1 /****************************************************************************
2 * RRDtool 1.0.28 Copyright Tobias Oetiker, 1997 - 2002
3 ****************************************************************************
4 * rrd_rpncalc.c RPN calculator functions
5 ****************************************************************************/
7 #include "rrd_tool.h"
8 #include "rrd_rpncalc.h"
9 #include <limits.h>
11 short addop2str(enum op_en op, enum op_en op_type, char *op_str,
12 char **result_str, unsigned short *offset);
13 int tzoffset(time_t); /* used to implement LTIME */
15 short rpn_compact(rpnp_t *rpnp, rpn_cdefds_t **rpnc, short *count)
16 {
17 short i;
18 *count = 0;
19 /* count the number of rpn nodes */
20 while(rpnp[*count].op != OP_END) (*count)++;
21 if (++(*count) > DS_CDEF_MAX_RPN_NODES) {
22 rrd_set_error("Maximum %d RPN nodes permitted",
23 DS_CDEF_MAX_RPN_NODES);
24 return -1;
25 }
27 /* allocate memory */
28 *rpnc = (rpn_cdefds_t *) calloc(*count,sizeof(rpn_cdefds_t));
29 for (i = 0; rpnp[i].op != OP_END; i++)
30 {
31 (*rpnc)[i].op = (char) rpnp[i].op;
32 if (rpnp[i].op == OP_NUMBER) {
33 /* rpnp.val is a double, rpnc.val is a short */
34 double temp = floor(rpnp[i].val);
35 if (temp < SHRT_MIN || temp > SHRT_MAX) {
36 rrd_set_error(
37 "constants must be integers in the interval (%d, %d)",
38 SHRT_MIN, SHRT_MAX);
39 free(*rpnc);
40 return -1;
41 }
42 (*rpnc)[i].val = (short) temp;
43 } else if (rpnp[i].op == OP_VARIABLE) {
44 (*rpnc)[i].val = (short) rpnp[i].ptr;
45 }
46 }
47 /* terminate the sequence */
48 (*rpnc)[(*count) - 1].op = OP_END;
49 return 0;
50 }
52 rpnp_t * rpn_expand(rpn_cdefds_t *rpnc)
53 {
54 short i;
55 rpnp_t *rpnp;
57 /* DS_CDEF_MAX_RPN_NODES is small, so at the expense of some wasted
58 * memory we avoid any reallocs */
59 rpnp = (rpnp_t *) calloc(DS_CDEF_MAX_RPN_NODES,sizeof(rpnp_t));
60 if (rpnp == NULL) return NULL;
61 for (i = 0; rpnc[i].op != OP_END; ++i)
62 {
63 rpnp[i].op = (long) rpnc[i].op;
64 if (rpnp[i].op == OP_NUMBER) {
65 rpnp[i].val = (double) rpnc[i].val;
66 } else if (rpnp[i].op == OP_VARIABLE) {
67 rpnp[i].ptr = (long) rpnc[i].val;
68 }
69 }
70 /* terminate the sequence */
71 rpnp[i].op = OP_END;
72 return rpnp;
73 }
75 /* rpn_compact2str: convert a compact sequence of RPN operator nodes back
76 * into a CDEF string. This function is used by rrd_dump.
77 * arguments:
78 * rpnc: an array of compact RPN operator nodes
79 * ds_def: a pointer to the data source definition section of an RRD header
80 * for lookup of data source names by index
81 * str: out string, memory is allocated by the function, must be freed by the
82 * the caller */
83 void rpn_compact2str(rpn_cdefds_t *rpnc,ds_def_t *ds_def,char **str)
84 {
85 unsigned short i,offset = 0;
86 char buffer[7]; /* short as a string */
88 for (i = 0; rpnc[i].op != OP_END; i++)
89 {
90 if (i > 0) (*str)[offset++] = ',';
92 #define add_op(VV,VVV) \
93 if (addop2str(rpnc[i].op, VV, VVV, str, &offset) == 1) continue;
95 if (rpnc[i].op == OP_NUMBER) {
96 /* convert a short into a string */
97 #ifdef WIN32
98 _itoa(rpnc[i].val,buffer,10);
99 #else
100 sprintf(buffer,"%d",rpnc[i].val);
101 #endif
102 add_op(OP_NUMBER,buffer)
103 }
105 if (rpnc[i].op == OP_VARIABLE) {
106 char *ds_name = ds_def[rpnc[i].val].ds_nam;
107 add_op(OP_VARIABLE, ds_name)
108 }
109 #undef add_op
111 #define add_op(VV,VVV) \
112 if (addop2str(rpnc[i].op, VV, #VVV, str, &offset) == 1) continue;
114 add_op(OP_ADD,+)
115 add_op(OP_SUB,-)
116 add_op(OP_MUL,*)
117 add_op(OP_DIV,/)
118 add_op(OP_MOD,%)
119 add_op(OP_SIN,SIN)
120 add_op(OP_COS,COS)
121 add_op(OP_LOG,LOG)
122 add_op(OP_FLOOR,FLOOR)
123 add_op(OP_CEIL,CEIL)
124 add_op(OP_EXP,EXP)
125 add_op(OP_DUP,DUP)
126 add_op(OP_EXC,EXC)
127 add_op(OP_POP,POP)
128 add_op(OP_LT,LT)
129 add_op(OP_LE,LE)
130 add_op(OP_GT,GT)
131 add_op(OP_GE,GE)
132 add_op(OP_EQ,EQ)
133 add_op(OP_IF,IF)
134 add_op(OP_MIN,MIN)
135 add_op(OP_MAX,MAX)
136 add_op(OP_LIMIT,LIMIT)
137 add_op(OP_UNKN,UNKN)
138 add_op(OP_UN,UN)
139 add_op(OP_NEGINF,NEGINF)
140 add_op(OP_PREV,PREV)
141 add_op(OP_INF,INF)
142 add_op(OP_NOW,NOW)
143 add_op(OP_LTIME,LTIME)
144 add_op(OP_TIME,TIME)
146 #undef add_op
147 }
148 (*str)[offset] = '\0';
150 }
152 short addop2str(enum op_en op, enum op_en op_type, char *op_str,
153 char **result_str, unsigned short *offset)
154 {
155 if (op == op_type) {
156 short op_len;
157 op_len = strlen(op_str);
158 *result_str = (char *) rrd_realloc(*result_str,
159 (op_len + 1 + *offset)*sizeof(char));
160 if (*result_str == NULL) {
161 rrd_set_error("failed to alloc memory in addop2str");
162 return -1;
163 }
164 strncpy(&((*result_str)[*offset]),op_str,op_len);
165 *offset += op_len;
166 return 1;
167 }
168 return 0;
169 }
171 void parseCDEF_DS(char *def,rrd_t *rrd, int ds_idx)
172 {
173 rpnp_t *rpnp = NULL;
174 rpn_cdefds_t *rpnc = NULL;
175 short count, i;
177 rpnp = rpn_parse((void*) rrd, def, &lookup_DS);
178 if (rpnp == NULL) {
179 rrd_set_error("failed to parse computed data source %s", def);
180 return;
181 }
182 /* Check for OP nodes not permitted in COMPUTE DS.
183 * Moved this check from within rpn_compact() because it really is
184 * COMPUTE DS specific. This is less efficient, but creation doesn't
185 * occur too often. */
186 for (i = 0; rpnp[i].op != OP_END; i++) {
187 if (rpnp[i].op == OP_TIME || rpnp[i].op == OP_LTIME ||
188 rpnp[i].op == OP_PREV)
189 {
190 rrd_set_error(
191 "operators time, ltime and prev not supported with DS COMPUTE");
192 free(rpnp);
193 return;
194 }
195 }
196 if (rpn_compact(rpnp,&rpnc,&count) == -1) {
197 free(rpnp);
198 return;
199 }
200 /* copy the compact rpn representation over the ds_def par array */
201 memcpy((void*) &(rrd -> ds_def[ds_idx].par[DS_cdef]),
202 (void*) rpnc, count*sizeof(rpn_cdefds_t));
203 free(rpnp);
204 free(rpnc);
205 }
207 /* lookup a data source name in the rrd struct and return the index,
208 * should use ds_match() here except:
209 * (1) need a void * pointer to the rrd
210 * (2) error handling is left to the caller
211 */
212 long lookup_DS(void *rrd_vptr,char *ds_name)
213 {
214 int i;
215 rrd_t *rrd;
217 rrd = (rrd_t *) rrd_vptr;
219 for (i = 0; i < rrd -> stat_head -> ds_cnt; ++i)
220 {
221 if(strcmp(ds_name,rrd -> ds_def[i].ds_nam) == 0)
222 return i;
223 }
224 /* the caller handles a bad data source name in the rpn string */
225 return -1;
226 }
228 /* rpn_parse : parse a string and generate a rpnp array; modified
229 * str2rpn() originally included in rrd_graph.c
230 * arguments:
231 * key_hash: a transparent argument passed to lookup(); conceptually this
232 * is a hash object for lookup of a numeric key given a variable name
233 * expr: the string RPN expression, including variable names
234 * lookup(): a function that retrieves a numeric key given a variable name
235 */
236 rpnp_t *
237 rpn_parse(void *key_hash,char *expr,long (*lookup)(void *,char*)){
238 int pos=0;
239 long steps=-1;
240 rpnp_t *rpnp;
241 char vname[30];
243 rpnp=NULL;
245 while(*expr){
246 if ((rpnp = (rpnp_t *) rrd_realloc(rpnp, (++steps + 2)*
247 sizeof(rpnp_t)))==NULL){
248 return NULL;
249 }
251 else if((sscanf(expr,"%lf%n",&rpnp[steps].val,&pos) == 1) && (expr[pos] == ',')){
252 rpnp[steps].op = OP_NUMBER;
253 expr+=pos;
254 }
256 #define match_op(VV,VVV) \
257 else if (strncmp(expr, #VVV, strlen(#VVV))==0){ \
258 rpnp[steps].op = VV; \
259 expr+=strlen(#VVV); \
260 }
262 match_op(OP_ADD,+)
263 match_op(OP_SUB,-)
264 match_op(OP_MUL,*)
265 match_op(OP_DIV,/)
266 match_op(OP_MOD,%)
267 match_op(OP_SIN,SIN)
268 match_op(OP_COS,COS)
269 match_op(OP_LOG,LOG)
270 match_op(OP_FLOOR,FLOOR)
271 match_op(OP_CEIL,CEIL)
272 match_op(OP_EXP,EXP)
273 match_op(OP_DUP,DUP)
274 match_op(OP_EXC,EXC)
275 match_op(OP_POP,POP)
276 match_op(OP_LT,LT)
277 match_op(OP_LE,LE)
278 match_op(OP_GT,GT)
279 match_op(OP_GE,GE)
280 match_op(OP_EQ,EQ)
281 match_op(OP_IF,IF)
282 match_op(OP_MIN,MIN)
283 match_op(OP_MAX,MAX)
284 match_op(OP_LIMIT,LIMIT)
285 /* order is important here ! .. match longest first */
286 match_op(OP_UNKN,UNKN)
287 match_op(OP_UN,UN)
288 match_op(OP_NEGINF,NEGINF)
289 match_op(OP_PREV,PREV)
290 match_op(OP_INF,INF)
291 match_op(OP_NOW,NOW)
292 match_op(OP_LTIME,LTIME)
293 match_op(OP_TIME,TIME)
295 #undef match_op
298 else if ((sscanf(expr,"%29[_A-Za-z0-9]%n",
299 vname,&pos) == 1)
300 && ((rpnp[steps].ptr = (*lookup)(key_hash,vname)) != -1)){
301 rpnp[steps].op = OP_VARIABLE;
302 expr+=pos;
303 }
305 else {
306 free(rpnp);
307 return NULL;
308 }
309 if (*expr == 0)
310 break;
311 if (*expr == ',')
312 expr++;
313 else {
314 free(rpnp);
315 return NULL;
316 }
317 }
318 rpnp[steps+1].op = OP_END;
319 return rpnp;
320 }
322 void
323 rpnstack_init(rpnstack_t *rpnstack)
324 {
325 rpnstack -> s = NULL;
326 rpnstack -> dc_stacksize = 0;
327 rpnstack -> dc_stackblock = 100;
328 }
330 void
331 rpnstack_free(rpnstack_t *rpnstack)
332 {
333 if (rpnstack -> s != NULL)
334 free(rpnstack -> s);
335 rpnstack -> dc_stacksize = 0;
336 }
338 /* rpn_calc: run the RPN calculator; also performs variable substitution;
339 * moved and modified from data_calc() originally included in rrd_graph.c
340 * arguments:
341 * rpnp : an array of RPN operators (including variable references)
342 * rpnstack : the initialized stack
343 * data_idx : when data_idx is a multiple of rpnp.step, the rpnp.data pointer
344 * is advanced by rpnp.ds_cnt; used only for variable substitution
345 * output : an array of output values; OP_PREV assumes this array contains
346 * the "previous" value at index position output_idx-1; the definition of
347 * "previous" depends on the calling environment
348 * output_idx : an index into the output array in which to store the output
349 * of the RPN calculator
350 * returns: -1 if the computation failed (also calls rrd_set_error)
351 * 0 on success
352 */
353 short
354 rpn_calc(rpnp_t *rpnp, rpnstack_t *rpnstack, long data_idx,
355 rrd_value_t *output, int output_idx)
356 {
357 int rpi;
358 long stptr = -1;
360 /* process each op from the rpn in turn */
361 for (rpi=0; rpnp[rpi].op != OP_END; rpi++){
362 /* allocate or grow the stack */
363 if (stptr + 5 > rpnstack -> dc_stacksize){
364 /* could move this to a separate function */
365 rpnstack -> dc_stacksize += rpnstack -> dc_stackblock;
366 rpnstack -> s = rrd_realloc(rpnstack -> s,
367 (rpnstack -> dc_stacksize)*sizeof(*(rpnstack -> s)));
368 if (rpnstack -> s == NULL){
369 rrd_set_error("RPN stack overflow");
370 return -1;
371 }
372 }
373 switch (rpnp[rpi].op){
374 case OP_NUMBER:
375 rpnstack -> s[++stptr] = rpnp[rpi].val;
376 break;
377 case OP_VARIABLE:
378 /* Sanity check: VDEFs shouldn't make it here */
379 if (rpnp[rpi].ds_cnt == 0) {
380 rrd_set_error("VDEF made it into rpn_calc... aborting");
381 return -1;
382 } else {
383 /* make sure we pull the correct value from
384 * the *.data array. Adjust the pointer into
385 * the array acordingly. Advance the ptr one
386 * row in the rra (skip over non-relevant
387 * data sources)
388 */
389 if (data_idx % rpnp[rpi].step == 0){
390 rpnp[rpi].data += rpnp[rpi].ds_cnt;
391 }
392 rpnstack -> s[++stptr] = *(rpnp[rpi].data);
393 }
394 break;
395 case OP_PREV:
396 if ((output_idx-1) <= 0) {
397 rpnstack -> s[++stptr] = DNAN;
398 } else {
399 rpnstack -> s[++stptr] = output[output_idx-1];
400 }
401 break;
402 case OP_UNKN:
403 rpnstack -> s[++stptr] = DNAN;
404 break;
405 case OP_INF:
406 rpnstack -> s[++stptr] = DINF;
407 break;
408 case OP_NEGINF:
409 rpnstack -> s[++stptr] = -DINF;
410 break;
411 case OP_NOW:
412 rpnstack -> s[++stptr] = (double)time(NULL);
413 break;
414 case OP_TIME:
415 /* HACK: this relies on the data_idx being the time,
416 * which the within-function scope is unaware of */
417 rpnstack -> s[++stptr] = (double) data_idx;
418 break;
419 case OP_LTIME:
420 rpnstack -> s[++stptr] = (double) tzoffset(data_idx) + (double)data_idx;
421 break;
422 case OP_ADD:
423 if(stptr<1){
424 rrd_set_error("RPN stack underflow");
425 return -1;
426 }
427 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1]
428 + rpnstack -> s[stptr];
429 stptr--;
430 break;
431 case OP_SUB:
432 if(stptr<1){
433 rrd_set_error("RPN stack underflow");
434 return -1;
435 }
436 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] - rpnstack -> s[stptr];
437 stptr--;
438 break;
439 case OP_MUL:
440 if(stptr<1){
441 rrd_set_error("RPN stack underflow");
442 return -1;
443 }
444 rpnstack -> s[stptr-1] = (rpnstack -> s[stptr-1]) * (rpnstack -> s[stptr]);
445 stptr--;
446 break;
447 case OP_DIV:
448 if(stptr<1){
449 rrd_set_error("RPN stack underflow");
450 return -1;
451 }
452 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] / rpnstack -> s[stptr];
453 stptr--;
454 break;
455 case OP_MOD:
456 if(stptr<1){
457 rrd_set_error("RPN stack underflow");
458 return -1;
459 }
460 rpnstack -> s[stptr-1] = fmod(rpnstack -> s[stptr-1],rpnstack -> s[stptr]);
461 stptr--;
462 break;
463 case OP_SIN:
464 if(stptr<0){
465 rrd_set_error("RPN stack underflow");
466 return -1;
467 }
468 rpnstack -> s[stptr] = sin(rpnstack -> s[stptr]);
469 break;
470 case OP_COS:
471 if(stptr<0){
472 rrd_set_error("RPN stack underflow");
473 return -1;
474 }
475 rpnstack -> s[stptr] = cos(rpnstack -> s[stptr]);
476 break;
477 case OP_CEIL:
478 if(stptr<0){
479 rrd_set_error("RPN stack underflow");
480 return -1;
481 }
482 rpnstack -> s[stptr] = ceil(rpnstack -> s[stptr]);
483 break;
484 case OP_FLOOR:
485 if(stptr<0){
486 rrd_set_error("RPN stack underflow");
487 return -1;
488 }
489 rpnstack -> s[stptr] = floor(rpnstack -> s[stptr]);
490 break;
491 case OP_LOG:
492 if(stptr<0){
493 rrd_set_error("RPN stack underflow");
494 return -1;
495 }
496 rpnstack -> s[stptr] = log(rpnstack -> s[stptr]);
497 break;
498 case OP_DUP:
499 if(stptr<0){
500 rrd_set_error("RPN stack underflow");
501 return -1;
502 }
503 rpnstack -> s[stptr+1] = rpnstack -> s[stptr];
504 stptr++;
505 break;
506 case OP_POP:
507 if(stptr<0){
508 rrd_set_error("RPN stack underflow");
509 return -1;
510 }
511 stptr--;
512 break;
513 case OP_EXC:
514 if(stptr<1){
515 rrd_set_error("RPN stack underflow");
516 return -1;
517 } else {
518 double dummy;
519 dummy = rpnstack -> s[stptr] ;
520 rpnstack -> s[stptr] = rpnstack -> s[stptr-1];
521 rpnstack -> s[stptr-1] = dummy;
522 }
523 break;
524 case OP_EXP:
525 if(stptr<0){
526 rrd_set_error("RPN stack underflow");
527 return -1;
528 }
529 rpnstack -> s[stptr] = exp(rpnstack -> s[stptr]);
530 break;
531 case OP_LT:
532 if(stptr<1){
533 rrd_set_error("RPN stack underflow");
534 return -1;
535 }
536 if (isnan(rpnstack -> s[stptr-1]))
537 ;
538 else if (isnan(rpnstack -> s[stptr]))
539 rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
540 else
541 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] < rpnstack -> s[stptr] ? 1.0 : 0.0;
542 stptr--;
543 break;
544 case OP_LE:
545 if(stptr<1){
546 rrd_set_error("RPN stack underflow");
547 return -1;
548 }
549 if (isnan(rpnstack -> s[stptr-1]))
550 ;
551 else if (isnan(rpnstack -> s[stptr]))
552 rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
553 else
554 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] <= rpnstack -> s[stptr] ? 1.0 : 0.0;
555 stptr--;
556 break;
557 case OP_GT:
558 if(stptr<1){
559 rrd_set_error("RPN stack underflow");
560 return -1;
561 }
562 if (isnan(rpnstack -> s[stptr-1]))
563 ;
564 else if (isnan(rpnstack -> s[stptr]))
565 rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
566 else
567 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] > rpnstack -> s[stptr] ? 1.0 : 0.0;
568 stptr--;
569 break;
570 case OP_GE:
571 if(stptr<1){
572 rrd_set_error("RPN stack underflow");
573 return -1;
574 }
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] >= rpnstack -> s[stptr] ? 1.0 : 0.0;
581 stptr--;
582 break;
583 case OP_EQ:
584 if(stptr<1){
585 rrd_set_error("RPN stack underflow");
586 return -1;
587 }
588 if (isnan(rpnstack -> s[stptr-1]))
589 ;
590 else if (isnan(rpnstack -> s[stptr]))
591 rpnstack -> s[stptr-1] = rpnstack -> s[stptr];
592 else
593 rpnstack -> s[stptr-1] = rpnstack -> s[stptr-1] == rpnstack -> s[stptr] ? 1.0 : 0.0;
594 stptr--;
595 break;
596 case OP_IF:
597 if(stptr<2){
598 rrd_set_error("RPN stack underflow");
599 return -1;
600 }
601 rpnstack->s[stptr-2] = rpnstack->s[stptr-2] != 0.0 ? rpnstack->s[stptr-1] : rpnstack->s[stptr];
602 stptr--;
603 stptr--;
604 break;
605 case OP_MIN:
606 if(stptr<1){
607 rrd_set_error("RPN stack underflow");
608 return -1;
609 }
610 if (isnan(rpnstack->s[stptr-1]))
611 ;
612 else if (isnan(rpnstack->s[stptr]))
613 rpnstack->s[stptr-1] = rpnstack->s[stptr];
614 else if (rpnstack->s[stptr-1] > rpnstack->s[stptr])
615 rpnstack->s[stptr-1] = rpnstack->s[stptr];
616 stptr--;
617 break;
618 case OP_MAX:
619 if(stptr<1){
620 rrd_set_error("RPN stack underflow");
621 return -1;
622 }
623 if (isnan(rpnstack->s[stptr-1]))
624 ;
625 else if (isnan(rpnstack->s[stptr]))
626 rpnstack->s[stptr-1] = rpnstack->s[stptr];
627 else if (rpnstack->s[stptr-1] < rpnstack->s[stptr])
628 rpnstack->s[stptr-1] = rpnstack->s[stptr];
629 stptr--;
630 break;
631 case OP_LIMIT:
632 if(stptr<2){
633 rrd_set_error("RPN stack underflow");
634 free(rpnstack->s);
635 return -1;
636 }
637 if (isnan(rpnstack->s[stptr-2]))
638 ;
639 else if (isnan(rpnstack->s[stptr-1]))
640 rpnstack->s[stptr-2] = rpnstack->s[stptr-1];
641 else if (isnan(rpnstack->s[stptr]))
642 rpnstack->s[stptr-2] = rpnstack->s[stptr];
643 else if (rpnstack->s[stptr-2] < rpnstack->s[stptr-1])
644 rpnstack->s[stptr-2] = DNAN;
645 else if (rpnstack->s[stptr-2] > rpnstack->s[stptr])
646 rpnstack->s[stptr-2] = DNAN;
647 stptr-=2;
648 break;
649 case OP_UN:
650 if(stptr<0){
651 rrd_set_error("RPN stack underflow");
652 return -1;
653 }
654 rpnstack->s[stptr] = isnan(rpnstack->s[stptr]) ? 1.0 : 0.0;
655 break;
656 case OP_END:
657 break;
658 }
659 }
660 if(stptr!=0){
661 rrd_set_error("RPN final stack size != 1");
662 return -1;
663 }
665 output[output_idx] = rpnstack->s[0];
666 return 0;
667 }
669 /* figure out what the local timezone offset for any point in
670 time was. Return it in seconds */
671 int
672 tzoffset( time_t now ){
673 int gm_sec, gm_min, gm_hour, gm_yday, gm_year,
674 l_sec, l_min, l_hour, l_yday, l_year;
675 struct tm *t;
676 int off;
677 t = gmtime(&now);
678 gm_sec = t->tm_sec;
679 gm_min = t->tm_min;
680 gm_hour = t->tm_hour;
681 gm_yday = t->tm_yday;
682 gm_year = t->tm_year;
683 t = localtime(&now);
684 l_sec = t->tm_sec;
685 l_min = t->tm_min;
686 l_hour = t->tm_hour;
687 l_yday = t->tm_yday;
688 l_year = t->tm_year;
689 off = (l_sec-gm_sec)+(l_min-gm_min)*60+(l_hour-gm_hour)*3600;
690 if ( l_yday > gm_yday || l_year > gm_year){
691 off += 24*3600;
692 } else if ( l_yday < gm_yday || l_year < gm_year){
693 off -= 24*3600;
694 }
695 return off;
696 }