1 /*
   2  * jdmarker.c
   3  *
   4  * Copyright (C) 1991-1998, Thomas G. Lane.
   5  * Modified 2009-2013 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 
  21 typedef 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_JPG8  = 0xf8,
  81   M_JPG13 = 0xfd,
  82   M_COM   = 0xfe,
  83 
  84   M_TEM   = 0x01,
  85 
  86   M_ERROR = 0x100
  87 } JPEG_MARKER;
  88 
  89 
  90 /* Private state */
  91 
  92 typedef struct {
  93   struct jpeg_marker_reader pub; /* public fields */
  94 
  95   /* Application-overridable marker processing methods */
  96   jpeg_marker_parser_method process_COM;
  97   jpeg_marker_parser_method process_APPn[16];
  98 
  99   /* Limit on marker data length to save for each marker type */
 100   unsigned int length_limit_COM;
 101   unsigned int length_limit_APPn[16];
 102 
 103   /* Status of COM/APPn marker saving */
 104   jpeg_saved_marker_ptr cur_marker;     /* NULL if not processing a marker */
 105   unsigned int bytes_read;              /* data bytes read so far in marker */
 106   /* Note: cur_marker is not linked into marker_list until it's all read. */
 107 } my_marker_reader;
 108 
 109 typedef my_marker_reader * my_marker_ptr;
 110 
 111 
 112 /*
 113  * Macros for fetching data from the data source module.
 114  *
 115  * At all times, cinfo->src->next_input_byte and ->bytes_in_buffer reflect
 116  * the current restart point; we update them only when we have reached a
 117  * suitable place to restart if a suspension occurs.
 118  */
 119 
 120 /* Declare and initialize local copies of input pointer/count */
 121 #define INPUT_VARS(cinfo)  \
 122         struct jpeg_source_mgr * datasrc = (cinfo)->src;  \
 123         const JOCTET * next_input_byte = datasrc->next_input_byte;  \
 124         size_t bytes_in_buffer = datasrc->bytes_in_buffer
 125 
 126 /* Unload the local copies --- do this only at a restart boundary */
 127 #define INPUT_SYNC(cinfo)  \
 128         ( datasrc->next_input_byte = next_input_byte,  \
 129           datasrc->bytes_in_buffer = bytes_in_buffer )
 130 
 131 /* Reload the local copies --- used only in MAKE_BYTE_AVAIL */
 132 #define INPUT_RELOAD(cinfo)  \
 133         ( next_input_byte = datasrc->next_input_byte,  \
 134           bytes_in_buffer = datasrc->bytes_in_buffer )
 135 
 136 /* Internal macro for INPUT_BYTE and INPUT_2BYTES: make a byte available.
 137  * Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
 138  * but we must reload the local copies after a successful fill.
 139  */
 140 #define MAKE_BYTE_AVAIL(cinfo,action)  \
 141         if (bytes_in_buffer == 0) {  \
 142           if (! (*datasrc->fill_input_buffer) (cinfo))  \
 143             { action; }  \
 144           INPUT_RELOAD(cinfo);  \
 145         }
 146 
 147 /* Read a byte into variable V.
 148  * If must suspend, take the specified action (typically "return FALSE").
 149  */
 150 #define INPUT_BYTE(cinfo,V,action)  \
 151         MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \
 152                   bytes_in_buffer--; \
 153                   V = GETJOCTET(*next_input_byte++); )
 154 
 155 /* As above, but read two bytes interpreted as an unsigned 16-bit integer.
 156  * V should be declared unsigned int or perhaps INT32.
 157  */
 158 #define INPUT_2BYTES(cinfo,V,action)  \
 159         MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \
 160                   bytes_in_buffer--; \
 161                   V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \
 162                   MAKE_BYTE_AVAIL(cinfo,action); \
 163                   bytes_in_buffer--; \
 164                   V += GETJOCTET(*next_input_byte++); )
 165 
 166 
 167 /*
 168  * Routines to process JPEG markers.
 169  *
 170  * Entry condition: JPEG marker itself has been read and its code saved
 171  *   in cinfo->unread_marker; input restart point is just after the marker.
 172  *
 173  * Exit: if return TRUE, have read and processed any parameters, and have
 174  *   updated the restart point to point after the parameters.
 175  *   If return FALSE, was forced to suspend before reaching end of
 176  *   marker parameters; restart point has not been moved.  Same routine
 177  *   will be called again after application supplies more input data.
 178  *
 179  * This approach to suspension assumes that all of a marker's parameters
 180  * can fit into a single input bufferload.  This should hold for "normal"
 181  * markers.  Some COM/APPn markers might have large parameter segments
 182  * that might not fit.  If we are simply dropping such a marker, we use
 183  * skip_input_data to get past it, and thereby put the problem on the
 184  * source manager's shoulders.  If we are saving the marker's contents
 185  * into memory, we use a slightly different convention: when forced to
 186  * suspend, the marker processor updates the restart point to the end of
 187  * what it's consumed (ie, the end of the buffer) before returning FALSE.
 188  * On resumption, cinfo->unread_marker still contains the marker code,
 189  * but the data source will point to the next chunk of marker data.
 190  * The marker processor must retain internal state to deal with this.
 191  *
 192  * Note that we don't bother to avoid duplicate trace messages if a
 193  * suspension occurs within marker parameters.  Other side effects
 194  * require more care.
 195  */
 196 
 197 
 198 LOCAL(boolean)
 199 get_soi (j_decompress_ptr cinfo)
 200 /* Process an SOI marker */
 201 {
 202   int i;
 203   
 204   TRACEMS(cinfo, 1, JTRC_SOI);
 205 
 206   if (cinfo->marker->saw_SOI)
 207     ERREXIT(cinfo, JERR_SOI_DUPLICATE);
 208 
 209   /* Reset all parameters that are defined to be reset by SOI */
 210 
 211   for (i = 0; i < NUM_ARITH_TBLS; i++) {
 212     cinfo->arith_dc_L[i] = 0;
 213     cinfo->arith_dc_U[i] = 1;
 214     cinfo->arith_ac_K[i] = 5;
 215   }
 216   cinfo->restart_interval = 0;
 217 
 218   /* Set initial assumptions for colorspace etc */
 219 
 220   cinfo->jpeg_color_space = JCS_UNKNOWN;
 221   cinfo->color_transform = JCT_NONE;
 222   cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling??? */
 223 
 224   cinfo->saw_JFIF_marker = FALSE;
 225   cinfo->JFIF_major_version = 1; /* set default JFIF APP0 values */
 226   cinfo->JFIF_minor_version = 1;
 227   cinfo->density_unit = 0;
 228   cinfo->X_density = 1;
 229   cinfo->Y_density = 1;
 230   cinfo->saw_Adobe_marker = FALSE;
 231   cinfo->Adobe_transform = 0;
 232 
 233   cinfo->marker->saw_SOI = TRUE;
 234 
 235   return TRUE;
 236 }
 237 
 238 
 239 LOCAL(boolean)
 240 get_sof (j_decompress_ptr cinfo, boolean is_baseline, boolean is_prog,
 241          boolean is_arith)
 242 /* Process a SOFn marker */
 243 {
 244   INT32 length;
 245   int c, ci, i;
 246   jpeg_component_info * compptr;
 247   INPUT_VARS(cinfo);
 248 
 249   cinfo->is_baseline = is_baseline;
 250   cinfo->progressive_mode = is_prog;
 251   cinfo->arith_code = is_arith;
 252 
 253   INPUT_2BYTES(cinfo, length, return FALSE);
 254 
 255   INPUT_BYTE(cinfo, cinfo->data_precision, return FALSE);
 256   INPUT_2BYTES(cinfo, cinfo->image_height, return FALSE);
 257   INPUT_2BYTES(cinfo, cinfo->image_width, return FALSE);
 258   INPUT_BYTE(cinfo, cinfo->num_components, return FALSE);
 259 
 260   length -= 8;
 261 
 262   TRACEMS4(cinfo, 1, JTRC_SOF, cinfo->unread_marker,
 263            (int) cinfo->image_width, (int) cinfo->image_height,
 264            cinfo->num_components);
 265 
 266   if (cinfo->marker->saw_SOF)
 267     ERREXIT(cinfo, JERR_SOF_DUPLICATE);
 268 
 269   /* We don't support files in which the image height is initially specified */
 270   /* as 0 and is later redefined by DNL.  As long as we have to check that,  */
 271   /* might as well have a general sanity check. */
 272   if (cinfo->image_height <= 0 || cinfo->image_width <= 0 ||
 273       cinfo->num_components <= 0)
 274     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
 275 
 276   if (length != (cinfo->num_components * 3))
 277     ERREXIT(cinfo, JERR_BAD_LENGTH);
 278 
 279   if (cinfo->comp_info == NULL)      /* do only once, even if suspend */
 280     cinfo->comp_info = (jpeg_component_info *) (*cinfo->mem->alloc_small)
 281                         ((j_common_ptr) cinfo, JPOOL_IMAGE,
 282                          cinfo->num_components * SIZEOF(jpeg_component_info));
 283 
 284   for (ci = 0; ci < cinfo->num_components; ci++) {
 285     INPUT_BYTE(cinfo, c, return FALSE);
 286     /* Check to see whether component id has already been seen   */
 287     /* (in violation of the spec, but unfortunately seen in some */
 288     /* files).  If so, create "fake" component id equal to the   */
 289     /* max id seen so far + 1. */
 290     for (i = 0, compptr = cinfo->comp_info; i < ci; i++, compptr++) {
 291       if (c == compptr->component_id) {
 292         compptr = cinfo->comp_info;
 293         c = compptr->component_id;
 294         compptr++;
 295         for (i = 1; i < ci; i++, compptr++) {
 296           if (compptr->component_id > c) c = compptr->component_id;
 297         }
 298         c++;
 299         break;
 300       }
 301     }
 302     compptr->component_id = c;
 303     compptr->component_index = ci;
 304     INPUT_BYTE(cinfo, c, return FALSE);
 305     compptr->h_samp_factor = (c >> 4) & 15;
 306     compptr->v_samp_factor = (c     ) & 15;
 307     INPUT_BYTE(cinfo, compptr->quant_tbl_no, return FALSE);
 308 
 309     TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT,
 310              compptr->component_id, compptr->h_samp_factor,
 311              compptr->v_samp_factor, compptr->quant_tbl_no);
 312   }
 313 
 314   cinfo->marker->saw_SOF = TRUE;
 315 
 316   INPUT_SYNC(cinfo);
 317   return TRUE;
 318 }
 319 
 320 
 321 LOCAL(boolean)
 322 get_sos (j_decompress_ptr cinfo)
 323 /* Process a SOS marker */
 324 {
 325   INT32 length;
 326   int c, ci, i, n;
 327   jpeg_component_info * compptr;
 328   INPUT_VARS(cinfo);
 329 
 330   if (! cinfo->marker->saw_SOF)
 331     ERREXITS(cinfo, JERR_SOF_BEFORE, "SOS");
 332 
 333   INPUT_2BYTES(cinfo, length, return FALSE);
 334 
 335   INPUT_BYTE(cinfo, n, return FALSE); /* Number of components */
 336 
 337   TRACEMS1(cinfo, 1, JTRC_SOS, n);
 338 
 339   if (length != (n * 2 + 6) || n > MAX_COMPS_IN_SCAN ||
 340       (n == 0 && !cinfo->progressive_mode))
 341       /* pseudo SOS marker only allowed in progressive mode */
 342     ERREXIT(cinfo, JERR_BAD_LENGTH);
 343 
 344   cinfo->comps_in_scan = n;
 345 
 346   /* Collect the component-spec parameters */
 347 
 348   for (i = 0; i < n; i++) {
 349     INPUT_BYTE(cinfo, c, return FALSE);
 350 
 351     /* Detect the case where component id's are not unique, and, if so, */
 352     /* create a fake component id using the same logic as in get_sof.   */
 353     /* Note:  This also ensures that all of the SOF components are      */
 354     /* referenced in the single scan case, which prevents access to     */
 355     /* uninitialized memory in later decoding stages. */
 356     for (ci = 0; ci < i; ci++) {
 357       if (c == cinfo->cur_comp_info[ci]->component_id) {
 358         c = cinfo->cur_comp_info[0]->component_id;
 359         for (ci = 1; ci < i; ci++) {
 360           compptr = cinfo->cur_comp_info[ci];
 361           if (compptr->component_id > c) c = compptr->component_id;
 362         }
 363         c++;
 364         break;
 365       }
 366     }
 367 
 368     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 369          ci++, compptr++) {
 370       if (c == compptr->component_id)
 371         goto id_found;
 372     }
 373 
 374     ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, c);
 375 
 376   id_found:
 377 
 378     cinfo->cur_comp_info[i] = compptr;
 379     INPUT_BYTE(cinfo, c, return FALSE);
 380     compptr->dc_tbl_no = (c >> 4) & 15;
 381     compptr->ac_tbl_no = (c     ) & 15;
 382 
 383     TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, compptr->component_id,
 384              compptr->dc_tbl_no, compptr->ac_tbl_no);
 385   }
 386 
 387   /* Collect the additional scan parameters Ss, Se, Ah/Al. */
 388   INPUT_BYTE(cinfo, c, return FALSE);
 389   cinfo->Ss = c;
 390   INPUT_BYTE(cinfo, c, return FALSE);
 391   cinfo->Se = c;
 392   INPUT_BYTE(cinfo, c, return FALSE);
 393   cinfo->Ah = (c >> 4) & 15;
 394   cinfo->Al = (c     ) & 15;
 395 
 396   TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo->Ss, cinfo->Se,
 397            cinfo->Ah, cinfo->Al);
 398 
 399   /* Prepare to scan data & restart markers */
 400   cinfo->marker->next_restart_num = 0;
 401 
 402   /* Count another (non-pseudo) SOS marker */
 403   if (n) cinfo->input_scan_number++;
 404 
 405   INPUT_SYNC(cinfo);
 406   return TRUE;
 407 }
 408 
 409 
 410 #ifdef D_ARITH_CODING_SUPPORTED
 411 
 412 LOCAL(boolean)
 413 get_dac (j_decompress_ptr cinfo)
 414 /* Process a DAC marker */
 415 {
 416   INT32 length;
 417   int index, val;
 418   INPUT_VARS(cinfo);
 419 
 420   INPUT_2BYTES(cinfo, length, return FALSE);
 421   length -= 2;
 422   
 423   while (length > 0) {
 424     INPUT_BYTE(cinfo, index, return FALSE);
 425     INPUT_BYTE(cinfo, val, return FALSE);
 426 
 427     length -= 2;
 428 
 429     TRACEMS2(cinfo, 1, JTRC_DAC, index, val);
 430 
 431     if (index < 0 || index >= (2*NUM_ARITH_TBLS))
 432       ERREXIT1(cinfo, JERR_DAC_INDEX, index);
 433 
 434     if (index >= NUM_ARITH_TBLS) { /* define AC table */
 435       cinfo->arith_ac_K[index-NUM_ARITH_TBLS] = (UINT8) val;
 436     } else {                    /* define DC table */
 437       cinfo->arith_dc_L[index] = (UINT8) (val & 0x0F);
 438       cinfo->arith_dc_U[index] = (UINT8) (val >> 4);
 439       if (cinfo->arith_dc_L[index] > cinfo->arith_dc_U[index])
 440         ERREXIT1(cinfo, JERR_DAC_VALUE, val);
 441     }
 442   }
 443 
 444   if (length != 0)
 445     ERREXIT(cinfo, JERR_BAD_LENGTH);
 446 
 447   INPUT_SYNC(cinfo);
 448   return TRUE;
 449 }
 450 
 451 #else /* ! D_ARITH_CODING_SUPPORTED */
 452 
 453 #define get_dac(cinfo)  skip_variable(cinfo)
 454 
 455 #endif /* D_ARITH_CODING_SUPPORTED */
 456 
 457 
 458 LOCAL(boolean)
 459 get_dht (j_decompress_ptr cinfo)
 460 /* Process a DHT marker */
 461 {
 462   INT32 length;
 463   UINT8 bits[17];
 464   UINT8 huffval[256];
 465   int i, index, count;
 466   JHUFF_TBL **htblptr;
 467   INPUT_VARS(cinfo);
 468 
 469   INPUT_2BYTES(cinfo, length, return FALSE);
 470   length -= 2;
 471   
 472   while (length > 16) {
 473     INPUT_BYTE(cinfo, index, return FALSE);
 474 
 475     TRACEMS1(cinfo, 1, JTRC_DHT, index);
 476       
 477     bits[0] = 0;
 478     count = 0;
 479     for (i = 1; i <= 16; i++) {
 480       INPUT_BYTE(cinfo, bits[i], return FALSE);
 481       count += bits[i];
 482     }
 483 
 484     length -= 1 + 16;
 485 
 486     TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
 487              bits[1], bits[2], bits[3], bits[4],
 488              bits[5], bits[6], bits[7], bits[8]);
 489     TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
 490              bits[9], bits[10], bits[11], bits[12],
 491              bits[13], bits[14], bits[15], bits[16]);
 492 
 493     /* Here we just do minimal validation of the counts to avoid walking
 494      * off the end of our table space.  jdhuff.c will check more carefully.
 495      */
 496     if (count > 256 || ((INT32) count) > length)
 497       ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
 498 
 499     MEMZERO(huffval, SIZEOF(huffval)); /* pre-zero array for later copy */
 500 
 501     for (i = 0; i < count; i++)
 502       INPUT_BYTE(cinfo, huffval[i], return FALSE);
 503 
 504     length -= count;
 505 
 506     if (index & 0x10) {             /* AC table definition */
 507       index -= 0x10;
 508       htblptr = &cinfo->ac_huff_tbl_ptrs[index];
 509     } else {                    /* DC table definition */
 510       htblptr = &cinfo->dc_huff_tbl_ptrs[index];
 511     }
 512 
 513     if (index < 0 || index >= NUM_HUFF_TBLS)
 514       ERREXIT1(cinfo, JERR_DHT_INDEX, index);
 515 
 516     if (*htblptr == NULL)
 517       *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
 518   
 519     MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));
 520     MEMCOPY((*htblptr)->huffval, huffval, SIZEOF((*htblptr)->huffval));
 521   }
 522 
 523   if (length != 0)
 524     ERREXIT(cinfo, JERR_BAD_LENGTH);
 525 
 526   INPUT_SYNC(cinfo);
 527   return TRUE;
 528 }
 529 
 530 
 531 LOCAL(boolean)
 532 get_dqt (j_decompress_ptr cinfo)
 533 /* Process a DQT marker */
 534 {
 535   INT32 length, count, i;
 536   int n, prec;
 537   unsigned int tmp;
 538   JQUANT_TBL *quant_ptr;
 539   const int *natural_order;
 540   INPUT_VARS(cinfo);
 541 
 542   INPUT_2BYTES(cinfo, length, return FALSE);
 543   length -= 2;
 544 
 545   while (length > 0) {
 546     length--;
 547     INPUT_BYTE(cinfo, n, return FALSE);
 548     prec = n >> 4;
 549     n &= 0x0F;
 550 
 551     TRACEMS2(cinfo, 1, JTRC_DQT, n, prec);
 552 
 553     if (n >= NUM_QUANT_TBLS)
 554       ERREXIT1(cinfo, JERR_DQT_INDEX, n);
 555       
 556     if (cinfo->quant_tbl_ptrs[n] == NULL)
 557       cinfo->quant_tbl_ptrs[n] = jpeg_alloc_quant_table((j_common_ptr) cinfo);
 558     quant_ptr = cinfo->quant_tbl_ptrs[n];
 559 
 560     if (prec) {
 561       if (length < DCTSIZE2 * 2) {
 562         /* Initialize full table for safety. */
 563         for (i = 0; i < DCTSIZE2; i++) {
 564           quant_ptr->quantval[i] = 1;
 565         }
 566         count = length >> 1;
 567       } else
 568         count = DCTSIZE2;
 569     } else {
 570       if (length < DCTSIZE2) {
 571         /* Initialize full table for safety. */
 572         for (i = 0; i < DCTSIZE2; i++) {
 573           quant_ptr->quantval[i] = 1;
 574         }
 575         count = length;
 576       } else
 577         count = DCTSIZE2;
 578     }
 579 
 580     switch (count) {
 581     case (2*2): natural_order = jpeg_natural_order2; break;
 582     case (3*3): natural_order = jpeg_natural_order3; break;
 583     case (4*4): natural_order = jpeg_natural_order4; break;
 584     case (5*5): natural_order = jpeg_natural_order5; break;
 585     case (6*6): natural_order = jpeg_natural_order6; break;
 586     case (7*7): natural_order = jpeg_natural_order7; break;
 587     default:    natural_order = jpeg_natural_order;  break;
 588     }
 589 
 590     for (i = 0; i < count; i++) {
 591       if (prec)
 592         INPUT_2BYTES(cinfo, tmp, return FALSE);
 593       else
 594         INPUT_BYTE(cinfo, tmp, return FALSE);
 595       /* We convert the zigzag-order table to natural array order. */
 596       quant_ptr->quantval[natural_order[i]] = (UINT16) tmp;
 597     }
 598 
 599     if (cinfo->err->trace_level >= 2) {
 600       for (i = 0; i < DCTSIZE2; i += 8) {
 601         TRACEMS8(cinfo, 2, JTRC_QUANTVALS,
 602                  quant_ptr->quantval[i],   quant_ptr->quantval[i+1],
 603                  quant_ptr->quantval[i+2], quant_ptr->quantval[i+3],
 604                  quant_ptr->quantval[i+4], quant_ptr->quantval[i+5],
 605                  quant_ptr->quantval[i+6], quant_ptr->quantval[i+7]);
 606       }
 607     }
 608 
 609     length -= count;
 610     if (prec) length -= count;
 611   }
 612 
 613   if (length != 0)
 614     ERREXIT(cinfo, JERR_BAD_LENGTH);
 615 
 616   INPUT_SYNC(cinfo);
 617   return TRUE;
 618 }
 619 
 620 
 621 LOCAL(boolean)
 622 get_dri (j_decompress_ptr cinfo)
 623 /* Process a DRI marker */
 624 {
 625   INT32 length;
 626   unsigned int tmp;
 627   INPUT_VARS(cinfo);
 628 
 629   INPUT_2BYTES(cinfo, length, return FALSE);
 630   
 631   if (length != 4)
 632     ERREXIT(cinfo, JERR_BAD_LENGTH);
 633 
 634   INPUT_2BYTES(cinfo, tmp, return FALSE);
 635 
 636   TRACEMS1(cinfo, 1, JTRC_DRI, tmp);
 637 
 638   cinfo->restart_interval = tmp;
 639 
 640   INPUT_SYNC(cinfo);
 641   return TRUE;
 642 }
 643 
 644 
 645 LOCAL(boolean)
 646 get_lse (j_decompress_ptr cinfo)
 647 /* Process an LSE marker */
 648 {
 649   INT32 length;
 650   unsigned int tmp;
 651   int cid;
 652   INPUT_VARS(cinfo);
 653 
 654   if (! cinfo->marker->saw_SOF)
 655     ERREXITS(cinfo, JERR_SOF_BEFORE, "LSE");
 656 
 657   if (cinfo->num_components < 3) goto bad;
 658 
 659   INPUT_2BYTES(cinfo, length, return FALSE);
 660 
 661   if (length != 24)
 662     ERREXIT(cinfo, JERR_BAD_LENGTH);
 663 
 664   INPUT_BYTE(cinfo, tmp, return FALSE);
 665   if (tmp != 0x0D)      /* ID inverse transform specification */
 666     ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
 667   INPUT_2BYTES(cinfo, tmp, return FALSE);
 668   if (tmp != MAXJSAMPLE) goto bad;              /* MAXTRANS */
 669   INPUT_BYTE(cinfo, tmp, return FALSE);
 670   if (tmp != 3) goto bad;                       /* Nt=3 */
 671   INPUT_BYTE(cinfo, cid, return FALSE);
 672   if (cid != cinfo->comp_info[1].component_id) goto bad;
 673   INPUT_BYTE(cinfo, cid, return FALSE);
 674   if (cid != cinfo->comp_info[0].component_id) goto bad;
 675   INPUT_BYTE(cinfo, cid, return FALSE);
 676   if (cid != cinfo->comp_info[2].component_id) goto bad;
 677   INPUT_BYTE(cinfo, tmp, return FALSE);
 678   if (tmp != 0x80) goto bad;            /* F1: CENTER1=1, NORM1=0 */
 679   INPUT_2BYTES(cinfo, tmp, return FALSE);
 680   if (tmp != 0) goto bad;                       /* A(1,1)=0 */
 681   INPUT_2BYTES(cinfo, tmp, return FALSE);
 682   if (tmp != 0) goto bad;                       /* A(1,2)=0 */
 683   INPUT_BYTE(cinfo, tmp, return FALSE);
 684   if (tmp != 0) goto bad;               /* F2: CENTER2=0, NORM2=0 */
 685   INPUT_2BYTES(cinfo, tmp, return FALSE);
 686   if (tmp != 1) goto bad;                       /* A(2,1)=1 */
 687   INPUT_2BYTES(cinfo, tmp, return FALSE);
 688   if (tmp != 0) goto bad;                       /* A(2,2)=0 */
 689   INPUT_BYTE(cinfo, tmp, return FALSE);
 690   if (tmp != 0) goto bad;               /* F3: CENTER3=0, NORM3=0 */
 691   INPUT_2BYTES(cinfo, tmp, return FALSE);
 692   if (tmp != 1) goto bad;                       /* A(3,1)=1 */
 693   INPUT_2BYTES(cinfo, tmp, return FALSE);
 694   if (tmp != 0) {                               /* A(3,2)=0 */
 695     bad:
 696     ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
 697   }
 698 
 699   /* OK, valid transform that we can handle. */
 700   cinfo->color_transform = JCT_SUBTRACT_GREEN;
 701 
 702   INPUT_SYNC(cinfo);
 703   return TRUE;
 704 }
 705 
 706 
 707 /*
 708  * Routines for processing APPn and COM markers.
 709  * These are either saved in memory or discarded, per application request.
 710  * APP0 and APP14 are specially checked to see if they are
 711  * JFIF and Adobe markers, respectively.
 712  */
 713 
 714 #define APP0_DATA_LEN   14      /* Length of interesting data in APP0 */
 715 #define APP14_DATA_LEN  12      /* Length of interesting data in APP14 */
 716 #define APPN_DATA_LEN   14      /* Must be the largest of the above!! */
 717 
 718 
 719 LOCAL(void)
 720 examine_app0 (j_decompress_ptr cinfo, JOCTET FAR * data,
 721               unsigned int datalen, INT32 remaining)
 722 /* Examine first few bytes from an APP0.
 723  * Take appropriate action if it is a JFIF marker.
 724  * datalen is # of bytes at data[], remaining is length of rest of marker data.
 725  */
 726 {
 727   INT32 totallen = (INT32) datalen + remaining;
 728 
 729   if (datalen >= APP0_DATA_LEN &&
 730       GETJOCTET(data[0]) == 0x4A &&
 731       GETJOCTET(data[1]) == 0x46 &&
 732       GETJOCTET(data[2]) == 0x49 &&
 733       GETJOCTET(data[3]) == 0x46 &&
 734       GETJOCTET(data[4]) == 0) {
 735     /* Found JFIF APP0 marker: save info */
 736     cinfo->saw_JFIF_marker = TRUE;
 737     cinfo->JFIF_major_version = GETJOCTET(data[5]);
 738     cinfo->JFIF_minor_version = GETJOCTET(data[6]);
 739     cinfo->density_unit = GETJOCTET(data[7]);
 740     cinfo->X_density = (GETJOCTET(data[8]) << 8) + GETJOCTET(data[9]);
 741     cinfo->Y_density = (GETJOCTET(data[10]) << 8) + GETJOCTET(data[11]);
 742     /* Check version.
 743      * Major version must be 1 or 2, anything else signals an incompatible
 744      * change.
 745      * (We used to treat this as an error, but now it's a nonfatal warning,
 746      * because some bozo at Hijaak couldn't read the spec.)
 747      * Minor version should be 0..2, but process anyway if newer.
 748      */
 749     if (cinfo->JFIF_major_version != 1 && cinfo->JFIF_major_version != 2)
 750       WARNMS2(cinfo, JWRN_JFIF_MAJOR,
 751               cinfo->JFIF_major_version, cinfo->JFIF_minor_version);
 752     /* Generate trace messages */
 753     TRACEMS5(cinfo, 1, JTRC_JFIF,
 754              cinfo->JFIF_major_version, cinfo->JFIF_minor_version,
 755              cinfo->X_density, cinfo->Y_density, cinfo->density_unit);
 756     /* Validate thumbnail dimensions and issue appropriate messages */
 757     if (GETJOCTET(data[12]) | GETJOCTET(data[13]))
 758       TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL,
 759                GETJOCTET(data[12]), GETJOCTET(data[13]));
 760     totallen -= APP0_DATA_LEN;
 761     if (totallen !=
 762         ((INT32)GETJOCTET(data[12]) * (INT32)GETJOCTET(data[13]) * (INT32) 3))
 763       TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) totallen);
 764   } else if (datalen >= 6 &&
 765       GETJOCTET(data[0]) == 0x4A &&
 766       GETJOCTET(data[1]) == 0x46 &&
 767       GETJOCTET(data[2]) == 0x58 &&
 768       GETJOCTET(data[3]) == 0x58 &&
 769       GETJOCTET(data[4]) == 0) {
 770     /* Found JFIF "JFXX" extension APP0 marker */
 771     /* The library doesn't actually do anything with these,
 772      * but we try to produce a helpful trace message.
 773      */
 774     switch (GETJOCTET(data[5])) {
 775     case 0x10:
 776       TRACEMS1(cinfo, 1, JTRC_THUMB_JPEG, (int) totallen);
 777       break;
 778     case 0x11:
 779       TRACEMS1(cinfo, 1, JTRC_THUMB_PALETTE, (int) totallen);
 780       break;
 781     case 0x13:
 782       TRACEMS1(cinfo, 1, JTRC_THUMB_RGB, (int) totallen);
 783       break;
 784     default:
 785       TRACEMS2(cinfo, 1, JTRC_JFIF_EXTENSION,
 786                GETJOCTET(data[5]), (int) totallen);
 787       break;
 788     }
 789   } else {
 790     /* Start of APP0 does not match "JFIF" or "JFXX", or too short */
 791     TRACEMS1(cinfo, 1, JTRC_APP0, (int) totallen);
 792   }
 793 }
 794 
 795 
 796 LOCAL(void)
 797 examine_app14 (j_decompress_ptr cinfo, JOCTET FAR * data,
 798                unsigned int datalen, INT32 remaining)
 799 /* Examine first few bytes from an APP14.
 800  * Take appropriate action if it is an Adobe marker.
 801  * datalen is # of bytes at data[], remaining is length of rest of marker data.
 802  */
 803 {
 804   unsigned int version, flags0, flags1, transform;
 805 
 806   if (datalen >= APP14_DATA_LEN &&
 807       GETJOCTET(data[0]) == 0x41 &&
 808       GETJOCTET(data[1]) == 0x64 &&
 809       GETJOCTET(data[2]) == 0x6F &&
 810       GETJOCTET(data[3]) == 0x62 &&
 811       GETJOCTET(data[4]) == 0x65) {
 812     /* Found Adobe APP14 marker */
 813     version = (GETJOCTET(data[5]) << 8) + GETJOCTET(data[6]);
 814     flags0 = (GETJOCTET(data[7]) << 8) + GETJOCTET(data[8]);
 815     flags1 = (GETJOCTET(data[9]) << 8) + GETJOCTET(data[10]);
 816     transform = GETJOCTET(data[11]);
 817     TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform);
 818     cinfo->saw_Adobe_marker = TRUE;
 819     cinfo->Adobe_transform = (UINT8) transform;
 820   } else {
 821     /* Start of APP14 does not match "Adobe", or too short */
 822     TRACEMS1(cinfo, 1, JTRC_APP14, (int) (datalen + remaining));
 823   }
 824 }
 825 
 826 
 827 METHODDEF(boolean)
 828 get_interesting_appn (j_decompress_ptr cinfo)
 829 /* Process an APP0 or APP14 marker without saving it */
 830 {
 831   INT32 length;
 832   JOCTET b[APPN_DATA_LEN];
 833   unsigned int i, numtoread;
 834   INPUT_VARS(cinfo);
 835 
 836   INPUT_2BYTES(cinfo, length, return FALSE);
 837   length -= 2;
 838 
 839   /* get the interesting part of the marker data */
 840   if (length >= APPN_DATA_LEN)
 841     numtoread = APPN_DATA_LEN;
 842   else if (length > 0)
 843     numtoread = (unsigned int) length;
 844   else
 845     numtoread = 0;
 846   for (i = 0; i < numtoread; i++)
 847     INPUT_BYTE(cinfo, b[i], return FALSE);
 848   length -= numtoread;
 849 
 850   /* process it */
 851   switch (cinfo->unread_marker) {
 852   case M_APP0:
 853     examine_app0(cinfo, (JOCTET FAR *) b, numtoread, length);
 854     break;
 855   case M_APP14:
 856     examine_app14(cinfo, (JOCTET FAR *) b, numtoread, length);
 857     break;
 858   default:
 859     /* can't get here unless jpeg_save_markers chooses wrong processor */
 860     ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
 861     break;
 862   }
 863 
 864   /* skip any remaining data -- could be lots */
 865   INPUT_SYNC(cinfo);
 866   if (length > 0)
 867     (*cinfo->src->skip_input_data) (cinfo, (long) length);
 868 
 869   return TRUE;
 870 }
 871 
 872 
 873 #ifdef SAVE_MARKERS_SUPPORTED
 874 
 875 METHODDEF(boolean)
 876 save_marker (j_decompress_ptr cinfo)
 877 /* Save an APPn or COM marker into the marker list */
 878 {
 879   my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
 880   jpeg_saved_marker_ptr cur_marker = marker->cur_marker;
 881   unsigned int bytes_read, data_length;
 882   JOCTET FAR * data;
 883   INT32 length = 0;
 884   INPUT_VARS(cinfo);
 885 
 886   if (cur_marker == NULL) {
 887     /* begin reading a marker */
 888     INPUT_2BYTES(cinfo, length, return FALSE);
 889     length -= 2;
 890     if (length >= 0) {               /* watch out for bogus length word */
 891       /* figure out how much we want to save */
 892       unsigned int limit;
 893       if (cinfo->unread_marker == (int) M_COM)
 894         limit = marker->length_limit_COM;
 895       else
 896         limit = marker->length_limit_APPn[cinfo->unread_marker - (int) M_APP0];
 897       if ((unsigned int) length < limit)
 898         limit = (unsigned int) length;
 899       /* allocate and initialize the marker item */
 900       cur_marker = (jpeg_saved_marker_ptr)
 901         (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 902                                     SIZEOF(struct jpeg_marker_struct) + limit);
 903       cur_marker->next = NULL;
 904       cur_marker->marker = (UINT8) cinfo->unread_marker;
 905       cur_marker->original_length = (unsigned int) length;
 906       cur_marker->data_length = limit;
 907       /* data area is just beyond the jpeg_marker_struct */
 908       data = cur_marker->data = (JOCTET FAR *) (cur_marker + 1);
 909       marker->cur_marker = cur_marker;
 910       marker->bytes_read = 0;
 911       bytes_read = 0;
 912       data_length = limit;
 913     } else {
 914       /* deal with bogus length word */
 915       bytes_read = data_length = 0;
 916       data = NULL;
 917     }
 918   } else {
 919     /* resume reading a marker */
 920     bytes_read = marker->bytes_read;
 921     data_length = cur_marker->data_length;
 922     data = cur_marker->data + bytes_read;
 923   }
 924 
 925   while (bytes_read < data_length) {
 926     INPUT_SYNC(cinfo);          /* move the restart point to here */
 927     marker->bytes_read = bytes_read;
 928     /* If there's not at least one byte in buffer, suspend */
 929     MAKE_BYTE_AVAIL(cinfo, return FALSE);
 930     /* Copy bytes with reasonable rapidity */
 931     while (bytes_read < data_length && bytes_in_buffer > 0) {
 932       *data++ = *next_input_byte++;
 933       bytes_in_buffer--;
 934       bytes_read++;
 935     }
 936   }
 937 
 938   /* Done reading what we want to read */
 939   if (cur_marker != NULL) {     /* will be NULL if bogus length word */
 940     /* Add new marker to end of list */
 941     if (cinfo->marker_list == NULL) {
 942       cinfo->marker_list = cur_marker;
 943     } else {
 944       jpeg_saved_marker_ptr prev = cinfo->marker_list;
 945       while (prev->next != NULL)
 946         prev = prev->next;
 947       prev->next = cur_marker;
 948     }
 949     /* Reset pointer & calc remaining data length */
 950     data = cur_marker->data;
 951     length = cur_marker->original_length - data_length;
 952   }
 953   /* Reset to initial state for next marker */
 954   marker->cur_marker = NULL;
 955 
 956   /* Process the marker if interesting; else just make a generic trace msg */
 957   switch (cinfo->unread_marker) {
 958   case M_APP0:
 959     examine_app0(cinfo, data, data_length, length);
 960     break;
 961   case M_APP14:
 962     examine_app14(cinfo, data, data_length, length);
 963     break;
 964   default:
 965     TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker,
 966              (int) (data_length + length));
 967     break;
 968   }
 969 
 970   /* skip any remaining data -- could be lots */
 971   INPUT_SYNC(cinfo);            /* do before skip_input_data */
 972   if (length > 0)
 973     (*cinfo->src->skip_input_data) (cinfo, (long) length);
 974 
 975   return TRUE;
 976 }
 977 
 978 #endif /* SAVE_MARKERS_SUPPORTED */
 979 
 980 
 981 METHODDEF(boolean)
 982 skip_variable (j_decompress_ptr cinfo)
 983 /* Skip over an unknown or uninteresting variable-length marker */
 984 {
 985   INT32 length;
 986   INPUT_VARS(cinfo);
 987 
 988   INPUT_2BYTES(cinfo, length, return FALSE);
 989   length -= 2;
 990   
 991   TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length);
 992 
 993   INPUT_SYNC(cinfo);            /* do before skip_input_data */
 994   if (length > 0)
 995     (*cinfo->src->skip_input_data) (cinfo, (long) length);
 996 
 997   return TRUE;
 998 }
 999 
1000 
1001 /*
1002  * Find the next JPEG marker, save it in cinfo->unread_marker.
1003  * Returns FALSE if had to suspend before reaching a marker;
1004  * in that case cinfo->unread_marker is unchanged.
1005  *
1006  * Note that the result might not be a valid marker code,
1007  * but it will never be 0 or FF.
1008  */
1009 
1010 LOCAL(boolean)
1011 next_marker (j_decompress_ptr cinfo)
1012 {
1013   int c;
1014   INPUT_VARS(cinfo);
1015 
1016   for (;;) {
1017     INPUT_BYTE(cinfo, c, return FALSE);
1018     /* Skip any non-FF bytes.
1019      * This may look a bit inefficient, but it will not occur in a valid file.
1020      * We sync after each discarded byte so that a suspending data source
1021      * can discard the byte from its buffer.
1022      */
1023     while (c != 0xFF) {
1024       cinfo->marker->discarded_bytes++;
1025       INPUT_SYNC(cinfo);
1026       INPUT_BYTE(cinfo, c, return FALSE);
1027     }
1028     /* This loop swallows any duplicate FF bytes.  Extra FFs are legal as
1029      * pad bytes, so don't count them in discarded_bytes.  We assume there
1030      * will not be so many consecutive FF bytes as to overflow a suspending
1031      * data source's input buffer.
1032      */
1033     do {
1034       INPUT_BYTE(cinfo, c, return FALSE);
1035     } while (c == 0xFF);
1036     if (c != 0)
1037       break;                    /* found a valid marker, exit loop */
1038     /* Reach here if we found a stuffed-zero data sequence (FF/00).
1039      * Discard it and loop back to try again.
1040      */
1041     cinfo->marker->discarded_bytes += 2;
1042     INPUT_SYNC(cinfo);
1043   }
1044 
1045   if (cinfo->marker->discarded_bytes != 0) {
1046     WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo->marker->discarded_bytes, c);
1047     cinfo->marker->discarded_bytes = 0;
1048   }
1049 
1050   cinfo->unread_marker = c;
1051 
1052   INPUT_SYNC(cinfo);
1053   return TRUE;
1054 }
1055 
1056 
1057 LOCAL(boolean)
1058 first_marker (j_decompress_ptr cinfo)
1059 /* Like next_marker, but used to obtain the initial SOI marker. */
1060 /* For this marker, we do not allow preceding garbage or fill; otherwise,
1061  * we might well scan an entire input file before realizing it ain't JPEG.
1062  * If an application wants to process non-JFIF files, it must seek to the
1063  * SOI before calling the JPEG library.
1064  */
1065 {
1066   int c, c2;
1067   INPUT_VARS(cinfo);
1068 
1069   INPUT_BYTE(cinfo, c, return FALSE);
1070   INPUT_BYTE(cinfo, c2, return FALSE);
1071   if (c != 0xFF || c2 != (int) M_SOI)
1072     ERREXIT2(cinfo, JERR_NO_SOI, c, c2);
1073 
1074   cinfo->unread_marker = c2;
1075 
1076   INPUT_SYNC(cinfo);
1077   return TRUE;
1078 }
1079 
1080 
1081 /*
1082  * Read markers until SOS or EOI.
1083  *
1084  * Returns same codes as are defined for jpeg_consume_input:
1085  * JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
1086  *
1087  * Note: This function may return a pseudo SOS marker (with zero
1088  * component number) for treat by input controller's consume_input.
1089  * consume_input itself should filter out (skip) the pseudo marker
1090  * after processing for the caller.
1091  */
1092 
1093 METHODDEF(int)
1094 read_markers (j_decompress_ptr cinfo)
1095 {
1096   /* Outer loop repeats once for each marker. */
1097   for (;;) {
1098     /* Collect the marker proper, unless we already did. */
1099     /* NB: first_marker() enforces the requirement that SOI appear first. */
1100     if (cinfo->unread_marker == 0) {
1101       if (! cinfo->marker->saw_SOI) {
1102         if (! first_marker(cinfo))
1103           return JPEG_SUSPENDED;
1104       } else {
1105         if (! next_marker(cinfo))
1106           return JPEG_SUSPENDED;
1107       }
1108     }
1109     /* At this point cinfo->unread_marker contains the marker code and the
1110      * input point is just past the marker proper, but before any parameters.
1111      * A suspension will cause us to return with this state still true.
1112      */
1113     switch (cinfo->unread_marker) {
1114     case M_SOI:
1115       if (! get_soi(cinfo))
1116         return JPEG_SUSPENDED;
1117       break;
1118 
1119     case M_SOF0:                /* Baseline */
1120       if (! get_sof(cinfo, TRUE, FALSE, FALSE))
1121         return JPEG_SUSPENDED;
1122       break;
1123 
1124     case M_SOF1:                /* Extended sequential, Huffman */
1125       if (! get_sof(cinfo, FALSE, FALSE, FALSE))
1126         return JPEG_SUSPENDED;
1127       break;
1128 
1129     case M_SOF2:                /* Progressive, Huffman */
1130       if (! get_sof(cinfo, FALSE, TRUE, FALSE))
1131         return JPEG_SUSPENDED;
1132       break;
1133 
1134     case M_SOF9:                /* Extended sequential, arithmetic */
1135       if (! get_sof(cinfo, FALSE, FALSE, TRUE))
1136         return JPEG_SUSPENDED;
1137       break;
1138 
1139     case M_SOF10:               /* Progressive, arithmetic */
1140       if (! get_sof(cinfo, FALSE, TRUE, TRUE))
1141         return JPEG_SUSPENDED;
1142       break;
1143 
1144     /* Currently unsupported SOFn types */
1145     case M_SOF3:                /* Lossless, Huffman */
1146     case M_SOF5:                /* Differential sequential, Huffman */
1147     case M_SOF6:                /* Differential progressive, Huffman */
1148     case M_SOF7:                /* Differential lossless, Huffman */
1149     case M_JPG:                 /* Reserved for JPEG extensions */
1150     case M_SOF11:               /* Lossless, arithmetic */
1151     case M_SOF13:               /* Differential sequential, arithmetic */
1152     case M_SOF14:               /* Differential progressive, arithmetic */
1153     case M_SOF15:               /* Differential lossless, arithmetic */
1154       ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo->unread_marker);
1155       break;
1156 
1157     case M_SOS:
1158       if (! get_sos(cinfo))
1159         return JPEG_SUSPENDED;
1160       cinfo->unread_marker = 0;      /* processed the marker */
1161       return JPEG_REACHED_SOS;
1162 
1163     case M_EOI:
1164       TRACEMS(cinfo, 1, JTRC_EOI);
1165       cinfo->unread_marker = 0;      /* processed the marker */
1166       return JPEG_REACHED_EOI;
1167 
1168     case M_DAC:
1169       if (! get_dac(cinfo))
1170         return JPEG_SUSPENDED;
1171       break;
1172 
1173     case M_DHT:
1174       if (! get_dht(cinfo))
1175         return JPEG_SUSPENDED;
1176       break;
1177 
1178     case M_DQT:
1179       if (! get_dqt(cinfo))
1180         return JPEG_SUSPENDED;
1181       break;
1182 
1183     case M_DRI:
1184       if (! get_dri(cinfo))
1185         return JPEG_SUSPENDED;
1186       break;
1187 
1188     case M_JPG8:
1189       if (! get_lse(cinfo))
1190         return JPEG_SUSPENDED;
1191       break;
1192 
1193     case M_APP0:
1194     case M_APP1:
1195     case M_APP2:
1196     case M_APP3:
1197     case M_APP4:
1198     case M_APP5:
1199     case M_APP6:
1200     case M_APP7:
1201     case M_APP8:
1202     case M_APP9:
1203     case M_APP10:
1204     case M_APP11:
1205     case M_APP12:
1206     case M_APP13:
1207     case M_APP14:
1208     case M_APP15:
1209       if (! (*((my_marker_ptr) cinfo->marker)->process_APPn[
1210                 cinfo->unread_marker - (int) M_APP0]) (cinfo))
1211         return JPEG_SUSPENDED;
1212       break;
1213 
1214     case M_COM:
1215       if (! (*((my_marker_ptr) cinfo->marker)->process_COM) (cinfo))
1216         return JPEG_SUSPENDED;
1217       break;
1218 
1219     case M_RST0:                /* these are all parameterless */
1220     case M_RST1:
1221     case M_RST2:
1222     case M_RST3:
1223     case M_RST4:
1224     case M_RST5:
1225     case M_RST6:
1226     case M_RST7:
1227     case M_TEM:
1228       TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo->unread_marker);
1229       break;
1230 
1231     case M_DNL:                 /* Ignore DNL ... perhaps the wrong thing */
1232       if (! skip_variable(cinfo))
1233         return JPEG_SUSPENDED;
1234       break;
1235 
1236     default:                    /* must be DHP, EXP, JPGn, or RESn */
1237       /* For now, we treat the reserved markers as fatal errors since they are
1238        * likely to be used to signal incompatible JPEG Part 3 extensions.
1239        * Once the JPEG 3 version-number marker is well defined, this code
1240        * ought to change!
1241        */
1242       ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
1243       break;
1244     }
1245     /* Successfully processed marker, so reset state variable */
1246     cinfo->unread_marker = 0;
1247   } /* end loop */
1248 }
1249 
1250 
1251 /*
1252  * Read a restart marker, which is expected to appear next in the datastream;
1253  * if the marker is not there, take appropriate recovery action.
1254  * Returns FALSE if suspension is required.
1255  *
1256  * This is called by the entropy decoder after it has read an appropriate
1257  * number of MCUs.  cinfo->unread_marker may be nonzero if the entropy decoder
1258  * has already read a marker from the data source.  Under normal conditions
1259  * cinfo->unread_marker will be reset to 0 before returning; if not reset,
1260  * it holds a marker which the decoder will be unable to read past.
1261  */
1262 
1263 METHODDEF(boolean)
1264 read_restart_marker (j_decompress_ptr cinfo)
1265 {
1266   /* Obtain a marker unless we already did. */
1267   /* Note that next_marker will complain if it skips any data. */
1268   if (cinfo->unread_marker == 0) {
1269     if (! next_marker(cinfo))
1270       return FALSE;
1271   }
1272 
1273   if (cinfo->unread_marker ==
1274       ((int) M_RST0 + cinfo->marker->next_restart_num)) {
1275     /* Normal case --- swallow the marker and let entropy decoder continue */
1276     TRACEMS1(cinfo, 3, JTRC_RST, cinfo->marker->next_restart_num);
1277     cinfo->unread_marker = 0;
1278   } else {
1279     /* Uh-oh, the restart markers have been messed up. */
1280     /* Let the data source manager determine how to resync. */
1281     if (! (*cinfo->src->resync_to_restart) (cinfo,
1282                                             cinfo->marker->next_restart_num))
1283       return FALSE;
1284   }
1285 
1286   /* Update next-restart state */
1287   cinfo->marker->next_restart_num = (cinfo->marker->next_restart_num + 1) & 7;
1288 
1289   return TRUE;
1290 }
1291 
1292 
1293 /*
1294  * This is the default resync_to_restart method for data source managers
1295  * to use if they don't have any better approach.  Some data source managers
1296  * may be able to back up, or may have additional knowledge about the data
1297  * which permits a more intelligent recovery strategy; such managers would
1298  * presumably supply their own resync method.
1299  *
1300  * read_restart_marker calls resync_to_restart if it finds a marker other than
1301  * the restart marker it was expecting.  (This code is *not* used unless
1302  * a nonzero restart interval has been declared.)  cinfo->unread_marker is
1303  * the marker code actually found (might be anything, except 0 or FF).
1304  * The desired restart marker number (0..7) is passed as a parameter.
1305  * This routine is supposed to apply whatever error recovery strategy seems
1306  * appropriate in order to position the input stream to the next data segment.
1307  * Note that cinfo->unread_marker is treated as a marker appearing before
1308  * the current data-source input point; usually it should be reset to zero
1309  * before returning.
1310  * Returns FALSE if suspension is required.
1311  *
1312  * This implementation is substantially constrained by wanting to treat the
1313  * input as a data stream; this means we can't back up.  Therefore, we have
1314  * only the following actions to work with:
1315  *   1. Simply discard the marker and let the entropy decoder resume at next
1316  *      byte of file.
1317  *   2. Read forward until we find another marker, discarding intervening
1318  *      data.  (In theory we could look ahead within the current bufferload,
1319  *      without having to discard data if we don't find the desired marker.
1320  *      This idea is not implemented here, in part because it makes behavior
1321  *      dependent on buffer size and chance buffer-boundary positions.)
1322  *   3. Leave the marker unread (by failing to zero cinfo->unread_marker).
1323  *      This will cause the entropy decoder to process an empty data segment,
1324  *      inserting dummy zeroes, and then we will reprocess the marker.
1325  *
1326  * #2 is appropriate if we think the desired marker lies ahead, while #3 is
1327  * appropriate if the found marker is a future restart marker (indicating
1328  * that we have missed the desired restart marker, probably because it got
1329  * corrupted).
1330  * We apply #2 or #3 if the found marker is a restart marker no more than
1331  * two counts behind or ahead of the expected one.  We also apply #2 if the
1332  * found marker is not a legal JPEG marker code (it's certainly bogus data).
1333  * If the found marker is a restart marker more than 2 counts away, we do #1
1334  * (too much risk that the marker is erroneous; with luck we will be able to
1335  * resync at some future point).
1336  * For any valid non-restart JPEG marker, we apply #3.  This keeps us from
1337  * overrunning the end of a scan.  An implementation limited to single-scan
1338  * files might find it better to apply #2 for markers other than EOI, since
1339  * any other marker would have to be bogus data in that case.
1340  */
1341 
1342 GLOBAL(boolean)
1343 jpeg_resync_to_restart (j_decompress_ptr cinfo, int desired)
1344 {
1345   int marker = cinfo->unread_marker;
1346   int action = 1;
1347   
1348   /* Always put up a warning. */
1349   WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired);
1350   
1351   /* Outer loop handles repeated decision after scanning forward. */
1352   for (;;) {
1353     if (marker < (int) M_SOF0)
1354       action = 2;               /* invalid marker */
1355     else if (marker < (int) M_RST0 || marker > (int) M_RST7)
1356       action = 3;               /* valid non-restart marker */
1357     else {
1358       if (marker == ((int) M_RST0 + ((desired+1) & 7)) ||
1359           marker == ((int) M_RST0 + ((desired+2) & 7)))
1360         action = 3;             /* one of the next two expected restarts */
1361       else if (marker == ((int) M_RST0 + ((desired-1) & 7)) ||
1362                marker == ((int) M_RST0 + ((desired-2) & 7)))
1363         action = 2;             /* a prior restart, so advance */
1364       else
1365         action = 1;             /* desired restart or too far away */
1366     }
1367     TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action);
1368     switch (action) {
1369     case 1:
1370       /* Discard marker and let entropy decoder resume processing. */
1371       cinfo->unread_marker = 0;
1372       return TRUE;
1373     case 2:
1374       /* Scan to the next marker, and repeat the decision loop. */
1375       if (! next_marker(cinfo))
1376         return FALSE;
1377       marker = cinfo->unread_marker;
1378       break;
1379     case 3:
1380       /* Return without advancing past this marker. */
1381       /* Entropy decoder will be forced to process an empty segment. */
1382       return TRUE;
1383     }
1384   } /* end loop */
1385 }
1386 
1387 
1388 /*
1389  * Reset marker processing state to begin a fresh datastream.
1390  */
1391 
1392 METHODDEF(void)
1393 reset_marker_reader (j_decompress_ptr cinfo)
1394 {
1395   my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1396 
1397   cinfo->comp_info = NULL;           /* until allocated by get_sof */
1398   cinfo->input_scan_number = 0;              /* no SOS seen yet */
1399   cinfo->unread_marker = 0;          /* no pending marker */
1400   marker->pub.saw_SOI = FALSE;               /* set internal state too */
1401   marker->pub.saw_SOF = FALSE;
1402   marker->pub.discarded_bytes = 0;
1403   marker->cur_marker = NULL;
1404 }
1405 
1406 
1407 /*
1408  * Initialize the marker reader module.
1409  * This is called only once, when the decompression object is created.
1410  */
1411 
1412 GLOBAL(void)
1413 jinit_marker_reader (j_decompress_ptr cinfo)
1414 {
1415   my_marker_ptr marker;
1416   int i;
1417 
1418   /* Create subobject in permanent pool */
1419   marker = (my_marker_ptr)
1420     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
1421                                 SIZEOF(my_marker_reader));
1422   cinfo->marker = &marker->pub;
1423   /* Initialize public method pointers */
1424   marker->pub.reset_marker_reader = reset_marker_reader;
1425   marker->pub.read_markers = read_markers;
1426   marker->pub.read_restart_marker = read_restart_marker;
1427   /* Initialize COM/APPn processing.
1428    * By default, we examine and then discard APP0 and APP14,
1429    * but simply discard COM and all other APPn.
1430    */
1431   marker->process_COM = skip_variable;
1432   marker->length_limit_COM = 0;
1433   for (i = 0; i < 16; i++) {
1434     marker->process_APPn[i] = skip_variable;
1435     marker->length_limit_APPn[i] = 0;
1436   }
1437   marker->process_APPn[0] = get_interesting_appn;
1438   marker->process_APPn[14] = get_interesting_appn;
1439   /* Reset marker processing state */
1440   reset_marker_reader(cinfo);
1441 }
1442 
1443 
1444 /*
1445  * Control saving of COM and APPn markers into marker_list.
1446  */
1447 
1448 #ifdef SAVE_MARKERS_SUPPORTED
1449 
1450 GLOBAL(void)
1451 jpeg_save_markers (j_decompress_ptr cinfo, int marker_code,
1452                    unsigned int length_limit)
1453 {
1454   my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1455   long maxlength;
1456   jpeg_marker_parser_method processor;
1457 
1458   /* Length limit mustn't be larger than what we can allocate
1459    * (should only be a concern in a 16-bit environment).
1460    */
1461   maxlength = cinfo->mem->max_alloc_chunk - SIZEOF(struct jpeg_marker_struct);
1462   if (((long) length_limit) > maxlength)
1463     length_limit = (unsigned int) maxlength;
1464 
1465   /* Choose processor routine to use.
1466    * APP0/APP14 have special requirements.
1467    */
1468   if (length_limit) {
1469     processor = save_marker;
1470     /* If saving APP0/APP14, save at least enough for our internal use. */
1471     if (marker_code == (int) M_APP0 && length_limit < APP0_DATA_LEN)
1472       length_limit = APP0_DATA_LEN;
1473     else if (marker_code == (int) M_APP14 && length_limit < APP14_DATA_LEN)
1474       length_limit = APP14_DATA_LEN;
1475   } else {
1476     processor = skip_variable;
1477     /* If discarding APP0/APP14, use our regular on-the-fly processor. */
1478     if (marker_code == (int) M_APP0 || marker_code == (int) M_APP14)
1479       processor = get_interesting_appn;
1480   }
1481 
1482   if (marker_code == (int) M_COM) {
1483     marker->process_COM = processor;
1484     marker->length_limit_COM = length_limit;
1485   } else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15) {
1486     marker->process_APPn[marker_code - (int) M_APP0] = processor;
1487     marker->length_limit_APPn[marker_code - (int) M_APP0] = length_limit;
1488   } else
1489     ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
1490 }
1491 
1492 #endif /* SAVE_MARKERS_SUPPORTED */
1493 
1494 
1495 /*
1496  * Install a special processing method for COM or APPn markers.
1497  */
1498 
1499 GLOBAL(void)
1500 jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
1501                            jpeg_marker_parser_method routine)
1502 {
1503   my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1504 
1505   if (marker_code == (int) M_COM)
1506     marker->process_COM = routine;
1507   else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15)
1508     marker->process_APPn[marker_code - (int) M_APP0] = routine;
1509   else
1510     ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
1511 }