granicus.if.org Git - imagemagick/blob - MagickCore/distribute-cache.c

   1 /*
   2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   3 %                                                                             %
   4 %                                                                             %
   5 %    DDDD    IIIII   SSSSS  TTTTT  RRRR   IIIII  BBBB   U   U  TTTTT  EEEEE   %
   6 %    D   D     I     SS       T    R   R    I    B   B  U   U    T    E       %
   7 %    D   D     I      SSS     T    RRRR     I    BBBB   U   U    T    EEE     %
   8 %    D   D     I        SS    T    R R      I    B   B  U   U    T    E       %
   9 %    DDDDA   IIIII   SSSSS    T    R  R   IIIII  BBBB    UUU     T    EEEEE   %
  10 %                                                                             %
  11 %                      CCCC   AAA    CCCC  H   H  EEEEE                       %
  12 %                     C      A   A  C      H   H  E                           %
  13 %                     C      AAAAA  C      HHHHH  EEE                         %
  14 %                     C      A   A  C      H   H  E                           %
  15 %                      CCCC  A   A   CCCC  H   H  EEEEE                       %
  16 %                                                                             %
  17 %                                                                             %
  18 %                 MagickCore Distributed Pixel Cache Methods                  %
  19 %                                                                             %
  20 %                              Software Design                                %
  21 %                                John Cristy                                  %
  22 %                                January 2013                                 %
  23 %                                                                             %
  24 %                                                                             %
  25 %  Copyright 1999-2013 ImageMagick Studio LLC, a non-profit organization      %
  26 %  dedicated to making software imaging solutions freely available.           %
  27 %                                                                             %
  28 %  You may not use this file except in compliance with the License.  You may  %
  29 %  obtain a copy of the License at                                            %
  30 %                                                                             %
  31 %    http://www.imagemagick.org/script/license.php                            %
  32 %                                                                             %
  33 %  Unless required by applicable law or agreed to in writing, software        %
  34 %  distributed under the License is distributed on an "AS IS" BASIS,          %
  35 %  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
  36 %  See the License for the specific language governing permissions and        %
  37 %  limitations under the License.                                             %
  38 %                                                                             %
  39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  40 %
  41 % A distributed pixel cache is an extension of the traditional pixel cache
  42 % available on a single host.  The distributed pixel cache may span multiple
  43 % servers so that it can grow in size and transactional capacity to support
  44 % very large images.  Start up the pixel cache server on one or more machines.
  45 % When you read or operate on an image and the local pixel cache resources are
  46 % exhausted, ImageMagick contacts one or more of these remote pixel servers to
  47 % store or retrieve pixels.
  48 %
  49 */
  50 \f
  51 /*
  52   Include declarations.
  53 */
  54 #include "MagickCore/studio.h"
  55 #include "MagickCore/cache.h"
  56 #include "MagickCore/cache-private.h"
  57 #include "MagickCore/distribute-cache.h"
  58 #include "MagickCore/distribute-cache-private.h"
  59 #include "MagickCore/exception.h"
  60 #include "MagickCore/exception-private.h"
  61 #include "MagickCore/geometry.h"
  62 #include "MagickCore/image.h"
  63 #include "MagickCore/locale_.h"
  64 #include "MagickCore/memory_.h"
  65 #include "MagickCore/policy.h"
  66 #include "MagickCore/random_.h"
  67 #include "MagickCore/registry.h"
  68 #include "MagickCore/splay-tree.h"
  69 #include "MagickCore/string_.h"
  70 #include "MagickCore/string-private.h"
  71 #if defined(MAGICKCORE_HAVE_SOCKET)
  72 #include <netinet/in.h>
  73 #include <netdb.h>
  74 #include <sys/socket.h>
  75 #include <arpa/inet.h>
  76 #endif
  77 \f
  78 /*
  79   Define declarations.
  80 */
  81 #define DPCHostname  "127.0.0.1"
  82 #define DPCPort  6668
  83 #define DPCSessionKeyLength  8
  84 \f
  85 /*
  86 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  87 %                                                                             %
  88 %                                                                             %
  89 %                                                                             %
  90 +   A c q u i r e D i s t r i b u t e C a c h e I n f o                       %
  91 %                                                                             %
  92 %                                                                             %
  93 %                                                                             %
  94 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  95 %
  96 %  AcquireDistributeCacheInfo() allocates the DistributeCacheInfo structure.
  97 %
  98 %  The format of the AcquireDistributeCacheInfo method is:
  99 %
 100 %      DistributeCacheInfo *AcquireDistributeCacheInfo(ExceptionInfo *exception)
 101 %
 102 %  A description of each parameter follows:
 103 %
 104 %    o exception: return any errors or warnings in this structure.
 105 %
 106 */
 107
 108 static MagickSizeType CRC64(const unsigned char *message,const size_t length)
 109 {
 110   MagickSizeType
 111     crc;
 112
 113   register ssize_t
 114     i;
 115
 116   static MagickBooleanType
 117     crc_initial = MagickFalse;
 118
 119   static MagickSizeType
 120     crc_xor[256];
 121
 122   if (crc_initial == MagickFalse)
 123     {
 124       MagickSizeType
 125         alpha;
 126
 127       for (i=0; i < 256; i++)
 128       {
 129         register ssize_t
 130           j;
 131
 132         alpha=(MagickSizeType) i;
 133         for (j=0; j < 8; j++)
 134         {
 135           if ((alpha & 0x01) == 0)
 136             alpha>>=1;
 137           else
 138             alpha=(MagickSizeType) ((alpha >> 1) ^
 139               MagickULLConstant(0xd800000000000000));
 140         }
 141         crc_xor[i]=alpha;
 142       }
 143       crc_initial=MagickTrue;
 144     }
 145   crc=0;
 146   for (i=0; i < (ssize_t) length; i++)
 147     crc=crc_xor[(crc ^ message[i]) & 0xff] ^ (crc >> 8);
 148   return(crc);
 149 }
 150
 151 static int ConnectPixelCacheServer(const char *hostname,const int port,
 152   MagickSizeType *session_key,ExceptionInfo *exception)
 153 {
 154 #if defined(MAGICKCORE_HAVE_SOCKET)
 155   char
 156     secret[MaxTextExtent];
 157
 158   const char
 159     *shared_secret;
 160
 161   int
 162     client_socket,
 163     status;
 164
 165   ssize_t
 166     count;
 167
 168   struct hostent
 169     *host;
 170
 171   struct sockaddr_in
 172     address;
 173
 174   unsigned char
 175     session[MaxTextExtent];
 176
 177   /*
 178     Connect to distributed pixel cache and get session key.
 179   */
 180   *session_key=0;
 181   shared_secret=GetPolicyValue("shared-secret");
 182   if (shared_secret == (const char *) NULL)
 183     {
 184       (void) ThrowMagickException(exception,GetMagickModule(),CacheError,
 185         "DistributedPixelCache","'%s'","shared secret expected");
 186       return(-1);
 187     }
 188   (void) CopyMagickString((char *) session,shared_secret,MaxTextExtent-
 189     DPCSessionKeyLength);
 190   host=gethostbyname(hostname);
 191   client_socket=socket(AF_INET,SOCK_STREAM,0);
 192   if (client_socket == -1)
 193     {
 194       (void) ThrowMagickException(exception,GetMagickModule(),CacheError,
 195         "DistributedPixelCache","'%s'",hostname);
 196       return(-1);
 197     }
 198   (void) ResetMagickMemory(&address,0,sizeof(address));
 199   address.sin_family=AF_INET;
 200   address.sin_port=htons((uint16_t) port);
 201   address.sin_addr=(*((struct in_addr *) host->h_addr));
 202   status=connect(client_socket,(struct sockaddr *) &address,(socklen_t)
 203     sizeof(struct sockaddr));
 204   if (status == -1)
 205     {
 206       (void) ThrowMagickException(exception,GetMagickModule(),CacheError,
 207         "DistributedPixelCache","'%s'",hostname);
 208       return(-1);
 209     }
 210   count=read(client_socket,secret,MaxTextExtent);
 211   if (count != -1)
 212     {
 213       (void) memcpy(session+strlen(shared_secret),secret,(size_t) count);
 214       *session_key=CRC64(session,strlen(shared_secret)+count);
 215     }
 216   if (*session_key == 0)
 217     {
 218       close(client_socket);
 219       client_socket=(-1);
 220     }
 221   return(client_socket);
 222 #else
 223   (void) ThrowMagickException(exception,GetMagickModule(),MissingDelegateError,
 224     "DelegateLibrarySupportNotBuiltIn","distributed pixel cache");
 225   return(MagickFalse);
 226 #endif
 227 }
 228
 229 static char *GetHostname(int *port,ExceptionInfo *exception)
 230 {
 231   char
 232     *host,
 233     *hosts,
 234     **hostlist;
 235
 236   int
 237     argc;
 238
 239   register ssize_t
 240     i;
 241
 242   static size_t
 243     id = 0;
 244
 245   /*
 246     Parse host list (e.g. 192.168.100.1:6668,192.168.100.2:6668).
 247   */
 248   hosts=(char *) GetImageRegistry(StringRegistryType,"cache:hosts",
 249     exception);
 250   if (hosts == (char *) NULL)
 251     {
 252       *port=DPCPort;
 253       return(AcquireString(DPCHostname));
 254     }
 255   (void) SubstituteString(&hosts,","," ");
 256   hostlist=StringToArgv(hosts,&argc);
 257   hosts=DestroyString(hosts);
 258   if (hostlist == (char **) NULL)
 259     {
 260       *port=DPCPort;
 261       return(AcquireString(DPCHostname));
 262     }
 263   hosts=AcquireString(hostlist[(id++ % (argc-1))+1]);
 264   for (i=0; i < (ssize_t) argc; i++)
 265     hostlist[i]=DestroyString(hostlist[i]);
 266   hostlist=(char **) RelinquishMagickMemory(hostlist);
 267   (void) SubstituteString(&hosts,":"," ");
 268   hostlist=StringToArgv(hosts,&argc);
 269   if (hostlist == (char **) NULL)
 270     {
 271       *port=DPCPort;
 272       return(AcquireString(DPCHostname));
 273     }
 274   host=AcquireString(hostlist[1]);
 275   if (hostlist[2] == (char *) NULL)
 276     *port=DPCPort;
 277   else
 278     *port=StringToLong(hostlist[2]);
 279   for (i=0; i < (ssize_t) argc; i++)
 280     hostlist[i]=DestroyString(hostlist[i]);
 281   hostlist=(char **) RelinquishMagickMemory(hostlist);
 282   return(host);
 283 }
 284
 285 MagickPrivate DistributeCacheInfo *AcquireDistributeCacheInfo(
 286   ExceptionInfo *exception)
 287 {
 288   char
 289     *hostname;
 290
 291   DistributeCacheInfo
 292     *distribute_cache_info;
 293
 294   MagickSizeType
 295     session_key;
 296
 297   distribute_cache_info=(DistributeCacheInfo *) AcquireMagickMemory(
 298     sizeof(*distribute_cache_info));
 299   if (distribute_cache_info == (DistributeCacheInfo *) NULL)
 300     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
 301   (void) ResetMagickMemory(distribute_cache_info,0,
 302     sizeof(*distribute_cache_info));
 303   distribute_cache_info->signature=MagickSignature;
 304   /*
 305     Contact pixel cache server.
 306   */
 307   distribute_cache_info->port=0;
 308   hostname=GetHostname(&distribute_cache_info->port,exception);
 309   session_key=0;
 310   distribute_cache_info->file=ConnectPixelCacheServer(hostname,
 311     distribute_cache_info->port,&session_key,exception);
 312   distribute_cache_info->session_key=session_key;
 313   (void) CopyMagickString(distribute_cache_info->hostname,hostname,
 314     MaxTextExtent);
 315   hostname=DestroyString(hostname);
 316   if (distribute_cache_info->file == -1)
 317     distribute_cache_info=DestroyDistributeCacheInfo(distribute_cache_info);
 318   return(distribute_cache_info);
 319 }
 320 \f
 321 /*
 322 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 323 %                                                                             %
 324 %                                                                             %
 325 %                                                                             %
 326 +   D e s t r o y D i s t r i b u t e C a c h e I n f o                       %
 327 %                                                                             %
 328 %                                                                             %
 329 %                                                                             %
 330 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 331 %
 332 %  DestroyDistributeCacheInfo() deallocates memory associated with an
 333 %  DistributeCacheInfo structure.
 334 %
 335 %  The format of the DestroyDistributeCacheInfo method is:
 336 %
 337 %      DistributeCacheInfo *DestroyDistributeCacheInfo(
 338 %        DistributeCacheInfo *distribute_cache_info)
 339 %
 340 %  A description of each parameter follows:
 341 %
 342 %    o distribute_cache_info: the distributed cache info.
 343 %
 344 */
 345 MagickPrivate DistributeCacheInfo *DestroyDistributeCacheInfo(
 346   DistributeCacheInfo *distribute_cache_info)
 347 {
 348   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
 349   assert(distribute_cache_info->signature == MagickSignature);
 350   distribute_cache_info->signature=(~MagickSignature);
 351   distribute_cache_info=(DistributeCacheInfo *) RelinquishMagickMemory(
 352     distribute_cache_info);
 353   return(distribute_cache_info);
 354 }
 355 \f
 356 /*
 357 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 358 %                                                                             %
 359 %                                                                             %
 360 %                                                                             %
 361 +   D i s t r i b u t e P i x e l C a c h e S e r v e r                       %
 362 %                                                                             %
 363 %                                                                             %
 364 %                                                                             %
 365 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 366 %
 367 %  DistributePixelCacheServer() waits on the specified port for commands to
 368 %  create, read, update, or destroy a pixel cache.
 369 %
 370 %  The format of the DistributePixelCacheServer() method is:
 371 %
 372 %      void DistributePixelCacheServer(const size_t port)
 373 %
 374 %  A description of each parameter follows:
 375 %
 376 %    o port: connect the distributed pixel cache at this port.
 377 %
 378 %    o exception: return any errors or warnings in this structure.
 379 %
 380 */
 381
 382 static MagickBooleanType CreateDistributeCache(SplayTreeInfo *image_registry,
 383   int file,const MagickSizeType session_key)
 384 {
 385   ExceptionInfo
 386     *exception;
 387
 388   Image
 389     *image;
 390
 391   MagickBooleanType
 392     status;
 393
 394   register unsigned char
 395     *p;
 396
 397   size_t
 398     length;
 399
 400   ssize_t
 401     count;
 402
 403   unsigned char
 404     buffer[MaxTextExtent];
 405
 406   exception=AcquireExceptionInfo();
 407   image=AcquireImage((ImageInfo *) NULL,exception);
 408   exception=DestroyExceptionInfo(exception);
 409   length=sizeof(image->columns)+sizeof(image->rows)+
 410     sizeof(image->number_channels);
 411   count=read(file,buffer,length);
 412   if (count != (ssize_t) length)
 413     return(MagickFalse);
 414   p=buffer;
 415   (void) memcpy(&image->columns,p,sizeof(image->columns));
 416   p+=sizeof(image->columns);
 417   (void) memcpy(&image->rows,p,sizeof(image->rows));
 418   p+=sizeof(image->rows);
 419   (void) memcpy(&image->number_channels,p,sizeof(image->number_channels));
 420   p+=sizeof(image->number_channels);
 421   status=AddValueToSplayTree(image_registry,(const void *) session_key,image);
 422   return(status);
 423 }
 424
 425 static MagickBooleanType DestroyDistributeCache(SplayTreeInfo *image_registry,
 426   int file,const MagickSizeType session_key)
 427 {
 428   return(DeleteNodeFromSplayTree(image_registry,(const void *) session_key));
 429 }
 430
 431 static MagickBooleanType ReadDistributeCacheMetacontent(
 432   SplayTreeInfo *image_registry,int file,const MagickSizeType session_key)
 433 {
 434   const unsigned char
 435     *metacontent;
 436
 437   ExceptionInfo
 438     *exception;
 439
 440   Image
 441     *image;
 442
 443   RectangleInfo
 444     region;
 445
 446   register const Quantum
 447     *p;
 448
 449   register unsigned char
 450     *q;
 451
 452   size_t
 453     length;
 454
 455   ssize_t
 456     count;
 457
 458   unsigned char
 459     buffer[MaxTextExtent];
 460
 461   image=(Image *) GetValueFromSplayTree(image_registry,(const void *)
 462     session_key);
 463   if (image == (Image *) NULL)
 464     return(MagickFalse);
 465   length=sizeof(region.width)+sizeof(region.height)+sizeof(region.x)+
 466     sizeof(region.y)+sizeof(length);
 467   count=read(file,buffer,length);
 468   if (count != (ssize_t) length)
 469     return(MagickFalse);
 470   q=buffer;
 471   (void) memcpy(&region.width,q,sizeof(region.width));
 472   q+=sizeof(region.width);
 473   (void) memcpy(&region.height,q,sizeof(region.height));
 474   q+=sizeof(region.width);
 475   (void) memcpy(&region.x,q,sizeof(region.x));
 476   q+=sizeof(region.width);
 477   (void) memcpy(&region.y,q,sizeof(region.y));
 478   q+=sizeof(region.width);
 479   (void) memcpy(&length,q,sizeof(length));
 480   q+=sizeof(length);
 481   exception=AcquireExceptionInfo();
 482   p=GetVirtualPixels(image,region.x,region.y,region.width,region.height,
 483     exception);
 484   exception=DestroyExceptionInfo(exception);
 485   if (p == (const Quantum *) NULL)
 486     return(MagickFalse);
 487   metacontent=GetVirtualMetacontent(image);
 488   count=write(file,metacontent,length);
 489   if (count != (ssize_t) length)
 490     return(MagickFalse);
 491   return(MagickTrue);
 492 }
 493
 494 static MagickBooleanType ReadDistributeCachePixels(
 495   SplayTreeInfo *image_registry,int file,const MagickSizeType session_key)
 496 {
 497   ExceptionInfo
 498     *exception;
 499
 500   Image
 501     *image;
 502
 503   RectangleInfo
 504     region;
 505
 506   register const Quantum
 507     *p;
 508
 509   register unsigned char
 510     *q;
 511
 512   size_t
 513     length;
 514
 515   ssize_t
 516     count;
 517
 518   unsigned char
 519     buffer[MaxTextExtent];
 520
 521   image=(Image *) GetValueFromSplayTree(image_registry,(const void *)
 522     session_key);
 523   if (image == (Image *) NULL)
 524     return(MagickFalse);
 525   length=sizeof(region.width)+sizeof(region.height)+sizeof(region.x)+
 526     sizeof(region.y)+sizeof(length);
 527   count=read(file,buffer,length);
 528   if (count != (ssize_t) length)
 529     return(MagickFalse);
 530   q=buffer;
 531   (void) memcpy(&region.width,q,sizeof(region.width));
 532   q+=sizeof(region.width);
 533   (void) memcpy(&region.height,q,sizeof(region.height));
 534   q+=sizeof(region.width);
 535   (void) memcpy(&region.x,q,sizeof(region.x));
 536   q+=sizeof(region.width);
 537   (void) memcpy(&region.y,q,sizeof(region.y));
 538   q+=sizeof(region.width);
 539   (void) memcpy(&length,q,sizeof(length));
 540   q+=sizeof(length);
 541   exception=AcquireExceptionInfo();
 542   p=GetVirtualPixels(image,region.x,region.y,region.width,region.height,
 543     exception);
 544   exception=DestroyExceptionInfo(exception);
 545   if (p == (const Quantum *) NULL)
 546     return(MagickFalse);
 547   count=write(file,p,length);
 548   if (count != (ssize_t) length)
 549     return(MagickFalse);
 550   return(MagickTrue);
 551 }
 552
 553 static MagickBooleanType WriteDistributeCacheMetacontent(
 554   SplayTreeInfo *image_registry,int file,const MagickSizeType session_key)
 555 {
 556   ExceptionInfo
 557     *exception;
 558
 559   Image
 560     *image;
 561
 562   MagickBooleanType
 563     status;
 564
 565   RectangleInfo
 566     region;
 567
 568   register Quantum
 569     *q;
 570
 571   register unsigned char
 572     *p;
 573
 574   size_t
 575     length;
 576
 577   ssize_t
 578     count;
 579
 580   unsigned char
 581     buffer[MaxTextExtent],
 582     *metacontent;
 583
 584   image=(Image *) GetValueFromSplayTree(image_registry,(const void *)
 585     session_key);
 586   if (image == (Image *) NULL)
 587     return(MagickFalse);
 588   length=sizeof(region.width)+sizeof(region.height)+sizeof(region.x)+
 589     sizeof(region.y)+sizeof(length);
 590   count=read(file,buffer,length);
 591   if (count != (ssize_t) length)
 592     return(MagickFalse);
 593   p=buffer;
 594   (void) memcpy(&region.width,p,sizeof(region.width));
 595   p+=sizeof(region.width);
 596   (void) memcpy(&region.height,p,sizeof(region.height));
 597   p+=sizeof(region.width);
 598   (void) memcpy(&region.x,p,sizeof(region.x));
 599   p+=sizeof(region.width);
 600   (void) memcpy(&region.y,p,sizeof(region.y));
 601   p+=sizeof(region.width);
 602   (void) memcpy(&length,p,sizeof(length));
 603   p+=sizeof(length);
 604   exception=AcquireExceptionInfo();
 605   q=GetAuthenticPixels(image,region.x,region.y,region.width,region.height,
 606     exception);
 607   exception=DestroyExceptionInfo(exception);
 608   if (q == (Quantum *) NULL)
 609     return(MagickFalse);
 610   metacontent=GetAuthenticMetacontent(image);
 611   count=read(file,metacontent,length);
 612   if (count != (ssize_t) length)
 613     return(MagickFalse);
 614   status=SyncAuthenticPixels(image,exception);
 615   return(status);
 616 }
 617
 618 static MagickBooleanType WriteDistributeCachePixels(
 619   SplayTreeInfo *image_registry,int file,const MagickSizeType session_key)
 620 {
 621   ExceptionInfo
 622     *exception;
 623
 624   Image
 625     *image;
 626
 627   MagickBooleanType
 628     status;
 629
 630   RectangleInfo
 631     region;
 632
 633   register Quantum
 634     *q;
 635
 636   register unsigned char
 637     *p;
 638
 639   size_t
 640     length;
 641
 642   ssize_t
 643     count;
 644
 645   unsigned char
 646     buffer[MaxTextExtent];
 647
 648   image=(Image *) GetValueFromSplayTree(image_registry,(const void *)
 649     session_key);
 650   if (image == (Image *) NULL)
 651     return(MagickFalse);
 652   length=sizeof(region.width)+sizeof(region.height)+sizeof(region.x)+
 653     sizeof(region.y)+sizeof(length);
 654   count=read(file,buffer,length);
 655   if (count != (ssize_t) length)
 656     return(MagickFalse);
 657   p=buffer;
 658   (void) memcpy(&region.width,p,sizeof(region.width));
 659   p+=sizeof(region.width);
 660   (void) memcpy(&region.height,p,sizeof(region.height));
 661   p+=sizeof(region.width);
 662   (void) memcpy(&region.x,p,sizeof(region.x));
 663   p+=sizeof(region.width);
 664   (void) memcpy(&region.y,p,sizeof(region.y));
 665   p+=sizeof(region.width);
 666   (void) memcpy(&length,p,sizeof(length));
 667   p+=sizeof(length);
 668   exception=AcquireExceptionInfo();
 669   q=GetAuthenticPixels(image,region.x,region.y,region.width,region.height,
 670     exception);
 671   exception=DestroyExceptionInfo(exception);
 672   if (q == (Quantum *) NULL)
 673     return(MagickFalse);
 674   count=read(file,q,length);
 675   if (count != (ssize_t) length)
 676     return(MagickFalse);
 677   status=SyncAuthenticPixels(image,exception);
 678   return(status);
 679 }
 680
 681 static void *DistributePixelCacheClient(void *socket)
 682 {
 683   const char
 684     *shared_secret;
 685
 686   int
 687     client_socket;
 688
 689   MagickBooleanType
 690     status;
 691
 692   MagickSizeType
 693     key,
 694     session_key;
 695
 696   RandomInfo
 697     *random_info;
 698
 699   SplayTreeInfo
 700     *image_registry;
 701
 702   ssize_t
 703     count;
 704
 705   StringInfo
 706     *secret;
 707
 708   unsigned char
 709     command,
 710     session[MaxTextExtent];
 711
 712   /*
 713     Generate session key.
 714   */
 715   shared_secret=GetPolicyValue("shared-secret");
 716   if (shared_secret == (const char *) NULL)
 717     ThrowFatalException(CacheFatalError,"shared secret expected");
 718   (void) CopyMagickString((char *) session,shared_secret,MaxTextExtent-
 719     DPCSessionKeyLength);
 720   random_info=AcquireRandomInfo();
 721   secret=GetRandomKey(random_info,DPCSessionKeyLength);
 722   (void) memcpy(session+strlen(shared_secret),GetStringInfoDatum(secret),
 723     DPCSessionKeyLength);
 724   session_key=CRC64(session,strlen(shared_secret)+DPCSessionKeyLength);
 725   random_info=DestroyRandomInfo(random_info);
 726   image_registry=NewSplayTree((int (*)(const void *,const void *)) NULL,
 727     (void *(*)(void *)) NULL,(void *(*)(void *)) NULL);
 728   client_socket=(*(int *) socket);
 729   count=write(client_socket,GetStringInfoDatum(secret),DPCSessionKeyLength);
 730   secret=DestroyStringInfo(secret);
 731   for ( ; ; )
 732   {
 733     count=read(client_socket,&command,1);
 734     if (count <= 0)
 735       break;
 736     count=read(client_socket,&key,sizeof(key));
 737     if ((count != (ssize_t) sizeof(key)) && (key != session_key))
 738       break;
 739     status=MagickFalse;
 740     switch (command)
 741     {
 742       case 'c':
 743       {
 744         status=CreateDistributeCache(image_registry,client_socket,session_key);
 745         break;
 746       }
 747       case 'r':
 748       {
 749         status=ReadDistributeCachePixels(image_registry,client_socket,
 750           session_key);
 751         break;
 752       }
 753       case 'u':
 754       {
 755         status=WriteDistributeCachePixels(image_registry,client_socket,
 756           session_key);
 757         break;
 758       }
 759       case 'd':
 760       {
 761         status=DestroyDistributeCache(image_registry,client_socket,session_key);
 762         break;
 763       }
 764       case 'm':
 765       {
 766         status=ReadDistributeCacheMetacontent(image_registry,client_socket,
 767           session_key);
 768         break;
 769       }
 770       case 'M':
 771       {
 772         status=WriteDistributeCacheMetacontent(image_registry,client_socket,
 773           session_key);
 774         break;
 775       }
 776       default:
 777         break;
 778     }
 779     count=write(client_socket,&status,sizeof(status));
 780     if (count != (ssize_t) sizeof(status))
 781       break;
 782   }
 783   return((void *) NULL);
 784 }
 785
 786 MagickExport void DistributePixelCacheServer(const size_t port,
 787   ExceptionInfo *exception)
 788 {
 789 #if defined(MAGICKCORE_HAVE_SOCKET) && defined(MAGICKCORE_THREAD_SUPPORT)
 790   int
 791     server_socket,
 792     status;
 793
 794   pthread_attr_t
 795     attributes;
 796
 797   pthread_t
 798     threads;
 799
 800   struct sockaddr_in
 801     address;
 802
 803   /*
 804     Launch distributed pixel cache server.
 805   */
 806   server_socket=socket(AF_INET,SOCK_STREAM,0);
 807   address.sin_family=AF_INET;
 808   address.sin_port=htons(port);
 809   address.sin_addr.s_addr=htonl(INADDR_ANY);
 810   status=bind(server_socket,(struct sockaddr *) &address,(socklen_t)
 811     sizeof(address));
 812   if (status != 0)
 813     ThrowFatalException(CacheFatalError,"UnableToBind");
 814   status=listen(server_socket,32);
 815   if (status != 0)
 816     ThrowFatalException(CacheFatalError,"UnableToListen");
 817   pthread_attr_init(&attributes);
 818   for ( ; ; )
 819   {
 820     int
 821       client_socket;
 822
 823     socklen_t
 824       length;
 825
 826     length=(socklen_t) sizeof(address);
 827     client_socket=accept(server_socket,(struct sockaddr *) &address,&length);
 828     if (client_socket == -1)
 829       ThrowFatalException(CacheFatalError,"UnableToEstablishConnection");
 830     status=pthread_create(&threads,&attributes,DistributePixelCacheClient,
 831       (void *) &client_socket);
 832     if (status == -1)
 833       ThrowFatalException(CacheFatalError,"UnableToCreateClientThread");
 834   }
 835   (void) close(server_socket);
 836 #else
 837   ThrowFatalException(MissingDelegateError,"distributed pixel cache");
 838 #endif
 839 }
 840 \f
 841 /*
 842 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 843 %                                                                             %
 844 %                                                                             %
 845 %                                                                             %
 846 +   G e t D i s t r i b u t e C a c h e F i l e                               %
 847 %                                                                             %
 848 %                                                                             %
 849 %                                                                             %
 850 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 851 %
 852 %  GetDistributeCacheFile() returns the file associated with this
 853 %  DistributeCacheInfo structure.
 854 %
 855 %  The format of the GetDistributeCacheFile method is:
 856 %
 857 %      int GetDistributeCacheFile(
 858 %        const DistributeCacheInfo *distribute_cache_info)
 859 %
 860 %  A description of each parameter follows:
 861 %
 862 %    o distribute_cache_info: the distributed cache info.
 863 %
 864 */
 865 MagickPrivate int GetDistributeCacheFile(
 866   const DistributeCacheInfo *distribute_cache_info)
 867 {
 868   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
 869   assert(distribute_cache_info->signature == MagickSignature);
 870   return(distribute_cache_info->file);
 871 }
 872 \f
 873 /*
 874 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 875 %                                                                             %
 876 %                                                                             %
 877 %                                                                             %
 878 +   G e t D i s t r i b u t e C a c h e H o s t n a m e                       %
 879 %                                                                             %
 880 %                                                                             %
 881 %                                                                             %
 882 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 883 %
 884 %  GetDistributeCacheHostname() returns the hostname associated with this
 885 %  DistributeCacheInfo structure.
 886 %
 887 %  The format of the GetDistributeCacheHostname method is:
 888 %
 889 %      const char *GetDistributeCacheHostname(
 890 %        const DistributeCacheInfo *distribute_cache_info)
 891 %
 892 %  A description of each parameter follows:
 893 %
 894 %    o distribute_cache_info: the distributed cache info.
 895 %
 896 */
 897 MagickPrivate const char *GetDistributeCacheHostname(
 898   const DistributeCacheInfo *distribute_cache_info)
 899 {
 900   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
 901   assert(distribute_cache_info->signature == MagickSignature);
 902   return(distribute_cache_info->hostname);
 903 }
 904 \f
 905 /*
 906 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 907 %                                                                             %
 908 %                                                                             %
 909 %                                                                             %
 910 +   G e t D i s t r i b u t e C a c h e P o r t                               %
 911 %                                                                             %
 912 %                                                                             %
 913 %                                                                             %
 914 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 915 %
 916 %  GetDistributeCachePort() returns the port associated with this
 917 %  DistributeCacheInfo structure.
 918 %
 919 %  The format of the GetDistributeCachePort method is:
 920 %
 921 %      int GetDistributeCachePort(
 922 %        const DistributeCacheInfo *distribute_cache_info)
 923 %
 924 %  A description of each parameter follows:
 925 %
 926 %    o distribute_cache_info: the distributed cache info.
 927 %
 928 */
 929 MagickPrivate int GetDistributeCachePort(
 930   const DistributeCacheInfo *distribute_cache_info)
 931 {
 932   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
 933   assert(distribute_cache_info->signature == MagickSignature);
 934   return(distribute_cache_info->port);
 935 }
 936 \f
 937 /*
 938 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 939 %                                                                             %
 940 %                                                                             %
 941 %                                                                             %
 942 +   O p e n D i s t r i b u t e P i x e l C a c h e                           %
 943 %                                                                             %
 944 %                                                                             %
 945 %                                                                             %
 946 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 947 %
 948 %  OpenDistributePixelCache() opens a pixel cache on a remote server.
 949 %
 950 %  The format of the OpenDistributePixelCache method is:
 951 %
 952 %      MagickBooleanType *OpenDistributePixelCache(
 953 %        DistributeCacheInfo *distribute_cache_info,Image *image)
 954 %
 955 %  A description of each parameter follows:
 956 %
 957 %    o distribute_cache_info: the distributed cache info.
 958 %
 959 %    o image: the image.
 960 %
 961 */
 962 MagickPrivate MagickBooleanType OpenDistributePixelCache(
 963   DistributeCacheInfo *distribute_cache_info,Image *image)
 964 {
 965   MagickBooleanType
 966     status;
 967
 968   register unsigned char
 969     *p;
 970
 971   ssize_t
 972     count;
 973
 974   unsigned char
 975     buffer[MaxTextExtent];
 976
 977   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
 978   assert(distribute_cache_info->signature == MagickSignature);
 979   assert(image != (Image *) NULL);
 980   assert(image->signature == MagickSignature);
 981   p=buffer;
 982   *p++='c';  /* create */
 983   (void) memcpy(p,&distribute_cache_info->session_key,
 984     sizeof(distribute_cache_info->session_key));
 985   p+=sizeof(distribute_cache_info->session_key);
 986   (void) memcpy(p,&image->columns,sizeof(image->columns));
 987   p+=sizeof(image->columns);
 988   (void) memcpy(p,&image->rows,sizeof(image->rows));
 989   p+=sizeof(image->rows);
 990   (void) memcpy(p,&image->number_channels,sizeof(image->number_channels));
 991   p+=sizeof(image->number_channels);
 992   count=write(distribute_cache_info->file,buffer,p-buffer);
 993   if (count != (ssize_t) (p-buffer))
 994     return(MagickFalse);
 995   count=read(distribute_cache_info->file,&status,sizeof(status));
 996   if (count != (ssize_t) sizeof(status))
 997     return(MagickFalse);
 998   return(MagickTrue);
 999 }
1000 \f
1001 /*
1002 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1003 %                                                                             %
1004 %                                                                             %
1005 %                                                                             %
1006 +   R e a d D i s t r i b u t e P i x e l C a c h e M e t a c o n t e n t     %
1007 %                                                                             %
1008 %                                                                             %
1009 %                                                                             %
1010 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1011 %
1012 %  ReadDistributePixelCacheMetacontents() reads metacontent from the specified
1013 %  region of the distributed pixel cache.
1014 %
1015 %  The format of the ReadDistributePixelCacheMetacontents method is:
1016 %
1017 %      MagickBooleanType *ReadDistributePixelCacheMetacontents(
1018 %        DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1019 %        const MagickSizeType length,unsigned char *metacontent)
1020 %
1021 %  A description of each parameter follows:
1022 %
1023 %    o distribute_cache_info: the distributed cache info.
1024 %
1025 %    o image: the image.
1026 %
1027 %    o region: read the metacontent from this region of the image.
1028 %
1029 %    o length: the length in bytes of the metacontent.
1030 %
1031 %    o metacontent: read these metacontent from the pixel cache.
1032 %
1033 */
1034 MagickPrivate MagickBooleanType ReadDistributePixelCacheMetacontent(
1035   DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1036   const MagickSizeType length,unsigned char *metacontent)
1037 {
1038   MagickBooleanType
1039     status;
1040
1041   register unsigned char
1042     *p;
1043
1044   ssize_t
1045     count;
1046
1047   unsigned char
1048     buffer[MaxTextExtent];
1049
1050   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
1051   assert(distribute_cache_info->signature == MagickSignature);
1052   assert(region != (RectangleInfo *) NULL);
1053   assert(metacontent != (unsigned char *) NULL);
1054   assert(length == ((size_t) length));
1055   p=buffer;
1056   *p++='m';  /* read */
1057   (void) memcpy(p,&distribute_cache_info->session_key,
1058     sizeof(distribute_cache_info->session_key));
1059   p+=sizeof(distribute_cache_info->session_key);
1060   (void) memcpy(p,&region->width,sizeof(region->width));
1061   p+=sizeof(region->width);
1062   (void) memcpy(p,&region->height,sizeof(region->height));
1063   p+=sizeof(region->height);
1064   (void) memcpy(p,&region->x,sizeof(region->x));
1065   p+=sizeof(region->x);
1066   (void) memcpy(p,&region->y,sizeof(region->y));
1067   p+=sizeof(region->y);
1068   (void) memcpy(p,&length,sizeof(length));
1069   p+=sizeof(length);
1070   count=write(distribute_cache_info->file,buffer,p-buffer);
1071   if (count != (ssize_t) (p-buffer))
1072     return(MagickFalse);
1073   count=read(distribute_cache_info->file,(unsigned char *) metacontent,(size_t)
1074     length);
1075   if (count != (ssize_t) length)
1076     return(MagickFalse);
1077   count=read(distribute_cache_info->file,&status,sizeof(status));
1078   if (count != (ssize_t) sizeof(status))
1079     return(MagickFalse);
1080   return(status != 0 ? MagickTrue : MagickFalse);
1081 }
1082 \f
1083 /*
1084 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1085 %                                                                             %
1086 %                                                                             %
1087 %                                                                             %
1088 +   R e a d D i s t r i b u t e P i x e l C a c h e P i x e l s               %
1089 %                                                                             %
1090 %                                                                             %
1091 %                                                                             %
1092 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1093 %
1094 %  ReadDistributePixelCachePixels() reads pixels from the specified region of
1095 %  the distributed pixel cache.
1096 %
1097 %  The format of the ReadDistributePixelCachePixels method is:
1098 %
1099 %      MagickBooleanType *ReadDistributePixelCachePixels(
1100 %        DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1101 %        const MagickSizeType length,unsigned char *pixels)
1102 %
1103 %  A description of each parameter follows:
1104 %
1105 %    o distribute_cache_info: the distributed cache info.
1106 %
1107 %    o image: the image.
1108 %
1109 %    o region: read the pixels from this region of the image.
1110 %
1111 %    o length: the length in bytes of the pixels.
1112 %
1113 %    o pixels: read these pixels from the pixel cache.
1114 %
1115 */
1116 MagickPrivate MagickBooleanType ReadDistributePixelCachePixels(
1117   DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1118   const MagickSizeType length,unsigned char *pixels)
1119 {
1120   MagickBooleanType
1121     status;
1122
1123   register unsigned char
1124     *p;
1125
1126   ssize_t
1127     count;
1128
1129   unsigned char
1130     buffer[MaxTextExtent];
1131
1132   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
1133   assert(distribute_cache_info->signature == MagickSignature);
1134   assert(region != (RectangleInfo *) NULL);
1135   assert(pixels != (unsigned char *) NULL);
1136   assert(length == ((size_t) length));
1137   p=buffer;
1138   *p++='r';  /* read */
1139   (void) memcpy(p,&distribute_cache_info->session_key,
1140     sizeof(distribute_cache_info->session_key));
1141   p+=sizeof(distribute_cache_info->session_key);
1142   (void) memcpy(p,&region->width,sizeof(region->width));
1143   p+=sizeof(region->width);
1144   (void) memcpy(p,&region->height,sizeof(region->height));
1145   p+=sizeof(region->height);
1146   (void) memcpy(p,&region->x,sizeof(region->x));
1147   p+=sizeof(region->x);
1148   (void) memcpy(p,&region->y,sizeof(region->y));
1149   p+=sizeof(region->y);
1150   (void) memcpy(p,&length,sizeof(length));
1151   p+=sizeof(length);
1152   count=write(distribute_cache_info->file,buffer,p-buffer);
1153   if (count != (ssize_t) (p-buffer))
1154     return(MagickFalse);
1155   count=read(distribute_cache_info->file,(unsigned char *) pixels,(size_t)
1156     length);
1157   if (count != (ssize_t) length)
1158     return(MagickFalse);
1159   count=read(distribute_cache_info->file,&status,sizeof(status));
1160   if (count != (ssize_t) sizeof(status))
1161     return(MagickFalse);
1162   return(status != 0 ? MagickTrue : MagickFalse);
1163 }
1164 \f
1165 /*
1166 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1167 %                                                                             %
1168 %                                                                             %
1169 %                                                                             %
1170 +   R e l i n q u i s h D i s t r i b u t e P i x e l C a c h e               %
1171 %                                                                             %
1172 %                                                                             %
1173 %                                                                             %
1174 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1175 %
1176 %  RelinquishDistributePixelCache() frees resources acquired with
1177 %  OpenDistributePixelCache().
1178 %
1179 %  The format of the RelinquishDistributePixelCache method is:
1180 %
1181 %      MagickBooleanType RelinquishDistributePixelCache(
1182 %        DistributeCacheInfo *distribute_cache_info)
1183 %
1184 %  A description of each parameter follows:
1185 %
1186 %    o distribute_cache_info: the distributed cache info.
1187 %
1188 */
1189 MagickPrivate MagickBooleanType RelinquishDistributePixelCache(
1190   DistributeCacheInfo *distribute_cache_info)
1191 {
1192   register unsigned char
1193     *p;
1194
1195   ssize_t
1196     count;
1197
1198   unsigned char
1199     buffer[MaxTextExtent];
1200
1201   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
1202   assert(distribute_cache_info->signature == MagickSignature);
1203   p=buffer;
1204   *p++='d';  /* delete */
1205   (void) memcpy(p,&distribute_cache_info->session_key,
1206     sizeof(distribute_cache_info->session_key));
1207   p+=sizeof(distribute_cache_info->session_key);
1208   count=write(distribute_cache_info->file,buffer,p-buffer);
1209   if (count != (ssize_t) (p-buffer))
1210     return(MagickFalse);
1211   return(MagickTrue);
1212 }
1213 \f
1214 /*
1215 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1216 %                                                                             %
1217 %                                                                             %
1218 %                                                                             %
1219 +   W r i t e D i s t r i b u t e P i x e l C a c h e M e t a c o n t e n t   %
1220 %                                                                             %
1221 %                                                                             %
1222 %                                                                             %
1223 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1224 %
1225 %  WriteDistributePixelCacheMetacontents() writes image metacontent to the
1226 %  specified region of the distributed pixel cache.
1227 %
1228 %
1229 %  The format of the WriteDistributePixelCacheMetacontents method is:
1230 %
1231 %      MagickBooleanType *WriteDistributePixelCacheMetacontents(
1232 %        DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1233 %        const MagickSizeType length,const unsigned char *metacontent)
1234 %
1235 %  A description of each parameter follows:
1236 %
1237 %    o distribute_cache_info: the distributed cache info.
1238 %
1239 %    o image: the image.
1240 %
1241 %    o region: write the metacontent to this region of the image.
1242 %
1243 %    o length: the length in bytes of the metacontent.
1244 %
1245 %    o metacontent: write these metacontent to the pixel cache.
1246 %
1247 */
1248 MagickPrivate MagickBooleanType WriteDistributePixelCacheMetacontent(
1249   DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1250   const MagickSizeType length,const unsigned char *metacontent)
1251 {
1252   MagickBooleanType
1253     status;
1254
1255   register unsigned char
1256     *p;
1257
1258   ssize_t
1259     count;
1260
1261   unsigned char
1262     buffer[MaxTextExtent];
1263
1264   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
1265   assert(distribute_cache_info->signature == MagickSignature);
1266   assert(region != (RectangleInfo *) NULL);
1267   assert(metacontent != (unsigned char *) NULL);
1268   assert(length == ((size_t) length));
1269   p=buffer;
1270   *p++='M';  /* update */
1271   (void) memcpy(p,&distribute_cache_info->session_key,
1272     sizeof(distribute_cache_info->session_key));
1273   p+=sizeof(distribute_cache_info->session_key);
1274   (void) memcpy(p,&region->width,sizeof(region->width));
1275   p+=sizeof(region->width);
1276   (void) memcpy(p,&region->height,sizeof(region->height));
1277   p+=sizeof(region->height);
1278   (void) memcpy(p,&region->x,sizeof(region->x));
1279   p+=sizeof(region->x);
1280   (void) memcpy(p,&region->y,sizeof(region->y));
1281   p+=sizeof(region->y);
1282   (void) memcpy(p,&length,sizeof(length));
1283   p+=sizeof(length);
1284   count=write(distribute_cache_info->file,buffer,p-buffer);
1285   if (count != (ssize_t) (p-buffer))
1286     return(MagickFalse);
1287   count=write(distribute_cache_info->file,(unsigned char *) metacontent,(size_t)
1288     length);
1289   if (count != (ssize_t) length)
1290     return(MagickFalse);
1291   count=read(distribute_cache_info->file,&status,sizeof(status));
1292   if (count != (ssize_t) sizeof(status))
1293     return(MagickFalse);
1294   return(status != 0 ? MagickTrue : MagickFalse);
1295 }
1296 \f
1297 /*
1298 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1299 %                                                                             %
1300 %                                                                             %
1301 %                                                                             %
1302 +   W r i t e D i s t r i b u t e P i x e l C a c h e P i x e l s             %
1303 %                                                                             %
1304 %                                                                             %
1305 %                                                                             %
1306 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1307 %
1308 %  WriteDistributePixelCachePixels() writes image pixels to the specified
1309 %  region of the distributed pixel cache.
1310 %
1311 %
1312 %  The format of the WriteDistributePixelCachePixels method is:
1313 %
1314 %      MagickBooleanType *WriteDistributePixelCachePixels(
1315 %        DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1316 %        const MagickSizeType length,const unsigned char *pixels)
1317 %
1318 %  A description of each parameter follows:
1319 %
1320 %    o distribute_cache_info: the distributed cache info.
1321 %
1322 %    o image: the image.
1323 %
1324 %    o region: write the pixels to this region of the image.
1325 %
1326 %    o length: the length in bytes of the pixels.
1327 %
1328 %    o pixels: write these pixels to the pixel cache.
1329 %
1330 */
1331 MagickPrivate MagickBooleanType WriteDistributePixelCachePixels(
1332   DistributeCacheInfo *distribute_cache_info,const RectangleInfo *region,
1333   const MagickSizeType length,const unsigned char *pixels)
1334 {
1335   MagickBooleanType
1336     status;
1337
1338   register unsigned char
1339     *p;
1340
1341   ssize_t
1342     count;
1343
1344   unsigned char
1345     buffer[MaxTextExtent];
1346
1347   assert(distribute_cache_info != (DistributeCacheInfo *) NULL);
1348   assert(distribute_cache_info->signature == MagickSignature);
1349   assert(region != (RectangleInfo *) NULL);
1350   assert(pixels != (const unsigned char *) NULL);
1351   assert(length == ((size_t) length));
1352   p=buffer;
1353   *p++='u';  /* update */
1354   (void) memcpy(p,&distribute_cache_info->session_key,
1355     sizeof(distribute_cache_info->session_key));
1356   p+=sizeof(distribute_cache_info->session_key);
1357   (void) memcpy(p,&region->width,sizeof(region->width));
1358   p+=sizeof(region->width);
1359   (void) memcpy(p,&region->height,sizeof(region->height));
1360   p+=sizeof(region->height);
1361   (void) memcpy(p,&region->x,sizeof(region->x));
1362   p+=sizeof(region->x);
1363   (void) memcpy(p,&region->y,sizeof(region->y));
1364   p+=sizeof(region->y);
1365   (void) memcpy(p,&length,sizeof(length));
1366   p+=sizeof(length);
1367   count=write(distribute_cache_info->file,buffer,p-buffer);
1368   if (count != (ssize_t) (p-buffer))
1369     return(MagickFalse);
1370   count=write(distribute_cache_info->file,(unsigned char *) pixels,(size_t)
1371     length);
1372   if (count != (ssize_t) length)
1373     return(MagickFalse);
1374   count=read(distribute_cache_info->file,&status,sizeof(status));
1375   if (count != (ssize_t) sizeof(status))
1376     return(MagickFalse);
1377   return(status != 0 ? MagickTrue : MagickFalse);
1378 }