ref: 7628681f83b663609eace87a50f8fbf68c31f40b
dir: /sys/src/9/port/devenv.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
enum
{
Maxenvsize = 1*MB,
Maxvalsize = Maxenvsize/2,
DELTAENV = 32,
};
static Egrp *envgrp(Chan *c);
static int envwritable(Chan *c);
static Egrp confegrp; /* global environment group containing the kernel configuration */
#define PATH(p,i) ((uvlong)(p) << 32 | (i))
#define QID(quidpath) ((uint)(quidpath) & 0x7FFFFFFF)
static Evalue*
envindex(Egrp *eg, uvlong qidpath)
{
Evalue *e;
int i;
i = QID(qidpath);
if(i >= eg->nent)
return nil;
e = eg->ent[i];
if(e != nil && e->path != qidpath)
return nil;
return e;
}
static Evalue**
envhash(Egrp *eg, char *name)
{
uint c, h = 0;
while(c = *name++)
h = h*131 + c;
return &eg->hash[h % ENVHASH];
}
static Evalue*
lookupname(Evalue *e, char *name)
{
while(e != nil){
if(strcmp(e->name, name) == 0)
break;
e = e->hash;
}
return e;
}
static int
envgen(Chan *c, char *name, Dirtab*, int, int s, Dir *dp)
{
Egrp *eg;
Evalue *e;
Qid q;
eg = envgrp(c);
if(s == DEVDOTDOT){
c->qid.vers = eg->vers;
devdir(c, c->qid, "#e", 0, eve, 0775, dp);
return 1;
}
rlock(eg);
if((c->qid.type & QTDIR) == 0) {
e = envindex(eg, c->qid.path);
if(e == nil)
goto Notfound;
} else if(name != nil) {
if(strlen(name) >= sizeof(up->genbuf))
goto Notfound;
e = lookupname(*envhash(eg, name), name);
if(e == nil)
goto Notfound;
} else if(s < eg->nent) {
e = eg->ent[s];
if(e == nil) {
runlock(eg);
return 0; /* deleted, try next */
}
} else {
Notfound:
runlock(eg);
return -1;
}
/* make sure name string continues to exist after we release lock */
kstrcpy(up->genbuf, e->name, sizeof(up->genbuf));
mkqid(&q, e->path, e->vers, QTFILE);
devdir(c, q, up->genbuf, e->len, eve,
eg == &confegrp || eg != up->egrp ? 0664: 0666, dp);
runlock(eg);
return 1;
}
static Chan*
envattach(char *spec)
{
Chan *c;
Egrp *egrp = nil;
if(spec != nil && *spec != '\0') {
if(strcmp(spec, "c") != 0)
error(Ebadarg);
egrp = &confegrp;
}
c = devattach('e', spec);
c->aux = egrp;
return c;
}
static Walkqid*
envwalk(Chan *c, Chan *nc, char **name, int nname)
{
return devwalk(c, nc, name, nname, nil, 0, envgen);
}
static int
envstat(Chan *c, uchar *db, int n)
{
return devstat(c, db, n, nil, 0, envgen);
}
static void*
envrealloc(Egrp *eg, void *old, int newsize)
{
int oldsize = old != nil ? msize(old) : 0;
void *new;
if(newsize == 0){
eg->alloc -= oldsize;
free(old);
return nil;
}
if(newsize < 0 || eg != &confegrp && (eg->alloc + newsize) - oldsize > Maxenvsize)
error(Enomem);
new = realloc(old, newsize);
if(new == nil)
error(Enomem);
eg->alloc += msize(new) - oldsize;
setmalloctag(new, getcallerpc(&eg));
return new;
}
static Chan*
envopen(Chan *c, int omode)
{
Egrp *eg;
Evalue *e;
eg = envgrp(c);
if(c->qid.type & QTDIR) {
if(omode != OREAD)
error(Eperm);
}
else {
int trunc = omode & OTRUNC;
if(omode != OREAD && !envwritable(c))
error(Eperm);
if(trunc)
wlock(eg);
else
rlock(eg);
e = envindex(eg, c->qid.path);
if(e == nil) {
if(trunc)
wunlock(eg);
else
runlock(eg);
error(Enonexist);
}
if(trunc && e->len > 0) {
e->value = envrealloc(eg, e->value, 0); /* free */
e->len = 0;
e->vers++;
}
c->qid.vers = e->vers;
if(trunc)
wunlock(eg);
else
runlock(eg);
}
c->mode = openmode(omode);
incref(eg);
c->aux = eg;
c->offset = 0;
c->flag |= COPEN;
return c;
}
static Chan*
envcreate(Chan *c, char *name, int omode, ulong)
{
Egrp *eg;
Evalue *e, **h;
int n, i;
if(c->qid.type != QTDIR || !envwritable(c))
error(Eperm);
n = strlen(name)+1;
if(n > sizeof(up->genbuf))
error(Etoolong);
omode = openmode(omode);
eg = envgrp(c);
wlock(eg);
if(waserror()) {
wunlock(eg);
nexterror();
}
h = envhash(eg, name);
if(lookupname(*h, name) != nil)
error(Eexist);
for(i = eg->low; i < eg->nent; i++)
if(eg->ent[i] == nil)
break;
if(i >= eg->nent){
if((eg->nent % DELTAENV) == 0)
eg->ent = envrealloc(eg, eg->ent, (eg->nent+DELTAENV) * sizeof(Evalue*));
i = eg->nent++;
eg->ent[i] = nil;
eg->low = i;
}
e = envrealloc(eg, nil, sizeof(Evalue)+n);
memmove(e->name, name, n);
e->value = nil;
e->len = 0;
e->vers = 0;
e->path = PATH(++eg->path, i);
e->hash = *h, *h = e;
eg->ent[i] = e;
eg->low = i+1;
eg->vers++;
mkqid(&c->qid, e->path, e->vers, QTFILE);
wunlock(eg);
poperror();
incref(eg);
c->aux = eg;
c->offset = 0;
c->mode = omode;
c->flag |= COPEN;
return c;
}
static void
envremove(Chan *c)
{
Egrp *eg;
Evalue *e, **h;
int i;
if(c->qid.type & QTDIR || !envwritable(c))
error(Eperm);
eg = envgrp(c);
wlock(eg);
e = envindex(eg, c->qid.path);
if(e == nil){
wunlock(eg);
error(Enonexist);
}
for(h = envhash(eg, e->name); *h != nil; h = &(*h)->hash){
if(*h == e){
*h = e->hash;
break;
}
}
i = QID(c->qid.path);
eg->ent[i] = nil;
if(i < eg->low)
eg->low = i;
eg->vers++;
/* free */
envrealloc(eg, e->value, 0);
envrealloc(eg, e, 0);
wunlock(eg);
}
static void
envclose(Chan *c)
{
if(c->flag & COPEN){
/*
* cclose can't fail, so errors from remove will be ignored.
* since permissions aren't checked,
* envremove can't not remove it if its there.
*/
if(c->flag & CRCLOSE && !waserror()){
envremove(c);
poperror();
}
closeegrp((Egrp*)c->aux);
c->aux = nil;
}
}
static long
envread(Chan *c, void *a, long n, vlong off)
{
Egrp *eg;
Evalue *e;
if(c->qid.type & QTDIR)
return devdirread(c, a, n, nil, 0, envgen);
eg = envgrp(c);
rlock(eg);
if(waserror()){
runlock(eg);
nexterror();
}
e = envindex(eg, c->qid.path);
if(e == nil)
error(Enonexist);
if(off >= e->len)
n = 0;
else if(off + n > e->len)
n = e->len - off;
if(n <= 0)
n = 0;
else
memmove(a, e->value+off, n);
runlock(eg);
poperror();
return n;
}
static long
envwrite(Chan *c, void *a, long n, vlong off)
{
Egrp *eg;
Evalue *e;
int diff;
eg = envgrp(c);
wlock(eg);
if(waserror()){
wunlock(eg);
nexterror();
}
e = envindex(eg, c->qid.path);
if(e == nil)
error(Enonexist);
if(off > Maxvalsize || n > (Maxvalsize - off))
error(Etoobig);
diff = (off+n) - e->len;
if(diff > 0)
e->value = envrealloc(eg, e->value, e->len+diff);
else
diff = 0;
memmove(e->value+off, a, n); /* might fault */
if(off > e->len)
memset(e->value+e->len, 0, off-e->len);
e->len += diff;
e->vers++;
eg->vers++;
wunlock(eg);
poperror();
return n;
}
Dev envdevtab = {
'e',
"env",
devreset,
devinit,
devshutdown,
envattach,
envwalk,
envstat,
envopen,
envcreate,
envclose,
envread,
devbread,
envwrite,
devbwrite,
envremove,
devwstat,
};
void
envcpy(Egrp *to, Egrp *from)
{
Evalue *e, *ne, **h;
int i, n;
rlock(from);
if(waserror()){
runlock(from);
nexterror();
}
to->nent = 0;
to->ent = envrealloc(to, nil, ROUND(from->nent, DELTAENV) * sizeof(Evalue*));
for(i = 0; i < from->nent; i++){
e = from->ent[i];
if(e == nil)
continue;
h = envhash(to, e->name);
n = strlen(e->name)+1;
ne = envrealloc(to, nil, sizeof(Evalue)+n);
memmove(ne->name, e->name, n);
ne->value = nil;
ne->len = 0;
ne->vers = 0;
ne->path = PATH(++to->path, to->nent);
ne->hash = *h, *h = ne;
to->ent[to->nent++] = ne;
if(e->len > 0){
ne->value = envrealloc(to, ne->value, e->len);
memmove(ne->value, e->value, e->len);
ne->len = e->len;
}
}
to->low = to->nent;
runlock(from);
poperror();
}
void
closeegrp(Egrp *eg)
{
Evalue *e;
int i;
if(decref(eg) || eg == &confegrp)
return;
for(i = 0; i < eg->nent; i++){
e = eg->ent[i];
if(e == nil)
continue;
free(e->value);
free(e);
}
free(eg->ent);
free(eg);
}
static Egrp*
envgrp(Chan *c)
{
if(c->aux == nil)
return up->egrp;
return c->aux;
}
static int
envwritable(Chan *c)
{
return c->aux == nil || c->aux == up->egrp || iseve();
}
/*
* to let the kernel set environment variables
*/
void
ksetenv(char *ename, char *eval, int conf)
{
Chan *c;
char buf[2*KNAMELEN];
snprint(buf, sizeof(buf), "#e%s/%s", conf?"c":"", ename);
c = namec(buf, Acreate, OWRITE, 0666);
devtab[c->type]->write(c, eval, strlen(eval), 0);
cclose(c);
}
/*
* Return a copy of configuration environment as a sequence of strings.
* The strings alternate between name and value. A zero length name string
* indicates the end of the list
*/
char *
getconfenv(void)
{
Egrp *eg = &confegrp;
Evalue *e;
char *p, *q;
int i, n;
rlock(eg);
n = 1;
for(i = 0; i < eg->nent; i++){
e = eg->ent[i];
if(e == nil)
continue;
n += strlen(e->name)+e->len+2;
}
p = malloc(n);
if(p == nil){
runlock(eg);
error(Enomem);
}
q = p;
for(i = 0; i < eg->nent; i++){
e = eg->ent[i];
if(e == nil)
continue;
n = strlen(e->name)+1;
memmove(q, e->name, n);
q += n;
memmove(q, e->value, e->len);
q[e->len] = 0;
/* move up to the first null */
q += strlen(q) + 1;
}
*q = '\0';
runlock(eg);
return p;
}