ref: 7975eec3e602fd5bc3e93c78f4166259190f2fe9
dir: /emu/port/uqid.c/
#include "dat.h" #include "fns.h" #include "error.h" /* * unique Qid path generation, * for exportfs.c and various devfs-* */ #define QIDMASK (((vlong)1<<48)-1) void uqidinit(Uqidtab *tab) { memset(tab, 0, sizeof(*tab)); } static int uqidhash(vlong path) { ulong p; p = (ulong)path; return ((p>>16) ^ (p>>8) ^ p) & (Nqidhash-1); } static Uqid ** uqidlook(Uqid **tab, Chan *c, vlong path) { Uqid **hp, *q; for(hp = &tab[uqidhash(path)]; (q = *hp) != nil; hp = &q->next) if(q->type == c->type && q->dev == c->dev && q->oldpath == path) break; return hp; } static int uqidexists(Uqid **tab, vlong path) { int i; Uqid *q; for(i=0; i<Nqidhash; i++) for(q = tab[i]; q != nil; q = q->next) if(q->newpath == path) return 1; return 0; } Uqid * uqidalloc(Uqidtab *tab, Chan *c) { Uqid **hp, *q; qlock(&tab->l); hp = uqidlook(tab->qids, c, c->qid.path); if((q = *hp) != nil){ incref(&q->r); qunlock(&tab->l); return q; } q = mallocz(sizeof(*q), 1); if(q == nil){ qunlock(&tab->l); error(Enomem); } q->r.ref = 1; q->type = c->type; q->dev = c->dev; q->oldpath = c->qid.path; q->newpath = c->qid.path; while(uqidexists(tab->qids, q->newpath)){ if(++tab->pathgen >= (1<<16)) tab->pathgen = 1; q->newpath = ((vlong)tab->pathgen<<48) | (q->newpath & QIDMASK); } q->next = nil; *hp = q; qunlock(&tab->l); return q; } void freeuqid(Uqidtab *tab, Uqid *q) { Uqid **hp; if(q == nil) return; qlock(&tab->l); if(decref(&q->r) == 0){ hp = &tab->qids[uqidhash(q->oldpath)]; for(; *hp != nil; hp = &(*hp)->next) if(*hp == q){ *hp = q->next; free(q); break; } } qunlock(&tab->l); } Qid mkuqid(Chan *c, Uqid *qid) { Qid q; if(qid == nil) return c->qid; q.path = qid->newpath; q.vers = c->qid.vers; q.type = c->qid.type; return q; }