Detect/report smb_fallochdr() and ftell() failures

Fix CID 33244: Argument cannot be negative

src/sbbs3/smbutil.c

@@ -1209,7 +1209,7 @@ void packmsgs(ulong packable)
 			}
 			else {
 				fseek(tmp_sdt,0L,SEEK_END);
-				offset=ftell(tmp_sdt); 
+				offset = ftello(tmp_sdt); 
 				if(offset < 0) {
 					fprintf(errfp,"\n%s!ftell() ERROR %d\n", beep, errno);
 					continue;
@@ -1235,10 +1235,15 @@ void packmsgs(ulong packable)
 
 		/* Write the new index entry */
 		length=smb_getmsghdrlen(&msg);
+		off_t offset;
 		if(smb.status.attr&SMB_HYPERALLOC)
-			msg.idx.offset=ftell(tmp_shd);
+			offset = ftello(tmp_shd);
 		else
-			msg.idx.offset=(uint32_t)smb_fallochdr(&smb,(ulong)length)+smb.status.header_offset;
+			offset = smb_fallochdr(&smb,(ulong)length)+smb.status.header_offset;
+		if(offset < 0) {
+			fprintf(errfp,"\n%s!header allocation ERROR %ld\n", beep, (long)offset);
+		} else {
+			msg.idx.offset = (uint32_t)offset;
 			smb_init_idx(&smb, &msg);
 			fseek(tmp_sid, l * idxreclen, SEEK_SET);
 			fwrite(&msg.idx, 1, sizeof(msg.idx), tmp_sid);
@@ -1257,6 +1262,7 @@ void packmsgs(ulong packable)
 				length++; 
 			}
 			total++;
+		}
 		smb_freemsgmem(&msg); 
 	}