grbseek.c

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/*--- READ ENTIRE MSG into GRIB HEADER's Entire_Msg ---*/
/*
*
* A.3.3.9          READ the entire message into Grib Hdr's Entire_Msg;
*                  IF (failed) THEN
*                      RETURN Fread error stat=1  !errmsg filled
*                  ENDIF
*/
	  fwa_msg = (char *)gh->entire_msg;
          if ((nread=fread (fwa_msg, 1, lMessageSize, *fp)) != lMessageSize) 
	    {
            DPRINT2 ( "%s:  failed to Fread EntireMsg (sz=%ld)\n",
	    func, lMessageSize);
	    sprintf(errmsg,
            "%s: %s has truncated msg @offs=%ld (got %ld out of %ld bytes)\n",
            func, InFile, *offset, nread, lMessageSize);
	    status= 1;  /* to get out of Outer loop */
	    goto DONE;  /* get out of WHILE */
	    }

/*--- if see '7777', asssign GH's pointers & len  ---*/
/*
* A.3.3.10         IF ('7777' is where expected) THEN
*/
          if (!strncmp((fwa_msg + lMessageSize - 4),"7777",4))
		/*  && fwa_msg[7]==1)  */
	  {  
 	        end_ptr = fwa_msg + lMessageSize;

		DPRINT0 ("Found string '7777' where expected\n");
		gh->msg_length= lMessageSize;
/*
* A.3.3.10.a.1         STORE loc & len of section 0 into Grib Hdr;
*/
		gh->ids_ptr= (unsigned char *)fwa_msg;    /* mark sect 0 */
		gh->ids_len= 8L;

/*
* A.3.3.10.a.2         STORE loc & len of PDS into Grib Hdr; 
*                     FUNCTION gbyte   !get 3-byte length
*/
	        ptr=  fwa_msg + gh->ids_len;
		gh->pds_ptr= (unsigned char *)ptr;            /* mark PDS */
		iskip= 0; gbyte(ptr ,(unsigned long *)&gh->pds_len,&iskip,24); 
		DPRINT0 (" pds length\n");
		iskip= 8*7; gbyte(ptr ,(unsigned long*)&gdsbmsflag, &iskip, 8);
		DPRINT1 (" (%x hex) Gds/Bms flag\n", gdsbmsflag);
/*
* A.3.3.10.a.3         IF (location of next Section  is out of bound) THEN
*                        PRINT message;
*                        GOTO drop this msg;
*                     ENDIF
*/
		ptr += gh->pds_len;
	        if (ptr > end_ptr) {
		    sprintf(errmsg,
		    "%s %s:  corrupt PDSlen= %ld, Totlen=%ld, drop msg @%ld;\n"
		    , func,InFile,  gh->pds_len, gh->msg_length, *offset);
		    gh->pds_len= 0;  		     /* reset */
		    goto DROPMSG_N_LOOP;
		    }

/*
*                     IF (Debug) FUNCTION hdr_print  !print PDS
*/
	        DPRINT1 ("gh->pds_len= %ld\n", gh->pds_len);
		HDR_PRINT("Grib_Seek's PDS",gh->pds_ptr, gh->pds_len);

/*
* A.3.3.10.a.4         IF (GDS is present) THEN
*                        STORE location & len of GDS into Grib Hdr's Gds_Ptr
*                        FUNCTION gbyte   !get 3-byte length
*                        IF (location of next Section  is out of bound) THEN
*                           PRINT message;
*                           DROP this msg & try to find another;
*                        ENDIF
*                        IF (Debug) FUNCTION hdr_print  !print GDS
*                     ENDIF
*/
		bit_set= gdsbmsflag >> 7 & 1;	/* mark GDS if present */
		if (bit_set) {
		    gh->gds_ptr= (unsigned char *)ptr;
		    iskip= 0; gbyte(ptr,(unsigned long*)&gh->gds_len,&iskip,24);
		    DPRINT0 (" Gds length\n");
		    ptr += gh->gds_len;	/* bump PTR to sect*/
	             if (ptr > end_ptr) {
		       sprintf(errmsg,
     		       "%s %s: corrupt GDSlen= %ld, Totlen=%ld, drop msg @%ld\n"
		        , func,InFile,  gh->gds_len, gh->msg_length, *offset);
		        gh->gds_len= 0;  		/* reset */
		        goto DROPMSG_N_LOOP;
     		        }
		       DPRINT1 ("gh->gds_len= %ld\n", gh->gds_len);
		       HDR_PRINT("Grib_Seek's GDS",gh->gds_ptr,gh->gds_len);
		    }

/*
* A.3.3.10.a.5         IF (BMS is present) THEN
*                        STORE location & len of BMS into Grib Hdr's Bms_Ptr
*                        FUNCTION gbyte   !get 3-byte length
*                        IF (location of next Section  is out of bound) THEN
*                           PRINT message;
*                           DROP this msg & try to find another;
*                        ENDIF
*                        IF (Debug) FUNCTION hdr_print   !byte dump
*                     ENDIF 
*/
		bit_set= gdsbmsflag >> 6 & 1;	/* mark BMS if present */
		if (bit_set) {
		    gh->bms_ptr= (unsigned char *)ptr; 	
		    iskip= 0; gbyte(ptr,(unsigned long*)&gh->bms_len,&iskip,24); 
		    DPRINT0 (" Bms length\n");

		    ptr += gh->bms_len;		/* bump PTR to sect */
	            if (ptr > end_ptr) {
		       sprintf(errmsg,
		       "%s %s: corrupt BMSlen= %ld, Totlen=%ld, drop msg @%ld\n"
			, func, InFile, gh->bms_len, gh->msg_length, *offset);
		        gh->bms_len= 0;  		/* reset */
		        goto DROPMSG_N_LOOP;
     		        }
		     DPRINT1 ("gh->bms_len= %ld\n", gh->bms_len);
		     HDR_PRINT ("Grib_Seek's BMS", gh->bms_ptr, 
				(gh->bms_len>100? 100: gh->bms_len));
		  }
/*
* A.3.3.10.a.6        STORE location and length of BDS into Grib Hdr's Bds_Ptr
*                    FUNCTION gbyte !get 3-byte length
*                    IF (location of next Section  is out of bound) THEN
*                        PRINT message;
*                        DROP this msg & try to find another;
*                    ENDIF
*                    IF (Debug) FUNCTION hdr_print   !byte dump
*/

		gh->bds_ptr= (unsigned char *)ptr; 	/* mark BDS */
		iskip= 0; gbyte(ptr,(unsigned long*)&gh->bds_len,&iskip,24);
		DPRINT0 (" Bds length\n");

		ptr += gh->bds_len;
	        if (ptr > end_ptr) {
		    sprintf(errmsg,
		    "%s %s:  corrupt BDSlen= %ld, Totlen=%ld, drop msg @%ld\n"
		    , func, InFile, gh->gds_len, gh->msg_length, *offset);
		    gh->gds_len= 0;  /* reset */
		    goto DROPMSG_N_LOOP;
		    }
		    DPRINT1 ("gh->bds_len= %ld\n", gh->bds_len);
	  	    HDR_PRINT ("Grib_Seek's BDS", gh->bds_ptr, 
			(gh->bds_len>100? 100: gh->bds_len));

/*
* A.3.3.10.a.7        STORE location & len of EDS into Grib Hdr's Eds_Ptr
*/
		gh->eds_ptr= (unsigned char *)ptr;  /* mark EDS */
		gh->eds_len= 4;   

/*
* A.3.3.10.a.8        SET 'gotone' flag 
*                    ! Return with Msg in Grib hdr, and good stat
*/
	    	gotone=1; 	/* to get out of FOR loop */
		status=0; 	/* Return with Msg , good stat */
	        goto DONE; 
/*
* A.3.3.10          ENDIF 
*/
	   } /* saw 77s  */
	else 
	if (Read_Index) {
		sprintf(errmsg,
		"%s %s:  no 7777 found for msg at %ld, check indexfile\n",
		func, InFile, *offset);
		}

/*
*
*          !====================================================
*          ! Drop Msg Area:   Only get here if :
*          ! - first G found not at Indexfile's offset;
*          ! - no RIB after G;
*          ! - GRIB string found not at Indexfile's offset;
*          ! - no 7777 at expected offset;
*          ! - got Corrupted Length; 
*          !====================================================
*/
DROPMSG_N_LOOP:
	   /* ERRMSG must already be loaded and the corrupted len reset to 0
	      so that Display GH won't go out of bound...
	    */
	   DPRINT2 ("\nDropping %s, cause=> %s\n", InFile, errmsg);

/*
* A.3.3.11         IF (Debug mode) THEN 
*                     FUNCTION display_gribhdr    !show what got loaded sofar
*                  ENDIF
*/
	  if (gh->msg_length > 0) 
	  DISPLAY_GRIBHDR(gh); /* before dropping msg*/

/*
*                  ! no message found yet, OR Msg Section lens are corrupted 
* A.3.3.12         CLEAR out header struct   !data in array is not valid
*/      
   	  gh->msg_length =0;
	  gh->ids_ptr=gh->pds_ptr= gh->eds_ptr=0;
   	  gh->gds_ptr=gh->bms_ptr=gh->bds_ptr= 0;
   	  memset ((void *)gh->entire_msg, '\0', gh->abs_size);

/*
* A.3.3.13         IF (Offset was read from Indexfile)   !quit searching
* A.3.3.13.a       THEN
*                      PUT Error msg in buffer
*                      RETURN with No Error status
* A.3.3.13.b       ELSE
*                      CLEAR out 'G' in tmp block        !go find next 'G' 
*                  ENDIF
*/
	  if (Read_Index) {
	      status = 0; 	/* Ret w/ no errors     */
	      goto DONE;	/* send CAUSE back in Errmsg */
	     }
	  else {
	     *GG='-';    /* let Memchr find next 'G' in curr. block */
	     DPRINT1 ("'GRIB' at location %ld is not a valid message\n",
	     bytenum+pos);
	     errmsg[0]='\0';  /* clear out buff */
	     }
/*
* A.3.3         ENDWHILE 
*/
     }  /* WHILE seeing 'G'*/


     if (Read_Index) {  /* Catch 3 cases:
			 - if no 'G' at all ;
			 - if no RIB after G ;
			 - if found GRIB but not at expected place
			*/
	   sprintf(errmsg,
	   "%s %s:  No Grib Msg found at IndexFile's offset = %ld; "\
	   " Check Index File\n" , func, InFile, *offset);
	   status = 0;  /* Return w/no errors  */
	   goto DONE;	/* but w/ Warn Msg in buff*/
	}

/*
A.3.4           DEBUG print  !no Sect0 found in this block
*/
      DPRINT2 ("No Section 0 found between address %ld and %ld\n", 
      pos, pos+check_limit);
/*
*
* A.3       ENDFOR    !Outer Loop,  stay until Status changes
*/
  }  /* check entire file */



DONE:
/*
*
* A.4        CLOSE input file;     !get here when found no messages
*
*/
/*
   if (fp) fclose(fp); 
*/

/*
* 
* A.5        IF (found a msg) THEN
*                BUMP caller's Offset to absolute Begining of Msg found;
*                DEBUG Print
*            ENDIF
*/
   if (gotone)  
       {
       *offset = (long)(pos+bytenum);  /* bump offset to abs. beg. of Msg */
       DPRINT3 ("Exiting %s w/stat=%d, offs=%d, msg in GRIB_HDR\n", 
	func, status, *offset);
       }
   else DPRINT2 ("Exiting %s w/stat=%d, no messages\n", func, status);

/*
* A.6        RETURN with status 
*/
   return (status); 
/*
*
* END OF FUNCTION
*
*/
}