ref: a00b6bdbfa72a1688a866edf5f825720c9874ada
dir: /sys/src/cmd/ip/ppp/block.c/
#include <u.h> #include <libc.h> #include <ip.h> #include <auth.h> #include "ppp.h" enum { PAD = 128, NLIST = (1<<5), BPOW = 10, }; typedef struct Barena Barena; struct Barena { QLock; Block* list[NLIST]; }; static Barena area; #define ADEBUG if(0) /* * allocation tracing */ enum { Npc= 64, }; typedef struct Arefent Arefent; struct Arefent { uint pc; uint n; }; typedef struct Aref Aref; struct Aref { Arefent tab[Npc]; QLock; }; Aref arefblock; static ulong callerpc(void*); static void aref(Aref*, ulong); static void aunref(Aref*, ulong); Block* allocb(int len) { int sz; Block *bp, **l; len += PAD; sz = (len>>BPOW)&(NLIST-1); qlock(&area); l = &area.list[sz]; for(bp = *l; bp; bp = bp->flist) { if(bp->bsz >= len) { *l = bp->flist; qunlock(&area); bp->next = nil; bp->list = nil; bp->flist = nil; bp->base = (uchar*)bp+sizeof(Block); bp->rptr = bp->base+PAD; bp->wptr = bp->rptr; bp->lim = bp->base+bp->bsz; bp->flow = nil; bp->flags= 0; ADEBUG { bp->pc = callerpc(&len); aref(&arefblock, bp->pc); } return bp; } l = &bp->flist; } qunlock(&area); bp = mallocz(sizeof(Block)+len, 1); bp->bsz = len; bp->base = (uchar*)bp+sizeof(Block); bp->rptr = bp->base+PAD; bp->wptr = bp->rptr; bp->lim = bp->base+len; ADEBUG { bp->pc = callerpc(&len); aref(&arefblock, bp->pc); } return bp; } void freeb(Block *bp) { int sz; Block **l, *next; qlock(&area); while(bp) { sz = (bp->bsz>>BPOW)&(NLIST-1); l = &area.list[sz]; bp->flist = *l; *l = bp; next = bp->next; /* to catch use after free */ bp->rptr = (uchar*)0xdeadbabe; bp->wptr = (uchar*)0xdeadbabe; bp->next = (Block*)0xdeadbabe; bp->list = (Block*)0xdeadbabe; ADEBUG aunref(&arefblock, bp->pc); bp = next; } qunlock(&area); } /* * concatenate a list of blocks into a single one and make sure * the result is at least min uchars */ Block* concat(Block *bp) { int len; Block *nb, *f; nb = allocb(blen(bp)); for(f = bp; f; f = f->next) { len = BLEN(f); memmove(nb->wptr, f->rptr, len); nb->wptr += len; } freeb(bp); return nb; } int blen(Block *bp) { int len; len = 0; while(bp) { len += BLEN(bp); bp = bp->next; } return len; } Block * pullup(Block *bp, int n) { int i; Block *nbp; /* * this should almost always be true, the rest it * just for to avoid every caller checking. */ if(BLEN(bp) >= n) return bp; /* * if not enough room in the first block, * add another to the front of the list. */ if(bp->lim - bp->rptr < n){ nbp = allocb(n); nbp->next = bp; bp = nbp; } /* * copy uchars from the trailing blocks into the first */ n -= BLEN(bp); while(nbp = bp->next){ i = BLEN(nbp); if(i >= n) { memmove(bp->wptr, nbp->rptr, n); bp->wptr += n; nbp->rptr += n; return bp; } else { memmove(bp->wptr, nbp->rptr, i); bp->wptr += i; bp->next = nbp->next; nbp->next = nil; freeb(nbp); n -= i; } } freeb(bp); return nil; } /* * Pad a block to the front with n uchars. This is used to add protocol * headers to the front of blocks. */ Block* padb(Block *bp, int n) { Block *nbp; if(bp->rptr-bp->base >= n) { bp->rptr -= n; return bp; } else { /* fprint(2, "padb: required %d PAD %d\n", n, PAD) = malloc(sizeof(*required %d PAD %d\n", n, PAD))); */ nbp = allocb(n); nbp->wptr = nbp->lim; nbp->rptr = nbp->wptr - n; nbp->next = bp; return nbp; } } Block * btrim(Block *bp, int offset, int len) { ulong l; Block *nb, *startb; if(blen(bp) < offset+len) { freeb(bp); return nil; } while((l = BLEN(bp)) < offset) { offset -= l; nb = bp->next; bp->next = nil; freeb(bp); bp = nb; } startb = bp; bp->rptr += offset; while((l = BLEN(bp)) < len) { len -= l; bp = bp->next; } bp->wptr -= (BLEN(bp) - len); bp->flags |= S_DELIM; if(bp->next) { freeb(bp->next); bp->next = nil; } return startb; } Block* copyb(Block *bp, int count) { int l; Block *nb, *head, **p; p = &head; head = nil; while(bp != nil && count != 0) { l = BLEN(bp); if(count < l) l = count; nb = allocb(l); memmove(nb->wptr, bp->rptr, l); nb->wptr += l; count -= l; nb->flags = bp->flags; *p = nb; p = &nb->next; bp = bp->next; } if(count) { nb = allocb(count); memset(nb->wptr, 0, count); nb->wptr += count; nb->flags |= S_DELIM; *p = nb; } if(blen(head) == 0) fprint(2, "copyb: zero length\n"); return head; } int pullb(Block **bph, int count) { Block *bp; int n, uchars; uchars = 0; if(bph == nil) return 0; while(*bph != nil && count != 0) { bp = *bph; n = BLEN(bp); if(count < n) n = count; uchars += n; count -= n; bp->rptr += n; if(BLEN(bp) == 0) { *bph = bp->next; bp->next = nil; freeb(bp); } } return uchars; } /* * handy routines for keeping track of allocations */ static ulong callerpc(void *a) { return ((ulong*)a)[-1]; } static void aref(Aref *ap, ulong pc) { Arefent *a, *e; e = &ap->tab[Npc-1]; qlock(ap); for(a = ap->tab; a < e; a++) if(a->pc == pc || a->pc == 0) break; a->pc = pc; a->n++; qunlock(ap); } static void aunref(Aref *ap, ulong pc) { Arefent *a, *e; e = &ap->tab[Npc-1]; qlock(ap); for(a = ap->tab; a < e; a++) if(a->pc == pc || a->pc == 0) break; a->n--; qunlock(ap); }