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/src/FreeImage/Source/LibJPEG/jdmarker.c

https://bitbucket.org/cabalistic/ogredeps/
C | 1406 lines | 888 code | 225 blank | 293 comment | 200 complexity | 85940e9cc3091b6026bf9996acbd1c30 MD5 | raw file
   1/*
   2 * jdmarker.c
   3 *
   4 * Copyright (C) 1991-1998, Thomas G. Lane.
   5 * Modified 2009 by Guido Vollbeding.
   6 * This file is part of the Independent JPEG Group's software.
   7 * For conditions of distribution and use, see the accompanying README file.
   8 *
   9 * This file contains routines to decode JPEG datastream markers.
  10 * Most of the complexity arises from our desire to support input
  11 * suspension: if not all of the data for a marker is available,
  12 * we must exit back to the application.  On resumption, we reprocess
  13 * the marker.
  14 */
  15
  16#define JPEG_INTERNALS
  17#include "jinclude.h"
  18#include "jpeglib.h"
  19
  20
  21typedef enum {			/* JPEG marker codes */
  22  M_SOF0  = 0xc0,
  23  M_SOF1  = 0xc1,
  24  M_SOF2  = 0xc2,
  25  M_SOF3  = 0xc3,
  26  
  27  M_SOF5  = 0xc5,
  28  M_SOF6  = 0xc6,
  29  M_SOF7  = 0xc7,
  30  
  31  M_JPG   = 0xc8,
  32  M_SOF9  = 0xc9,
  33  M_SOF10 = 0xca,
  34  M_SOF11 = 0xcb,
  35  
  36  M_SOF13 = 0xcd,
  37  M_SOF14 = 0xce,
  38  M_SOF15 = 0xcf,
  39  
  40  M_DHT   = 0xc4,
  41  
  42  M_DAC   = 0xcc,
  43  
  44  M_RST0  = 0xd0,
  45  M_RST1  = 0xd1,
  46  M_RST2  = 0xd2,
  47  M_RST3  = 0xd3,
  48  M_RST4  = 0xd4,
  49  M_RST5  = 0xd5,
  50  M_RST6  = 0xd6,
  51  M_RST7  = 0xd7,
  52  
  53  M_SOI   = 0xd8,
  54  M_EOI   = 0xd9,
  55  M_SOS   = 0xda,
  56  M_DQT   = 0xdb,
  57  M_DNL   = 0xdc,
  58  M_DRI   = 0xdd,
  59  M_DHP   = 0xde,
  60  M_EXP   = 0xdf,
  61  
  62  M_APP0  = 0xe0,
  63  M_APP1  = 0xe1,
  64  M_APP2  = 0xe2,
  65  M_APP3  = 0xe3,
  66  M_APP4  = 0xe4,
  67  M_APP5  = 0xe5,
  68  M_APP6  = 0xe6,
  69  M_APP7  = 0xe7,
  70  M_APP8  = 0xe8,
  71  M_APP9  = 0xe9,
  72  M_APP10 = 0xea,
  73  M_APP11 = 0xeb,
  74  M_APP12 = 0xec,
  75  M_APP13 = 0xed,
  76  M_APP14 = 0xee,
  77  M_APP15 = 0xef,
  78  
  79  M_JPG0  = 0xf0,
  80  M_JPG13 = 0xfd,
  81  M_COM   = 0xfe,
  82  
  83  M_TEM   = 0x01,
  84  
  85  M_ERROR = 0x100
  86} JPEG_MARKER;
  87
  88
  89/* Private state */
  90
  91typedef struct {
  92  struct jpeg_marker_reader pub; /* public fields */
  93
  94  /* Application-overridable marker processing methods */
  95  jpeg_marker_parser_method process_COM;
  96  jpeg_marker_parser_method process_APPn[16];
  97
  98  /* Limit on marker data length to save for each marker type */
  99  unsigned int length_limit_COM;
 100  unsigned int length_limit_APPn[16];
 101
 102  /* Status of COM/APPn marker saving */
 103  jpeg_saved_marker_ptr cur_marker;	/* NULL if not processing a marker */
 104  unsigned int bytes_read;		/* data bytes read so far in marker */
 105  /* Note: cur_marker is not linked into marker_list until it's all read. */
 106} my_marker_reader;
 107
 108typedef my_marker_reader * my_marker_ptr;
 109
 110
 111/*
 112 * Macros for fetching data from the data source module.
 113 *
 114 * At all times, cinfo->src->next_input_byte and ->bytes_in_buffer reflect
 115 * the current restart point; we update them only when we have reached a
 116 * suitable place to restart if a suspension occurs.
 117 */
 118
 119/* Declare and initialize local copies of input pointer/count */
 120#define INPUT_VARS(cinfo)  \
 121	struct jpeg_source_mgr * datasrc = (cinfo)->src;  \
 122	const JOCTET * next_input_byte = datasrc->next_input_byte;  \
 123	size_t bytes_in_buffer = datasrc->bytes_in_buffer
 124
 125/* Unload the local copies --- do this only at a restart boundary */
 126#define INPUT_SYNC(cinfo)  \
 127	( datasrc->next_input_byte = next_input_byte,  \
 128	  datasrc->bytes_in_buffer = bytes_in_buffer )
 129
 130/* Reload the local copies --- used only in MAKE_BYTE_AVAIL */
 131#define INPUT_RELOAD(cinfo)  \
 132	( next_input_byte = datasrc->next_input_byte,  \
 133	  bytes_in_buffer = datasrc->bytes_in_buffer )
 134
 135/* Internal macro for INPUT_BYTE and INPUT_2BYTES: make a byte available.
 136 * Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
 137 * but we must reload the local copies after a successful fill.
 138 */
 139#define MAKE_BYTE_AVAIL(cinfo,action)  \
 140	if (bytes_in_buffer == 0) {  \
 141	  if (! (*datasrc->fill_input_buffer) (cinfo))  \
 142	    { action; }  \
 143	  INPUT_RELOAD(cinfo);  \
 144	}
 145
 146/* Read a byte into variable V.
 147 * If must suspend, take the specified action (typically "return FALSE").
 148 */
 149#define INPUT_BYTE(cinfo,V,action)  \
 150	MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \
 151		  bytes_in_buffer--; \
 152		  V = GETJOCTET(*next_input_byte++); )
 153
 154/* As above, but read two bytes interpreted as an unsigned 16-bit integer.
 155 * V should be declared unsigned int or perhaps INT32.
 156 */
 157#define INPUT_2BYTES(cinfo,V,action)  \
 158	MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \
 159		  bytes_in_buffer--; \
 160		  V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \
 161		  MAKE_BYTE_AVAIL(cinfo,action); \
 162		  bytes_in_buffer--; \
 163		  V += GETJOCTET(*next_input_byte++); )
 164
 165
 166/*
 167 * Routines to process JPEG markers.
 168 *
 169 * Entry condition: JPEG marker itself has been read and its code saved
 170 *   in cinfo->unread_marker; input restart point is just after the marker.
 171 *
 172 * Exit: if return TRUE, have read and processed any parameters, and have
 173 *   updated the restart point to point after the parameters.
 174 *   If return FALSE, was forced to suspend before reaching end of
 175 *   marker parameters; restart point has not been moved.  Same routine
 176 *   will be called again after application supplies more input data.
 177 *
 178 * This approach to suspension assumes that all of a marker's parameters
 179 * can fit into a single input bufferload.  This should hold for "normal"
 180 * markers.  Some COM/APPn markers might have large parameter segments
 181 * that might not fit.  If we are simply dropping such a marker, we use
 182 * skip_input_data to get past it, and thereby put the problem on the
 183 * source manager's shoulders.  If we are saving the marker's contents
 184 * into memory, we use a slightly different convention: when forced to
 185 * suspend, the marker processor updates the restart point to the end of
 186 * what it's consumed (ie, the end of the buffer) before returning FALSE.
 187 * On resumption, cinfo->unread_marker still contains the marker code,
 188 * but the data source will point to the next chunk of marker data.
 189 * The marker processor must retain internal state to deal with this.
 190 *
 191 * Note that we don't bother to avoid duplicate trace messages if a
 192 * suspension occurs within marker parameters.  Other side effects
 193 * require more care.
 194 */
 195
 196
 197LOCAL(boolean)
 198get_soi (j_decompress_ptr cinfo)
 199/* Process an SOI marker */
 200{
 201  int i;
 202  
 203  TRACEMS(cinfo, 1, JTRC_SOI);
 204
 205  if (cinfo->marker->saw_SOI)
 206    ERREXIT(cinfo, JERR_SOI_DUPLICATE);
 207
 208  /* Reset all parameters that are defined to be reset by SOI */
 209
 210  for (i = 0; i < NUM_ARITH_TBLS; i++) {
 211    cinfo->arith_dc_L[i] = 0;
 212    cinfo->arith_dc_U[i] = 1;
 213    cinfo->arith_ac_K[i] = 5;
 214  }
 215  cinfo->restart_interval = 0;
 216
 217  /* Set initial assumptions for colorspace etc */
 218
 219  cinfo->jpeg_color_space = JCS_UNKNOWN;
 220  cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling??? */
 221
 222  cinfo->saw_JFIF_marker = FALSE;
 223  cinfo->JFIF_major_version = 1; /* set default JFIF APP0 values */
 224  cinfo->JFIF_minor_version = 1;
 225  cinfo->density_unit = 0;
 226  cinfo->X_density = 1;
 227  cinfo->Y_density = 1;
 228  cinfo->saw_Adobe_marker = FALSE;
 229  cinfo->Adobe_transform = 0;
 230
 231  cinfo->marker->saw_SOI = TRUE;
 232
 233  return TRUE;
 234}
 235
 236
 237LOCAL(boolean)
 238get_sof (j_decompress_ptr cinfo, boolean is_baseline, boolean is_prog,
 239	 boolean is_arith)
 240/* Process a SOFn marker */
 241{
 242  INT32 length;
 243  int c, ci;
 244  jpeg_component_info * compptr;
 245  INPUT_VARS(cinfo);
 246
 247  cinfo->is_baseline = is_baseline;
 248  cinfo->progressive_mode = is_prog;
 249  cinfo->arith_code = is_arith;
 250
 251  INPUT_2BYTES(cinfo, length, return FALSE);
 252
 253  INPUT_BYTE(cinfo, cinfo->data_precision, return FALSE);
 254  INPUT_2BYTES(cinfo, cinfo->image_height, return FALSE);
 255  INPUT_2BYTES(cinfo, cinfo->image_width, return FALSE);
 256  INPUT_BYTE(cinfo, cinfo->num_components, return FALSE);
 257
 258  length -= 8;
 259
 260  TRACEMS4(cinfo, 1, JTRC_SOF, cinfo->unread_marker,
 261	   (int) cinfo->image_width, (int) cinfo->image_height,
 262	   cinfo->num_components);
 263
 264  if (cinfo->marker->saw_SOF)
 265    ERREXIT(cinfo, JERR_SOF_DUPLICATE);
 266
 267  /* We don't support files in which the image height is initially specified */
 268  /* as 0 and is later redefined by DNL.  As long as we have to check that,  */
 269  /* might as well have a general sanity check. */
 270  if (cinfo->image_height <= 0 || cinfo->image_width <= 0
 271      || cinfo->num_components <= 0)
 272    ERREXIT(cinfo, JERR_EMPTY_IMAGE);
 273
 274  if (length != (cinfo->num_components * 3))
 275    ERREXIT(cinfo, JERR_BAD_LENGTH);
 276
 277  if (cinfo->comp_info == NULL)	/* do only once, even if suspend */
 278    cinfo->comp_info = (jpeg_component_info *) (*cinfo->mem->alloc_small)
 279			((j_common_ptr) cinfo, JPOOL_IMAGE,
 280			 cinfo->num_components * SIZEOF(jpeg_component_info));
 281  
 282  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 283       ci++, compptr++) {
 284    compptr->component_index = ci;
 285    INPUT_BYTE(cinfo, compptr->component_id, return FALSE);
 286    INPUT_BYTE(cinfo, c, return FALSE);
 287    compptr->h_samp_factor = (c >> 4) & 15;
 288    compptr->v_samp_factor = (c     ) & 15;
 289    INPUT_BYTE(cinfo, compptr->quant_tbl_no, return FALSE);
 290
 291    TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT,
 292	     compptr->component_id, compptr->h_samp_factor,
 293	     compptr->v_samp_factor, compptr->quant_tbl_no);
 294  }
 295
 296  cinfo->marker->saw_SOF = TRUE;
 297
 298  INPUT_SYNC(cinfo);
 299  return TRUE;
 300}
 301
 302
 303LOCAL(boolean)
 304get_sos (j_decompress_ptr cinfo)
 305/* Process a SOS marker */
 306{
 307  INT32 length;
 308  int i, ci, n, c, cc;
 309  jpeg_component_info * compptr;
 310  INPUT_VARS(cinfo);
 311
 312  if (! cinfo->marker->saw_SOF)
 313    ERREXIT(cinfo, JERR_SOS_NO_SOF);
 314
 315  INPUT_2BYTES(cinfo, length, return FALSE);
 316
 317  INPUT_BYTE(cinfo, n, return FALSE); /* Number of components */
 318
 319  TRACEMS1(cinfo, 1, JTRC_SOS, n);
 320
 321  if (length != (n * 2 + 6) || n > MAX_COMPS_IN_SCAN ||
 322      (n == 0 && !cinfo->progressive_mode))
 323      /* pseudo SOS marker only allowed in progressive mode */
 324    ERREXIT(cinfo, JERR_BAD_LENGTH);
 325
 326  cinfo->comps_in_scan = n;
 327
 328  /* Collect the component-spec parameters */
 329
 330  for (i = 0; i < n; i++) {
 331    INPUT_BYTE(cinfo, cc, return FALSE);
 332    INPUT_BYTE(cinfo, c, return FALSE);
 333    
 334    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 335	 ci++, compptr++) {
 336      if (cc == compptr->component_id)
 337	goto id_found;
 338    }
 339
 340    ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, cc);
 341
 342  id_found:
 343
 344    cinfo->cur_comp_info[i] = compptr;
 345    compptr->dc_tbl_no = (c >> 4) & 15;
 346    compptr->ac_tbl_no = (c     ) & 15;
 347    
 348    TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, cc,
 349	     compptr->dc_tbl_no, compptr->ac_tbl_no);
 350  }
 351
 352  /* Collect the additional scan parameters Ss, Se, Ah/Al. */
 353  INPUT_BYTE(cinfo, c, return FALSE);
 354  cinfo->Ss = c;
 355  INPUT_BYTE(cinfo, c, return FALSE);
 356  cinfo->Se = c;
 357  INPUT_BYTE(cinfo, c, return FALSE);
 358  cinfo->Ah = (c >> 4) & 15;
 359  cinfo->Al = (c     ) & 15;
 360
 361  TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo->Ss, cinfo->Se,
 362	   cinfo->Ah, cinfo->Al);
 363
 364  /* Prepare to scan data & restart markers */
 365  cinfo->marker->next_restart_num = 0;
 366
 367  /* Count another (non-pseudo) SOS marker */
 368  if (n) cinfo->input_scan_number++;
 369
 370  INPUT_SYNC(cinfo);
 371  return TRUE;
 372}
 373
 374
 375#ifdef D_ARITH_CODING_SUPPORTED
 376
 377LOCAL(boolean)
 378get_dac (j_decompress_ptr cinfo)
 379/* Process a DAC marker */
 380{
 381  INT32 length;
 382  int index, val;
 383  INPUT_VARS(cinfo);
 384
 385  INPUT_2BYTES(cinfo, length, return FALSE);
 386  length -= 2;
 387  
 388  while (length > 0) {
 389    INPUT_BYTE(cinfo, index, return FALSE);
 390    INPUT_BYTE(cinfo, val, return FALSE);
 391
 392    length -= 2;
 393
 394    TRACEMS2(cinfo, 1, JTRC_DAC, index, val);
 395
 396    if (index < 0 || index >= (2*NUM_ARITH_TBLS))
 397      ERREXIT1(cinfo, JERR_DAC_INDEX, index);
 398
 399    if (index >= NUM_ARITH_TBLS) { /* define AC table */
 400      cinfo->arith_ac_K[index-NUM_ARITH_TBLS] = (UINT8) val;
 401    } else {			/* define DC table */
 402      cinfo->arith_dc_L[index] = (UINT8) (val & 0x0F);
 403      cinfo->arith_dc_U[index] = (UINT8) (val >> 4);
 404      if (cinfo->arith_dc_L[index] > cinfo->arith_dc_U[index])
 405	ERREXIT1(cinfo, JERR_DAC_VALUE, val);
 406    }
 407  }
 408
 409  if (length != 0)
 410    ERREXIT(cinfo, JERR_BAD_LENGTH);
 411
 412  INPUT_SYNC(cinfo);
 413  return TRUE;
 414}
 415
 416#else /* ! D_ARITH_CODING_SUPPORTED */
 417
 418#define get_dac(cinfo)  skip_variable(cinfo)
 419
 420#endif /* D_ARITH_CODING_SUPPORTED */
 421
 422
 423LOCAL(boolean)
 424get_dht (j_decompress_ptr cinfo)
 425/* Process a DHT marker */
 426{
 427  INT32 length;
 428  UINT8 bits[17];
 429  UINT8 huffval[256];
 430  int i, index, count;
 431  JHUFF_TBL **htblptr;
 432  INPUT_VARS(cinfo);
 433
 434  INPUT_2BYTES(cinfo, length, return FALSE);
 435  length -= 2;
 436  
 437  while (length > 16) {
 438    INPUT_BYTE(cinfo, index, return FALSE);
 439
 440    TRACEMS1(cinfo, 1, JTRC_DHT, index);
 441      
 442    bits[0] = 0;
 443    count = 0;
 444    for (i = 1; i <= 16; i++) {
 445      INPUT_BYTE(cinfo, bits[i], return FALSE);
 446      count += bits[i];
 447    }
 448
 449    length -= 1 + 16;
 450
 451    TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
 452	     bits[1], bits[2], bits[3], bits[4],
 453	     bits[5], bits[6], bits[7], bits[8]);
 454    TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
 455	     bits[9], bits[10], bits[11], bits[12],
 456	     bits[13], bits[14], bits[15], bits[16]);
 457
 458    /* Here we just do minimal validation of the counts to avoid walking
 459     * off the end of our table space.  jdhuff.c will check more carefully.
 460     */
 461    if (count > 256 || ((INT32) count) > length)
 462      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
 463
 464    for (i = 0; i < count; i++)
 465      INPUT_BYTE(cinfo, huffval[i], return FALSE);
 466
 467    length -= count;
 468
 469    if (index & 0x10) {		/* AC table definition */
 470      index -= 0x10;
 471      htblptr = &cinfo->ac_huff_tbl_ptrs[index];
 472    } else {			/* DC table definition */
 473      htblptr = &cinfo->dc_huff_tbl_ptrs[index];
 474    }
 475
 476    if (index < 0 || index >= NUM_HUFF_TBLS)
 477      ERREXIT1(cinfo, JERR_DHT_INDEX, index);
 478
 479    if (*htblptr == NULL)
 480      *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
 481  
 482    MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));
 483    MEMCOPY((*htblptr)->huffval, huffval, SIZEOF((*htblptr)->huffval));
 484  }
 485
 486  if (length != 0)
 487    ERREXIT(cinfo, JERR_BAD_LENGTH);
 488
 489  INPUT_SYNC(cinfo);
 490  return TRUE;
 491}
 492
 493
 494LOCAL(boolean)
 495get_dqt (j_decompress_ptr cinfo)
 496/* Process a DQT marker */
 497{
 498  INT32 length, count, i;
 499  int n, prec;
 500  unsigned int tmp;
 501  JQUANT_TBL *quant_ptr;
 502  const int *natural_order;
 503  INPUT_VARS(cinfo);
 504
 505  INPUT_2BYTES(cinfo, length, return FALSE);
 506  length -= 2;
 507
 508  while (length > 0) {
 509    length--;
 510    INPUT_BYTE(cinfo, n, return FALSE);
 511    prec = n >> 4;
 512    n &= 0x0F;
 513
 514    TRACEMS2(cinfo, 1, JTRC_DQT, n, prec);
 515
 516    if (n >= NUM_QUANT_TBLS)
 517      ERREXIT1(cinfo, JERR_DQT_INDEX, n);
 518      
 519    if (cinfo->quant_tbl_ptrs[n] == NULL)
 520      cinfo->quant_tbl_ptrs[n] = jpeg_alloc_quant_table((j_common_ptr) cinfo);
 521    quant_ptr = cinfo->quant_tbl_ptrs[n];
 522
 523    if (prec) {
 524      if (length < DCTSIZE2 * 2) {
 525	/* Initialize full table for safety. */
 526	for (i = 0; i < DCTSIZE2; i++) {
 527	  quant_ptr->quantval[i] = 1;
 528	}
 529	count = length >> 1;
 530      } else
 531	count = DCTSIZE2;
 532    } else {
 533      if (length < DCTSIZE2) {
 534	/* Initialize full table for safety. */
 535	for (i = 0; i < DCTSIZE2; i++) {
 536	  quant_ptr->quantval[i] = 1;
 537	}
 538	count = length;
 539      } else
 540	count = DCTSIZE2;
 541    }
 542
 543    switch (count) {
 544    case (2*2): natural_order = jpeg_natural_order2; break;
 545    case (3*3): natural_order = jpeg_natural_order3; break;
 546    case (4*4): natural_order = jpeg_natural_order4; break;
 547    case (5*5): natural_order = jpeg_natural_order5; break;
 548    case (6*6): natural_order = jpeg_natural_order6; break;
 549    case (7*7): natural_order = jpeg_natural_order7; break;
 550    default:    natural_order = jpeg_natural_order;  break;
 551    }
 552
 553    for (i = 0; i < count; i++) {
 554      if (prec)
 555	INPUT_2BYTES(cinfo, tmp, return FALSE);
 556      else
 557	INPUT_BYTE(cinfo, tmp, return FALSE);
 558      /* We convert the zigzag-order table to natural array order. */
 559      quant_ptr->quantval[natural_order[i]] = (UINT16) tmp;
 560    }
 561
 562    if (cinfo->err->trace_level >= 2) {
 563      for (i = 0; i < DCTSIZE2; i += 8) {
 564	TRACEMS8(cinfo, 2, JTRC_QUANTVALS,
 565		 quant_ptr->quantval[i],   quant_ptr->quantval[i+1],
 566		 quant_ptr->quantval[i+2], quant_ptr->quantval[i+3],
 567		 quant_ptr->quantval[i+4], quant_ptr->quantval[i+5],
 568		 quant_ptr->quantval[i+6], quant_ptr->quantval[i+7]);
 569      }
 570    }
 571
 572    length -= count;
 573    if (prec) length -= count;
 574  }
 575
 576  if (length != 0)
 577    ERREXIT(cinfo, JERR_BAD_LENGTH);
 578
 579  INPUT_SYNC(cinfo);
 580  return TRUE;
 581}
 582
 583
 584LOCAL(boolean)
 585get_dri (j_decompress_ptr cinfo)
 586/* Process a DRI marker */
 587{
 588  INT32 length;
 589  unsigned int tmp;
 590  INPUT_VARS(cinfo);
 591
 592  INPUT_2BYTES(cinfo, length, return FALSE);
 593  
 594  if (length != 4)
 595    ERREXIT(cinfo, JERR_BAD_LENGTH);
 596
 597  INPUT_2BYTES(cinfo, tmp, return FALSE);
 598
 599  TRACEMS1(cinfo, 1, JTRC_DRI, tmp);
 600
 601  cinfo->restart_interval = tmp;
 602
 603  INPUT_SYNC(cinfo);
 604  return TRUE;
 605}
 606
 607
 608/*
 609 * Routines for processing APPn and COM markers.
 610 * These are either saved in memory or discarded, per application request.
 611 * APP0 and APP14 are specially checked to see if they are
 612 * JFIF and Adobe markers, respectively.
 613 */
 614
 615#define APP0_DATA_LEN	14	/* Length of interesting data in APP0 */
 616#define APP14_DATA_LEN	12	/* Length of interesting data in APP14 */
 617#define APPN_DATA_LEN	14	/* Must be the largest of the above!! */
 618
 619
 620LOCAL(void)
 621examine_app0 (j_decompress_ptr cinfo, JOCTET FAR * data,
 622	      unsigned int datalen, INT32 remaining)
 623/* Examine first few bytes from an APP0.
 624 * Take appropriate action if it is a JFIF marker.
 625 * datalen is # of bytes at data[], remaining is length of rest of marker data.
 626 */
 627{
 628  INT32 totallen = (INT32) datalen + remaining;
 629
 630  if (datalen >= APP0_DATA_LEN &&
 631      GETJOCTET(data[0]) == 0x4A &&
 632      GETJOCTET(data[1]) == 0x46 &&
 633      GETJOCTET(data[2]) == 0x49 &&
 634      GETJOCTET(data[3]) == 0x46 &&
 635      GETJOCTET(data[4]) == 0) {
 636    /* Found JFIF APP0 marker: save info */
 637    cinfo->saw_JFIF_marker = TRUE;
 638    cinfo->JFIF_major_version = GETJOCTET(data[5]);
 639    cinfo->JFIF_minor_version = GETJOCTET(data[6]);
 640    cinfo->density_unit = GETJOCTET(data[7]);
 641    cinfo->X_density = (GETJOCTET(data[8]) << 8) + GETJOCTET(data[9]);
 642    cinfo->Y_density = (GETJOCTET(data[10]) << 8) + GETJOCTET(data[11]);
 643    /* Check version.
 644     * Major version must be 1, anything else signals an incompatible change.
 645     * (We used to treat this as an error, but now it's a nonfatal warning,
 646     * because some bozo at Hijaak couldn't read the spec.)
 647     * Minor version should be 0..2, but process anyway if newer.
 648     */
 649    if (cinfo->JFIF_major_version != 1)
 650      WARNMS2(cinfo, JWRN_JFIF_MAJOR,
 651	      cinfo->JFIF_major_version, cinfo->JFIF_minor_version);
 652    /* Generate trace messages */
 653    TRACEMS5(cinfo, 1, JTRC_JFIF,
 654	     cinfo->JFIF_major_version, cinfo->JFIF_minor_version,
 655	     cinfo->X_density, cinfo->Y_density, cinfo->density_unit);
 656    /* Validate thumbnail dimensions and issue appropriate messages */
 657    if (GETJOCTET(data[12]) | GETJOCTET(data[13]))
 658      TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL,
 659	       GETJOCTET(data[12]), GETJOCTET(data[13]));
 660    totallen -= APP0_DATA_LEN;
 661    if (totallen !=
 662	((INT32)GETJOCTET(data[12]) * (INT32)GETJOCTET(data[13]) * (INT32) 3))
 663      TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) totallen);
 664  } else if (datalen >= 6 &&
 665      GETJOCTET(data[0]) == 0x4A &&
 666      GETJOCTET(data[1]) == 0x46 &&
 667      GETJOCTET(data[2]) == 0x58 &&
 668      GETJOCTET(data[3]) == 0x58 &&
 669      GETJOCTET(data[4]) == 0) {
 670    /* Found JFIF "JFXX" extension APP0 marker */
 671    /* The library doesn't actually do anything with these,
 672     * but we try to produce a helpful trace message.
 673     */
 674    switch (GETJOCTET(data[5])) {
 675    case 0x10:
 676      TRACEMS1(cinfo, 1, JTRC_THUMB_JPEG, (int) totallen);
 677      break;
 678    case 0x11:
 679      TRACEMS1(cinfo, 1, JTRC_THUMB_PALETTE, (int) totallen);
 680      break;
 681    case 0x13:
 682      TRACEMS1(cinfo, 1, JTRC_THUMB_RGB, (int) totallen);
 683      break;
 684    default:
 685      TRACEMS2(cinfo, 1, JTRC_JFIF_EXTENSION,
 686	       GETJOCTET(data[5]), (int) totallen);
 687      break;
 688    }
 689  } else {
 690    /* Start of APP0 does not match "JFIF" or "JFXX", or too short */
 691    TRACEMS1(cinfo, 1, JTRC_APP0, (int) totallen);
 692  }
 693}
 694
 695
 696LOCAL(void)
 697examine_app14 (j_decompress_ptr cinfo, JOCTET FAR * data,
 698	       unsigned int datalen, INT32 remaining)
 699/* Examine first few bytes from an APP14.
 700 * Take appropriate action if it is an Adobe marker.
 701 * datalen is # of bytes at data[], remaining is length of rest of marker data.
 702 */
 703{
 704  unsigned int version, flags0, flags1, transform;
 705
 706  if (datalen >= APP14_DATA_LEN &&
 707      GETJOCTET(data[0]) == 0x41 &&
 708      GETJOCTET(data[1]) == 0x64 &&
 709      GETJOCTET(data[2]) == 0x6F &&
 710      GETJOCTET(data[3]) == 0x62 &&
 711      GETJOCTET(data[4]) == 0x65) {
 712    /* Found Adobe APP14 marker */
 713    version = (GETJOCTET(data[5]) << 8) + GETJOCTET(data[6]);
 714    flags0 = (GETJOCTET(data[7]) << 8) + GETJOCTET(data[8]);
 715    flags1 = (GETJOCTET(data[9]) << 8) + GETJOCTET(data[10]);
 716    transform = GETJOCTET(data[11]);
 717    TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform);
 718    cinfo->saw_Adobe_marker = TRUE;
 719    cinfo->Adobe_transform = (UINT8) transform;
 720  } else {
 721    /* Start of APP14 does not match "Adobe", or too short */
 722    TRACEMS1(cinfo, 1, JTRC_APP14, (int) (datalen + remaining));
 723  }
 724}
 725
 726
 727METHODDEF(boolean)
 728get_interesting_appn (j_decompress_ptr cinfo)
 729/* Process an APP0 or APP14 marker without saving it */
 730{
 731  INT32 length;
 732  JOCTET b[APPN_DATA_LEN];
 733  unsigned int i, numtoread;
 734  INPUT_VARS(cinfo);
 735
 736  INPUT_2BYTES(cinfo, length, return FALSE);
 737  length -= 2;
 738
 739  /* get the interesting part of the marker data */
 740  if (length >= APPN_DATA_LEN)
 741    numtoread = APPN_DATA_LEN;
 742  else if (length > 0)
 743    numtoread = (unsigned int) length;
 744  else
 745    numtoread = 0;
 746  for (i = 0; i < numtoread; i++)
 747    INPUT_BYTE(cinfo, b[i], return FALSE);
 748  length -= numtoread;
 749
 750  /* process it */
 751  switch (cinfo->unread_marker) {
 752  case M_APP0:
 753    examine_app0(cinfo, (JOCTET FAR *) b, numtoread, length);
 754    break;
 755  case M_APP14:
 756    examine_app14(cinfo, (JOCTET FAR *) b, numtoread, length);
 757    break;
 758  default:
 759    /* can't get here unless jpeg_save_markers chooses wrong processor */
 760    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
 761    break;
 762  }
 763
 764  /* skip any remaining data -- could be lots */
 765  INPUT_SYNC(cinfo);
 766  if (length > 0)
 767    (*cinfo->src->skip_input_data) (cinfo, (long) length);
 768
 769  return TRUE;
 770}
 771
 772
 773#ifdef SAVE_MARKERS_SUPPORTED
 774
 775METHODDEF(boolean)
 776save_marker (j_decompress_ptr cinfo)
 777/* Save an APPn or COM marker into the marker list */
 778{
 779  my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
 780  jpeg_saved_marker_ptr cur_marker = marker->cur_marker;
 781  unsigned int bytes_read, data_length;
 782  JOCTET FAR * data;
 783  INT32 length = 0;
 784  INPUT_VARS(cinfo);
 785
 786  if (cur_marker == NULL) {
 787    /* begin reading a marker */
 788    INPUT_2BYTES(cinfo, length, return FALSE);
 789    length -= 2;
 790    if (length >= 0) {		/* watch out for bogus length word */
 791      /* figure out how much we want to save */
 792      unsigned int limit;
 793      if (cinfo->unread_marker == (int) M_COM)
 794	limit = marker->length_limit_COM;
 795      else
 796	limit = marker->length_limit_APPn[cinfo->unread_marker - (int) M_APP0];
 797      if ((unsigned int) length < limit)
 798	limit = (unsigned int) length;
 799      /* allocate and initialize the marker item */
 800      cur_marker = (jpeg_saved_marker_ptr)
 801	(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 802				    SIZEOF(struct jpeg_marker_struct) + limit);
 803      cur_marker->next = NULL;
 804      cur_marker->marker = (UINT8) cinfo->unread_marker;
 805      cur_marker->original_length = (unsigned int) length;
 806      cur_marker->data_length = limit;
 807      /* data area is just beyond the jpeg_marker_struct */
 808      data = cur_marker->data = (JOCTET FAR *) (cur_marker + 1);
 809      marker->cur_marker = cur_marker;
 810      marker->bytes_read = 0;
 811      bytes_read = 0;
 812      data_length = limit;
 813    } else {
 814      /* deal with bogus length word */
 815      bytes_read = data_length = 0;
 816      data = NULL;
 817    }
 818  } else {
 819    /* resume reading a marker */
 820    bytes_read = marker->bytes_read;
 821    data_length = cur_marker->data_length;
 822    data = cur_marker->data + bytes_read;
 823  }
 824
 825  while (bytes_read < data_length) {
 826    INPUT_SYNC(cinfo);		/* move the restart point to here */
 827    marker->bytes_read = bytes_read;
 828    /* If there's not at least one byte in buffer, suspend */
 829    MAKE_BYTE_AVAIL(cinfo, return FALSE);
 830    /* Copy bytes with reasonable rapidity */
 831    while (bytes_read < data_length && bytes_in_buffer > 0) {
 832      *data++ = *next_input_byte++;
 833      bytes_in_buffer--;
 834      bytes_read++;
 835    }
 836  }
 837
 838  /* Done reading what we want to read */
 839  if (cur_marker != NULL) {	/* will be NULL if bogus length word */
 840    /* Add new marker to end of list */
 841    if (cinfo->marker_list == NULL) {
 842      cinfo->marker_list = cur_marker;
 843    } else {
 844      jpeg_saved_marker_ptr prev = cinfo->marker_list;
 845      while (prev->next != NULL)
 846	prev = prev->next;
 847      prev->next = cur_marker;
 848    }
 849    /* Reset pointer & calc remaining data length */
 850    data = cur_marker->data;
 851    length = cur_marker->original_length - data_length;
 852  }
 853  /* Reset to initial state for next marker */
 854  marker->cur_marker = NULL;
 855
 856  /* Process the marker if interesting; else just make a generic trace msg */
 857  switch (cinfo->unread_marker) {
 858  case M_APP0:
 859    examine_app0(cinfo, data, data_length, length);
 860    break;
 861  case M_APP14:
 862    examine_app14(cinfo, data, data_length, length);
 863    break;
 864  default:
 865    TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker,
 866	     (int) (data_length + length));
 867    break;
 868  }
 869
 870  /* skip any remaining data -- could be lots */
 871  INPUT_SYNC(cinfo);		/* do before skip_input_data */
 872  if (length > 0)
 873    (*cinfo->src->skip_input_data) (cinfo, (long) length);
 874
 875  return TRUE;
 876}
 877
 878#endif /* SAVE_MARKERS_SUPPORTED */
 879
 880
 881METHODDEF(boolean)
 882skip_variable (j_decompress_ptr cinfo)
 883/* Skip over an unknown or uninteresting variable-length marker */
 884{
 885  INT32 length;
 886  INPUT_VARS(cinfo);
 887
 888  INPUT_2BYTES(cinfo, length, return FALSE);
 889  length -= 2;
 890  
 891  TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length);
 892
 893  INPUT_SYNC(cinfo);		/* do before skip_input_data */
 894  if (length > 0)
 895    (*cinfo->src->skip_input_data) (cinfo, (long) length);
 896
 897  return TRUE;
 898}
 899
 900
 901/*
 902 * Find the next JPEG marker, save it in cinfo->unread_marker.
 903 * Returns FALSE if had to suspend before reaching a marker;
 904 * in that case cinfo->unread_marker is unchanged.
 905 *
 906 * Note that the result might not be a valid marker code,
 907 * but it will never be 0 or FF.
 908 */
 909
 910LOCAL(boolean)
 911next_marker (j_decompress_ptr cinfo)
 912{
 913  int c;
 914  INPUT_VARS(cinfo);
 915
 916  for (;;) {
 917    INPUT_BYTE(cinfo, c, return FALSE);
 918    /* Skip any non-FF bytes.
 919     * This may look a bit inefficient, but it will not occur in a valid file.
 920     * We sync after each discarded byte so that a suspending data source
 921     * can discard the byte from its buffer.
 922     */
 923    while (c != 0xFF) {
 924      cinfo->marker->discarded_bytes++;
 925      INPUT_SYNC(cinfo);
 926      INPUT_BYTE(cinfo, c, return FALSE);
 927    }
 928    /* This loop swallows any duplicate FF bytes.  Extra FFs are legal as
 929     * pad bytes, so don't count them in discarded_bytes.  We assume there
 930     * will not be so many consecutive FF bytes as to overflow a suspending
 931     * data source's input buffer.
 932     */
 933    do {
 934      INPUT_BYTE(cinfo, c, return FALSE);
 935    } while (c == 0xFF);
 936    if (c != 0)
 937      break;			/* found a valid marker, exit loop */
 938    /* Reach here if we found a stuffed-zero data sequence (FF/00).
 939     * Discard it and loop back to try again.
 940     */
 941    cinfo->marker->discarded_bytes += 2;
 942    INPUT_SYNC(cinfo);
 943  }
 944
 945  if (cinfo->marker->discarded_bytes != 0) {
 946    WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo->marker->discarded_bytes, c);
 947    cinfo->marker->discarded_bytes = 0;
 948  }
 949
 950  cinfo->unread_marker = c;
 951
 952  INPUT_SYNC(cinfo);
 953  return TRUE;
 954}
 955
 956
 957LOCAL(boolean)
 958first_marker (j_decompress_ptr cinfo)
 959/* Like next_marker, but used to obtain the initial SOI marker. */
 960/* For this marker, we do not allow preceding garbage or fill; otherwise,
 961 * we might well scan an entire input file before realizing it ain't JPEG.
 962 * If an application wants to process non-JFIF files, it must seek to the
 963 * SOI before calling the JPEG library.
 964 */
 965{
 966  int c, c2;
 967  INPUT_VARS(cinfo);
 968
 969  INPUT_BYTE(cinfo, c, return FALSE);
 970  INPUT_BYTE(cinfo, c2, return FALSE);
 971  if (c != 0xFF || c2 != (int) M_SOI)
 972    ERREXIT2(cinfo, JERR_NO_SOI, c, c2);
 973
 974  cinfo->unread_marker = c2;
 975
 976  INPUT_SYNC(cinfo);
 977  return TRUE;
 978}
 979
 980
 981/*
 982 * Read markers until SOS or EOI.
 983 *
 984 * Returns same codes as are defined for jpeg_consume_input:
 985 * JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 986 *
 987 * Note: This function may return a pseudo SOS marker (with zero
 988 * component number) for treat by input controller's consume_input.
 989 * consume_input itself should filter out (skip) the pseudo marker
 990 * after processing for the caller.
 991 */
 992
 993METHODDEF(int)
 994read_markers (j_decompress_ptr cinfo)
 995{
 996  /* Outer loop repeats once for each marker. */
 997  for (;;) {
 998    /* Collect the marker proper, unless we already did. */
 999    /* NB: first_marker() enforces the requirement that SOI appear first. */
1000    if (cinfo->unread_marker == 0) {
1001      if (! cinfo->marker->saw_SOI) {
1002	if (! first_marker(cinfo))
1003	  return JPEG_SUSPENDED;
1004      } else {
1005	if (! next_marker(cinfo))
1006	  return JPEG_SUSPENDED;
1007      }
1008    }
1009    /* At this point cinfo->unread_marker contains the marker code and the
1010     * input point is just past the marker proper, but before any parameters.
1011     * A suspension will cause us to return with this state still true.
1012     */
1013    switch (cinfo->unread_marker) {
1014    case M_SOI:
1015      if (! get_soi(cinfo))
1016	return JPEG_SUSPENDED;
1017      break;
1018
1019    case M_SOF0:		/* Baseline */
1020      if (! get_sof(cinfo, TRUE, FALSE, FALSE))
1021	return JPEG_SUSPENDED;
1022      break;
1023
1024    case M_SOF1:		/* Extended sequential, Huffman */
1025      if (! get_sof(cinfo, FALSE, FALSE, FALSE))
1026	return JPEG_SUSPENDED;
1027      break;
1028
1029    case M_SOF2:		/* Progressive, Huffman */
1030      if (! get_sof(cinfo, FALSE, TRUE, FALSE))
1031	return JPEG_SUSPENDED;
1032      break;
1033
1034    case M_SOF9:		/* Extended sequential, arithmetic */
1035      if (! get_sof(cinfo, FALSE, FALSE, TRUE))
1036	return JPEG_SUSPENDED;
1037      break;
1038
1039    case M_SOF10:		/* Progressive, arithmetic */
1040      if (! get_sof(cinfo, FALSE, TRUE, TRUE))
1041	return JPEG_SUSPENDED;
1042      break;
1043
1044    /* Currently unsupported SOFn types */
1045    case M_SOF3:		/* Lossless, Huffman */
1046    case M_SOF5:		/* Differential sequential, Huffman */
1047    case M_SOF6:		/* Differential progressive, Huffman */
1048    case M_SOF7:		/* Differential lossless, Huffman */
1049    case M_JPG:			/* Reserved for JPEG extensions */
1050    case M_SOF11:		/* Lossless, arithmetic */
1051    case M_SOF13:		/* Differential sequential, arithmetic */
1052    case M_SOF14:		/* Differential progressive, arithmetic */
1053    case M_SOF15:		/* Differential lossless, arithmetic */
1054      ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo->unread_marker);
1055      break;
1056
1057    case M_SOS:
1058      if (! get_sos(cinfo))
1059	return JPEG_SUSPENDED;
1060      cinfo->unread_marker = 0;	/* processed the marker */
1061      return JPEG_REACHED_SOS;
1062    
1063    case M_EOI:
1064      TRACEMS(cinfo, 1, JTRC_EOI);
1065      cinfo->unread_marker = 0;	/* processed the marker */
1066      return JPEG_REACHED_EOI;
1067      
1068    case M_DAC:
1069      if (! get_dac(cinfo))
1070	return JPEG_SUSPENDED;
1071      break;
1072      
1073    case M_DHT:
1074      if (! get_dht(cinfo))
1075	return JPEG_SUSPENDED;
1076      break;
1077      
1078    case M_DQT:
1079      if (! get_dqt(cinfo))
1080	return JPEG_SUSPENDED;
1081      break;
1082      
1083    case M_DRI:
1084      if (! get_dri(cinfo))
1085	return JPEG_SUSPENDED;
1086      break;
1087      
1088    case M_APP0:
1089    case M_APP1:
1090    case M_APP2:
1091    case M_APP3:
1092    case M_APP4:
1093    case M_APP5:
1094    case M_APP6:
1095    case M_APP7:
1096    case M_APP8:
1097    case M_APP9:
1098    case M_APP10:
1099    case M_APP11:
1100    case M_APP12:
1101    case M_APP13:
1102    case M_APP14:
1103    case M_APP15:
1104      if (! (*((my_marker_ptr) cinfo->marker)->process_APPn[
1105		cinfo->unread_marker - (int) M_APP0]) (cinfo))
1106	return JPEG_SUSPENDED;
1107      break;
1108      
1109    case M_COM:
1110      if (! (*((my_marker_ptr) cinfo->marker)->process_COM) (cinfo))
1111	return JPEG_SUSPENDED;
1112      break;
1113
1114    case M_RST0:		/* these are all parameterless */
1115    case M_RST1:
1116    case M_RST2:
1117    case M_RST3:
1118    case M_RST4:
1119    case M_RST5:
1120    case M_RST6:
1121    case M_RST7:
1122    case M_TEM:
1123      TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo->unread_marker);
1124      break;
1125
1126    case M_DNL:			/* Ignore DNL ... perhaps the wrong thing */
1127      if (! skip_variable(cinfo))
1128	return JPEG_SUSPENDED;
1129      break;
1130
1131    default:			/* must be DHP, EXP, JPGn, or RESn */
1132      /* For now, we treat the reserved markers as fatal errors since they are
1133       * likely to be used to signal incompatible JPEG Part 3 extensions.
1134       * Once the JPEG 3 version-number marker is well defined, this code
1135       * ought to change!
1136       */
1137      ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
1138      break;
1139    }
1140    /* Successfully processed marker, so reset state variable */
1141    cinfo->unread_marker = 0;
1142  } /* end loop */
1143}
1144
1145
1146/*
1147 * Read a restart marker, which is expected to appear next in the datastream;
1148 * if the marker is not there, take appropriate recovery action.
1149 * Returns FALSE if suspension is required.
1150 *
1151 * This is called by the entropy decoder after it has read an appropriate
1152 * number of MCUs.  cinfo->unread_marker may be nonzero if the entropy decoder
1153 * has already read a marker from the data source.  Under normal conditions
1154 * cinfo->unread_marker will be reset to 0 before returning; if not reset,
1155 * it holds a marker which the decoder will be unable to read past.
1156 */
1157
1158METHODDEF(boolean)
1159read_restart_marker (j_decompress_ptr cinfo)
1160{
1161  /* Obtain a marker unless we already did. */
1162  /* Note that next_marker will complain if it skips any data. */
1163  if (cinfo->unread_marker == 0) {
1164    if (! next_marker(cinfo))
1165      return FALSE;
1166  }
1167
1168  if (cinfo->unread_marker ==
1169      ((int) M_RST0 + cinfo->marker->next_restart_num)) {
1170    /* Normal case --- swallow the marker and let entropy decoder continue */
1171    TRACEMS1(cinfo, 3, JTRC_RST, cinfo->marker->next_restart_num);
1172    cinfo->unread_marker = 0;
1173  } else {
1174    /* Uh-oh, the restart markers have been messed up. */
1175    /* Let the data source manager determine how to resync. */
1176    if (! (*cinfo->src->resync_to_restart) (cinfo,
1177					    cinfo->marker->next_restart_num))
1178      return FALSE;
1179  }
1180
1181  /* Update next-restart state */
1182  cinfo->marker->next_restart_num = (cinfo->marker->next_restart_num + 1) & 7;
1183
1184  return TRUE;
1185}
1186
1187
1188/*
1189 * This is the default resync_to_restart method for data source managers
1190 * to use if they don't have any better approach.  Some data source managers
1191 * may be able to back up, or may have additional knowledge about the data
1192 * which permits a more intelligent recovery strategy; such managers would
1193 * presumably supply their own resync method.
1194 *
1195 * read_restart_marker calls resync_to_restart if it finds a marker other than
1196 * the restart marker it was expecting.  (This code is *not* used unless
1197 * a nonzero restart interval has been declared.)  cinfo->unread_marker is
1198 * the marker code actually found (might be anything, except 0 or FF).
1199 * The desired restart marker number (0..7) is passed as a parameter.
1200 * This routine is supposed to apply whatever error recovery strategy seems
1201 * appropriate in order to position the input stream to the next data segment.
1202 * Note that cinfo->unread_marker is treated as a marker appearing before
1203 * the current data-source input point; usually it should be reset to zero
1204 * before returning.
1205 * Returns FALSE if suspension is required.
1206 *
1207 * This implementation is substantially constrained by wanting to treat the
1208 * input as a data stream; this means we can't back up.  Therefore, we have
1209 * only the following actions to work with:
1210 *   1. Simply discard the marker and let the entropy decoder resume at next
1211 *      byte of file.
1212 *   2. Read forward until we find another marker, discarding intervening
1213 *      data.  (In theory we could look ahead within the current bufferload,
1214 *      without having to discard data if we don't find the desired marker.
1215 *      This idea is not implemented here, in part because it makes behavior
1216 *      dependent on buffer size and chance buffer-boundary positions.)
1217 *   3. Leave the marker unread (by failing to zero cinfo->unread_marker).
1218 *      This will cause the entropy decoder to process an empty data segment,
1219 *      inserting dummy zeroes, and then we will reprocess the marker.
1220 *
1221 * #2 is appropriate if we think the desired marker lies ahead, while #3 is
1222 * appropriate if the found marker is a future restart marker (indicating
1223 * that we have missed the desired restart marker, probably because it got
1224 * corrupted).
1225 * We apply #2 or #3 if the found marker is a restart marker no more than
1226 * two counts behind or ahead of the expected one.  We also apply #2 if the
1227 * found marker is not a legal JPEG marker code (it's certainly bogus data).
1228 * If the found marker is a restart marker more than 2 counts away, we do #1
1229 * (too much risk that the marker is erroneous; with luck we will be able to
1230 * resync at some future point).
1231 * For any valid non-restart JPEG marker, we apply #3.  This keeps us from
1232 * overrunning the end of a scan.  An implementation limited to single-scan
1233 * files might find it better to apply #2 for markers other than EOI, since
1234 * any other marker would have to be bogus data in that case.
1235 */
1236
1237GLOBAL(boolean)
1238jpeg_resync_to_restart (j_decompress_ptr cinfo, int desired)
1239{
1240  int marker = cinfo->unread_marker;
1241  int action = 1;
1242  
1243  /* Always put up a warning. */
1244  WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired);
1245  
1246  /* Outer loop handles repeated decision after scanning forward. */
1247  for (;;) {
1248    if (marker < (int) M_SOF0)
1249      action = 2;		/* invalid marker */
1250    else if (marker < (int) M_RST0 || marker > (int) M_RST7)
1251      action = 3;		/* valid non-restart marker */
1252    else {
1253      if (marker == ((int) M_RST0 + ((desired+1) & 7)) ||
1254	  marker == ((int) M_RST0 + ((desired+2) & 7)))
1255	action = 3;		/* one of the next two expected restarts */
1256      else if (marker == ((int) M_RST0 + ((desired-1) & 7)) ||
1257	       marker == ((int) M_RST0 + ((desired-2) & 7)))
1258	action = 2;		/* a prior restart, so advance */
1259      else
1260	action = 1;		/* desired restart or too far away */
1261    }
1262    TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action);
1263    switch (action) {
1264    case 1:
1265      /* Discard marker and let entropy decoder resume processing. */
1266      cinfo->unread_marker = 0;
1267      return TRUE;
1268    case 2:
1269      /* Scan to the next marker, and repeat the decision loop. */
1270      if (! next_marker(cinfo))
1271	return FALSE;
1272      marker = cinfo->unread_marker;
1273      break;
1274    case 3:
1275      /* Return without advancing past this marker. */
1276      /* Entropy decoder will be forced to process an empty segment. */
1277      return TRUE;
1278    }
1279  } /* end loop */
1280}
1281
1282
1283/*
1284 * Reset marker processing state to begin a fresh datastream.
1285 */
1286
1287METHODDEF(void)
1288reset_marker_reader (j_decompress_ptr cinfo)
1289{
1290  my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1291
1292  cinfo->comp_info = NULL;		/* until allocated by get_sof */
1293  cinfo->input_scan_number = 0;		/* no SOS seen yet */
1294  cinfo->unread_marker = 0;		/* no pending marker */
1295  marker->pub.saw_SOI = FALSE;		/* set internal state too */
1296  marker->pub.saw_SOF = FALSE;
1297  marker->pub.discarded_bytes = 0;
1298  marker->cur_marker = NULL;
1299}
1300
1301
1302/*
1303 * Initialize the marker reader module.
1304 * This is called only once, when the decompression object is created.
1305 */
1306
1307GLOBAL(void)
1308jinit_marker_reader (j_decompress_ptr cinfo)
1309{
1310  my_marker_ptr marker;
1311  int i;
1312
1313  /* Create subobject in permanent pool */
1314  marker = (my_marker_ptr)
1315    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
1316				SIZEOF(my_marker_reader));
1317  cinfo->marker = (struct jpeg_marker_reader *) marker;
1318  /* Initialize public method pointers */
1319  marker->pub.reset_marker_reader = reset_marker_reader;
1320  marker->pub.read_markers = read_markers;
1321  marker->pub.read_restart_marker = read_restart_marker;
1322  /* Initialize COM/APPn processing.
1323   * By default, we examine and then discard APP0 and APP14,
1324   * but simply discard COM and all other APPn.
1325   */
1326  marker->process_COM = skip_variable;
1327  marker->length_limit_COM = 0;
1328  for (i = 0; i < 16; i++) {
1329    marker->process_APPn[i] = skip_variable;
1330    marker->length_limit_APPn[i] = 0;
1331  }
1332  marker->process_APPn[0] = get_interesting_appn;
1333  marker->process_APPn[14] = get_interesting_appn;
1334  /* Reset marker processing state */
1335  reset_marker_reader(cinfo);
1336}
1337
1338
1339/*
1340 * Control saving of COM and APPn markers into marker_list.
1341 */
1342
1343#ifdef SAVE_MARKERS_SUPPORTED
1344
1345GLOBAL(void)
1346jpeg_save_markers (j_decompress_ptr cinfo, int marker_code,
1347		   unsigned int length_limit)
1348{
1349  my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1350  long maxlength;
1351  jpeg_marker_parser_method processor;
1352
1353  /* Length limit mustn't be larger than what we can allocate
1354   * (should only be a concern in a 16-bit environment).
1355   */
1356  maxlength = cinfo->mem->max_alloc_chunk - SIZEOF(struct jpeg_marker_struct);
1357  if (((long) length_limit) > maxlength)
1358    length_limit = (unsigned int) maxlength;
1359
1360  /* Choose processor routine to use.
1361   * APP0/APP14 have special requirements.
1362   */
1363  if (length_limit) {
1364    processor = save_marker;
1365    /* If saving APP0/APP14, save at least enough for our internal use. */
1366    if (marker_code == (int) M_APP0 && length_limit < APP0_DATA_LEN)
1367      length_limit = APP0_DATA_LEN;
1368    else if (marker_code == (int) M_APP14 && length_limit < APP14_DATA_LEN)
1369      length_limit = APP14_DATA_LEN;
1370  } else {
1371    processor = skip_variable;
1372    /* If discarding APP0/APP14, use our regular on-the-fly processor. */
1373    if (marker_code == (int) M_APP0 || marker_code == (int) M_APP14)
1374      processor = get_interesting_appn;
1375  }
1376
1377  if (marker_code == (int) M_COM) {
1378    marker->process_COM = processor;
1379    marker->length_limit_COM = length_limit;
1380  } else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15) {
1381    marker->process_APPn[marker_code - (int) M_APP0] = processor;
1382    marker->length_limit_APPn[marker_code - (int) M_APP0] = length_limit;
1383  } else
1384    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
1385}
1386
1387#endif /* SAVE_MARKERS_SUPPORTED */
1388
1389
1390/*
1391 * Install a special processing method for COM or APPn markers.
1392 */
1393
1394GLOBAL(void)
1395jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
1396			   jpeg_marker_parser_method routine)
1397{
1398  my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1399
1400  if (marker_code == (int) M_COM)
1401    marker->process_COM = routine;
1402  else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15)
1403    marker->process_APPn[marker_code - (int) M_APP0] = routine;
1404  else
1405    ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
1406}