned char *inend,
 371                  unsigned char **outptrp, unsigned char *outend,
 372                  size_t *irreversible EXTRA_LOOP_DECLS)
 373 {
 374   mbstate_t *state = step_data->__statep;
 375 #  ifdef LOOP_NEED_FLAGS
 376   int flags = step_data->__flags;
 377 #  endif
 378 #  ifdef LOOP_NEED_DATA
 379   void *data = step->__data;
 380 #  endif
 381   int result = __GCONV_OK;
 382   unsigned char bytebuf[MAX_NEEDED_INPUT];
 383   const unsigned char *inptr = *inptrp;
 384   unsigned char *outptr = *outptrp;
 385   size_t inlen;
 386
 387 #  ifdef INIT_PARAMS
 388   INIT_PARAMS;
 389 #  endif
 390
 391 #  ifdef UNPACK_BYTES
 392   UNPACK_BYTES
 393 #  else
 394   /* Add the bytes from the state to the input buffer.  */
 395   assert ((state->__count & 7) <= sizeof (state->__value));
 396   for (inlen = 0; inlen < (size_t) (state->__count & 7); ++inlen)
 397     bytebuf[inlen] = state->__value.__wchb[inlen];
 398 #  endif
 399
 400   /* Are there enough bytes in the input buffer?  */
 401   if (MIN_NEEDED_INPUT > 1
 402       && __builtin_expect (inptr + (MIN_NEEDED_INPUT - inlen) > inend, 0))
 403     {
 404       *inptrp = inend;
 405 #  ifdef STORE_REST
 406
 407       /* Building with -O3 GCC emits a `array subscript is above array
 408          bounds' warning.  GCC BZ #64739 has been opened for this.  */
 409       DIAG_PUSH_NEEDS_COMMENT;
 410       DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Warray-bounds");
 411       while (inptr < inend)
 412         bytebuf[inlen++] = *inptr++;
 413       DIAG_POP_NEEDS_COMMENT;
 414
 415       inptr = bytebuf;
 416       inptrp = &inptr;
 417       inend = &bytebuf[inlen];
 418
 419       STORE_REST
 420 #  else
 421       /* We don't have enough input for another complete input
 422          character.  */
 423       size_t inlen_after = inlen + (inend - inptr);
 424       assert (inlen_after <= sizeof (state->__value.__wchb));
 425       for (; inlen < inlen_after; inlen++)
 426         state->__value.__wchb[inlen] = *inptr++;
 427 #  endif
 428
 429       return __GCONV_INCOMPLETE_INPUT;
 430     }
 431
 432   /* Enough space in output buffer.  */
 433   if ((MIN_NEEDED_OUTPUT != 1 && outptr + MIN_NEEDED_OUTPUT > outend)
 434       || (MIN_NEEDED_OUTPUT == 1 && outptr >= outend))
 435     /* Overflow in the output buffer.  */
 436     return __GCONV_FULL_OUTPUT;
 437
 438   /*  Now add characters from the normal input buffer.  */
 439   do
 440     bytebuf[inlen++] = *inptr++;
 441   while (inlen < MAX_NEEDED_INPUT && inptr < inend);
 442
 443   inptr = bytebuf;
 444   inend = &bytebuf[inlen];
 445
 446   do
 447     {
 448       BODY
 449     }
 450   while (0);
 451
 452   /* Now we either have produced an output character and consumed all the
 453      bytes from the state and at least one more, or the character is still
 454      incomplete, or we have some other error (like illegal input character,
 455      no space in output buffer).  */
 456   if (__glibc_likely (inptr != bytebuf))
 457     {
 458       /* We found a new character.  */
 459       assert (inptr - bytebuf > (state->__count & 7));
 460
 461       *inptrp += inptr - bytebuf - (state->__count & 7);
 462       *outptrp = outptr;
 463
 464       result = __GCONV_OK;
 465
 466       /* Clear the state buffer.  */
 467 #  ifdef CLEAR_STATE
 468       CLEAR_STATE;
 469 #  else
 470       state->__count &= ~7;
 471 #  endif
 472     }
 473   else if (result == __GCONV_INCOMPLETE_INPUT)
 474     {
 475       /* This can only happen if we have less than MAX_NEEDED_INPUT bytes
 476          available.  */
 477       assert (inend != &bytebuf[MAX_NEEDED_INPUT]);
 478
 479       *inptrp += inend - bytebuf - (state->__count & 7);
 480 #  ifdef STORE_REST
 481       inptrp = &inptr;
 482
 483       STORE_REST
 484 #  else
 485       /* We don't have enough input for another complete input
 486          character.  */
 487       assert (inend - inptr > (state->__count & ~7));
 488       assert (inend - inptr <= sizeof (state->__value.__wchb));
 489       state->__count = (state->__count & ~7) | (inend - inptr);
 490       for (inlen = 0; inlen < inend - inptr; inlen++)
 491         state->__value.__wchb[inlen] = inptr[inlen];
 492       inptr = inend;
 493 #  endif
 494     }
 495
 496   return result;
 497 }
 498 #  undef SINGLE
 499 #  undef SINGLE2
 500 # endif
 501
 502
 503 # ifdef ONEBYTE_BODY
 504 /* Define the shortcut function for btowc.  */
 505 static wint_t
 506 gconv_btowc (struct __gconv_step *step, unsigned char c)
 507   ONEBYTE_BODY
 508 #  define FROM_ONEBYTE gconv_btowc
 509 # endif
 510
 511 #endif
 512
 513 /* We remove the macro definitions so that we can include this file again
 514    for the definition of another function.  */
 515 #undef MIN_NEEDED_INPUT
 516 #undef MAX_NEEDED_INPUT
 517 #undef MIN_NEEDED_OUTPUT
 518 #undef MAX_NEEDED_OUTPUT
 519 #undef LOOPFCT
 520 #undef BODY
 521 #undef LOOPFCT
 522 #undef EXTRA_LOOP_DECLS
 523 #undef INIT_PARAMS
 524 #undef UPDATE_PARAMS
 525 #undef REINIT_PARAMS
 526 #undef ONEBYTE_BODY
 527 #undef UNPACK_BYTES
 528 #undef CLEAR_STATE
 529 #undef LOOP_NEED_STATE
 530 #undef LOOP_NEED_FLAGS
 531 #undef LOOP_NEED_DATA
 532 #undef get16
 533 #undef get32
 534 #undef put16
 535 #undef put32
 536 #undef unaligned