src/rrd_rpncalc.c

   1 /****************************************************************************
   2  * RRDtool 1.2rc6  Copyright by Tobi Oetiker, 1997-2005
   3  ****************************************************************************
   4  * rrd_rpncalc.c  RPN calculator functions
   5  ****************************************************************************/
   6
   7 #include "rrd_tool.h"
   8 #include "rrd_rpncalc.h"
   9 #include "rrd_graph.h"
  10 #include <limits.h>
  11
  12 short addop2str(enum op_en op, enum op_en op_type, char *op_str,
  13             char **result_str, unsigned short *offset);
  14 int tzoffset(time_t); /* used to implement LTIME */
  15
  16 short rpn_compact(rpnp_t *rpnp, rpn_cdefds_t **rpnc, short *count)
  17 {
  18     short i;
  19     *count = 0;
  20     /* count the number of rpn nodes */
  21     while(rpnp[*count].op != OP_END) (*count)++;
  22     if (++(*count) > DS_CDEF_MAX_RPN_NODES) {
  23         rrd_set_error("Maximum %d RPN nodes permitted",
  24                       DS_CDEF_MAX_RPN_NODES);
  25         return -1;
  26     }
  27
  28     /* allocate memory */
  29     *rpnc = (rpn_cdefds_t *) calloc(*count,sizeof(rpn_cdefds_t));
  30     for (i = 0; rpnp[i].op != OP_END; i++)
  31     {
  32         (*rpnc)[i].op = (char) rpnp[i].op;
  33         if (rpnp[i].op == OP_NUMBER) {
  34             /* rpnp.val is a double, rpnc.val is a short */
  35             double temp = floor(rpnp[i].val);
  36             if (temp < SHRT_MIN || temp > SHRT_MAX) {
  37                 rrd_set_error(
  38                     "constants must be integers in the interval (%d, %d)",
  39                     SHRT_MIN, SHRT_MAX);
  40                 free(*rpnc);
  41                 return -1;
  42             }
  43             (*rpnc)[i].val = (short) temp;
  44           } else if (rpnp[i].op == OP_VARIABLE ||
  45                                  rpnp[i].op == OP_PREV_OTHER) {
  46             (*rpnc)[i].val = (short) rpnp[i].ptr;
  47         }
  48     }
  49     /* terminate the sequence */
  50     (*rpnc)[(*count) - 1].op = OP_END;
  51     return 0;
  52 }
  53
  54 rpnp_t * rpn_expand(rpn_cdefds_t *rpnc)
  55 {
  56     short i;
  57     rpnp_t *rpnp;
  58
  59     /* DS_CDEF_MAX_RPN_NODES is small, so at the expense of some wasted
  60      * memory we avoid any reallocs */
  61     rpnp = (rpnp_t *) calloc(DS_CDEF_MAX_RPN_NODES,sizeof(rpnp_t));
  62     if (rpnp == NULL) return NULL;
  63     for (i = 0; rpnc[i].op != OP_END; ++i)
  64     {
  65         rpnp[i].op = (long) rpnc[i].op;
  66         if (rpnp[i].op == OP_NUMBER) {
  67             rpnp[i].val = (double) rpnc[i].val;
  68           } else if (rpnp[i].op == OP_VARIABLE ||
  69                                  rpnp[i].op == OP_PREV_OTHER) {
  70             rpnp[i].ptr = (long) rpnc[i].val;
  71         }
  72     }
  73     /* terminate the sequence */
  74     rpnp[i].op = OP_END;
  75     return rpnp;
  76 }
  77
  78 /* rpn_compact2str: convert a compact sequence of RPN operator nodes back
  79  * into a CDEF string. This function is used by rrd_dump.
  80  * arguments:
  81  *  rpnc: an array of compact RPN operator nodes
  82  *  ds_def: a pointer to the data source definition section of an RRD header
  83  *   for lookup of data source names by index
  84  *  str: out string, memory is allocated by the function, must be freed by the
  85  *   the caller */
  86 void rpn_compact2str(rpn_cdefds_t *rpnc,ds_def_t *ds_def,char **str)
  87 {
  88     unsigned short i,offset = 0;
  89     char buffer[7]; /* short as a string */
  90
  91     for (i = 0; rpnc[i].op != OP_END; i++)
  92     {
  93         if (i > 0) (*str)[offset++] = ',';
  94
  95 #define add_op(VV,VVV) \
  96           if (addop2str(rpnc[i].op, VV, VVV, str, &offset) == 1) continue;
  97
  98         if (rpnc[i].op == OP_NUMBER) {
  99             /* convert a short into a string */
 100 #if defined(WIN32) && !defined(__CYGWIN__) && !defined(__CYGWIN32__)
 101             _itoa(rpnc[i].val,buffer,10);
 102 #else
 103             sprintf(buffer,"%d",rpnc[i].val);
 104 #endif
 105             add_op(OP_NUMBER,buffer)
 106                 }
 107
 108         if (rpnc[i].op == OP_VARIABLE) {
 109             char *ds_name = ds_def[rpnc[i].val].ds_nam;
 110             add_op(OP_VARIABLE, ds_name)
 111                 }
 112
 113           if (rpnc[i].op == OP_PREV_OTHER) {
 114                 char *ds_name = ds_def[rpnc[i].val].ds_nam;
 115                 add_op(OP_VARIABLE, ds_name)
 116           }
 117
 118 #undef add_op
 119
 120 #define add_op(VV,VVV) \
 121           if (addop2str(rpnc[i].op, VV, #VVV, str, &offset) == 1) continue;
 122
 123           add_op(OP_ADD,+)
 124           add_op(OP_SUB,-)
 125           add_op(OP_MUL,*)
 126           add_op(OP_DIV,/)
 127           add_op(OP_MOD,%)
 128           add_op(OP_SIN,SIN)
 129           add_op(OP_COS,COS)
 130           add_op(OP_LOG,LOG)
 131           add_op(OP_FLOOR,FLOOR)
 132           add_op(OP_CEIL,CEIL)
 133           add_op(OP_EXP,EXP)
 134           add_op(OP_DUP,DUP)
 135           add_op(OP_EXC,EXC)
 136           add_op(OP_POP,POP)
 137           add_op(OP_LT,LT)
 138           add_op(OP_LE,LE)
 139           add_op(OP_GT,GT)
 140           add_op(OP_GE,GE)
 141           add_op(OP_EQ,EQ)
 142           add_op(OP_IF,IF)
 143           add_op(OP_MIN,MIN)
 144           add_op(OP_MAX,MAX)
 145           add_op(OP_LIMIT,LIMIT)
 146           add_op(OP_UNKN,UNKN)
 147           add_op(OP_UN,UN)
 148           add_op(OP_NEGINF,NEGINF)
 149           add_op(OP_NE,NE)
 150           add_op(OP_PREV,PREV)
 151           add_op(OP_INF,INF)
 152           add_op(OP_ISINF,ISINF)
 153           add_op(OP_NOW,NOW)
 154           add_op(OP_LTIME,LTIME)
 155           add_op(OP_TIME,TIME)
 156           add_op(OP_ATAN,ATAN)
 157           add_op(OP_SQRT,SQRT)
 158           add_op(OP_SORT,SORT)
 159           add_op(OP_REV,REV)
 160           add_op(OP_TREND,TREND)
 161 #undef add_op
 162               }
 163     (*str)[offset] = '\0';
 164
 165 }
 166
 167 short addop2str(enum op_en op, enum op_en op_type, char *op_str,
 168                 char **result_str, unsigned short *offset)
 169 {
 170     if (op == op_type) {
 171         short op_len;
 172         op_len = strlen(op_str);
 173         *result_str =  (char *) rrd_realloc(*result_str,
 174                                             (op_len + 1 + *offset)*sizeof(char));
 175         if (*result_str == NULL) {
 176             rrd_set_error("failed to alloc memory in addop2str");
 177             return -1;
 178         }
 179         strncpy(&((*result_str)[*offset]),op_str,op_len);
 180         *offset += op_len;
 181         return 1;
 182     }
 183     return 0;
 184 }
 185
 186 void parseCDEF_DS(char *def,rrd_t *rrd, int ds_idx)
 187 {
 188     rpnp_t *rpnp = NULL;
 189     rpn_cdefds_t *rpnc = NULL;
 190     short count, i;
 191
 192     rpnp = rpn_parse((void*) rrd, def, &lookup_DS);
 193     if (rpnp == NULL) {
 194         rrd_set_error("failed to parse computed data source %s", def);
 195         return;
 196     }
 197     /* Check for OP nodes not permitted in COMPUTE DS.
 198      * Moved this check from within rpn_compact() because it really is
 199      * COMPUTE DS specific. This is less efficient, but creation doesn't
 200      * occur too often. */
 201     for (i = 0; rpnp[i].op != OP_END; i++) {
 202         if (rpnp[i].op == OP_TIME || rpnp[i].op == OP_LTIME ||
 203             rpnp[i].op == OP_PREV || rpnp[i].op == OP_COUNT)
 204         {
 205             rrd_set_error(
 206                 "operators time, ltime, prev and count not supported with DS COMPUTE");
 207             free(rpnp);
 208             return;
 209         }
 210     }
 211     if (rpn_compact(rpnp,&rpnc,&count) == -1) {
 212         free(rpnp);
 213         return;
 214     }
 215     /* copy the compact rpn representation over the ds_def par array */
 216     memcpy((void*) &(rrd -> ds_def[ds_idx].par[DS_cdef]),
 217            (void*) rpnc, count*sizeof(rpn_cdefds_t));
 218     free(rpnp);
 219     free(rpnc);
 220 }
 221
 222 /* lookup a data source name in the rrd struct and return the index,
 223  * should use ds_match() here except:
 224  * (1) need a void * pointer to the rrd
 225  * (2) error handling is left to the caller
 226  */
 227 long lookup_DS(void *rrd_vptr,char *ds_name)
 228 {
 229     unsigned int i;
 230     rrd_t *rrd;
 231
 232     rrd = (rrd_t *) rrd_vptr;
 233
 234     for (i = 0; i < rrd -> stat_head -> ds_cnt; ++i)
 235     {
 236         if(strcmp(ds_name,rrd -> ds_def[i].ds_nam) == 0)
 237             return i;
 238     }
 239     /* the caller handles a bad data source name in the rpn string */
 240     return -1;
 241 }
 242
 243 /* rpn_parse : parse a string and generate a rpnp array; modified
 244  * str2rpn() originally included in rrd_graph.c
 245  * arguments:
 246  * key_hash: a transparent argument passed to lookup(); conceptually this
 247  *    is a hash object for lookup of a numeric key given a variable name
 248  * expr: the string RPN expression, including variable names
 249  * lookup(): a function that retrieves a numeric key given a variable name
 250  */
 251 rpnp_t *
 252 rpn_parse(void *key_hash,char *expr,long (*lookup)(void *,char*)){
 253     int pos=0;
 254     long steps=-1;
 255     rpnp_t  *rpnp;
 256     char vname[30];
 257
 258     rpnp=NULL;
 259
 260     while(*expr){
 261         if ((rpnp = (rpnp_t *) rrd_realloc(rpnp, (++steps + 2)*
 262                                        sizeof(rpnp_t)))==NULL){
 263             return NULL;
 264         }
 265
 266         else if((sscanf(expr,"%lf%n",&rpnp[steps].val,&pos) == 1) && (expr[pos] == ',')){
 267             rpnp[steps].op = OP_NUMBER;
 268             expr+=pos;
 269         }
 270
 271 #define match_op(VV,VVV) \
 272         else if (strncmp(expr, #VVV, strlen(#VVV))==0){ \
 273             rpnp[steps].op = VV; \
 274             expr+=strlen(#VVV); \
 275         }
 276
 277
 278 #define match_op_param(VV,VVV) \
 279         else if (sscanf(expr, #VVV "(" DEF_NAM_FMT ")",vname) == 1) { \
 280           int length = 0; \
 281           if ((length = strlen(#VVV)+strlen(vname)+2, \
 282               expr[length] == ',' || expr[length] == '\0') ) { \
 283              rpnp[steps].op = VV; \
 284              rpnp[steps].ptr = (*lookup)(key_hash,vname); \
 285              if (rpnp[steps].ptr < 0) { \
 286                            free(rpnp); \
 287                            return NULL; \
 288                          } else expr+=length; \
 289           } \
 290         }
 291
 292         match_op(OP_ADD,+)
 293         match_op(OP_SUB,-)
 294         match_op(OP_MUL,*)
 295         match_op(OP_DIV,/)
 296         match_op(OP_MOD,%)
 297         match_op(OP_SIN,SIN)
 298         match_op(OP_COS,COS)
 299         match_op(OP_LOG,LOG)
 300         match_op(OP_FLOOR,FLOOR)
 301         match_op(OP_CEIL,CEIL)
 302         match_op(OP_EXP,EXP)
 303         match_op(OP_DUP,DUP)
 304         match_op(OP_EXC,EXC)
 305         match_op(OP_POP,POP)
 306         match_op(OP_LTIME,LTIME)
 307         match_op(OP_LT,LT)
 308         match_op(OP_LE,LE)
 309         match_op(OP_GT,GT)
 310         match_op(OP_GE,GE)
 311         match_op(OP_EQ,EQ)
 312         match_op(OP_IF,IF)
 313         match_op(OP_MIN,MIN)
 314         match_op(OP_MAX,MAX)
 315         match_op(OP_LIMIT,LIMIT)
 316           /* order is important here ! .. match longest first */
 317         match_op(OP_UNKN,UNKN)
 318         match_op(OP_UN,UN)
 319         match_op(OP_NEGINF,NEGINF)
 320         match_op(OP_NE,NE)
 321         match_op(OP_COUNT,COUNT)
 322         match_op_param(OP_PREV_OTHER,PREV)
 323         match_op(OP_PREV,PREV)
 324         match_op(OP_INF,INF)
 325         match_op(OP_ISINF,ISINF)
 326         match_op(OP_NOW,NOW)
 327         match_op(OP_TIME,TIME)
 328         match_op(OP_ATAN,ATAN)
 329         match_op(OP_SQRT,SQRT)
 330         match_op(OP_SORT,SORT)
 331         match_op(OP_REV,REV)
 332         match_op(OP_TREND,TREND)
 333 #undef match_op
 334
 335
 336             else if ((sscanf(expr, DEF_NAM_FMT "%n",
 337                              vname,&pos) == 1)
 338                      && ((rpnp[steps].ptr = (*lookup)(key_hash,vname)) != -1)){
 339                 rpnp[steps].op = OP_VARIABLE;
 340                 expr+=pos;
 341             }
 342
 343         else {
 344             free(rpnp);
 345             return NULL;
 346         }
 347         if (*expr == 0)
 348             break;
 349         if (*expr == ',')
 350             expr++;
 351         else {
 352             free(rpnp);
 353             return NULL;
 354         }
 355     }
 356     rpnp[steps+1].op = OP_END;
 357     return rpnp;
 358 }
 359
 360 void
 361 rpnstack_init(rpnstack_t *rpnstack)
 362 {
 363     rpnstack -> s = NULL;
 364     rpnstack -> dc_stacksize = 0;
 365     rpnstack -> dc_stackblock = 100;
 366 }
 367
 368 void
 369 rpnstack_free(rpnstack_t *rpnstack)
 370 {
 371    if (rpnstack -> s != NULL)
 372           free(rpnstack -> s);
 373    rpnstack -> dc_stacksize = 0;
 374 }
 375
 376 static int
 377 rpn_compare_double(const void *x, const void *y)
 378 {
 379         double  diff = *((const double *)x) - *((const double *)y);
 380
 381         return (diff < 0) ? -1 : (diff > 0) ? 1 : 0;
 382 }
 383
 384 /* rpn_calc: run the RPN calculator; also performs variable substitution;
 385  * moved and modified from data_calc() originally included in rrd_graph.c
 386  * arguments:
 387  * rpnp : an array of RPN operators (including variable references)
 388  * rpnstack : the initialized stack
 389  * data_idx : when data_idx is a multiple of rpnp.step, the rpnp.data pointer
 390  *   is advanced by rpnp.ds_cnt; used only for variable substitution
 391  * output : an array of output values; OP_PREV assumes this array contains
 392  *   the "previous" value at index position output_idx-1; the definition of
 393  *   "previous" depends on the calling environment
 394  * output_idx : an index into the output array in which to store the output
 395  *   of the RPN calculator
 396  * returns: -1 if the computation failed (also calls rrd_set_error)
 397  *           0 on success
 398  */
 399 short
 400 rpn_calc(rpnp_t *rpnp, rpnstack_t *rpnstack, long data_idx,
 401                 rrd_value_t *output, int output_idx)
 402 {
 403     int rpi;
 404     long stptr = -1;
 405
 406     /* process each op from the rpn in turn */
 407     for (rpi=0; rpnp[rpi].op != OP_END; rpi++){
 408         /* allocate or grow the stack */
 409         if (stptr + 5 > rpnstack -> dc_stacksize){
 410             /* could move this to a separate function */
 411             rpnstack -> dc_stacksize += rpnstack -> dc_stackblock;
 412             rpnstack -> s = rrd_realloc(rpnstack -> s,
 413                         (rpnstack -> dc_stacksize)*sizeof(*(rpnstack -> s)));
 414             if (rpnstack -> s == NULL){
 415                 rrd_set_error("RPN stack overflow");
 416                 return -1;
 417             }
 418         }
 419
 420 #define stackunderflow(MINSIZE)                         \
 421         if(stptr<MINSIZE){                              \
 422             rrd_set_error("RPN stack underflow");       \
 423             return -1;                                  \
 424         }
 425
 426         switch (rpnp[rpi].op){
 427             case OP_NUMBER:
 428                 rpnstack -> s[++stptr] = rpnp[rpi].val;
 429                 break;
 430             case OP_VARIABLE:
 431                 /* Sanity check: VDEFs shouldn't make it here */
 432                 if (rpnp[rpi].ds_cnt == 0) {
 433                     rrd_set_error("VDEF made it into rpn_calc... aborting");
 434                     return -1;
 435                 } else {
 436                     /* make sure we pull the correct value from
 437                      * the *.data array. Adjust the pointer into
 438                      * the array acordingly. Advance the ptr one
 439                      * row in the rra (skip over non-relevant
 440                      * data sources)
 441                      */
 442                     rpnstack -> s[++stptr] =  *(rpnp[rpi].data);
 443                     if (data_idx % rpnp[rpi].step == 0){
 444                         rpnp[rpi].data += rpnp[rpi].ds_cnt;
 445                     }
 446                 }
 447                 break;
 448             case OP_COUNT:
 449                 rpnstack -> s[++stptr] = (output_idx+1); /* Note: Counter starts at 1 */
 450                 break;
 451             case OP_PREV:
 452                 if ((output_idx) <= 0) {
 453                     rpnstack -> s[++stptr] = DNAN;
 454                 } else {
 455                     rpnstack -> s[++stptr] = output[output_idx-1];
 456                 }
 457                 break;
 458         case OP_PREV_OTHER:
 459           if ((output_idx) <= 0) {
 460                 rpnstack -> s[++stptr] = DNAN;
 461           } else {
 462                 rpnstack -> s[++stptr] = rpnp[rpnp[rpi].ptr].data[output_idx-1];
 463           }
 464           break;
 465             case OP_UNKN:
 466                 rpnstack -> s[++stptr] = DNAN;
 467                 break;
 468             case OP_INF:
 469                 rpnstack -> s[++stptr] = DINF;
 470                 break;
 471             case OP_NEGINF:
 472                 rpnstack -> s[++stptr] = -DINF;
 473                 break;
 474             case OP_NOW:
 475                 rpnstack -> s[++stptr] = (double)time(NULL);
 476                 break;
 477             case OP_TIME:
 478                 /* HACK: this relies on the data_idx being the time,
 479                 ** which the within-function scope is unaware of */
 480                 rpnstack -> s[++stptr] = (double) data_idx;
 481                 break;
 482             case OP_LTIME:
 483                 rpnstack -> s[++stptr] =
 484                         (double) tzoffset(data_idx) + (double)data_idx;
 485                 break;
 486             case OP_ADD:
 487                 stackunderflow(1);
 488                 rpnstack -> s[stptr-1]  = rpnstack -> s[stptr-1]
 489                                         + rpnstack -> s[stptr];
 490                 stptr--;
 491                 break;
 492             case OP_SUB:
 493                 stackunderflow(1);
 494                 rpnstack -> s[stptr-1]  = rpnstack -> s[stptr-1]
 495                                         - rpnstack -> s[stptr];
 496                 stptr--;
 497                 break;
 498             case OP_MUL:
 499                 stackunderflow(1);
 500                 rpnstack -> s[stptr-1]  = (rpnstack -> s[stptr-1])
 501                                         * (rpnstack -> s[stptr]);
 502                 stptr--;
 503                 break;
 504             case OP_DIV:
 505                 stackunderflow(1);
 506                 rpnstack -> s[stptr-1]  = rpnstack -> s[stptr-1]
 507                                         / rpnstack -> s[stptr];
 508                 stptr--;
 509                 break;
 510             case OP_MOD:
 511                 stackunderflow(1);
 512                 rpnstack -> s[stptr-1]= fmod(   rpnstack -> s[stptr-1]
 513                                                 ,rpnstack -> s[stptr]);
 514                 stptr--;
 515                 break;
 516             case OP_SIN:
 517                 stackunderflow(0);
 518                 rpnstack -> s[stptr] = sin(rpnstack -> s[stptr]);
 519                 break;
 520             case OP_ATAN:
 521                 stackunderflow(0);
 522                 rpnstack -> s[stptr] = atan(rpnstack -> s[stptr]);
 523                 break;
 524             case OP_COS:
 525                 stackunderflow(0);
 526                 rpnstack -> s[stptr] = cos(rpnstack -> s[stptr]);
 527                 break;
 528             case OP_CEIL:
 529                 stackunderflow(0);
 530                 rpnstack -> s[stptr] = ceil(rpnstack -> s[stptr]);
 531                 break;
 532             case OP_FLOOR:
 533                 stackunderflow(0);
 534                 rpnstack -> s[stptr] = floor(rpnstack -> s[stptr]);
 535                 break;
 536             case OP_LOG:
 537                 stackunderflow(0);
 538                 rpnstack -> s[stptr] = log(rpnstack -> s[stptr]);
 539                 break;
 540             case OP_DUP:
 541                 stackunderflow(0);
 542                 rpnstack -> s[stptr+1] = rpnstack -> s[stptr];
 543                 stptr++;
 544                 break;
 545             case OP_POP:
 546                 stackunderflow(0);
 547                 stptr--;
 548                 break;
 549             case OP_EXC:
 550                 stackunderflow(1);
 551                 {
 552                     double dummy;
 553                     dummy = rpnstack -> s[stptr] ;
 554                     rpnstack -> s[stptr] = rpnstack -> s[stptr-1];
 555                     rpnstack -> s[stptr-1] = dummy;
 556                 }
 557                 break;
 558             case OP_EXP:
 559                 stackunderflow(0);
 560                 rpnstack -> s[stptr] = exp(rpnstack -> s[stptr]);
 561                 break;
 562             case OP_LT:
 563                 stackunderflow(1);
 564                 if (isnan(rpnstack -> s[stptr-1]))
 565                     ;
 566                 else if (isnan(rpnstack -> s[stptr]))
 567                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
 568                 else
 569                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] <
 570                                         rpnstack -> s[stptr] ? 1.0 : 0.0;
 571                 stptr--;
 572                 break;
 573             case OP_LE:
 574                 stackunderflow(1);
 575                 if (isnan(rpnstack -> s[stptr-1]))
 576                     ;
 577                 else if (isnan(rpnstack -> s[stptr]))
 578                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
 579                 else
 580                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] <=
 581                                         rpnstack -> s[stptr] ? 1.0 : 0.0;
 582                 stptr--;
 583                 break;
 584             case OP_GT:
 585                 stackunderflow(1);
 586                 if (isnan(rpnstack -> s[stptr-1]))
 587                     ;
 588                 else if (isnan(rpnstack -> s[stptr]))
 589                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
 590                 else
 591                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] >
 592                                         rpnstack -> s[stptr] ? 1.0 : 0.0;
 593                 stptr--;
 594                 break;
 595             case OP_GE:
 596                 stackunderflow(1);
 597                 if (isnan(rpnstack -> s[stptr-1]))
 598                     ;
 599                 else if (isnan(rpnstack -> s[stptr]))
 600                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
 601                 else
 602                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] >=
 603                                         rpnstack -> s[stptr] ? 1.0 : 0.0;
 604                 stptr--;
 605                 break;
 606             case OP_NE:
 607                 stackunderflow(1);
 608                 if (isnan(rpnstack -> s[stptr-1]))
 609                     ;
 610                 else if (isnan(rpnstack -> s[stptr]))
 611                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
 612                 else
 613                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] ==
 614                                         rpnstack -> s[stptr] ? 0.0 : 1.0;
 615                 stptr--;
 616                 break;
 617             case OP_EQ:
 618                 stackunderflow(1);
 619                 if (isnan(rpnstack -> s[stptr-1]))
 620                     ;
 621                 else if (isnan(rpnstack -> s[stptr]))
 622                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
 623                 else
 624                     rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] ==
 625                                         rpnstack -> s[stptr] ? 1.0 : 0.0;
 626                 stptr--;
 627                 break;
 628             case OP_IF:
 629                 stackunderflow(2);
 630                 rpnstack->s[stptr-2] = rpnstack->s[stptr-2] != 0.0 ?
 631                                 rpnstack->s[stptr-1] : rpnstack->s[stptr];
 632                 stptr--;
 633                 stptr--;
 634                 break;
 635             case OP_MIN:
 636                 stackunderflow(1);
 637                 if (isnan(rpnstack->s[stptr-1]))
 638                     ;
 639                 else if (isnan(rpnstack->s[stptr]))
 640                     rpnstack->s[stptr-1] = rpnstack->s[stptr];
 641                 else if (rpnstack->s[stptr-1] > rpnstack->s[stptr])
 642                     rpnstack->s[stptr-1] = rpnstack->s[stptr];
 643                 stptr--;
 644                 break;
 645             case OP_MAX:
 646                 stackunderflow(1);
 647                 if (isnan(rpnstack->s[stptr-1]))
 648                ;
 649                 else if (isnan(rpnstack->s[stptr]))
 650                     rpnstack->s[stptr-1] = rpnstack->s[stptr];
 651                 else if (rpnstack->s[stptr-1] < rpnstack->s[stptr])
 652                     rpnstack->s[stptr-1] = rpnstack->s[stptr];
 653                 stptr--;
 654                 break;
 655             case OP_LIMIT:
 656                 stackunderflow(2);
 657                 if (isnan(rpnstack->s[stptr-2]))
 658                     ;
 659                 else if (isnan(rpnstack->s[stptr-1]))
 660                     rpnstack->s[stptr-2] = rpnstack->s[stptr-1];
 661                 else if (isnan(rpnstack->s[stptr]))
 662                     rpnstack->s[stptr-2] = rpnstack->s[stptr];
 663                 else if (rpnstack->s[stptr-2] < rpnstack->s[stptr-1])
 664                     rpnstack->s[stptr-2] = DNAN;
 665                 else if (rpnstack->s[stptr-2] > rpnstack->s[stptr])
 666                     rpnstack->s[stptr-2] = DNAN;
 667                 stptr-=2;
 668                 break;
 669             case OP_UN:
 670                 stackunderflow(0);
 671                 rpnstack->s[stptr] = isnan(rpnstack->s[stptr]) ? 1.0 : 0.0;
 672                 break;
 673             case OP_ISINF:
 674                 stackunderflow(0);
 675                 rpnstack->s[stptr] = isinf(rpnstack->s[stptr]) ? 1.0 : 0.0;
 676                 break;
 677             case OP_SQRT:
 678                 stackunderflow(0);
 679                 rpnstack -> s[stptr] = sqrt(rpnstack -> s[stptr]);
 680                 break;
 681             case OP_SORT:
 682                 stackunderflow(0);
 683                 {
 684                     int spn = (int)rpnstack -> s[stptr--];
 685
 686                     stackunderflow(spn-1);
 687                     qsort(rpnstack -> s + stptr-spn+1, spn, sizeof(double),
 688                           rpn_compare_double);
 689                 }
 690                 break;
 691             case OP_REV:
 692                 stackunderflow(0);
 693                 {
 694                     int spn = (int)rpnstack -> s[stptr--];
 695                     double *p, *q;
 696
 697                     stackunderflow(spn-1);
 698
 699                     p = rpnstack -> s + stptr-spn+1;
 700                     q = rpnstack -> s + stptr;
 701                     while (p < q) {
 702                             double      x = *q;
 703
 704                             *q-- = *p;
 705                             *p++ = x;
 706                     }
 707                 }
 708                 break;
 709             case OP_TREND:
 710                 stackunderflow(1);
 711                 if ((rpi < 2) || (rpnp[rpi-2].op != OP_VARIABLE)) {
 712                     rrd_set_error("malformed trend arguments");
 713                     return -1;
 714                 } else {
 715                     time_t dur = (time_t)rpnstack -> s[stptr];
 716                     time_t step = (time_t)rpnp[rpi-2].step;
 717
 718                     if (output_idx > (int)ceil((float)dur / (float)step)) {
 719                         double accum = 0.0;
 720                         int i = 0;
 721
 722                         do {
 723                             accum += rpnp[rpi-2].data[rpnp[rpi-2].ds_cnt * i--];
 724                             dur -= step;
 725                         } while (dur > 0);
 726
 727                         rpnstack -> s[--stptr] = (accum / -i);
 728                     } else
 729                         rpnstack -> s[--stptr] = DNAN;
 730                 }
 731                 break;
 732             case OP_END:
 733                 break;
 734        }
 735 #undef stackunderflow
 736    }
 737    if(stptr!=0){
 738        rrd_set_error("RPN final stack size != 1");
 739        return -1;
 740    }
 741
 742    output[output_idx] = rpnstack->s[0];
 743    return 0;
 744 }
 745
 746 /* figure out what the local timezone offset for any point in
 747    time was. Return it in seconds */
 748 int
 749 tzoffset( time_t now ){
 750     int gm_sec, gm_min, gm_hour, gm_yday, gm_year,
 751         l_sec, l_min, l_hour, l_yday, l_year;
 752     struct tm t;
 753     int off;
 754     gmtime_r(&now, &t);
 755     gm_sec = t.tm_sec;
 756     gm_min = t.tm_min;
 757     gm_hour = t.tm_hour;
 758     gm_yday = t.tm_yday;
 759     gm_year = t.tm_year;
 760     localtime_r(&now, &t);
 761     l_sec = t.tm_sec;
 762     l_min = t.tm_min;
 763     l_hour = t.tm_hour;
 764     l_yday = t.tm_yday;
 765     l_year = t.tm_year;
 766     off = (l_sec-gm_sec)+(l_min-gm_min)*60+(l_hour-gm_hour)*3600;
 767     if ( l_yday > gm_yday || l_year > gm_year){
 768         off += 24*3600;
 769     } else if ( l_yday < gm_yday || l_year < gm_year){
 770         off -= 24*3600;
 771     }
 772    return off;
 773 }
 774