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root/radiance/ray/src/rt/ambient.c
Revision: 2.42
Committed: Thu Jan 2 09:37:13 1997 UTC (27 years, 4 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.41: +2 -1 lines
Log Message:
corrected problem in error reporting

File Contents

# Content
1 /* Copyright (c) 1996 Regents of the University of California */
2
3 #ifndef lint
4 static char SCCSid[] = "$SunId$ LBL";
5 #endif
6
7 /*
8 * ambient.c - routines dealing with ambient (inter-reflected) component.
9 */
10
11 #include "ray.h"
12
13 #include "octree.h"
14
15 #include "otypes.h"
16
17 #include "ambient.h"
18
19 #include "random.h"
20
21 #ifndef OCTSCALE
22 #define OCTSCALE 1.0 /* ceil((valid rad.)/(cube size)) */
23 #endif
24
25 typedef struct ambtree {
26 AMBVAL *alist; /* ambient value list */
27 struct ambtree *kid; /* 8 child nodes */
28 } AMBTREE; /* ambient octree */
29
30 extern CUBE thescene; /* contains space boundaries */
31
32 extern char *shm_boundary; /* memory sharing boundary */
33
34 #define MAXASET 511 /* maximum number of elements in ambient set */
35 OBJECT ambset[MAXASET+1]={0}; /* ambient include/exclude set */
36
37 double maxarad; /* maximum ambient radius */
38 double minarad; /* minimum ambient radius */
39
40 static AMBTREE atrunk; /* our ambient trunk node */
41
42 static FILE *ambfp = NULL; /* ambient file pointer */
43 static int nunflshed = 0; /* number of unflushed ambient values */
44
45 #ifndef SORT_THRESH
46 #ifdef BIGMEM
47 #define SORT_THRESH ((9L<<20)/sizeof(AMBVAL))
48 #else
49 #define SORT_THRESH ((3L<<20)/sizeof(AMBVAL))
50 #endif
51 #endif
52 #ifndef SORT_INTVL
53 #define SORT_INTVL (SORT_THRESH<<1)
54 #endif
55 #ifndef MAX_SORT_INTVL
56 #define MAX_SORT_INTVL (SORT_INTVL<<6)
57 #endif
58
59 static COLOR avsum = BLKCOLOR; /* computed ambient value sum */
60 static unsigned int nambvals = 0; /* total number of indirect values */
61 static unsigned int nambshare = 0; /* number of values from file */
62 static unsigned long ambclock = 0; /* ambient access clock */
63 static unsigned long lastsort = 0; /* time of last value sort */
64 static long sortintvl = SORT_INTVL; /* time until next sort */
65
66 #define MAXACLOCK (1L<<30) /* clock turnover value */
67 /*
68 * Track access times unless we are sharing ambient values
69 * through memory on a multiprocessor, when we want to avoid
70 * claiming our own memory (copy on write). Go ahead anyway
71 * if more than two thirds of our values are unshared.
72 */
73 #define tracktime (shm_boundary == NULL || nambvals > 3*nambshare)
74
75 #define AMBFLUSH (BUFSIZ/AMBVALSIZ)
76
77 #define newambval() (AMBVAL *)bmalloc(sizeof(AMBVAL))
78
79 extern long ftell(), lseek();
80 static int initambfile(), avsave(), avinsert(), sortambvals(), avlmemi();
81 static AMBVAL *avstore();
82 #ifdef F_SETLKW
83 static aflock();
84 #endif
85
86
87 setambres(ar) /* set ambient resolution */
88 int ar;
89 {
90 ambres = ar < 0 ? 0 : ar; /* may be done already */
91 /* set min & max radii */
92 if (ar <= 0) {
93 minarad = 0;
94 maxarad = thescene.cusize / 2.0;
95 } else {
96 minarad = thescene.cusize / ar;
97 maxarad = 64 * minarad; /* heuristic */
98 if (maxarad > thescene.cusize / 2.0)
99 maxarad = thescene.cusize / 2.0;
100 }
101 if (minarad <= FTINY)
102 minarad = 10*FTINY;
103 if (maxarad <= minarad)
104 maxarad = 64 * minarad;
105 }
106
107
108 setambacc(newa) /* set ambient accuracy */
109 double newa;
110 {
111 double ambdiff;
112
113 if (newa < 0.0)
114 newa = 0.0;
115 ambdiff = fabs(newa - ambacc);
116 if (ambdiff >= .01 && (ambacc = newa) > FTINY && nambvals > 0)
117 sortambvals(1); /* rebuild tree */
118 }
119
120
121 setambient(afile) /* initialize calculation */
122 char *afile;
123 {
124 long pos, flen;
125 AMBVAL amb;
126 /* init ambient limits */
127 setambres(ambres);
128 setambacc(ambacc);
129 if (afile == NULL)
130 return;
131 if (ambacc <= FTINY) {
132 sprintf(errmsg, "zero ambient accuracy so \"%s\" not opened",
133 afile);
134 error(WARNING, errmsg);
135 return;
136 }
137 /* open ambient file */
138 if ((ambfp = fopen(afile, "r+")) != NULL) {
139 initambfile(0);
140 pos = ftell(ambfp);
141 while (readambval(&amb, ambfp))
142 avinsert(avstore(&amb));
143 /* align */
144 pos += (long)nambvals*AMBVALSIZ;
145 flen = lseek(fileno(ambfp), 0L, 2);
146 if (flen != pos) {
147 sprintf(errmsg,
148 "ignoring last %ld values in ambient file (corrupted)",
149 (flen - pos)/AMBVALSIZ);
150 error(WARNING, errmsg);
151 fseek(ambfp, pos, 0);
152 ftruncate(fileno(ambfp), pos);
153 }
154 nambshare = nambvals;
155 } else if ((ambfp = fopen(afile, "w+")) != NULL)
156 initambfile(1);
157 else {
158 sprintf(errmsg, "cannot open ambient file \"%s\"", afile);
159 error(SYSTEM, errmsg);
160 }
161 nunflshed++; /* lie */
162 ambsync();
163 }
164
165
166 ambnotify(obj) /* record new modifier */
167 OBJECT obj;
168 {
169 static int hitlimit = 0;
170 register OBJREC *o = objptr(obj);
171 register char **amblp;
172
173 if (hitlimit || !ismodifier(o->otype))
174 return;
175 for (amblp = amblist; *amblp != NULL; amblp++)
176 if (!strcmp(o->oname, *amblp)) {
177 if (ambset[0] >= MAXASET) {
178 error(WARNING, "too many modifiers in ambient list");
179 hitlimit++;
180 return; /* should this be fatal? */
181 }
182 insertelem(ambset, obj);
183 return;
184 }
185 }
186
187
188 ambient(acol, r, nrm) /* compute ambient component for ray */
189 COLOR acol;
190 register RAY *r;
191 FVECT nrm;
192 {
193 static int rdepth = 0; /* ambient recursion */
194 double d;
195
196 if (ambdiv <= 0) /* no ambient calculation */
197 goto dumbamb;
198 /* check number of bounces */
199 if (rdepth >= ambounce)
200 goto dumbamb;
201 /* check ambient list */
202 if (ambincl != -1 && r->ro != NULL &&
203 ambincl != inset(ambset, r->ro->omod))
204 goto dumbamb;
205
206 if (ambacc <= FTINY) { /* no ambient storage */
207 rdepth++;
208 d = doambient(acol, r, r->rweight, NULL, NULL);
209 rdepth--;
210 if (d <= FTINY)
211 goto dumbamb;
212 return;
213 }
214
215 if (tracktime) /* sort to minimize thrashing */
216 sortambvals(0);
217 /* get ambient value */
218 setcolor(acol, 0.0, 0.0, 0.0);
219 d = sumambient(acol, r, nrm, rdepth,
220 &atrunk, thescene.cuorg, thescene.cusize);
221 if (d > FTINY) {
222 scalecolor(acol, 1.0/d);
223 return;
224 }
225 rdepth++; /* need to cache new value */
226 d = makeambient(acol, r, nrm, rdepth-1);
227 rdepth--;
228 if (d > FTINY)
229 return;
230 dumbamb: /* return global value */
231 copycolor(acol, ambval);
232 if (ambvwt <= 0 | nambvals == 0)
233 return;
234 scalecolor(acol, (double)ambvwt);
235 addcolor(acol, avsum); /* average in computations */
236 d = 1.0/(ambvwt+nambvals);
237 scalecolor(acol, d);
238 }
239
240
241 double
242 sumambient(acol, r, rn, al, at, c0, s) /* get interpolated ambient value */
243 COLOR acol;
244 register RAY *r;
245 FVECT rn;
246 int al;
247 AMBTREE *at;
248 FVECT c0;
249 double s;
250 {
251 double d, e1, e2, wt, wsum;
252 COLOR ct;
253 FVECT ck0;
254 int i;
255 register int j;
256 register AMBVAL *av;
257
258 wsum = 0.0;
259 /* do this node */
260 for (av = at->alist; av != NULL; av = av->next) {
261 if (tracktime)
262 av->latick = ambclock;
263 /*
264 * Ambient level test.
265 */
266 if (av->lvl > al) /* list sorted, so this works */
267 break;
268 if (av->weight < r->rweight-FTINY)
269 continue;
270 /*
271 * Ambient radius test.
272 */
273 d = av->pos[0] - r->rop[0];
274 e1 = d * d;
275 d = av->pos[1] - r->rop[1];
276 e1 += d * d;
277 d = av->pos[2] - r->rop[2];
278 e1 += d * d;
279 e1 /= av->rad * av->rad;
280 if (e1 > ambacc*ambacc*1.21)
281 continue;
282 /*
283 * Normal direction test.
284 */
285 e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
286 if (e2 < 0.0) e2 = 0.0;
287 if (e1 + e2 > ambacc*ambacc*1.21)
288 continue;
289 /*
290 * Ray behind test.
291 */
292 d = 0.0;
293 for (j = 0; j < 3; j++)
294 d += (r->rop[j] - av->pos[j]) *
295 (av->dir[j] + r->ron[j]);
296 if (d*0.5 < -minarad*ambacc-.001)
297 continue;
298 /*
299 * Jittering final test reduces image artifacts.
300 */
301 wt = sqrt(e1) + sqrt(e2);
302 if (wt > ambacc*(.9+.2*urand(9015+samplendx)))
303 continue;
304 if (wt <= 1e-3)
305 wt = 1e3;
306 else
307 wt = 1.0 / wt;
308 wsum += wt;
309 extambient(ct, av, r->rop, rn);
310 scalecolor(ct, wt);
311 addcolor(acol, ct);
312 }
313 if (at->kid == NULL)
314 return(wsum);
315 /* do children */
316 s *= 0.5;
317 for (i = 0; i < 8; i++) {
318 for (j = 0; j < 3; j++) {
319 ck0[j] = c0[j];
320 if (1<<j & i)
321 ck0[j] += s;
322 if (r->rop[j] < ck0[j] - OCTSCALE*s)
323 break;
324 if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
325 break;
326 }
327 if (j == 3)
328 wsum += sumambient(acol, r, rn, al, at->kid+i, ck0, s);
329 }
330 return(wsum);
331 }
332
333
334 double
335 makeambient(acol, r, rn, al) /* make a new ambient value */
336 COLOR acol;
337 register RAY *r;
338 FVECT rn;
339 int al;
340 {
341 AMBVAL amb;
342 FVECT gp, gd;
343 /* compute weight */
344 amb.weight = pow(AVGREFL, (double)al);
345 if (r->rweight < 0.1*amb.weight) /* heuristic */
346 amb.weight = r->rweight;
347 /* compute ambient */
348 amb.rad = doambient(acol, r, amb.weight, gp, gd);
349 if (amb.rad <= FTINY)
350 return(0.0);
351 /* store it */
352 VCOPY(amb.pos, r->rop);
353 VCOPY(amb.dir, r->ron);
354 amb.lvl = al;
355 copycolor(amb.val, acol);
356 VCOPY(amb.gpos, gp);
357 VCOPY(amb.gdir, gd);
358 /* insert into tree */
359 avsave(&amb); /* and save to file */
360 if (rn != r->ron)
361 extambient(acol, &amb, r->rop, rn); /* texture */
362 return(amb.rad);
363 }
364
365
366 extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
367 COLOR cr;
368 register AMBVAL *ap;
369 FVECT pv, nv;
370 {
371 FVECT v1, v2;
372 register int i;
373 double d;
374
375 d = 1.0; /* zeroeth order */
376 /* gradient due to translation */
377 for (i = 0; i < 3; i++)
378 d += ap->gpos[i]*(pv[i]-ap->pos[i]);
379 /* gradient due to rotation */
380 VCOPY(v1, ap->dir);
381 fcross(v2, v1, nv);
382 d += DOT(ap->gdir, v2);
383 if (d <= 0.0) {
384 setcolor(cr, 0.0, 0.0, 0.0);
385 return;
386 }
387 copycolor(cr, ap->val);
388 scalecolor(cr, d);
389 }
390
391
392 static
393 initambfile(creat) /* initialize ambient file */
394 int creat;
395 {
396 extern char *progname, *octname, VersionID[];
397
398 #ifdef F_SETLKW
399 aflock(creat ? F_WRLCK : F_RDLCK);
400 #endif
401 #ifdef MSDOS
402 setmode(fileno(ambfp), O_BINARY);
403 #endif
404 setbuf(ambfp, bmalloc(BUFSIZ+8));
405 if (creat) { /* new file */
406 newheader("RADIANCE", ambfp);
407 fprintf(ambfp, "%s -av %g %g %g -aw %d -ab %d -aa %g ",
408 progname, colval(ambval,RED),
409 colval(ambval,GRN), colval(ambval,BLU),
410 ambvwt, ambounce, ambacc);
411 fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
412 ambdiv, ambssamp, ambres,
413 octname==NULL ? "" : octname);
414 fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
415 fputformat(AMBFMT, ambfp);
416 putc('\n', ambfp);
417 putambmagic(ambfp);
418 } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
419 error(USER, "bad ambient file");
420 }
421
422
423 static
424 avsave(av) /* insert and save an ambient value */
425 AMBVAL *av;
426 {
427 avinsert(avstore(av));
428 if (ambfp == NULL)
429 return;
430 if (writambval(av, ambfp) < 0)
431 goto writerr;
432 if (++nunflshed >= AMBFLUSH)
433 if (ambsync() == EOF)
434 goto writerr;
435 return;
436 writerr:
437 error(SYSTEM, "error writing ambient file");
438 }
439
440
441 static AMBVAL *
442 avstore(aval) /* allocate memory and store aval */
443 register AMBVAL *aval;
444 {
445 register AMBVAL *av;
446
447 if ((av = newambval()) == NULL)
448 error(SYSTEM, "out of memory in avstore");
449 copystruct(av, aval);
450 av->latick = ambclock;
451 av->next = NULL;
452 addcolor(avsum, av->val); /* add to sum for averaging */
453 nambvals++;
454 return(av);
455 }
456
457
458 #define ATALLOCSZ 512 /* #/8 trees to allocate at once */
459
460 static AMBTREE *atfreelist = NULL; /* free ambient tree structures */
461
462
463 static
464 AMBTREE *
465 newambtree() /* allocate 8 ambient tree structs */
466 {
467 register AMBTREE *atp, *upperlim;
468
469 if (atfreelist == NULL) { /* get more nodes */
470 atfreelist = (AMBTREE *)bmalloc(ATALLOCSZ*8*sizeof(AMBTREE));
471 if (atfreelist == NULL)
472 return(NULL);
473 /* link new free list */
474 upperlim = atfreelist + 8*(ATALLOCSZ-1);
475 for (atp = atfreelist; atp < upperlim; atp += 8)
476 atp->kid = atp + 8;
477 atp->kid = NULL;
478 }
479 atp = atfreelist;
480 atfreelist = atp->kid;
481 bzero((char *)atp, 8*sizeof(AMBTREE));
482 return(atp);
483 }
484
485
486 static
487 freeambtree(atp) /* free 8 ambient tree structs */
488 AMBTREE *atp;
489 {
490 atp->kid = atfreelist;
491 atfreelist = atp;
492 }
493
494
495 static
496 avinsert(av) /* insert ambient value in our tree */
497 register AMBVAL *av;
498 {
499 register AMBTREE *at;
500 register AMBVAL *ap;
501 AMBVAL avh;
502 FVECT ck0;
503 double s;
504 int branch;
505 register int i;
506
507 if (av->rad <= FTINY)
508 error(CONSISTENCY, "zero ambient radius in avinsert");
509 at = &atrunk;
510 VCOPY(ck0, thescene.cuorg);
511 s = thescene.cusize;
512 while (s*(OCTSCALE/2) > av->rad*ambacc) {
513 if (at->kid == NULL)
514 if ((at->kid = newambtree()) == NULL)
515 error(SYSTEM, "out of memory in avinsert");
516 s *= 0.5;
517 branch = 0;
518 for (i = 0; i < 3; i++)
519 if (av->pos[i] > ck0[i] + s) {
520 ck0[i] += s;
521 branch |= 1 << i;
522 }
523 at = at->kid + branch;
524 }
525 avh.next = at->alist; /* order by increasing level */
526 for (ap = &avh; ap->next != NULL; ap = ap->next)
527 if (ap->next->lvl >= av->lvl)
528 break;
529 av->next = ap->next;
530 ap->next = av;
531 at->alist = avh.next;
532 }
533
534
535 static
536 unloadatree(at, f) /* unload an ambient value tree */
537 register AMBTREE *at;
538 int (*f)();
539 {
540 register AMBVAL *av;
541 register int i;
542 /* transfer values at this node */
543 for (av = at->alist; av != NULL; av = at->alist) {
544 at->alist = av->next;
545 (*f)(av);
546 }
547 if (at->kid == NULL)
548 return;
549 for (i = 0; i < 8; i++) /* transfer and free children */
550 unloadatree(at->kid+i, f);
551 freeambtree(at->kid);
552 at->kid = NULL;
553 }
554
555
556 static struct avl {
557 AMBVAL *p;
558 unsigned long t;
559 } *avlist1; /* ambient value list with ticks */
560 static AMBVAL **avlist2; /* memory positions for sorting */
561 static int i_avlist; /* index for lists */
562
563
564 static
565 av2list(av)
566 register AMBVAL *av;
567 {
568 #ifdef DEBUG
569 if (i_avlist >= nambvals)
570 error(CONSISTENCY, "too many ambient values in av2list1");
571 #endif
572 avlist1[i_avlist].p = avlist2[i_avlist] = av;
573 avlist1[i_avlist++].t = av->latick;
574 }
575
576
577 static int
578 alatcmp(av1, av2) /* compare ambient values for MRA */
579 struct avl *av1, *av2;
580 {
581 register long lc = av2->t - av1->t;
582 return(lc<0 ? -1 : lc>0 ? 1 : 0);
583 }
584
585
586 static int
587 aposcmp(avp1, avp2) /* compare ambient value positions */
588 AMBVAL **avp1, **avp2;
589 {
590 return(*avp1 - *avp2);
591 }
592
593
594 #if 1
595 static int
596 avlmemi(avaddr) /* find list position from address */
597 AMBVAL *avaddr;
598 {
599 register AMBVAL **avlpp;
600
601 avlpp = (AMBVAL **)bsearch((char *)&avaddr, (char *)avlist2,
602 nambvals, sizeof(AMBVAL *), aposcmp);
603 if (avlpp == NULL)
604 error(CONSISTENCY, "address not found in avlmemi");
605 return(avlpp - avlist2);
606 }
607 #else
608 #define avlmemi(avaddr) ((AMBVAL **)bsearch((char *)&avaddr,(char *)avlist2, \
609 nambvals,sizeof(AMBVAL *),aposcmp) - avlist2)
610 #endif
611
612
613 static
614 sortambvals(always) /* resort ambient values */
615 int always;
616 {
617 AMBTREE oldatrunk;
618 AMBVAL tav, *tap, *pnext;
619 register int i, j;
620 /* see if it's time yet */
621 if (!always && (ambclock++ < lastsort+sortintvl ||
622 nambvals < SORT_THRESH))
623 return;
624 /*
625 * The idea here is to minimize memory thrashing
626 * in VM systems by improving reference locality.
627 * We do this by periodically sorting our stored ambient
628 * values in memory in order of most recently to least
629 * recently accessed. This ordering was chosen so that new
630 * ambient values (which tend to be less important) go into
631 * higher memory with the infrequently accessed values.
632 * Since we expect our values to need sorting less
633 * frequently as the process continues, we double our
634 * waiting interval after each call.
635 * This routine is also called by setambacc() with
636 * the "always" parameter set to 1 so that the ambient
637 * tree will be rebuilt with the new accuracy parameter.
638 */
639 if (tracktime) { /* allocate pointer arrays to sort */
640 avlist2 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
641 avlist1 = (struct avl *)malloc(nambvals*sizeof(struct avl));
642 } else {
643 avlist2 = NULL;
644 avlist1 = NULL;
645 }
646 if (avlist1 == NULL) { /* no time tracking -- rebuild tree? */
647 if (avlist2 != NULL)
648 free((char *)avlist2);
649 if (always) { /* rebuild without sorting */
650 copystruct(&oldatrunk, &atrunk);
651 atrunk.alist = NULL;
652 atrunk.kid = NULL;
653 unloadatree(&oldatrunk, avinsert);
654 }
655 } else { /* sort memory by last access time */
656 /*
657 * Sorting memory is tricky because it isn't contiguous.
658 * We have to sort an array of pointers by MRA and also
659 * by memory position. We then copy values in "loops"
660 * to minimize memory hits. Nevertheless, we will visit
661 * everyone at least twice, and this is an expensive process
662 * when we're thrashing, which is when we need to do it.
663 */
664 #ifdef DEBUG
665 sprintf(errmsg, "sorting %u ambient values at ambclock=%lu...",
666 nambvals, ambclock);
667 eputs(errmsg);
668 #endif
669 i_avlist = 0;
670 unloadatree(&atrunk, av2list); /* empty current tree */
671 #ifdef DEBUG
672 if (i_avlist < nambvals)
673 error(CONSISTENCY, "missing ambient values in sortambvals");
674 #endif
675 qsort((char *)avlist1, nambvals, sizeof(struct avl), alatcmp);
676 qsort((char *)avlist2, nambvals, sizeof(AMBVAL *), aposcmp);
677 for (i = 0; i < nambvals; i++) {
678 if (avlist1[i].p == NULL)
679 continue;
680 tap = avlist2[i];
681 copystruct(&tav, tap);
682 for (j = i; (pnext = avlist1[j].p) != tap;
683 j = avlmemi(pnext)) {
684 copystruct(avlist2[j], pnext);
685 avinsert(avlist2[j]);
686 avlist1[j].p = NULL;
687 }
688 copystruct(avlist2[j], &tav);
689 avinsert(avlist2[j]);
690 avlist1[j].p = NULL;
691 }
692 free((char *)avlist1);
693 free((char *)avlist2);
694 /* compute new sort interval */
695 sortintvl = ambclock - lastsort;
696 if (sortintvl >= MAX_SORT_INTVL/2)
697 sortintvl = MAX_SORT_INTVL;
698 else
699 sortintvl <<= 1; /* wait twice as long next */
700 #ifdef DEBUG
701 eputs("done\n");
702 #endif
703 }
704 if (ambclock >= MAXACLOCK)
705 ambclock = MAXACLOCK/2;
706 lastsort = ambclock;
707 }
708
709
710 #ifdef F_SETLKW
711
712 static
713 aflock(typ) /* lock/unlock ambient file */
714 int typ;
715 {
716 static struct flock fls; /* static so initialized to zeroes */
717
718 fls.l_type = typ;
719 if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
720 error(SYSTEM, "cannot (un)lock ambient file");
721 }
722
723
724 int
725 ambsync() /* synchronize ambient file */
726 {
727 static FILE *ambinp = NULL;
728 static long lastpos = -1;
729 long flen;
730 AMBVAL avs;
731 register int n;
732
733 if (nunflshed == 0)
734 return(0);
735 if (lastpos < 0) /* initializing (locked in initambfile) */
736 goto syncend;
737 /* gain exclusive access */
738 aflock(F_WRLCK);
739 /* see if file has grown */
740 if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
741 goto seekerr;
742 if (n = flen - lastpos) { /* file has grown */
743 if (ambinp == NULL) { /* use duplicate filedes */
744 ambinp = fdopen(dup(fileno(ambfp)), "r");
745 if (ambinp == NULL)
746 error(SYSTEM, "fdopen failed in ambsync");
747 }
748 if (fseek(ambinp, lastpos, 0) < 0)
749 goto seekerr;
750 while (n >= AMBVALSIZ) { /* load contributed values */
751 if (!readambval(&avs, ambinp)) {
752 sprintf(errmsg,
753 "ambient file corrupted near character %ld",
754 flen - n);
755 error(WARNING, errmsg);
756 break;
757 }
758 avinsert(avstore(&avs));
759 n -= AMBVALSIZ;
760 }
761 /*** seek always as safety measure
762 if (n) ***/ /* alignment */
763 if (lseek(fileno(ambfp), flen-n, 0) < 0)
764 goto seekerr;
765 }
766 #ifdef DEBUG
767 if (ambfp->_ptr - ambfp->_base != nunflshed*AMBVALSIZ) {
768 sprintf(errmsg, "ambient file buffer at %d rather than %d",
769 ambfp->_ptr - ambfp->_base,
770 nunflshed*AMBVALSIZ);
771 error(CONSISTENCY, errmsg);
772 }
773 #endif
774 syncend:
775 n = fflush(ambfp); /* calls write() at last */
776 if ((lastpos = lseek(fileno(ambfp), 0L, 1)) < 0)
777 goto seekerr;
778 aflock(F_UNLCK); /* release file */
779 nunflshed = 0;
780 return(n);
781 seekerr:
782 error(SYSTEM, "seek failed in ambsync");
783 }
784
785 #else
786
787 int
788 ambsync() /* flush ambient file */
789 {
790 if (nunflshed == 0)
791 return(0);
792 nunflshed = 0;
793 return(fflush(ambfp));
794 }
795
796 #endif