ref: 02ac617541ca1a7bf82b1615fb5a58235469b5d3
dir: /liblogfs/read.c/
#include "logfsos.h"
#include "logfs.h"
#include "local.h"
#include "fcall.h"
struct DirReadState {
u32int offset;
u32int lastoffset;
u32int limit;
uchar *data;
};
typedef struct ReaderState {
uchar *buf;
u32int maxoffset;
LogfsServer *server;
char *errmsg;
} ReaderState;
static DirReadState *
drsinit(LogfsIdentityStore *is, Entry *list, uchar *buf, u32int buflen, u32int *rcount)
{
Entry *p, *q;
DirReadState *drs;
u32int k;
/*
* stash as many entries as will fit in the read buffer
*/
*rcount = 0;
for(p = list; p; p = p->next) {
uint len = logfsflattenentry(is, buf, buflen, p);
if(len == 0)
break;
*rcount += len;
buf += len;
buflen -= len;
}
drs = logfsrealloc(nil, sizeof(*drs));
if(drs == nil)
return nil;
drs->offset = *rcount;
drs->lastoffset = drs->offset;
k = 0;
for(q = p; q; q = q->next)
k += logfsflattenentry(is, nil, 0, q);
if(k) {
u32int k2;
// print("drsinit: %ud bytes extra\n", k);
drs->data = logfsrealloc(nil, k);
if(drs->data == nil) {
logfsfreemem(drs);
return nil;
}
k2 = 0;
for(q = p; q; q = q->next)
k2 += logfsflattenentry(is, drs->data + k2, k - k2, q);
drs->limit = drs->offset + k;
}
// print("drsinit: rcount %ud\n", *rcount);
return drs;
}
static void
drsread(DirReadState *drs, uchar *buf, u32int buflen, u32int *rcount)
{
uchar *p;
*rcount = 0;
p = drs->data + drs->lastoffset - drs->offset;
while(drs->lastoffset < drs->limit) {
/*
* copy an entry, if it fits
*/
uint len = GBIT16(p) + BIT16SZ;
if(len > buflen)
break;
memmove(buf, p, len);
drs->lastoffset += len;
*rcount += len;
buf += len;
buflen -= len;
p += len;
}
if(drs->lastoffset >= drs->limit) {
logfsfreemem(drs->data);
drs->data = nil;
}
}
void
logfsdrsfree(DirReadState **drsp)
{
DirReadState *drs = *drsp;
if(drs) {
logfsfreemem(drs->data);
logfsfreemem(drs);
*drsp = nil;
}
}
static int
reader(void *magic, u32int baseoffset, u32int limitoffset, Extent *e, u32int extentoffset)
{
ReaderState *s = magic;
LogfsServer *server;
LogfsLowLevel *ll;
LogfsLowLevelReadResult llrr;
long seq;
int page;
int offset;
long block;
int pagesize;
LogSegment *seg;
int replace;
if(e == nil) {
//print("fill(%d, %d)\n", baseoffset, limitoffset);
memset(s->buf + baseoffset, 0, limitoffset - baseoffset);
if(limitoffset > s->maxoffset)
s->maxoffset = limitoffset;
return 1;
}
server = s->server;
ll = server->ll;
/*
* extentoffset is how much to trim off the front of the extent
*/
logfsflashaddr2spo(server, e->flashaddr + extentoffset, &seq, &page, &offset);
/*
* offset is the offset within the page to where e->min is stored
*/
//print("read(%d, %d, %c%ld/%ud/%ud)\n",
// baseoffset, limitoffset, (e->flashaddr & LogAddr) ? 'L' : 'D', seq, page, offset);
if(e->flashaddr & LogAddr) {
if(seq >= server->activelog->unsweptblockindex && seq <= server->activelog->curblockindex)
seg = server->activelog;
else if(server->sweptlog && seq <= server->sweptlog->curblockindex)
seg = server->sweptlog;
else {
print("logfsserverread: illegal log sequence number %ld (active=[%ld, %ld], swept=[%ld, %ld])\n",
seq, server->activelog->unsweptblockindex, server->activelog->curblockindex,
server->sweptlog ? 0L : -1L, server->sweptlog ? server->sweptlog->curblockindex : -1L);
s->errmsg = logfseinternal;
return -1;
}
if(seg->curpage == page && seg->curblockindex == seq) {
/*
* it hasn't made it to disk yet
*/
memmove(s->buf + baseoffset, seg->pagebuf + offset, limitoffset - baseoffset);
goto done;
}
if(seq < seg->unsweptblockindex) {
/* data already swept */
print("logfsserverread: log address has been swept\n");
s->errmsg = logfseinternal;
return -1;
}
block = seg->blockmap[seq];
}
else {
seg = nil;
if(seq >= server->ndatablocks)
block = -1;
else
block = server->datablock[seq].block;
if(block < 0) {
print("logfsserveread: data address does not exist\n");
s->errmsg = logfseinternal;
return -1;
}
}
/*
* read as many pages as necessary to get to the limitoffset
*/
pagesize = 1 << ll->l2pagesize;
replace = 0;
while(baseoffset < limitoffset) {
u32int thistime;
thistime = pagesize - offset;
if(thistime > (limitoffset - baseoffset))
thistime = limitoffset - baseoffset;
s->errmsg = (*ll->readpagerange)(ll, s->buf + baseoffset, block, page,
offset, thistime, &llrr);
if(s->errmsg)
return -1;
if(llrr != LogfsLowLevelReadResultOk) {
replace = 1;
}
baseoffset += thistime;
page++;
offset = 0;
}
if(replace) {
s->errmsg = logfsserverreplaceblock(server, seg, seq);
if(s->errmsg)
return -1;
}
done:
if(limitoffset > s->maxoffset)
s->maxoffset = limitoffset;
return 1;
}
char *
logfsserverread(LogfsServer *server, u32int fid, u32int offset, u32int count, uchar *buf, u32int buflen, u32int *rcount)
{
Fid *f;
Entry *e;
ReaderState s;
int rv;
if(server->trace > 1)
print("logfsserverread(%ud, %ud, %ud)\n", fid, offset, count);
f = logfsfidmapfindentry(server->fidmap, fid);
if(f == nil)
return logfsebadfid;
if(f->openmode < 0)
return logfsefidnotopen;
if((f->openmode & 3) == OWRITE)
return logfseaccess;
if(count > buflen)
return Etoobig;
e = f->entry;
if(e->deadandgone)
return Eio;
if(e->qid.type & QTDIR) {
if(offset != 0) {
if(f->drs == nil || f->drs->lastoffset != offset)
return Eio;
drsread(f->drs, buf, count, rcount);
}
else {
logfsdrsfree(&f->drs);
f->drs = drsinit(server->is, e->u.dir.list, buf, count, rcount);
if(f->drs == nil)
return Enomem;
}
return nil;
}
if(offset >= e->u.file.length) {
*rcount = 0;
return nil;
}
s.buf = buf;
s.server = server;
s.maxoffset = 0;
rv = logfsextentlistwalkrange(e->u.file.extent, reader, &s, offset, offset + count);
if(rv < 0)
return s.errmsg;
*rcount = s.maxoffset;
return nil;
}