Actual source code: send.c

      2: #include <petscsys.h>

      4: #if defined(PETSC_NEEDS_UTYPE_TYPEDEFS)
      5: /* Some systems have inconsistent include files that use but do not
      6:    ensure that the following definitions are made */
      7: typedef unsigned char   u_char;
      8: typedef unsigned short  u_short;
      9: typedef unsigned short  ushort;
     10: typedef unsigned int    u_int;
     11: typedef unsigned long   u_long;
     12: #endif

     14: #include <errno.h>
     15: #include <ctype.h>
     16: #if defined(PETSC_HAVE_MACHINE_ENDIAN_H)
     17: #include <machine/endian.h>
     18: #endif
     19: #if defined(PETSC_HAVE_UNISTD_H)
     20: #include <unistd.h>
     21: #endif
     22: #if defined(PETSC_HAVE_SYS_SOCKET_H)
     23: #include <sys/socket.h>
     24: #endif
     25: #if defined(PETSC_HAVE_SYS_WAIT_H)
     26: #include <sys/wait.h>
     27: #endif
     28: #if defined(PETSC_HAVE_NETINET_IN_H)
     29: #include <netinet/in.h>
     30: #endif
     31: #if defined(PETSC_HAVE_NETDB_H)
     32: #include <netdb.h>
     33: #endif
     34: #if defined(PETSC_HAVE_FCNTL_H)
     35: #include <fcntl.h>
     36: #endif
     37: #if defined(PETSC_HAVE_IO_H)
     38: #include <io.h>
     39: #endif
     40: #if defined(PETSC_HAVE_WINSOCK2_H)
     41: #include <Winsock2.h>
     42: #endif
     43: #include <sys/stat.h>
     44: #include <../src/sys/classes/viewer/impls/socket/socket.h>

     46: #if defined(PETSC_NEED_CLOSE_PROTO)
     47: PETSC_EXTERN int close(int);
     48: #endif
     49: #if defined(PETSC_NEED_SOCKET_PROTO)
     50: PETSC_EXTERN int socket(int,int,int);
     51: #endif
     52: #if defined(PETSC_NEED_SLEEP_PROTO)
     53: PETSC_EXTERN int sleep(unsigned);
     54: #endif
     55: #if defined(PETSC_NEED_CONNECT_PROTO)
     56: PETSC_EXTERN int connect(int,struct sockaddr*,int);
     57: #endif

     59: /*--------------------------------------------------------------*/
     60: static PetscErrorCode PetscViewerDestroy_Socket(PetscViewer viewer)
     61: {
     62:   PetscViewer_Socket *vmatlab = (PetscViewer_Socket*)viewer->data;
     63:   PetscErrorCode     ierr;

     65:   if (vmatlab->port) {
     66: #if defined(PETSC_HAVE_CLOSESOCKET)
     67:     closesocket(vmatlab->port);
     68: #else
     69:     close(vmatlab->port);
     70: #endif
     72:   }
     73:   PetscFree(vmatlab);
     74:   return 0;
     75: }

     77: /*--------------------------------------------------------------*/
     78: /*@C
     79:     PetscSocketOpen - handles connected to an open port where someone is waiting.

     81:     Input Parameters:
     82: +    url - for example www.mcs.anl.gov
     83: -    portnum - for example 80

     85:     Output Parameter:
     86: .    t - the socket number

     88:     Notes:
     89:     Use close() to close the socket connection

     91:     Use read() or PetscHTTPRequest() to read from the socket

     93:     Level: advanced

     95: .seealso:   PetscSocketListen(), PetscSocketEstablish(), PetscHTTPRequest(), PetscHTTPSConnect()
     96: @*/
     97: PetscErrorCode  PetscOpenSocket(const char hostname[],int portnum,int *t)
     98: {
     99:   struct sockaddr_in sa;
    100:   struct hostent     *hp;
    101:   int                s = 0;
    102:   PetscBool          flg = PETSC_TRUE;
    103:   static int         refcnt = 0;

    105:   if (!(hp=gethostbyname(hostname))) {
    106:     perror("SEND: error gethostbyname: ");
    107:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"system error open connection to %s",hostname);
    108:   }
    109:   PetscMemzero(&sa,sizeof(sa));
    110:   PetscMemcpy(&sa.sin_addr,hp->h_addr_list[0],hp->h_length);

    112:   sa.sin_family = hp->h_addrtype;
    113:   sa.sin_port   = htons((u_short) portnum);
    114:   while (flg) {
    115:     if ((s=socket(hp->h_addrtype,SOCK_STREAM,0)) < 0) {
    116:       perror("SEND: error socket");  SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"system error");
    117:     }
    118:     if (connect(s,(struct sockaddr*)&sa,sizeof(sa)) < 0) {
    119: #if defined(PETSC_HAVE_WSAGETLASTERROR)
    120:       WSAGetLastError();
    121:       if (ierr == WSAEADDRINUSE)    (*PetscErrorPrintf)("SEND: address is in use\n");
    122:       else if (ierr == WSAEALREADY) (*PetscErrorPrintf)("SEND: socket is non-blocking \n");
    123:       else if (ierr == WSAEISCONN) {
    124:         (*PetscErrorPrintf)("SEND: socket already connected\n");
    125:         Sleep((unsigned) 1);
    126:       } else if (ierr == WSAECONNREFUSED) {
    127:         /* (*PetscErrorPrintf)("SEND: forcefully rejected\n"); */
    128:         Sleep((unsigned) 1);
    129:       } else {
    130:         perror(NULL); SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"system error");
    131:       }
    132: #else
    133:       if (errno == EADDRINUSE)    (*PetscErrorPrintf)("SEND: address is in use\n");
    134:       else if (errno == EALREADY) (*PetscErrorPrintf)("SEND: socket is non-blocking \n");
    135:       else if (errno == EISCONN) {
    136:         (*PetscErrorPrintf)("SEND: socket already connected\n");
    137:         sleep((unsigned) 1);
    138:       } else if (errno == ECONNREFUSED) {
    139:         refcnt++;
    141:         PetscInfo(NULL,"Connection refused in attaching socket, trying again\n");
    142:         sleep((unsigned) 1);
    143:       } else {
    144:         perror(NULL); SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"system error");
    145:       }
    146: #endif
    147:       flg = PETSC_TRUE;
    148: #if defined(PETSC_HAVE_CLOSESOCKET)
    149:       closesocket(s);
    150: #else
    151:       close(s);
    152: #endif
    153:     } else flg = PETSC_FALSE;
    154:   }
    155:   *t = s;
    156:   return 0;
    157: }

    159: /*@C
    160:    PetscSocketEstablish - starts a listener on a socket

    162:    Input Parameters:
    163: .    portnumber - the port to wait at

    165:    Output Parameters:
    166: .     ss - the socket to be used with PetscSocketListen()

    168:     Level: advanced

    170: .seealso:   PetscSocketListen(), PetscOpenSocket()

    172: @*/
    173: PETSC_INTERN PetscErrorCode PetscSocketEstablish(int portnum,int *ss)
    174: {
    175:   static size_t      MAXHOSTNAME = 100;
    176:   char               myname[MAXHOSTNAME+1];
    177:   int                s;
    178:   struct sockaddr_in sa;
    179:   struct hostent     *hp;

    181:   PetscGetHostName(myname,sizeof(myname));

    183:   PetscMemzero(&sa,sizeof(struct sockaddr_in));

    185:   hp = gethostbyname(myname);

    188:   sa.sin_family = hp->h_addrtype;
    189:   sa.sin_port   = htons((u_short)portnum);

    192: #if defined(PETSC_HAVE_SO_REUSEADDR)
    193:   {
    194:     int optval = 1; /* Turn on the option */
    195:     setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char*)&optval,sizeof(optval));
    196:   }
    197: #endif

    199:   while (bind(s,(struct sockaddr*)&sa,sizeof(sa)) < 0) {
    200: #if defined(PETSC_HAVE_WSAGETLASTERROR)
    201:     WSAGetLastError();
    202:     if (ierr != WSAEADDRINUSE) {
    203: #else
    204:     if (errno != EADDRINUSE) {
    205: #endif
    206:       close(s);
    207:       SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"Error from bind()");
    208:     }
    209:   }
    210:   listen(s,0);
    211:   *ss = s;
    212:   return(0);
    213: }

    215: /*@C
    216:    PetscSocketListen - Listens at a socket created with PetscSocketEstablish()

    218:    Input Parameter:
    219: .    listenport - obtained with PetscSocketEstablish()

    221:    Output Parameter:
    222: .     t - pass this to read() to read what is passed to this connection

    224:     Level: advanced

    226: .seealso:   PetscSocketEstablish()
    227: @*/
    228: PETSC_INTERN PetscErrorCode PetscSocketListen(int listenport,int *t)
    229: {
    230:   struct sockaddr_in isa;
    231: #if defined(PETSC_HAVE_ACCEPT_SIZE_T)
    232:   size_t             i;
    233: #else
    234:   int                i;
    235: #endif

    237:   /* wait for someone to try to connect */
    238:   i = sizeof(struct sockaddr_in);
    240:   return 0;
    241: }

    243: /*@C
    244:    PetscViewerSocketOpen - Opens a connection to a MATLAB or other socket based server.

    246:    Collective

    248:    Input Parameters:
    249: +  comm - the MPI communicator
    250: .  machine - the machine the server is running on,, use NULL for the local machine, use "server" to passively wait for
    251:              a connection from elsewhere
    252: -  port - the port to connect to, use PETSC_DEFAULT for the default

    254:    Output Parameter:
    255: .  lab - a context to use when communicating with the server

    257:    Level: intermediate

    259:    Notes:
    260:    Most users should employ the following commands to access the
    261:    MATLAB PetscViewers
    262: $
    263: $    PetscViewerSocketOpen(MPI_Comm comm, char *machine,int port,PetscViewer &viewer)
    264: $    MatView(Mat matrix,PetscViewer viewer)
    265: $
    266: $                or
    267: $
    268: $    PetscViewerSocketOpen(MPI_Comm comm,char *machine,int port,PetscViewer &viewer)
    269: $    VecView(Vec vector,PetscViewer viewer)

    271:    Options Database Keys:
    272:    For use with  PETSC_VIEWER_SOCKET_WORLD, PETSC_VIEWER_SOCKET_SELF,
    273:    PETSC_VIEWER_SOCKET_() or if
    274:     NULL is passed for machine or PETSC_DEFAULT is passed for port
    275: $    -viewer_socket_machine <machine>
    276: $    -viewer_socket_port <port>

    278:    Environmental variables:
    279: +   PETSC_VIEWER_SOCKET_PORT - portnumber
    280: -   PETSC_VIEWER_SOCKET_MACHINE - machine name

    282:      Currently the only socket client available is MATLAB. See
    283:      src/dm/tests/ex12.c and ex12.m for an example of usage.

    285:    Notes:
    286:     The socket viewer is in some sense a subclass of the binary viewer, to read and write to the socket
    287:           use PetscViewerBinaryRead(), PetscViewerBinaryWrite(), PetscViewerBinarWriteStringArray(), PetscViewerBinaryGetDescriptor().

    289:      Use this for communicating with an interactive MATLAB session, see PETSC_VIEWER_MATLAB_() for writing output to a
    290:      .mat file. Use PetscMatlabEngineCreate() or PETSC_MATLAB_ENGINE_(), PETSC_MATLAB_ENGINE_SELF, or PETSC_MATLAB_ENGINE_WORLD
    291:      for communicating with a MATLAB Engine

    293: .seealso: MatView(), VecView(), PetscViewerDestroy(), PetscViewerCreate(), PetscViewerSetType(),
    294:           PetscViewerSocketSetConnection(), PETSC_VIEWER_SOCKET_, PETSC_VIEWER_SOCKET_WORLD,
    295:           PETSC_VIEWER_SOCKET_SELF, PetscViewerBinaryWrite(), PetscViewerBinaryRead(), PetscViewerBinaryWriteStringArray(),
    296:           PetscBinaryViewerGetDescriptor(), PetscMatlabEngineCreate()
    297: @*/
    298: PetscErrorCode  PetscViewerSocketOpen(MPI_Comm comm,const char machine[],int port,PetscViewer *lab)
    299: {
    300:   PetscViewerCreate(comm,lab);
    301:   PetscViewerSetType(*lab,PETSCVIEWERSOCKET);
    302:   PetscViewerSocketSetConnection(*lab,machine,port);
    303:   return 0;
    304: }

    306: static PetscErrorCode PetscViewerSetFromOptions_Socket(PetscOptionItems *PetscOptionsObject,PetscViewer v)
    307: {
    308:   PetscInt       def = -1;
    309:   char           sdef[256];
    310:   PetscBool      tflg;

    312:   /*
    313:        These options are not processed here, they are processed in PetscViewerSocketSetConnection(), they
    314:     are listed here for the GUI to display
    315:   */
    316:   PetscOptionsHead(PetscOptionsObject,"Socket PetscViewer Options");
    317:   PetscOptionsGetenv(PetscObjectComm((PetscObject)v),"PETSC_VIEWER_SOCKET_PORT",sdef,16,&tflg);
    318:   if (tflg) {
    319:     PetscOptionsStringToInt(sdef,&def);
    320:   } else def = PETSCSOCKETDEFAULTPORT;
    321:   PetscOptionsInt("-viewer_socket_port","Port number to use for socket","PetscViewerSocketSetConnection",def,NULL,NULL);

    323:   PetscOptionsString("-viewer_socket_machine","Machine to use for socket","PetscViewerSocketSetConnection",sdef,NULL,sizeof(sdef),NULL);
    324:   PetscOptionsGetenv(PetscObjectComm((PetscObject)v),"PETSC_VIEWER_SOCKET_MACHINE",sdef,sizeof(sdef),&tflg);
    325:   if (!tflg) {
    326:     PetscGetHostName(sdef,sizeof(sdef));
    327:   }
    328:   PetscOptionsTail();
    329:   return 0;
    330: }

    332: static PetscErrorCode PetscViewerBinaryGetSkipHeader_Socket(PetscViewer viewer,PetscBool  *skip)
    333: {
    334:   PetscViewer_Socket *vsocket = (PetscViewer_Socket*)viewer->data;

    336:   *skip = vsocket->skipheader;
    337:   return 0;
    338: }

    340: static PetscErrorCode PetscViewerBinarySetSkipHeader_Socket(PetscViewer viewer,PetscBool skip)
    341: {
    342:   PetscViewer_Socket *vsocket = (PetscViewer_Socket*)viewer->data;

    344:   vsocket->skipheader = skip;
    345:   return 0;
    346: }

    348: static PetscErrorCode  PetscViewerBinaryGetFlowControl_Socket(PetscViewer viewer,PetscInt *fc)
    349: {
    350:   *fc = 0;
    351:   return 0;
    352: }

    354: /*MC
    355:    PETSCVIEWERSOCKET - A viewer that writes to a Unix socket

    357: .seealso:  PetscViewerSocketOpen(), PetscViewerDrawOpen(), PETSC_VIEWER_DRAW_(),PETSC_VIEWER_DRAW_SELF, PETSC_VIEWER_DRAW_WORLD,
    358:            PetscViewerCreate(), PetscViewerASCIIOpen(), PetscViewerBinaryOpen(), PETSCVIEWERBINARY, PETSCVIEWERDRAW,
    359:            PetscViewerMatlabOpen(), VecView(), DMView(), PetscViewerMatlabPutArray(), PETSCVIEWERASCII, PETSCVIEWERMATLAB,
    360:            PetscViewerFileSetName(), PetscViewerFileSetMode(), PetscViewerFormat, PetscViewerType, PetscViewerSetType()

    362:   Level: beginner
    363: M*/

    365: PETSC_EXTERN PetscErrorCode PetscViewerCreate_Socket(PetscViewer v)
    366: {
    367:   PetscViewer_Socket *vmatlab;

    369:   PetscNewLog(v,&vmatlab);
    370:   vmatlab->port          = 0;
    371:   v->data                = (void*)vmatlab;
    372:   v->ops->destroy        = PetscViewerDestroy_Socket;
    373:   v->ops->flush          = NULL;
    374:   v->ops->setfromoptions = PetscViewerSetFromOptions_Socket;

    376:   /* lie and say this is a binary viewer; then all the XXXView_Binary() methods will work correctly on it */
    377:   PetscObjectChangeTypeName((PetscObject)v,PETSCVIEWERBINARY);
    378:   PetscObjectComposeFunction((PetscObject)v,"PetscViewerBinarySetSkipHeader_C",PetscViewerBinarySetSkipHeader_Socket);
    379:   PetscObjectComposeFunction((PetscObject)v,"PetscViewerBinaryGetSkipHeader_C",PetscViewerBinaryGetSkipHeader_Socket);
    380:   PetscObjectComposeFunction((PetscObject)v,"PetscViewerBinaryGetFlowControl_C",PetscViewerBinaryGetFlowControl_Socket);

    382:   return 0;
    383: }

    385: /*@C
    386:       PetscViewerSocketSetConnection - Sets the machine and port that a PETSc socket
    387:              viewer is to use

    389:   Logically Collective on PetscViewer

    391:   Input Parameters:
    392: +   v - viewer to connect
    393: .   machine - host to connect to, use NULL for the local machine,use "server" to passively wait for
    394:              a connection from elsewhere
    395: -   port - the port on the machine one is connecting to, use PETSC_DEFAULT for default

    397:     Level: advanced

    399: .seealso: PetscViewerSocketOpen()
    400: @*/
    401: PetscErrorCode  PetscViewerSocketSetConnection(PetscViewer v,const char machine[],int port)
    402: {
    403:   PetscMPIInt        rank;
    404:   char               mach[256];
    405:   PetscBool          tflg;
    406:   PetscViewer_Socket *vmatlab;

    410:   vmatlab = (PetscViewer_Socket*)v->data;
    412:   if (port <= 0) {
    413:     char portn[16];
    414:     PetscOptionsGetenv(PetscObjectComm((PetscObject)v),"PETSC_VIEWER_SOCKET_PORT",portn,16,&tflg);
    415:     if (tflg) {
    416:       PetscInt pport;
    417:       PetscOptionsStringToInt(portn,&pport);
    418:       port = (int)pport;
    419:     } else port = PETSCSOCKETDEFAULTPORT;
    420:   }
    421:   if (!machine) {
    422:     PetscOptionsGetenv(PetscObjectComm((PetscObject)v),"PETSC_VIEWER_SOCKET_MACHINE",mach,sizeof(mach),&tflg);
    423:     if (!tflg) {
    424:       PetscGetHostName(mach,sizeof(mach));
    425:     }
    426:   } else {
    427:     PetscStrncpy(mach,machine,sizeof(mach));
    428:   }

    430:   MPI_Comm_rank(PetscObjectComm((PetscObject)v),&rank);
    431:   if (rank == 0) {
    432:     PetscStrcmp(mach,"server",&tflg);
    433:     if (tflg) {
    434:       int listenport;
    435:       PetscInfo(v,"Waiting for connection from socket process on port %d\n",port);
    436:       PetscSocketEstablish(port,&listenport);
    437:       PetscSocketListen(listenport,&vmatlab->port);
    438:       close(listenport);
    439:     } else {
    440:       PetscInfo(v,"Connecting to socket process on port %d machine %s\n",port,mach);
    441:       PetscOpenSocket(mach,port,&vmatlab->port);
    442:     }
    443:   }
    444:   return 0;
    445: }

    447: /* ---------------------------------------------------------------------*/
    448: /*
    449:     The variable Petsc_Viewer_Socket_keyval is used to indicate an MPI attribute that
    450:   is attached to a communicator, in this case the attribute is a PetscViewer.
    451: */
    452: PetscMPIInt Petsc_Viewer_Socket_keyval = MPI_KEYVAL_INVALID;

    454: /*@C
    455:      PETSC_VIEWER_SOCKET_ - Creates a socket viewer shared by all processors in a communicator.

    457:      Collective

    459:      Input Parameter:
    460: .    comm - the MPI communicator to share the socket PetscViewer

    462:      Level: intermediate

    464:    Options Database Keys:
    465:    For use with the default PETSC_VIEWER_SOCKET_WORLD or if
    466:     NULL is passed for machine or PETSC_DEFAULT is passed for port
    467: $    -viewer_socket_machine <machine>
    468: $    -viewer_socket_port <port>

    470:    Environmental variables:
    471: +   PETSC_VIEWER_SOCKET_PORT - portnumber
    472: -   PETSC_VIEWER_SOCKET_MACHINE - machine name

    474:      Notes:
    475:      Unlike almost all other PETSc routines, Petsc_VIEWER_SOCKET_ does not return
    476:      an error code, it returns NULL if it fails. The socket PetscViewer is usually used in the form
    477: $       XXXView(XXX object,PETSC_VIEWER_SOCKET_(comm));

    479:      Currently the only socket client available is MATLAB. See
    480:      src/dm/tests/ex12.c and ex12.m for an example of usage.

    482:      Connects to a waiting socket and stays connected until PetscViewerDestroy() is called.

    484:      Use this for communicating with an interactive MATLAB session, see PETSC_VIEWER_MATLAB_() for writing output to a
    485:      .mat file. Use PetscMatlabEngineCreate() or PETSC_MATLAB_ENGINE_(), PETSC_MATLAB_ENGINE_SELF, or PETSC_MATLAB_ENGINE_WORLD
    486:      for communicating with a MATLAB Engine

    488: .seealso: PETSC_VIEWER_SOCKET_WORLD, PETSC_VIEWER_SOCKET_SELF, PetscViewerSocketOpen(), PetscViewerCreate(),
    489:           PetscViewerSocketSetConnection(), PetscViewerDestroy(), PETSC_VIEWER_SOCKET_(), PetscViewerBinaryWrite(), PetscViewerBinaryRead(),
    490:           PetscViewerBinaryWriteStringArray(), PetscViewerBinaryGetDescriptor(), PETSC_VIEWER_MATLAB_()
    491: @*/
    492: PetscViewer  PETSC_VIEWER_SOCKET_(MPI_Comm comm)
    493: {
    495:   PetscBool      flg;
    496:   PetscViewer    viewer;
    497:   MPI_Comm       ncomm;

    499:   PetscCommDuplicate(comm,&ncomm,NULL);if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL," ");return NULL;}
    500:   if (Petsc_Viewer_Socket_keyval == MPI_KEYVAL_INVALID) {
    501:     MPI_Comm_create_keyval(MPI_COMM_NULL_COPY_FN,MPI_COMM_NULL_DELETE_FN,&Petsc_Viewer_Socket_keyval,NULL);
    502:     if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL," ");return NULL;}
    503:   }
    504:   MPI_Comm_get_attr(ncomm,Petsc_Viewer_Socket_keyval,(void**)&viewer,(int*)&flg);
    505:   if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL," ");return NULL;}
    506:   if (!flg) { /* PetscViewer not yet created */
    507:     PetscViewerSocketOpen(ncomm,NULL,0,&viewer);
    508:     if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_REPEAT," ");return NULL;}
    509:     PetscObjectRegisterDestroy((PetscObject)viewer);
    510:     if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_REPEAT," ");return NULL;}
    511:     MPI_Comm_set_attr(ncomm,Petsc_Viewer_Socket_keyval,(void*)viewer);
    512:     if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_INITIAL," ");return NULL;}
    513:   }
    514:   PetscCommDestroy(&ncomm);
    515:   if (ierr) {PetscError(PETSC_COMM_SELF,__LINE__,"PETSC_VIEWER_SOCKET_",__FILE__,PETSC_ERR_PLIB,PETSC_ERROR_REPEAT," ");return NULL;}
    516:   return viewer;
    517: }