src/rrd_rpncalc.c

   1 /****************************************************************************
   2  * RRDtool 1.4.3  Copyright by Tobi Oetiker, 1997-2010
   3  ****************************************************************************
   4  * rrd_rpncalc.c  RPN calculator functions
   5  ****************************************************************************/
   6
   7 #include <limits.h>
   8 #include <locale.h>
   9 #include <stdlib.h>
  10
  11 #include "rrd_tool.h"
  12 #include "rrd_rpncalc.h"
  13 // #include "rrd_graph.h"
  14
  15 short     addop2str(
  16     enum op_en op,
  17     enum op_en op_type,
  18     char *op_str,
  19     char **result_str,
  20     unsigned short *offset);
  21 int       tzoffset(
  22     time_t);            /* used to implement LTIME */
  23
  24 short rpn_compact(
  25     rpnp_t *rpnp,
  26     rpn_cdefds_t **rpnc,
  27     short *count)
  28 {
  29     short     i;
  30
  31     *count = 0;
  32     /* count the number of rpn nodes */
  33     while (rpnp[*count].op != OP_END)
  34         (*count)++;
  35     if (++(*count) > DS_CDEF_MAX_RPN_NODES) {
  36         rrd_set_error("Maximum %d RPN nodes permitted",
  37                       DS_CDEF_MAX_RPN_NODES);
  38         return -1;
  39     }
  40
  41     /* allocate memory */
  42     *rpnc = (rpn_cdefds_t *) calloc(*count, sizeof(rpn_cdefds_t));
  43     for (i = 0; rpnp[i].op != OP_END; i++) {
  44         (*rpnc)[i].op = (char) rpnp[i].op;
  45         if (rpnp[i].op == OP_NUMBER) {
  46             /* rpnp.val is a double, rpnc.val is a short */
  47             double    temp = floor(rpnp[i].val);
  48
  49             if (temp < SHRT_MIN || temp > SHRT_MAX) {
  50                 rrd_set_error
  51                     ("constants must be integers in the interval (%d, %d)",
  52                      SHRT_MIN, SHRT_MAX);
  53                 free(*rpnc);
  54                 return -1;
  55             }
  56             (*rpnc)[i].val = (short) temp;
  57         } else if (rpnp[i].op == OP_VARIABLE || rpnp[i].op == OP_PREV_OTHER) {
  58             (*rpnc)[i].val = (short) rpnp[i].ptr;
  59         }
  60     }
  61     /* terminate the sequence */
  62     (*rpnc)[(*count) - 1].op = OP_END;
  63     return 0;
  64 }
  65
  66 rpnp_t   *rpn_expand(
  67     rpn_cdefds_t *rpnc)
  68 {
  69     short     i;
  70     rpnp_t   *rpnp;
  71
  72     /* DS_CDEF_MAX_RPN_NODES is small, so at the expense of some wasted
  73      * memory we avoid any reallocs */
  74     rpnp = (rpnp_t *) calloc(DS_CDEF_MAX_RPN_NODES, sizeof(rpnp_t));
  75     if (rpnp == NULL) {
  76         rrd_set_error("failed allocating rpnp array");
  77         return NULL;
  78     }
  79     for (i = 0; rpnc[i].op != OP_END; ++i) {
  80         rpnp[i].op = (enum op_en)rpnc[i].op;
  81         if (rpnp[i].op == OP_NUMBER) {
  82             rpnp[i].val = (double) rpnc[i].val;
  83         } else if (rpnp[i].op == OP_VARIABLE || rpnp[i].op == OP_PREV_OTHER) {
  84             rpnp[i].ptr = (long) rpnc[i].val;
  85         }
  86     }
  87     /* terminate the sequence */
  88     rpnp[i].op = OP_END;
  89     return rpnp;
  90 }
  91
  92 /* rpn_compact2str: convert a compact sequence of RPN operator nodes back
  93  * into a CDEF string. This function is used by rrd_dump.
  94  * arguments:
  95  *  rpnc: an array of compact RPN operator nodes
  96  *  ds_def: a pointer to the data source definition section of an RRD header
  97  *   for lookup of data source names by index
  98  *  str: out string, memory is allocated by the function, must be freed by the
  99  *   the caller */
 100 void rpn_compact2str(
 101     rpn_cdefds_t *rpnc,
 102     ds_def_t *ds_def,
 103     char **str)
 104 {
 105     unsigned short i, offset = 0;
 106     char      buffer[7];    /* short as a string */
 107
 108     for (i = 0; rpnc[i].op != OP_END; i++) {
 109         if (i > 0)
 110             (*str)[offset++] = ',';
 111
 112 #define add_op(VV,VVV) \
 113           if (addop2str((enum op_en)(rpnc[i].op), VV, VVV, str, &offset) == 1) continue;
 114
 115         if (rpnc[i].op == OP_NUMBER) {
 116             /* convert a short into a string */
 117 #if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__CYGWIN32__)
 118             _itoa(rpnc[i].val, buffer, 10);
 119 #else
 120             sprintf(buffer, "%d", rpnc[i].val);
 121 #endif
 122             add_op(OP_NUMBER, buffer)
 123         }
 124
 125         if (rpnc[i].op == OP_VARIABLE) {
 126             char     *ds_name = ds_def[rpnc[i].val].ds_nam;
 127
 128             add_op(OP_VARIABLE, ds_name)
 129         }
 130
 131         if (rpnc[i].op == OP_PREV_OTHER) {
 132             char     *ds_name = ds_def[rpnc[i].val].ds_nam;
 133
 134             add_op(OP_VARIABLE, ds_name)
 135         }
 136 #undef add_op
 137
 138 #define add_op(VV,VVV) \
 139           if (addop2str((enum op_en)rpnc[i].op, VV, #VVV, str, &offset) == 1) continue;
 140
 141         add_op(OP_ADD, +)
 142             add_op(OP_SUB, -)
 143             add_op(OP_MUL, *)
 144             add_op(OP_DIV, /)
 145             add_op(OP_MOD, %)
 146             add_op(OP_SIN, SIN)
 147             add_op(OP_COS, COS)
 148             add_op(OP_LOG, LOG)
 149             add_op(OP_FLOOR, FLOOR)
 150             add_op(OP_CEIL, CEIL)
 151             add_op(OP_EXP, EXP)
 152             add_op(OP_DUP, DUP)
 153             add_op(OP_EXC, EXC)
 154             add_op(OP_POP, POP)
 155             add_op(OP_LT, LT)
 156             add_op(OP_LE, LE)
 157             add_op(OP_GT, GT)
 158             add_op(OP_GE, GE)
 159             add_op(OP_EQ, EQ)
 160             add_op(OP_IF, IF)
 161             add_op(OP_MIN, MIN)
 162             add_op(OP_MAX, MAX)
 163             add_op(OP_LIMIT, LIMIT)
 164             add_op(OP_UNKN, UNKN)
 165             add_op(OP_UN, UN)
 166             add_op(OP_NEGINF, NEGINF)
 167             add_op(OP_NE, NE)
 168             add_op(OP_PREV, PREV)
 169             add_op(OP_INF, INF)
 170             add_op(OP_ISINF, ISINF)
 171             add_op(OP_NOW, NOW)
 172             add_op(OP_LTIME, LTIME)
 173             add_op(OP_TIME, TIME)
 174             add_op(OP_ATAN2, ATAN2)
 175             add_op(OP_ATAN, ATAN)
 176             add_op(OP_SQRT, SQRT)
 177             add_op(OP_SORT, SORT)
 178             add_op(OP_REV, REV)
 179             add_op(OP_TREND, TREND)
 180             add_op(OP_TRENDNAN, TRENDNAN)
 181             add_op(OP_PREDICT, PREDICT)
 182             add_op(OP_PREDICTSIGMA, PREDICTSIGMA)
 183             add_op(OP_RAD2DEG, RAD2DEG)
 184             add_op(OP_DEG2RAD, DEG2RAD)
 185             add_op(OP_AVG, AVG)
 186             add_op(OP_ABS, ABS)
 187             add_op(OP_ADDNAN, ADDNAN)
 188 #undef add_op
 189     }
 190     (*str)[offset] = '\0';
 191
 192 }
 193
 194 short addop2str(
 195     enum op_en op,
 196     enum op_en op_type,
 197     char *op_str,
 198     char **result_str,
 199     unsigned short *offset)
 200 {
 201     if (op == op_type) {
 202         short     op_len;
 203
 204         op_len = strlen(op_str);
 205         *result_str = (char *) rrd_realloc(*result_str,
 206                                            (op_len + 1 +
 207                                             *offset) * sizeof(char));
 208         if (*result_str == NULL) {
 209             rrd_set_error("failed to alloc memory in addop2str");
 210             return -1;
 211         }
 212         strncpy(&((*result_str)[*offset]), op_str, op_len);
 213         *offset += op_len;
 214         return 1;
 215     }
 216     return 0;
 217 }
 218
 219 void parseCDEF_DS(
 220     const char *def,
 221     rrd_t *rrd,
 222     int ds_idx)
 223 {
 224     rpnp_t   *rpnp = NULL;
 225     rpn_cdefds_t *rpnc = NULL;
 226     short     count, i;
 227
 228     rpnp = rpn_parse((void *) rrd, def, &lookup_DS);
 229     if (rpnp == NULL) {
 230         rrd_set_error("failed to parse computed data source");
 231         return;
 232     }
 233     /* Check for OP nodes not permitted in COMPUTE DS.
 234      * Moved this check from within rpn_compact() because it really is
 235      * COMPUTE DS specific. This is less efficient, but creation doesn't
 236      * occur too often. */
 237     for (i = 0; rpnp[i].op != OP_END; i++) {
 238         if (rpnp[i].op == OP_TIME || rpnp[i].op == OP_LTIME ||
 239             rpnp[i].op == OP_PREV || rpnp[i].op == OP_COUNT) {
 240             rrd_set_error
 241                 ("operators time, ltime, prev and count not supported with DS COMPUTE");
 242             free(rpnp);
 243             return;
 244         }
 245     }
 246     if (rpn_compact(rpnp, &rpnc, &count) == -1) {
 247         free(rpnp);
 248         return;
 249     }
 250     /* copy the compact rpn representation over the ds_def par array */
 251     memcpy((void *) &(rrd->ds_def[ds_idx].par[DS_cdef]),
 252            (void *) rpnc, count * sizeof(rpn_cdefds_t));
 253     free(rpnp);
 254     free(rpnc);
 255 }
 256
 257 /* lookup a data source name in the rrd struct and return the index,
 258  * should use ds_match() here except:
 259  * (1) need a void * pointer to the rrd
 260  * (2) error handling is left to the caller
 261  */
 262 long lookup_DS(
 263     void *rrd_vptr,
 264     char *ds_name)
 265 {
 266     unsigned int i;
 267     rrd_t    *rrd;
 268
 269     rrd = (rrd_t *) rrd_vptr;
 270
 271     for (i = 0; i < rrd->stat_head->ds_cnt; ++i) {
 272         if (strcmp(ds_name, rrd->ds_def[i].ds_nam) == 0)
 273             return i;
 274     }
 275     /* the caller handles a bad data source name in the rpn string */
 276     return -1;
 277 }
 278
 279 /* rpn_parse : parse a string and generate a rpnp array; modified
 280  * str2rpn() originally included in rrd_graph.c
 281  * arguments:
 282  * key_hash: a transparent argument passed to lookup(); conceptually this
 283  *    is a hash object for lookup of a numeric key given a variable name
 284  * expr: the string RPN expression, including variable names
 285  * lookup(): a function that retrieves a numeric key given a variable name
 286  */
 287 rpnp_t   *rpn_parse(
 288     void *key_hash,
 289     const char *const expr_const,
 290     long      (*lookup) (void *,
 291                          char *))
 292 {
 293     int       pos = 0;
 294     char     *expr;
 295     long      steps = -1;
 296     rpnp_t   *rpnp;
 297     char      vname[MAX_VNAME_LEN + 10];
 298     char     *old_locale;
 299
 300     old_locale = setlocale(LC_NUMERIC, "C");
 301
 302     rpnp = NULL;
 303     expr = (char *) expr_const;
 304
 305     while (*expr) {
 306         if ((rpnp = (rpnp_t *) rrd_realloc(rpnp, (++steps + 2) *
 307                                            sizeof(rpnp_t))) == NULL) {
 308             setlocale(LC_NUMERIC, old_locale);
 309             return NULL;
 310         }
 311
 312         else if ((sscanf(expr, "%lf%n", &rpnp[steps].val, &pos) == 1)
 313                  && (expr[pos] == ',')) {
 314             rpnp[steps].op = OP_NUMBER;
 315             expr += pos;
 316         }
 317 #define match_op(VV,VVV) \
 318         else if (strncmp(expr, #VVV, strlen(#VVV))==0 && ( expr[strlen(#VVV)] == ',' || expr[strlen(#VVV)] == '\0' )){ \
 319             rpnp[steps].op = VV; \
 320             expr+=strlen(#VVV); \
 321         }
 322
 323 #define match_op_param(VV,VVV) \
 324         else if (sscanf(expr, #VVV "(" DEF_NAM_FMT ")",vname) == 1) { \
 325           int length = 0; \
 326           if ((length = strlen(#VVV)+strlen(vname)+2, \
 327               expr[length] == ',' || expr[length] == '\0') ) { \
 328              rpnp[steps].op = VV; \
 329              rpnp[steps].ptr = (*lookup)(key_hash,vname); \
 330              if (rpnp[steps].ptr < 0) { \
 331                            free(rpnp); \
 332                            return NULL; \
 333                          } else expr+=length; \
 334           } \
 335         }
 336
 337         match_op(OP_ADD, +)
 338             match_op(OP_SUB, -)
 339             match_op(OP_MUL, *)
 340             match_op(OP_DIV, /)
 341             match_op(OP_MOD, %)
 342             match_op(OP_SIN, SIN)
 343             match_op(OP_COS, COS)
 344             match_op(OP_LOG, LOG)
 345             match_op(OP_FLOOR, FLOOR)
 346             match_op(OP_CEIL, CEIL)
 347             match_op(OP_EXP, EXP)
 348             match_op(OP_DUP, DUP)
 349             match_op(OP_EXC, EXC)
 350             match_op(OP_POP, POP)
 351             match_op(OP_LTIME, LTIME)
 352             match_op(OP_LT, LT)
 353             match_op(OP_LE, LE)
 354             match_op(OP_GT, GT)
 355             match_op(OP_GE, GE)
 356             match_op(OP_EQ, EQ)
 357             match_op(OP_IF, IF)
 358             match_op(OP_MIN, MIN)
 359             match_op(OP_MAX, MAX)
 360             match_op(OP_LIMIT, LIMIT)
 361             /* order is important here ! .. match longest first */
 362             match_op(OP_UNKN, UNKN)
 363             match_op(OP_UN, UN)
 364             match_op(OP_NEGINF, NEGINF)
 365             match_op(OP_NE, NE)
 366             match_op(OP_COUNT, COUNT)
 367             match_op_param(OP_PREV_OTHER, PREV)
 368             match_op(OP_PREV, PREV)
 369             match_op(OP_INF, INF)
 370             match_op(OP_ISINF, ISINF)
 371             match_op(OP_NOW, NOW)
 372             match_op(OP_TIME, TIME)
 373             match_op(OP_ATAN2, ATAN2)
 374             match_op(OP_ATAN, ATAN)
 375             match_op(OP_SQRT, SQRT)
 376             match_op(OP_SORT, SORT)
 377             match_op(OP_REV, REV)
 378             match_op(OP_TREND, TREND)
 379             match_op(OP_TRENDNAN, TRENDNAN)
 380             match_op(OP_PREDICT, PREDICT)
 381             match_op(OP_PREDICTSIGMA, PREDICTSIGMA)
 382             match_op(OP_RAD2DEG, RAD2DEG)
 383             match_op(OP_DEG2RAD, DEG2RAD)
 384             match_op(OP_AVG, AVG)
 385             match_op(OP_ABS, ABS)
 386             match_op(OP_ADDNAN, ADDNAN)
 387 #undef match_op
 388             else if ((sscanf(expr, DEF_NAM_FMT "%n", vname, &pos) == 1)
 389                      && ((rpnp[steps].ptr = (*lookup) (key_hash, vname)) !=
 390                          -1)) {
 391             rpnp[steps].op = OP_VARIABLE;
 392             expr += pos;
 393         }
 394
 395         else {
 396             setlocale(LC_NUMERIC, old_locale);
 397             free(rpnp);
 398             return NULL;
 399         }
 400
 401         if (*expr == 0)
 402             break;
 403         if (*expr == ',')
 404             expr++;
 405         else {
 406             setlocale(LC_NUMERIC, old_locale);
 407             free(rpnp);
 408             return NULL;
 409         }
 410     }
 411     rpnp[steps + 1].op = OP_END;
 412     setlocale(LC_NUMERIC, old_locale);
 413     return rpnp;
 414 }
 415
 416 void rpnstack_init(
 417     rpnstack_t *rpnstack)
 418 {
 419     rpnstack->s = NULL;
 420     rpnstack->dc_stacksize = 0;
 421     rpnstack->dc_stackblock = 100;
 422 }
 423
 424 void rpnstack_free(
 425     rpnstack_t *rpnstack)
 426 {
 427     if (rpnstack->s != NULL)
 428         free(rpnstack->s);
 429     rpnstack->dc_stacksize = 0;
 430 }
 431
 432 static int rpn_compare_double(
 433     const void *x,
 434     const void *y)
 435 {
 436     double    diff = *((const double *) x) - *((const double *) y);
 437
 438     return (diff < 0) ? -1 : (diff > 0) ? 1 : 0;
 439 }
 440
 441 /* rpn_calc: run the RPN calculator; also performs variable substitution;
 442  * moved and modified from data_calc() originally included in rrd_graph.c
 443  * arguments:
 444  * rpnp : an array of RPN operators (including variable references)
 445  * rpnstack : the initialized stack
 446  * data_idx : when data_idx is a multiple of rpnp.step, the rpnp.data pointer
 447  *   is advanced by rpnp.ds_cnt; used only for variable substitution
 448  * output : an array of output values; OP_PREV assumes this array contains
 449  *   the "previous" value at index position output_idx-1; the definition of
 450  *   "previous" depends on the calling environment
 451  * output_idx : an index into the output array in which to store the output
 452  *   of the RPN calculator
 453  * returns: -1 if the computation failed (also calls rrd_set_error)
 454  *           0 on success
 455  */
 456 short rpn_calc(
 457     rpnp_t *rpnp,
 458     rpnstack_t *rpnstack,
 459     long data_idx,
 460     rrd_value_t *output,
 461     int output_idx)
 462 {
 463     int       rpi;
 464     long      stptr = -1;
 465
 466     /* process each op from the rpn in turn */
 467     for (rpi = 0; rpnp[rpi].op != OP_END; rpi++) {
 468         /* allocate or grow the stack */
 469         if (stptr + 5 > rpnstack->dc_stacksize) {
 470             /* could move this to a separate function */
 471             rpnstack->dc_stacksize += rpnstack->dc_stackblock;
 472             rpnstack->s = (double*)rrd_realloc(rpnstack->s,
 473                                       (rpnstack->dc_stacksize) *
 474                                       sizeof(*(rpnstack->s)));
 475             if (rpnstack->s == NULL) {
 476                 rrd_set_error("RPN stack overflow");
 477                 return -1;
 478             }
 479         }
 480 #define stackunderflow(MINSIZE)                         \
 481         if(stptr<MINSIZE){                              \
 482             rrd_set_error("RPN stack underflow");       \
 483             return -1;                                  \
 484         }
 485
 486         switch (rpnp[rpi].op) {
 487         case OP_NUMBER:
 488             rpnstack->s[++stptr] = rpnp[rpi].val;
 489             break;
 490         case OP_VARIABLE:
 491         case OP_PREV_OTHER:
 492             /* Sanity check: VDEFs shouldn't make it here */
 493             if (rpnp[rpi].ds_cnt == 0) {
 494                 rrd_set_error("VDEF made it into rpn_calc... aborting");
 495                 return -1;
 496             } else {
 497                 /* make sure we pull the correct value from
 498                  * the *.data array. Adjust the pointer into
 499                  * the array acordingly. Advance the ptr one
 500                  * row in the rra (skip over non-relevant
 501                  * data sources)
 502                  */
 503                 if (rpnp[rpi].op == OP_VARIABLE) {
 504                     rpnstack->s[++stptr] = *(rpnp[rpi].data);
 505                 } else {
 506                     if ((output_idx) <= 0) {
 507                         rpnstack->s[++stptr] = DNAN;
 508                     } else {
 509                         rpnstack->s[++stptr] =
 510                             *(rpnp[rpi].data - rpnp[rpi].ds_cnt);
 511                     }
 512
 513                 }
 514                 if (data_idx % rpnp[rpi].step == 0) {
 515                     rpnp[rpi].data += rpnp[rpi].ds_cnt;
 516                 }
 517             }
 518             break;
 519         case OP_COUNT:
 520             rpnstack->s[++stptr] = (output_idx + 1);    /* Note: Counter starts at 1 */
 521             break;
 522         case OP_PREV:
 523             if ((output_idx) <= 0) {
 524                 rpnstack->s[++stptr] = DNAN;
 525             } else {
 526                 rpnstack->s[++stptr] = output[output_idx - 1];
 527             }
 528             break;
 529         case OP_UNKN:
 530             rpnstack->s[++stptr] = DNAN;
 531             break;
 532         case OP_INF:
 533             rpnstack->s[++stptr] = DINF;
 534             break;
 535         case OP_NEGINF:
 536             rpnstack->s[++stptr] = -DINF;
 537             break;
 538         case OP_NOW:
 539             rpnstack->s[++stptr] = (double) time(NULL);
 540             break;
 541         case OP_TIME:
 542             /* HACK: this relies on the data_idx being the time,
 543              ** which the within-function scope is unaware of */
 544             rpnstack->s[++stptr] = (double) data_idx;
 545             break;
 546         case OP_LTIME:
 547             rpnstack->s[++stptr] =
 548                 (double) tzoffset(data_idx) + (double) data_idx;
 549             break;
 550         case OP_ADD:
 551             stackunderflow(1);
 552             rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]
 553                 + rpnstack->s[stptr];
 554             stptr--;
 555             break;
 556         case OP_ADDNAN:
 557             stackunderflow(1);
 558             if (isnan(rpnstack->s[stptr - 1])) {
 559                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 560             } else if (isnan(rpnstack->s[stptr])) {
 561                 /* NOOP */
 562                 /* rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]; */
 563             } else {
 564                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]
 565                     + rpnstack->s[stptr];
 566             }
 567
 568             stptr--;
 569             break;
 570         case OP_SUB:
 571             stackunderflow(1);
 572             rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]
 573                 - rpnstack->s[stptr];
 574             stptr--;
 575             break;
 576         case OP_MUL:
 577             stackunderflow(1);
 578             rpnstack->s[stptr - 1] = (rpnstack->s[stptr - 1])
 579                 * (rpnstack->s[stptr]);
 580             stptr--;
 581             break;
 582         case OP_DIV:
 583             stackunderflow(1);
 584             rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]
 585                 / rpnstack->s[stptr];
 586             stptr--;
 587             break;
 588         case OP_MOD:
 589             stackunderflow(1);
 590             rpnstack->s[stptr - 1] = fmod(rpnstack->s[stptr - 1]
 591                                           , rpnstack->s[stptr]);
 592             stptr--;
 593             break;
 594         case OP_SIN:
 595             stackunderflow(0);
 596             rpnstack->s[stptr] = sin(rpnstack->s[stptr]);
 597             break;
 598         case OP_ATAN:
 599             stackunderflow(0);
 600             rpnstack->s[stptr] = atan(rpnstack->s[stptr]);
 601             break;
 602         case OP_RAD2DEG:
 603             stackunderflow(0);
 604             rpnstack->s[stptr] = 57.29577951 * rpnstack->s[stptr];
 605             break;
 606         case OP_DEG2RAD:
 607             stackunderflow(0);
 608             rpnstack->s[stptr] = 0.0174532952 * rpnstack->s[stptr];
 609             break;
 610         case OP_ATAN2:
 611             stackunderflow(1);
 612             rpnstack->s[stptr - 1] = atan2(rpnstack->s[stptr - 1],
 613                                            rpnstack->s[stptr]);
 614             stptr--;
 615             break;
 616         case OP_COS:
 617             stackunderflow(0);
 618             rpnstack->s[stptr] = cos(rpnstack->s[stptr]);
 619             break;
 620         case OP_CEIL:
 621             stackunderflow(0);
 622             rpnstack->s[stptr] = ceil(rpnstack->s[stptr]);
 623             break;
 624         case OP_FLOOR:
 625             stackunderflow(0);
 626             rpnstack->s[stptr] = floor(rpnstack->s[stptr]);
 627             break;
 628         case OP_LOG:
 629             stackunderflow(0);
 630             rpnstack->s[stptr] = log(rpnstack->s[stptr]);
 631             break;
 632         case OP_DUP:
 633             stackunderflow(0);
 634             rpnstack->s[stptr + 1] = rpnstack->s[stptr];
 635             stptr++;
 636             break;
 637         case OP_POP:
 638             stackunderflow(0);
 639             stptr--;
 640             break;
 641         case OP_EXC:
 642             stackunderflow(1);
 643             {
 644                 double    dummy;
 645
 646                 dummy = rpnstack->s[stptr];
 647                 rpnstack->s[stptr] = rpnstack->s[stptr - 1];
 648                 rpnstack->s[stptr - 1] = dummy;
 649             }
 650             break;
 651         case OP_EXP:
 652             stackunderflow(0);
 653             rpnstack->s[stptr] = exp(rpnstack->s[stptr]);
 654             break;
 655         case OP_LT:
 656             stackunderflow(1);
 657             if (isnan(rpnstack->s[stptr - 1]));
 658             else if (isnan(rpnstack->s[stptr]))
 659                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 660             else
 661                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1] <
 662                     rpnstack->s[stptr] ? 1.0 : 0.0;
 663             stptr--;
 664             break;
 665         case OP_LE:
 666             stackunderflow(1);
 667             if (isnan(rpnstack->s[stptr - 1]));
 668             else if (isnan(rpnstack->s[stptr]))
 669                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 670             else
 671                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1] <=
 672                     rpnstack->s[stptr] ? 1.0 : 0.0;
 673             stptr--;
 674             break;
 675         case OP_GT:
 676             stackunderflow(1);
 677             if (isnan(rpnstack->s[stptr - 1]));
 678             else if (isnan(rpnstack->s[stptr]))
 679                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 680             else
 681                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1] >
 682                     rpnstack->s[stptr] ? 1.0 : 0.0;
 683             stptr--;
 684             break;
 685         case OP_GE:
 686             stackunderflow(1);
 687             if (isnan(rpnstack->s[stptr - 1]));
 688             else if (isnan(rpnstack->s[stptr]))
 689                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 690             else
 691                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1] >=
 692                     rpnstack->s[stptr] ? 1.0 : 0.0;
 693             stptr--;
 694             break;
 695         case OP_NE:
 696             stackunderflow(1);
 697             if (isnan(rpnstack->s[stptr - 1]));
 698             else if (isnan(rpnstack->s[stptr]))
 699                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 700             else
 701                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1] ==
 702                     rpnstack->s[stptr] ? 0.0 : 1.0;
 703             stptr--;
 704             break;
 705         case OP_EQ:
 706             stackunderflow(1);
 707             if (isnan(rpnstack->s[stptr - 1]));
 708             else if (isnan(rpnstack->s[stptr]))
 709                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 710             else
 711                 rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1] ==
 712                     rpnstack->s[stptr] ? 1.0 : 0.0;
 713             stptr--;
 714             break;
 715         case OP_IF:
 716             stackunderflow(2);
 717             rpnstack->s[stptr - 2] = (isnan(rpnstack->s[stptr - 2])
 718                                       || rpnstack->s[stptr - 2] ==
 719                                       0.0) ? rpnstack->s[stptr] : rpnstack->
 720                 s[stptr - 1];
 721             stptr--;
 722             stptr--;
 723             break;
 724         case OP_MIN:
 725             stackunderflow(1);
 726             if (isnan(rpnstack->s[stptr - 1]));
 727             else if (isnan(rpnstack->s[stptr]))
 728                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 729             else if (rpnstack->s[stptr - 1] > rpnstack->s[stptr])
 730                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 731             stptr--;
 732             break;
 733         case OP_MAX:
 734             stackunderflow(1);
 735             if (isnan(rpnstack->s[stptr - 1]));
 736             else if (isnan(rpnstack->s[stptr]))
 737                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 738             else if (rpnstack->s[stptr - 1] < rpnstack->s[stptr])
 739                 rpnstack->s[stptr - 1] = rpnstack->s[stptr];
 740             stptr--;
 741             break;
 742         case OP_LIMIT:
 743             stackunderflow(2);
 744             if (isnan(rpnstack->s[stptr - 2]));
 745             else if (isnan(rpnstack->s[stptr - 1]))
 746                 rpnstack->s[stptr - 2] = rpnstack->s[stptr - 1];
 747             else if (isnan(rpnstack->s[stptr]))
 748                 rpnstack->s[stptr - 2] = rpnstack->s[stptr];
 749             else if (rpnstack->s[stptr - 2] < rpnstack->s[stptr - 1])
 750                 rpnstack->s[stptr - 2] = DNAN;
 751             else if (rpnstack->s[stptr - 2] > rpnstack->s[stptr])
 752                 rpnstack->s[stptr - 2] = DNAN;
 753             stptr -= 2;
 754             break;
 755         case OP_UN:
 756             stackunderflow(0);
 757             rpnstack->s[stptr] = isnan(rpnstack->s[stptr]) ? 1.0 : 0.0;
 758             break;
 759         case OP_ISINF:
 760             stackunderflow(0);
 761             rpnstack->s[stptr] = isinf(rpnstack->s[stptr]) ? 1.0 : 0.0;
 762             break;
 763         case OP_SQRT:
 764             stackunderflow(0);
 765             rpnstack->s[stptr] = sqrt(rpnstack->s[stptr]);
 766             break;
 767         case OP_SORT:
 768             stackunderflow(0);
 769             {
 770                 int       spn = (int) rpnstack->s[stptr--];
 771
 772                 stackunderflow(spn - 1);
 773                 qsort(rpnstack->s + stptr - spn + 1, spn, sizeof(double),
 774                       rpn_compare_double);
 775             }
 776             break;
 777         case OP_REV:
 778             stackunderflow(0);
 779             {
 780                 int       spn = (int) rpnstack->s[stptr--];
 781                 double   *p, *q;
 782
 783                 stackunderflow(spn - 1);
 784
 785                 p = rpnstack->s + stptr - spn + 1;
 786                 q = rpnstack->s + stptr;
 787                 while (p < q) {
 788                     double    x = *q;
 789
 790                     *q-- = *p;
 791                     *p++ = x;
 792                 }
 793             }
 794             break;
 795         case OP_PREDICT:
 796         case OP_PREDICTSIGMA:
 797             stackunderflow(2);
 798             {
 799                 /* the local averaging window (similar to trend, but better here, as we get better statistics thru numbers)*/
 800                 int   locstepsize = rpnstack->s[--stptr];
 801                 /* the number of shifts and range-checking*/
 802                 int     shifts = rpnstack->s[--stptr];
 803                 stackunderflow(shifts);
 804                 // handle negative shifts special
 805                 if (shifts<0) {
 806                     stptr--;
 807                 } else {
 808                     stptr-=shifts;
 809                 }
 810                 /* the real calculation */
 811                 double val=DNAN;
 812                 /* the info on the datasource */
 813                 time_t  dsstep = (time_t) rpnp[rpi - 1].step;
 814                 int    dscount = rpnp[rpi - 1].ds_cnt;
 815                 int   locstep = (int)ceil((float)locstepsize/(float)dsstep);
 816
 817                 /* the sums */
 818                 double    sum = 0;
 819                 double    sum2 = 0;
 820                 int       count = 0;
 821                 /* now loop for each position */
 822                 int doshifts=shifts;
 823                 if (shifts<0) { doshifts=-shifts; }
 824                 for(int loop=0;loop<doshifts;loop++) {
 825                     /* calculate shift step */
 826                     int shiftstep=1;
 827                     if (shifts<0) {
 828                         shiftstep = loop*rpnstack->s[stptr];
 829                     } else {
 830                         shiftstep = rpnstack->s[stptr+loop];
 831                     }
 832                     if(shiftstep <0) {
 833                         rrd_set_error("negative shift step not allowed: %i",shiftstep);
 834                         return -1;
 835                     }
 836                     shiftstep=(int)ceil((float)shiftstep/(float)dsstep);
 837                     /* loop all local shifts */
 838                     for(int i=0;i<=locstep;i++) {
 839                         /* now calculate offset into data-array - relative to output_idx*/
 840                         int offset=shiftstep+i;
 841                         /* and process if we have index 0 of above */
 842                         if ((offset>=0)&&(offset<output_idx)) {
 843                             /* get the value */
 844                             val =rpnp[rpi - 1].data[-dscount * offset];
 845                             /* and handle the non NAN case only*/
 846                             if (! isnan(val)) {
 847                                 sum+=val;
 848                                 sum2+=val*val;
 849                                 count++;
 850                             }
 851                         }
 852                     }
 853                 }
 854                 /* do the final calculations */
 855                 val=DNAN;
 856                 if (rpnp[rpi].op == OP_PREDICT) {  /* the average */
 857                     if (count>0) {
 858                         val = sum/(double)count;
 859                     }
 860                 } else {
 861                     if (count>1) { /* the sigma case */
 862                         val=count*sum2-sum*sum;
 863                         if (val<0) {
 864                             val=DNAN;
 865                         } else {
 866                             val=sqrt(val/((float)count*((float)count-1.0)));
 867                         }
 868                     }
 869                 }
 870                 rpnstack->s[stptr] = val;
 871             }
 872             break;
 873         case OP_TREND:
 874         case OP_TRENDNAN:
 875             stackunderflow(1);
 876             if ((rpi < 2) || (rpnp[rpi - 2].op != OP_VARIABLE)) {
 877                 rrd_set_error("malformed trend arguments");
 878                 return -1;
 879             } else {
 880                 time_t    dur = (time_t) rpnstack->s[stptr];
 881                 time_t    step = (time_t) rpnp[rpi - 2].step;
 882
 883                 if (output_idx > (int) ceil((float) dur / (float) step)) {
 884                     int       ignorenan = (rpnp[rpi].op == OP_TREND);
 885                     double    accum = 0.0;
 886                     int       i = 0;
 887                     int       count = 0;
 888
 889                     do {
 890                         double    val =
 891                             rpnp[rpi - 2].data[rpnp[rpi - 2].ds_cnt * i--];
 892                         if (ignorenan || !isnan(val)) {
 893                             accum += val;
 894                             ++count;
 895                         }
 896
 897                         dur -= step;
 898                     } while (dur > 0);
 899
 900                     rpnstack->s[--stptr] =
 901                         (count == 0) ? DNAN : (accum / count);
 902                 } else
 903                     rpnstack->s[--stptr] = DNAN;
 904             }
 905             break;
 906         case OP_AVG:
 907             stackunderflow(0);
 908             {
 909                 int       i = (int) rpnstack->s[stptr--];
 910                 double    sum = 0;
 911                 int       count = 0;
 912
 913                 stackunderflow(i - 1);
 914                 while (i > 0) {
 915                     double    val = rpnstack->s[stptr--];
 916
 917                     i--;
 918                     if (isnan(val)) {
 919                         continue;
 920                     }
 921                     count++;
 922                     sum += val;
 923                 }
 924                 /* now push the result back on stack */
 925                 if (count > 0) {
 926                     rpnstack->s[++stptr] = sum / count;
 927                 } else {
 928                     rpnstack->s[++stptr] = DNAN;
 929                 }
 930             }
 931             break;
 932         case OP_ABS:
 933             stackunderflow(0);
 934             rpnstack->s[stptr] = fabs(rpnstack->s[stptr]);
 935             break;
 936         case OP_END:
 937             break;
 938         }
 939 #undef stackunderflow
 940     }
 941     if (stptr != 0) {
 942         rrd_set_error("RPN final stack size != 1");
 943         return -1;
 944     }
 945
 946     output[output_idx] = rpnstack->s[0];
 947     return 0;
 948 }
 949
 950 /* figure out what the local timezone offset for any point in
 951    time was. Return it in seconds */
 952 int tzoffset(
 953     time_t now)
 954 {
 955     int       gm_sec, gm_min, gm_hour, gm_yday, gm_year,
 956         l_sec, l_min, l_hour, l_yday, l_year;
 957     struct tm t;
 958     int       off;
 959
 960     gmtime_r(&now, &t);
 961     gm_sec = t.tm_sec;
 962     gm_min = t.tm_min;
 963     gm_hour = t.tm_hour;
 964     gm_yday = t.tm_yday;
 965     gm_year = t.tm_year;
 966     localtime_r(&now, &t);
 967     l_sec = t.tm_sec;
 968     l_min = t.tm_min;
 969     l_hour = t.tm_hour;
 970     l_yday = t.tm_yday;
 971     l_year = t.tm_year;
 972     off =
 973         (l_sec - gm_sec) + (l_min - gm_min) * 60 + (l_hour - gm_hour) * 3600;
 974     if (l_yday > gm_yday || l_year > gm_year) {
 975         off += 24 * 3600;
 976     } else if (l_yday < gm_yday || l_year < gm_year) {
 977         off -= 24 * 3600;
 978     }
 979     return off;
 980 }