src/rt/ambient.c

static const char       RCSid[] = "$Id: ambient.c,v 2.121 2024/01/29 19:24:00 greg Exp $";
/*
 *  ambient.c - routines dealing with ambient (inter-reflected) component.
 *
 *  Declarations of external symbols in ambient.h
 */

#include "copyright.h"

#include <string.h>

#include  "platform.h"
#include  "ray.h"
#include  "otypes.h"
#include  "otspecial.h"
#include  "resolu.h"
#include  "ambient.h"
#include  "random.h"
#include  "pmapamb.h"

#ifndef  OCTSCALE
#define  OCTSCALE       1.0     /* ceil((valid rad.)/(cube size)) */
#endif

#ifndef  MAXASET
#define  MAXASET        4095    /* maximum number of elements in ambient set */
#endif
OBJECT  ambset[MAXASET+1]={0};  /* ambient include/exclude set */

double  maxarad;                /* maximum ambient radius */
double  minarad;                /* minimum ambient radius */

static AMBTREE  atrunk;         /* our ambient trunk node */

static FILE  *ambfp = NULL;     /* ambient file pointer */
static int  nunflshed = 0;      /* number of unflushed ambient values */

static double  avsum = 0.;              /* computed ambient value sum (log) */
static unsigned int  navsum = 0;        /* number of values in avsum */
static unsigned int  nambvals = 0;      /* total number of indirect values */
static unsigned int  nambshare = 0;     /* number of values from file */
static FILE  *ambinp = NULL;            /* auxiliary file for input */
static long  lastpos = -1;              /* last flush position */

#define  AMBFLUSH       (BUFSIZ/AMBVALSIZ)

#define  AVSIZE         (sizeof(AMBVAL)-sizeof(SCOLOR)+sizeof(COLORV)*NCSAMP)
#define  newambval()    (AMBVAL *)malloc(AVSIZE)

#define  tfunc(x0, x, x1)       (((x)-(x0))/((x1)-(x0)))

static void initambfile(int cre8);
static void avsave(AMBVAL *av);
static AMBVAL *avstore(AMBVAL  *aval);
static AMBTREE *newambtree(void);
static void freeambtree(AMBTREE  *atp);

typedef void unloadtf_t(AMBVAL *);
static unloadtf_t avinsert;
static unloadtf_t avfree;
static void unloadatree(AMBTREE  *at, unloadtf_t *f);

static void sortambvals(void);

static int      plugaleak(RAY *r, AMBVAL *ap, FVECT anorm, double ang);
static double   sumambient(SCOLOR acol, RAY *r, FVECT rn, int al,
                                AMBTREE *at, FVECT c0, double s);
static int      makeambient(SCOLOR acol, RAY *r, FVECT rn, int al);
static int      extambient(SCOLOR cr, AMBVAL *ap, FVECT pv, FVECT nv,
                                FVECT uvw[3]);

#ifdef  F_SETLKW
static void aflock(int  typ);
#endif


void
setambres(                              /* set ambient resolution */
        int  ar
)
{
        ambres = ar < 0 ? 0 : ar;               /* may be done already */
                                                /* set min & max radii */
        if (ar <= 0) {
                minarad = 0;
                maxarad = thescene.cusize*0.2;
        } else {
                minarad = thescene.cusize / ar;
                maxarad = 64.0 * minarad;               /* heuristic */
                if (maxarad > thescene.cusize*0.2)
                        maxarad = thescene.cusize*0.2;
        }
        if (minarad <= FTINY)
                minarad = 10.0*FTINY;
        if (maxarad <= minarad)
                maxarad = 64.0 * minarad;
}


void
setambacc(                              /* set ambient accuracy */
        double  newa
)
{
        static double   olda;           /* remember previous setting here */
        
        newa *= (newa > 0);
        if (fabs(newa - olda) >= .05*(newa + olda)) {
                ambacc = newa;
                if (ambacc > FTINY && nambvals > 0)
                        sortambvals();          /* rebuild tree */
        }
}


void
setambient(void)                                /* initialize calculation */
{
        int     readonly = 0;
        long    flen;
        AMBVAL  amb;
                                                /* make sure we're fresh */
        ambdone();
                                                /* init ambient limits */
        setambres(ambres);
        setambacc(ambacc);
        if (ambfile == NULL || !ambfile[0])
                return;
        if (ambacc <= FTINY) {
                sprintf(errmsg, "zero ambient accuracy so \"%s\" not opened",
                                ambfile);
                error(WARNING, errmsg);
                return;
        }
                                                /* open ambient file */
        if ((ambfp = fopen(ambfile, "r+")) == NULL)
                readonly = (ambfp = fopen(ambfile, "r")) != NULL;
        if (ambfp != NULL) {
                initambfile(0);                 /* file exists */
                lastpos = ftell(ambfp);
                while (readambval(&amb, ambfp))
                        avstore(&amb);
                nambshare = nambvals;           /* share loaded values */
                if (readonly) {
                        sprintf(errmsg,
                                "loaded %u values from read-only ambient file",
                                        nambvals);
                        error(WARNING, errmsg);
                        fclose(ambfp);          /* close file so no writes */
                        ambfp = NULL;
                        return;                 /* avoid ambsync() */
                }
                                                /* align file pointer */
                lastpos += (long)nambvals*AMBVALSIZ;
                flen = lseek(fileno(ambfp), (off_t)0, SEEK_END);
                if (flen != lastpos) {
                        sprintf(errmsg,
                        "ignoring last %ld values in ambient file (corrupted)",
                                        (flen - lastpos)/AMBVALSIZ);
                        error(WARNING, errmsg);
                        fseek(ambfp, lastpos, SEEK_SET);
                        ftruncate(fileno(ambfp), (off_t)lastpos);
                }
        } else if ((ambfp = fopen(ambfile, "w+")) != NULL) {
                initambfile(1);                 /* else create new file */
                fflush(ambfp);
                lastpos = ftell(ambfp);
        } else {
                sprintf(errmsg, "cannot open ambient file \"%s\"", ambfile);
                error(SYSTEM, errmsg);
        }
#ifdef  F_SETLKW
        aflock(F_UNLCK);                        /* release file */
#endif
}


void
ambdone(void)                   /* close ambient file and free memory */
{
        if (ambfp != NULL) {            /* close ambient file */
                ambsync();
                fclose(ambfp);
                ambfp = NULL;
                if (ambinp != NULL) {   
                        fclose(ambinp);
                        ambinp = NULL;
                }
                lastpos = -1;
        }
                                        /* free ambient tree */
        unloadatree(&atrunk, avfree);
                                        /* reset state variables */
        avsum = 0.;
        navsum = 0;
        nambvals = 0;
        nambshare = 0;
}


void
ambnotify(                      /* record new modifier */
        OBJECT  obj
)
{
        static int  hitlimit = 0;
        OBJREC   *o;
        char  **amblp;

        if (obj == OVOID) {             /* starting over */
                ambset[0] = 0;
                hitlimit = 0;
                return;
        }
        o = objptr(obj);
        if (hitlimit || !ismodifier(o->otype))
                return;
        for (amblp = amblist; *amblp != NULL; amblp++)
                if (!strcmp(o->oname, *amblp)) {
                        if (ambset[0] >= MAXASET) {
                                error(WARNING, "too many modifiers in ambient list");
                                hitlimit++;
                                return;         /* should this be fatal? */
                        }
                        insertelem(ambset, obj);
                        return;
                }
}


void
multambient(            /* compute ambient component & multiply by coef. */
        SCOLOR  aval,
        RAY  *r,
        FVECT  nrm
)
{
        static double  logAvgAbsorp = 1;
        static int  rdepth = 0;                 /* ambient recursion */
        SCOLOR  acol, caustic;
        int     i, ok;
        double  d, l;

        /* PMAP: Factor in ambient from photon map, if enabled and ray is
         * ambient. Return as all ambient components accounted for, else
         * continue. */
        if (ambPmap(aval, r, rdepth))
                return;

        if (logAvgAbsorp > 0)                   /* exclude in -aw to avoid growth */
                logAvgAbsorp = log(1.-AVGREFL);

        /* PMAP: Factor in specular-diffuse ambient (caustics) from photon
         * map, if enabled and ray is primary, else caustic is zero.  Continue
         * with RADIANCE ambient calculation */
{/* XXX TEMPORARY */
        COLOR   pmc;
        scolor_color(pmc, aval);
        ambPmapCaustic(pmc, r, rdepth);
        setscolor(caustic, colval(pmc,RED), colval(pmc,GRN), colval(pmc,BLU));
}
        if (ambdiv <= 0)                        /* no ambient calculation */
                goto dumbamb;
                                                /* check number of bounces */
        if (rdepth >= ambounce)
                goto dumbamb;
                                                /* check ambient list */
        if (ambincl != -1 && r->ro != NULL &&
                        ambincl != inset(ambset, r->ro->omod))
                goto dumbamb;

        if (ambacc <= FTINY) {                  /* no ambient storage */
                FVECT   uvd[2];
                float   dgrad[2], *dgp = NULL;

                if (nrm != r->ron && DOT(nrm,r->ron) < 0.9999)
                        dgp = dgrad;            /* compute rotational grad. */
                copyscolor(acol, aval);
                rdepth++;
                ok = doambient(acol, r, r->rweight,
                                uvd, NULL, NULL, dgp, NULL);
                rdepth--;
                if (!ok)
                        goto dumbamb;
                if ((ok > 0) & (dgp != NULL)) { /* apply texture */
                        FVECT   v1;
                        VCROSS(v1, r->ron, nrm);
                        d = 1.0;
                        for (i = 3; i--; )
                                d += v1[i] * (dgp[0]*uvd[0][i] + dgp[1]*uvd[1][i]);
                        if (d >= 0.05)
                                scalescolor(acol, d);
                }
                copyscolor(aval, acol);

                /* PMAP: add in caustic */
                saddscolor(aval, caustic);
                return;
        }
                                                /* interpolate ambient value */
        scolorblack(acol);
        d = sumambient(acol, r, nrm, rdepth,
                        &atrunk, thescene.cuorg, thescene.cusize);
                        
        if (d > FTINY) {
                scalescolor(acol, 1.0/d);
                smultscolor(aval, acol);

                /* PMAP: add in caustic */
                saddscolor(aval, caustic);
                return;
        }
        
        rdepth++;                               /* need to cache new value */
        ok = makeambient(acol, r, nrm, rdepth-1);
        rdepth--;
        
        if (ok) {
                smultscolor(aval, acol);        /* computed new value */

                /* PMAP: add in caustic */
                saddscolor(aval, caustic);
                return;
        }
        
dumbamb:                                        /* return global value */
        if ((ambvwt <= 0) | (navsum == 0)) {
                smultcolor(aval, ambval);
                
                /* PMAP: add in caustic */
                saddscolor(aval, caustic);
                return;
        }
        
        l = bright(ambval);                     /* average in computations */   
        if (l > FTINY) {
                d = (log(l)*(double)ambvwt + avsum + logAvgAbsorp*navsum) /
                                (double)(ambvwt + navsum);
                d = exp(d) / l;
                scalescolor(aval, d);
                smultcolor(aval, ambval);       /* apply color of ambval */
        } else {
                d = exp( avsum/(double)navsum + logAvgAbsorp );
                scalescolor(aval, d);           /* neutral color */
        }
}


/* Plug a potential leak where ambient cache value is occluded */
static int
plugaleak(RAY *r, AMBVAL *ap, FVECT anorm, double ang)
{
        const double    cost70sq = 0.1169778;   /* cos(70deg)^2 */
        RAY             rtst;
        FVECT           vdif;
        double          normdot, ndotd, nadotd;
        double          a, b, c, t[2];

        ang += 2.*PI*(ang < 0);                 /* check direction flags */
        if ( !(ap->corral>>(int)(ang*(16./PI)) & 1) )
                return(0);
        /*
         * Generate test ray, targeting 20 degrees above sample point plane
         * along surface normal from cache position.  This should be high
         * enough to miss local geometry we don't really care about.
         */
        VSUB(vdif, ap->pos, r->rop);
        normdot = DOT(anorm, r->ron);
        ndotd = DOT(vdif, r->ron);
        nadotd = DOT(vdif, anorm);
        a = normdot*normdot - cost70sq;
        b = 2.0*(normdot*ndotd - nadotd*cost70sq);
        c = ndotd*ndotd - DOT(vdif,vdif)*cost70sq;
        if (quadratic(t, a, b, c) != 2)
                return(1);                      /* should rarely happen */
        if (t[1] <= FTINY)
                return(0);                      /* should fail behind test */
        rayorigin(&rtst, SHADOW, r, NULL);
        VSUM(rtst.rdir, vdif, anorm, t[1]);     /* further dist. > plane */
        rtst.rmax = normalize(rtst.rdir);       /* short ray test */
        while (localhit(&rtst, &thescene)) {    /* check for occluder */
                OBJREC  *m = findmaterial(rtst.ro);
                if (m != NULL && !istransp(m->otype) && !isBSDFproxy(m) &&
                                (rtst.clipset == NULL ||
                                        !inset(rtst.clipset, rtst.ro->omod)))
                        return(1);              /* plug light leak */
                VCOPY(rtst.rorg, rtst.rop);     /* skip invisible surface */
                rtst.rmax -= rtst.rot;
                rayclear(&rtst);
        }
        return(0);                              /* seems we're OK */
}


static double
sumambient(             /* get interpolated ambient value */
        SCOLOR  acol,
        RAY  *r,
        FVECT  rn,
        int  al,
        AMBTREE  *at,
        FVECT  c0,
        double  s
)
{                       /* initial limit is 10 degrees plus ambacc radians */
        const double    minangle = 10.0 * PI/180.;
        double          maxangle = minangle + ambacc;
        double          wsum = 0.0;
        FVECT           ck0;
        int             i, j;
        AMBVAL          *av;

        if (at->kid != NULL) {          /* sum children first */                                
                s *= 0.5;
                for (i = 0; i < 8; i++) {
                        for (j = 0; j < 3; j++) {
                                ck0[j] = c0[j];
                                if (1<<j & i)
                                        ck0[j] += s;
                                if (r->rop[j] < ck0[j] - OCTSCALE*s)
                                        break;
                                if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
                                        break;
                        }
                        if (j == 3)
                                wsum += sumambient(acol, r, rn, al,
                                                        at->kid+i, ck0, s);
                }
                                        /* good enough? */
                if ((wsum >= 0.05) & (s*ambacc > minarad))
                        return(wsum);
        }
                                        /* adjust maximum angle */
        if (at->alist != NULL && (at->alist->lvl <= al) & (r->rweight < 0.6))
                maxangle = (maxangle - PI/2.)*pow(r->rweight,0.13) + PI/2.;
                                        /* sum this node */
        for (av = at->alist; av != NULL; av = av->next) {
                double  u, v, d, delta_r2, delta_t2;
                SCOLOR  sct;
                FVECT   uvw[3];
                /*
                 *  Ambient level test
                 */
                if (av->lvl > al ||     /* list sorted, so this works */
                                (av->lvl == al) & (av->weight < 0.9*r->rweight))
                        break;
                /*
                 *  Direction test using unperturbed normal
                 */
                decodedir(uvw[2], av->ndir);
                d = DOT(uvw[2], r->ron);
                if (d <= 0.0)           /* >= 90 degrees */
                        continue;
                delta_r2 = 2.0 - 2.0*d; /* approx. radians^2 */
                if (delta_r2 >= maxangle*maxangle)
                        continue;
                /*
                 *  Modified ray behind test
                 */
                VSUB(ck0, r->rop, av->pos);
                d = DOT(ck0, uvw[2]);
                if (d < -minarad*ambacc)
                        continue;
                d /= av->rad[0];
                delta_t2 = d*d;
                if (delta_t2 >= ambacc*ambacc)
                        continue;
                /*
                 *  Elliptical radii test based on Hessian
                 */
                decodedir(uvw[0], av->udir);
                VCROSS(uvw[1], uvw[2], uvw[0]);
                d = (u = DOT(ck0, uvw[0])) / av->rad[0];
                delta_t2 += d*d;
                d = (v = DOT(ck0, uvw[1])) / av->rad[1];
                delta_t2 += d*d;
                if (delta_t2 >= ambacc*ambacc)
                        continue;
                /*
                 *  Test for potential light leak
                 */
                if (av->corral && plugaleak(r, av, uvw[2], atan2a(v,u)))
                        continue;
                /*
                 *  Extrapolate value and compute final weight (hat function)
                 */
                if (!extambient(sct, av, r->rop, rn, uvw))
                        continue;
                d = tfunc(maxangle, sqrt(delta_r2), 0.0) *
                        tfunc(ambacc, sqrt(delta_t2), 0.0);
                scalescolor(sct, d);
                saddscolor(acol, sct);
                wsum += d;
        }
        return(wsum);
}


static int
makeambient(            /* make a new ambient value for storage */
        SCOLOR  acol,
        RAY  *r,
        FVECT  rn,
        int  al
)
{
        AMBVAL  amb;
        FVECT   uvw[3];
        int     i;

        amb.weight = 1.0;                       /* compute weight */
        for (i = al; i-- > 0; )
                amb.weight *= AVGREFL;
        if (r->rweight < 0.1*amb.weight)        /* heuristic override */
                amb.weight = 1.25*r->rweight;
        setscolor(acol, AVGREFL, AVGREFL, AVGREFL);
                                                /* compute ambient */
        i = doambient(acol, r, amb.weight,
                        uvw, amb.rad, amb.gpos, amb.gdir, &amb.corral);
        scalescolor(acol, 1./AVGREFL);          /* undo assumed reflectance */
        if (i <= 0 || amb.rad[0] <= FTINY)      /* no Hessian or zero radius */
                return(i);
                                                /* store value */
        VCOPY(amb.pos, r->rop);
        amb.ndir = encodedir(r->ron);
        amb.udir = encodedir(uvw[0]);
        amb.lvl = al;
        copyscolor(amb.val, acol);
                                                /* insert into tree */
        avsave(&amb);                           /* and save to file */
        if (rn != r->ron) {                     /* texture */
                VCOPY(uvw[2], r->ron);
                extambient(acol, &amb, r->rop, rn, uvw);
        }
        return(1);
}


static int
extambient(             /* extrapolate value at pv, nv */
        SCOLOR  scr,
        AMBVAL   *ap,
        FVECT  pv,
        FVECT  nv,
        FVECT  uvw[3]
)
{
        const double    min_d = 0.05;
        const double    max_d = 20.;
        static FVECT    my_uvw[3];
        FVECT           v1;
        int             i;
        double          d = 1.0;        /* zeroeth order */

        if (uvw == NULL) {              /* need local coordinates? */
                decodedir(my_uvw[2], ap->ndir);
                decodedir(my_uvw[0], ap->udir);
                VCROSS(my_uvw[1], my_uvw[2], my_uvw[0]);
                uvw = my_uvw;
        }
        for (i = 3; i--; )              /* gradient due to translation */
                d += (pv[i] - ap->pos[i]) *
                        (ap->gpos[0]*uvw[0][i] + ap->gpos[1]*uvw[1][i]);

        VCROSS(v1, uvw[2], nv);         /* gradient due to rotation */
        for (i = 3; i--; )
                d += v1[i] * (ap->gdir[0]*uvw[0][i] + ap->gdir[1]*uvw[1][i]);
        
        if (d < min_d)                  /* clamp min/max scaling */
                d = min_d;
        else if (d > max_d)
                d = max_d;
        copyscolor(scr, ap->val);
        scalescolor(scr, d);
        return(d > min_d);
}


static void
avinsert(                               /* insert ambient value in our tree */
        AMBVAL *av
)
{
        AMBTREE  *at;
        AMBVAL  *ap;
        AMBVAL  avh;
        FVECT  ck0;
        double  s;
        int  branch;
        int  i;

        if (av->rad[0] <= FTINY)
                error(CONSISTENCY, "zero ambient radius in avinsert");
        at = &atrunk;
        VCOPY(ck0, thescene.cuorg);
        s = thescene.cusize;
        while (s*(OCTSCALE/2) > av->rad[1]*ambacc) {
                if (at->kid == NULL)
                        if ((at->kid = newambtree()) == NULL)
                                error(SYSTEM, "out of memory in avinsert");
                s *= 0.5;
                branch = 0;
                for (i = 0; i < 3; i++)
                        if (av->pos[i] > ck0[i] + s) {
                                ck0[i] += s;
                                branch |= 1 << i;
                        }
                at = at->kid + branch;
        }
        avh.next = at->alist;           /* order by increasing level */
        for (ap = &avh; ap->next != NULL; ap = ap->next)
                if ( ap->next->lvl > av->lvl ||
                                (ap->next->lvl == av->lvl) &
                                (ap->next->weight <= av->weight) )
                        break;
        av->next = ap->next;
        ap->next = (AMBVAL*)av;
        at->alist = avh.next;
}


static void
initambfile(            /* initialize ambient file */
        int  cre8
)
{
        extern char  *progname, *octname;
        static char  *mybuf = NULL;

#ifdef  F_SETLKW
        aflock(cre8 ? F_WRLCK : F_RDLCK);
#endif
        SET_FILE_BINARY(ambfp);
        if (mybuf == NULL)
                mybuf = (char *)bmalloc(BUFSIZ+8);
        setbuf(ambfp, mybuf);
retry:
        if (cre8) {                     /* new file */
                newheader("RADIANCE", ambfp);
                fprintf(ambfp, "%s -av %g %g %g -aw %d -ab %d -aa %g ",
                                progname, colval(ambval,RED),
                                colval(ambval,GRN), colval(ambval,BLU),
                                ambvwt, ambounce, ambacc);
                fprintf(ambfp, "-ad %d -as %d -ar %d ",
                                ambdiv, ambssamp, ambres);
                fprintf(ambfp, "-dr %d -ds %g -dt %g -dc %g ", directrelay,
                                srcsizerat, shadthresh, shadcert);
                fprintf(ambfp, "-ss %g -st %g -lr %d -lw %g ", specjitter,
                                specthresh, maxdepth, minweight);
                fprintf(ambfp, "-cw %g %g -cs %d ", WLPART[3], WLPART[0], NCSAMP);
                if (octname != NULL)
                        fputs(octname, ambfp);
                fputc('\n', ambfp);     /* end of command line, not header! */
                fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
                fputnow(ambfp);
                AMB_CNDX = CNDX;        /* use current spectral sampling */
                AMB_WLPART = WLPART;
                fputwlsplit(WLPART, ambfp);
                fputncomp(NCSAMP, ambfp);
                fputformat(AMBFMT, ambfp);
                fputc('\n', ambfp);
                putambmagic(ambfp);
        } else if (getheader(ambfp, amb_headline, NULL) < 0 || !hasambmagic(ambfp)) {
#ifndef  F_SETLKW
                static int      ntries = 3;
                if (--ntries > 0 && ftell(ambfp) == 0) {
                        clearerr(ambfp);
                        sleep(2);
                        goto retry;
                }
#endif
                error(USER, "bad/incompatible ambient file");
        }
        if ((AMB_CNDX != CNDX) | (AMB_WLPART != WLPART)) {
                if (setspectrsamp(AMB_CNDX, AMB_WLPART) < 0)
                        error(USER, "bad wavelength sampling in ambient file");
                if (AMB_CNDX[3] == CNDX[3] && FABSEQ(AMB_WLPART[0],WLPART[0]) &&
                                        FABSEQ(AMB_WLPART[3],WLPART[3])) {
                        AMB_CNDX = CNDX;
                        AMB_WLPART = WLPART;            /* just the same */
                } else
                        error(WARNING, "different ambient file wavelength sampling");
        }
}


static void
avsave(                         /* insert and save an ambient value */
        AMBVAL  *av
)
{
        avstore(av);
        if (ambfp == NULL)
                return;
        if (writambval(av, ambfp) < 0)
                goto writerr;
        if (++nunflshed >= AMBFLUSH)
                if (ambsync() == EOF)
                        goto writerr;
        return;
writerr:
        error(SYSTEM, "error writing to ambient file");
}


static AMBVAL *
avstore(                                /* allocate memory and save aval */
        AMBVAL  *aval
)
{
        AMBVAL  *av;
        double  d;

        if ((av = newambval()) == NULL)
                error(SYSTEM, "out of memory in avstore");
        memcpy(av, aval, AVSIZE);       /* AVSIZE <= sizeof(AMBVAL) */
        av->next = NULL;
        nambvals++;
        d = pbright(av->val);
        if (d > FTINY) {                /* add to log sum for averaging */
                avsum += log(d);
                navsum++;
        }
        avinsert(av);                   /* insert in our cache tree */
        return(av);
}


#define ATALLOCSZ       512             /* #/8 trees to allocate at once */

static AMBTREE  *atfreelist = NULL;     /* free ambient tree structures */


static AMBTREE *
newambtree(void)                                /* allocate 8 ambient tree structs */
{
        AMBTREE  *atp, *upperlim;

        if (atfreelist == NULL) {       /* get more nodes */
                atfreelist = (AMBTREE *)malloc(ATALLOCSZ*8*sizeof(AMBTREE));
                if (atfreelist == NULL)
                        return(NULL);
                                        /* link new free list */
                upperlim = atfreelist + 8*(ATALLOCSZ-1);
                for (atp = atfreelist; atp < upperlim; atp += 8)
                        atp->kid = atp + 8;
                atp->kid = NULL;
        }
        atp = atfreelist;
        atfreelist = atp->kid;
        memset(atp, 0, 8*sizeof(AMBTREE));
        return(atp);
}


static void
freeambtree(                    /* free 8 ambient tree structs */
        AMBTREE  *atp
)
{
        atp->kid = atfreelist;
        atfreelist = atp;
}


static void
unloadatree(                    /* unload an ambient value tree */
        AMBTREE  *at,
        unloadtf_t *f
)
{
        AMBVAL  *av;
        int  i;
                                        /* transfer values at this node */
        for (av = at->alist; av != NULL; av = at->alist) {
                at->alist = av->next;
                av->next = NULL;
                (*f)(av);
        }
        if (at->kid == NULL)
                return;
        for (i = 0; i < 8; i++)         /* transfer and free children */
                unloadatree(at->kid+i, f);
        freeambtree(at->kid);
        at->kid = NULL;
}


static void
avfree(AMBVAL *av)
{
        free(av);
}


static void
sortambvals(void)                       /* resort ambient values */
{
        AMBTREE  oldatrunk = atrunk;

        atrunk.alist = NULL;
        atrunk.kid = NULL;
        unloadatree(&oldatrunk, avinsert);
}


#ifdef  F_SETLKW

static void
aflock(                 /* lock/unlock ambient file */
        int  typ
)
{
        static struct flock  fls;       /* static so initialized to zeroes */

        if (typ == fls.l_type)          /* already called? */
                return;

        fls.l_type = typ;
        do
                if (fcntl(fileno(ambfp), F_SETLKW, &fls) != -1)
                        return;
        while (errno == EINTR);
        
        error(SYSTEM, "cannot (un)lock ambient file");
}


int
ambsync(void)                   /* synchronize ambient file */
{
        long  flen;
        AMBVAL  avs;
        int  n;

        if (ambfp == NULL)      /* no ambient file? */
                return(0);
                                /* gain appropriate access */
        aflock(nunflshed ? F_WRLCK : F_RDLCK);
                                /* see if file has grown */
        if ((flen = lseek(fileno(ambfp), (off_t)0, SEEK_END)) < 0)
                goto seekerr;
        if ((n = flen - lastpos) > 0) {         /* file has grown */
                if (ambinp == NULL) {           /* get new file pointer */
                        ambinp = fopen(ambfile, "rb");
                        if (ambinp == NULL)
                                error(SYSTEM, "fopen failed in ambsync");
                }
                if (fseek(ambinp, lastpos, SEEK_SET) < 0)
                        goto seekerr;
                while (n >= AMBVALSIZ) {        /* load contributed values */
                        if (!readambval(&avs, ambinp)) {
                                sprintf(errmsg,
                        "ambient file \"%s\" corrupted near character %ld",
                                                ambfile, flen - n);
                                error(WARNING, errmsg);
                                break;
                        }
                        avstore(&avs);
                        n -= AMBVALSIZ;
                }
                lastpos = flen - n;             /* check alignment */
                if (n && lseek(fileno(ambfp), (off_t)lastpos, SEEK_SET) < 0)
                        goto seekerr;
        }
        n = fflush(ambfp);                      /* calls write() at last */
        lastpos += (long)nunflshed*AMBVALSIZ;
        aflock(F_UNLCK);                        /* release file */
        nunflshed = 0;
        return(n);
seekerr:
        error(SYSTEM, "seek failed in ambsync");
        return(EOF);    /* pro forma return */
}

#else   /* ! F_SETLKW */

int
ambsync(void)                   /* flush ambient file */
{
        if (ambfp == NULL)
                return(0);
        nunflshed = 0;
        return(fflush(ambfp));
}

#endif  /* ! F_SETLKW */
Revision:	2.122
Committed:	Wed Jan 31 04:03:03 2024 UTC (3 months, 1 week ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.121:	+4 -3 lines
Log Message:	fix: improvement to last fix for ambient file opening race condition