ref: a04fd342727c329584a9f443092caf21e3884bdf
dir: /sys/src/cmd/disk/sacfs/sacfs.c/
#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include "sac.h"
#include "sacfs.h"
/*
* Rather than reading /adm/users, which is a lot of work for
* a toy program, we assume all groups have the form
* NNN:user:user:
* meaning that each user is the leader of his own group.
*/
enum
{
OPERM = 0x3, /* mask of all permission types in open mode */
Nram = 512,
OffsetSize = 4, /* size in bytes of an offset */
CacheSize = 20,
};
typedef struct Fid Fid;
typedef struct Path Path;
typedef struct Sac Sac;
typedef struct Cache Cache;
struct Fid
{
short busy;
short open;
int fid;
char *user;
Qid qid;
Sac *sac;
Fid *next;
};
struct Sac
{
SacDir;
Path *path;
};
struct Path
{
int ref;
Path *up;
long blocks;
int entry;
int nentry;
};
struct Cache
{
long block;
ulong age;
uchar *data;
};
enum
{
Pexec = 1,
Pwrite = 2,
Pread = 4,
Pother = 1,
Pgroup = 8,
Powner = 64,
};
Fid *fids;
uchar *data;
int mfd[2];
char user[NAMELEN];
char mdata[MAXMSG+MAXFDATA];
Fcall rhdr;
Fcall thdr;
int blocksize;
Sac root;
Cache cache[CacheSize];
ulong cacheage;
Fid * newfid(int);
void sacstat(SacDir*, char*);
void error(char*);
void io(void);
void *erealloc(void*, ulong);
void *emalloc(ulong);
void usage(void);
int perm(Fid*, Sac*, int);
ulong getl(void *p);
void init(char*);
Sac *saccpy(Sac *s);
Sac *saclookup(Sac *s, char *name);
int sacdirread(Sac *s, char *p, long off, long cnt);
void loadblock(void *buf, uchar *offset, int blocksize);
void sacfree(Sac*);
char *rflush(Fid*), *rnop(Fid*), *rsession(Fid*),
*rattach(Fid*), *rclone(Fid*), *rwalk(Fid*),
*rclwalk(Fid*), *ropen(Fid*), *rcreate(Fid*),
*rread(Fid*), *rwrite(Fid*), *rclunk(Fid*),
*rremove(Fid*), *rstat(Fid*), *rwstat(Fid*);
char *(*fcalls[])(Fid*) = {
[Tflush] rflush,
[Tsession] rsession,
[Tnop] rnop,
[Tattach] rattach,
[Tclone] rclone,
[Twalk] rwalk,
[Tclwalk] rclwalk,
[Topen] ropen,
[Tcreate] rcreate,
[Tread] rread,
[Twrite] rwrite,
[Tclunk] rclunk,
[Tremove] rremove,
[Tstat] rstat,
[Twstat] rwstat,
};
char Eperm[] = "permission denied";
char Enotdir[] = "not a directory";
char Enoauth[] = "no authentication in ramfs";
char Enotexist[] = "file does not exist";
char Einuse[] = "file in use";
char Eexist[] = "file exists";
char Enotowner[] = "not owner";
char Eisopen[] = "file already open for I/O";
char Excl[] = "exclusive use file already open";
char Ename[] = "illegal name";
char Erdonly[] = "read only file system";
int debug;
void
notifyf(void *a, char *s)
{
USED(a);
if(strncmp(s, "interrupt", 9) == 0)
noted(NCONT);
noted(NDFLT);
}
void
main(int argc, char *argv[])
{
char *defmnt;
int p[2];
char buf[12];
int fd;
int stdio = 0;
defmnt = "/n/c:";
ARGBEGIN{
case 'd':
debug = 1;
break;
case 'i':
defmnt = 0;
stdio = 1;
mfd[0] = 0;
mfd[1] = 1;
break;
case 's':
defmnt = 0;
break;
case 'm':
defmnt = ARGF();
break;
default:
usage();
}ARGEND
if(argc != 1)
usage();
init(argv[0]);
if(pipe(p) < 0)
error("pipe failed");
if(!stdio){
mfd[0] = p[0];
mfd[1] = p[0];
if(defmnt == 0){
fd = create("#s/sacfs", OWRITE, 0666);
if(fd < 0)
error("create of /srv/sacfs failed");
sprint(buf, "%d", p[1]);
if(write(fd, buf, strlen(buf)) < 0)
error("writing /srv/sacfs");
}
}
if(debug)
fmtinstall('F', fcallconv);
switch(rfork(RFFDG|RFPROC|RFNAMEG|RFNOTEG)){
case -1:
error("fork");
case 0:
close(p[1]);
io();
break;
default:
close(p[0]); /* don't deadlock if child fails */
if(defmnt && mount(p[1], defmnt, MREPL|MCREATE, "") == -1)
error("mount failed");
}
exits(0);
}
char*
rnop(Fid *f)
{
USED(f);
return 0;
}
char*
rsession(Fid *unused)
{
Fid *f;
USED(unused);
for(f = fids; f; f = f->next)
if(f->busy)
rclunk(f);
memset(thdr.authid, 0, sizeof(thdr.authid));
memset(thdr.authdom, 0, sizeof(thdr.authdom));
memset(thdr.chal, 0, sizeof(thdr.chal));
return 0;
}
char*
rflush(Fid *f)
{
USED(f);
return 0;
}
char*
rattach(Fid *f)
{
/* no authentication! */
f->busy = 1;
f->qid = (Qid){getl(root.qid), 0};
f->sac = saccpy(&root);
thdr.qid = f->qid;
if(rhdr.uname[0])
f->user = strdup(rhdr.uname);
else
f->user = "none";
return 0;
}
char*
rclone(Fid *f)
{
Fid *nf;
if(f->open)
return Eisopen;
if(f->busy == 0)
return Enotexist;
nf = newfid(rhdr.newfid);
nf->busy = 1;
nf->open = 0;
nf->qid = f->qid;
nf->sac = saccpy(f->sac);
nf->user = strdup(f->user);
return 0;
}
char*
rwalk(Fid *f)
{
char *name;
Sac *sac;
if((f->qid.path & CHDIR) == 0)
return Enotdir;
if(f->busy == 0)
return Enotexist;
name = rhdr.name;
sac = f->sac;
if(strcmp(name, ".") == 0){
thdr.qid = f->qid;
return 0;
}
if(!perm(f, sac, Pexec))
return Eperm;
sac = saclookup(sac, name);
if(sac == nil)
return Enotexist;
f->sac = sac;
f->qid = (Qid){getl(sac->qid), 0};
thdr.qid = f->qid;
return 0;
}
char *
rclwalk(Fid *f)
{
Fid *nf;
char *err;
nf = newfid(rhdr.newfid);
nf->busy = 1;
nf->sac = saccpy(f->sac);
nf->user = strdup(f->user);
if(err = rwalk(nf))
rclunk(nf);
return err;
}
char *
ropen(Fid *f)
{
int mode, trunc;
if(f->open)
return Eisopen;
if(f->busy == 0)
return Enotexist;
mode = rhdr.mode;
if(f->qid.path & CHDIR){
if(mode != OREAD)
return Eperm;
thdr.qid = f->qid;
return 0;
}
if(mode & ORCLOSE)
return Erdonly;
trunc = mode & OTRUNC;
mode &= OPERM;
if(mode==OWRITE || mode==ORDWR || trunc)
return Erdonly;
if(mode==OREAD)
if(!perm(f, f->sac, Pread))
return Eperm;
if(mode==OEXEC)
if(!perm(f, f->sac, Pexec))
return Eperm;
thdr.qid = f->qid;
f->open = 1;
return 0;
}
char *
rcreate(Fid *f)
{
if(f->open)
return Eisopen;
if(f->busy == 0)
return Enotexist;
return Erdonly;
}
char*
rread(Fid *f)
{
Sac *sac;
char *buf, *buf2;
long off;
int n, cnt, i, j;
uchar *blocks;
long length;
if(f->busy == 0)
return Enotexist;
sac = f->sac;
thdr.count = 0;
off = rhdr.offset;
buf = thdr.data;
cnt = rhdr.count;
if(f->qid.path & CHDIR){
cnt = (rhdr.count/DIRLEN)*DIRLEN;
if(off%DIRLEN)
return "i/o error";
thdr.count = sacdirread(sac, buf, off, cnt);
return 0;
}
length = getl(sac->length);
if(off >= length) {
rhdr.count = 0;
return 0;
}
if(cnt > length-off)
cnt = length-off;
thdr.count = cnt;
if(cnt == 0)
return 0;
blocks = data + getl(sac->blocks);
buf2 = malloc(blocksize);
if(buf2 == nil)
sysfatal("malloc failed");
while(cnt > 0) {
i = off/blocksize;
n = blocksize;
if(n > length-i*blocksize)
n = length-i*blocksize;
loadblock(buf2, blocks+i*OffsetSize, n);
j = off-i*blocksize;
n = blocksize-j;
if(n > cnt)
n = cnt;
memmove(buf, buf2+j, n);
cnt -= n;
off += n;
buf += n;
}
free(buf2);
return 0;
}
char*
rwrite(Fid *f)
{
if(f->busy == 0)
return Enotexist;
return Erdonly;
}
char *
rclunk(Fid *f)
{
f->busy = 0;
f->open = 0;
free(f->user);
sacfree(f->sac);
return 0;
}
char *
rremove(Fid *f)
{
f->busy = 0;
f->open = 0;
free(f->user);
sacfree(f->sac);
return Erdonly;
}
char *
rstat(Fid *f)
{
if(f->busy == 0)
return Enotexist;
sacstat(f->sac, thdr.stat);
return 0;
}
char *
rwstat(Fid *f)
{
if(f->busy == 0)
return Enotexist;
return Erdonly;
}
Sac*
saccpy(Sac *s)
{
Sac *ss;
ss = emalloc(sizeof(Sac));
*ss = *s;
if(ss->path)
ss->path->ref++;
return ss;
}
Path *
pathalloc(Path *p, long blocks, int entry, int nentry)
{
Path *pp = emalloc(sizeof(Path));
pp->ref = 1;
pp->blocks = blocks;
pp->entry = entry;
pp->nentry = nentry;
pp->up = p;
return pp;
}
void
pathfree(Path *p)
{
if(p == nil)
return;
p->ref--;
if(p->ref > 0)
return;
pathfree(p->up);
free(p);
}
void
sacfree(Sac *s)
{
pathfree(s->path);
free(s);
}
void
sacstat(SacDir *s, char *buf)
{
Dir dir;
memmove(dir.name, s->name, NAMELEN);
dir.qid = (Qid){getl(s->qid), 0};
dir.mode = getl(s->mode);
dir.length = getl(s->length);
if(dir.mode &CHDIR)
dir.length *= DIRLEN;
memmove(dir.uid, s->uid, NAMELEN);
memmove(dir.gid, s->gid, NAMELEN);
dir.atime = getl(s->atime);
dir.mtime = getl(s->mtime);
convD2M(&dir, buf);
}
void
loadblock(void *buf, uchar *offset, int blocksize)
{
long block, n;
ulong age;
int i, j;
block = getl(offset);
if(block < 0) {
block = -block;
cacheage++;
// age has wraped
if(cacheage == 0) {
for(i=0; i<CacheSize; i++)
cache[i].age = 0;
}
j = 0;
age = cache[0].age;
for(i=0; i<CacheSize; i++) {
if(cache[i].age < age) {
age = cache[i].age;
j = i;
}
if(cache[i].block != block)
continue;
memmove(buf, cache[i].data, blocksize);
cache[i].age = cacheage;
return;
}
n = getl(offset+OffsetSize);
if(n < 0)
n = -n;
n -= block;
if(unsac(buf, data+block, blocksize, n)<0)
sysfatal("unsac failed!");
memmove(cache[j].data, buf, blocksize);
cache[j].age = cacheage;
cache[j].block = block;
} else {
memmove(buf, data+block, blocksize);
}
}
Sac*
sacparent(Sac *s)
{
uchar *blocks;
SacDir *buf;
int per, i, n;
Path *p;
p = s->path;
if(p == nil || p->up == nil) {
pathfree(p);
*s = root;
return s;
}
p = p->up;
blocks = data + p->blocks;
per = blocksize/sizeof(SacDir);
i = p->entry/per;
n = per;
if(n > p->nentry-i*per)
n = p->nentry-i*per;
buf = emalloc(per*sizeof(SacDir));
loadblock(buf, blocks + i*OffsetSize, n*sizeof(SacDir));
s->SacDir = buf[p->entry-i*per];
free(buf);
p->ref++;
pathfree(s->path);
s->path = p;
return s;
}
int
sacdirread(Sac *s, char *p, long off, long cnt)
{
uchar *blocks;
SacDir *buf;
int iblock, per, i, j, ndir, n;
blocks = data + getl(s->blocks);
per = blocksize/sizeof(SacDir);
ndir = getl(s->length);
off /= DIRLEN;
cnt /= DIRLEN;
if(off >= ndir)
return 0;
if(cnt > ndir-off)
cnt = ndir-off;
iblock = -1;
buf = emalloc(per*sizeof(SacDir));
for(i=off; i<off+cnt; i++) {
j = i/per;
if(j != iblock) {
n = per;
if(n > ndir-j*per)
n = ndir-j*per;
loadblock(buf, blocks + j*OffsetSize, n*sizeof(SacDir));
iblock = j;
}
sacstat(buf+i-j*per, p);
p += DIRLEN;
}
free(buf);
return cnt*DIRLEN;
}
Sac*
saclookup(Sac *s, char *name)
{
int ndir;
int top, bot, i, j, k, n, per;
uchar *blocks;
SacDir *buf;
int iblock;
SacDir *sd;
if(strcmp(name, "..") == 0)
return sacparent(s);
blocks = data + getl(s->blocks);
per = blocksize/sizeof(SacDir);
ndir = getl(s->length);
buf = malloc(per*sizeof(SacDir));
if(buf == nil)
sysfatal("malloc failed");
iblock = -1;
if(1) {
// linear search
for(i=0; i<ndir; i++) {
j = i/per;
if(j != iblock) {
n = per;
if(n > ndir-j*per)
n = ndir-j*per;
loadblock(buf, blocks + j*OffsetSize, n*sizeof(SacDir));
iblock = j;
}
sd = buf+i-j*per;
k = strcmp(name, sd->name);
if(k == 0) {
s->path = pathalloc(s->path, getl(s->blocks), i, ndir);
s->SacDir = *sd;
free(buf);
return s;
}
}
free(buf);
return 0;
}
// binary search
top = ndir;
bot = 0;
while(bot != top){
i = (bot+top)>>1;
j = i/per;
if(j != iblock) {
n = per;
if(n > ndir-j*per)
n = ndir-j*per;
loadblock(buf, blocks + j*OffsetSize, n*sizeof(SacDir));
iblock = j;
}
j *= per;
sd = buf+i-j;
k = strcmp(name, sd->name);
if(k == 0) {
s->path = pathalloc(s->path, getl(s->blocks), i, ndir);
s->SacDir = *sd;
free(buf);
}
if(k < 0) {
top = i;
sd = buf;
if(strcmp(name, sd->name) < 0)
top = j;
} else {
bot = i+1;
if(ndir-j < per)
i = ndir-j;
else
i = per;
sd = buf+i-1;
if(strcmp(name, sd->name) > 0)
bot = j+i;
}
}
return 0;
}
Fid *
newfid(int fid)
{
Fid *f, *ff;
ff = 0;
for(f = fids; f; f = f->next)
if(f->fid == fid)
return f;
else if(!ff && !f->busy)
ff = f;
if(ff){
ff->fid = fid;
return ff;
}
f = emalloc(sizeof *f);
memset(f, 0 , sizeof(Fid));
f->fid = fid;
f->next = fids;
fids = f;
return f;
}
void
io(void)
{
char *err;
int n;
for(;;){
/*
* reading from a pipe or a network device
* will give an error after a few eof reads
* however, we cannot tell the difference
* between a zero-length read and an interrupt
* on the processes writing to us,
* so we wait for the error
*/
n = read(mfd[0], mdata, sizeof mdata);
if(n == 0)
continue;
if(n < 0)
error("mount read");
if(convM2S(mdata, &rhdr, n) == 0)
continue;
if(debug)
fprint(2, "sacfs:<-%F\n", &rhdr);
thdr.data = mdata + MAXMSG;
if(!fcalls[rhdr.type])
err = "bad fcall type";
else
err = (*fcalls[rhdr.type])(newfid(rhdr.fid));
if(err){
thdr.type = Rerror;
strncpy(thdr.ename, err, ERRLEN);
}else{
thdr.type = rhdr.type + 1;
thdr.fid = rhdr.fid;
}
thdr.tag = rhdr.tag;
if(debug)
fprint(2, "ramfs:->%F\n", &thdr);/**/
n = convS2M(&thdr, mdata);
if(write(mfd[1], mdata, n) != n)
error("mount write");
}
}
int
perm(Fid *f, Sac *s, int p)
{
ulong perm = getl(s->mode);
if((p*Pother) & perm)
return 1;
if(strcmp(f->user, s->gid)==0 && ((p*Pgroup) & perm))
return 1;
if(strcmp(f->user, s->uid)==0 && ((p*Powner) & perm))
return 1;
return 0;
}
void
init(char *file)
{
SacHeader *hdr;
Dir dir;
int fd;
int i;
uchar *p;
notify(notifyf);
strcpy(user, getuser());
if(dirstat(file, &dir) < 0)
error("bad file");
data = emalloc(dir.length);
fd = open(file, OREAD);
if(fd < 0)
error("opening file");
if(read(fd, data, dir.length) < dir.length)
error("reading file");
hdr = (SacHeader*)data;
if(getl(hdr->magic) != Magic)
error("bad magic");
if(getl(hdr->length) != (ulong)(dir.length))
error("bad length");
blocksize = getl(hdr->blocksize);
root.SacDir = *(SacDir*)(data + sizeof(SacHeader));
p = malloc(CacheSize*blocksize);
if(p == nil)
error("allocating cache");
for(i=0; i<CacheSize; i++) {
cache[i].data = p;
p += blocksize;
}
}
void
error(char *s)
{
fprint(2, "%s: %s: %r\n", argv0, s);
exits(s);
}
void *
emalloc(ulong n)
{
void *p;
p = malloc(n);
if(!p)
error("out of memory");
return p;
}
void *
erealloc(void *p, ulong n)
{
p = realloc(p, n);
if(!p)
error("out of memory");
return p;
}
void
usage(void)
{
fprint(2, "usage: %s [-i infd outfd] [-s] [-m mountpoint] sacfsfile\n", argv0);
exits("usage");
}
ulong
getl(void *p)
{
uchar *a = p;
return (a[0]<<24) | (a[1]<<16) | (a[2]<<8) | a[3];
}