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/*
* devenv - environment
*/
#include "dat.h"
#include "fns.h"
#include "error.h"
static void envremove(Chan*);
static int
envgen(Chan *c, char *name, Dirtab *d, int nd, int s, Dir *dp)
{
Egrp *eg;
Evalue *e;
USED(name);
USED(d);
USED(nd);
if(s == DEVDOTDOT){
devdir(c, c->qid, "#e", 0, eve, DMDIR|0775, dp);
return 1;
}
eg = up->env->egrp;
qlock(&eg->l);
for(e = eg->entries; e != nil && s != 0; e = e->next)
s--;
if(e == nil) {
qunlock(&eg->l);
return -1;
}
/* make sure name string continues to exist after we release lock */
kstrcpy(up->genbuf, e->var, sizeof up->genbuf);
devdir(c, e->qid, up->genbuf, e->len, eve, 0666, dp);
qunlock(&eg->l);
return 1;
}
static Chan*
envattach(char *spec)
{
return devattach('e', spec);
}
static Walkqid*
envwalk(Chan *c, Chan *nc, char **name, int nname)
{
return devwalk(c, nc, name, nname, 0, 0, envgen);
}
static int
envstat(Chan *c, uchar *db, int n)
{
if(c->qid.type & QTDIR)
c->qid.vers = up->env->egrp->vers;
return devstat(c, db, n, 0, 0, envgen);
}
static Chan *
envopen(Chan *c, int mode)
{
Egrp *eg;
Evalue *e;
if(c->qid.type & QTDIR) {
if(mode != OREAD)
error(Eperm);
c->mode = mode;
c->flag |= COPEN;
c->offset = 0;
return c;
}
eg = up->env->egrp;
qlock(&eg->l);
for(e = eg->entries; e != nil; e = e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil) {
qunlock(&eg->l);
error(Enonexist);
}
if(mode == (OWRITE|OTRUNC) && e->val) {
free(e->val);
e->val = 0;
e->len = 0;
e->qid.vers++;
}
qunlock(&eg->l);
c->offset = 0;
c->flag |= COPEN;
c->mode = mode&~OTRUNC;
return c;
}
static void
envcreate(Chan *c, char *name, int mode, ulong perm)
{
Egrp *eg;
Evalue *e, *le;
USED(perm);
if(c->qid.type != QTDIR)
error(Eperm);
if(strlen(name) >= sizeof(up->genbuf))
error("name too long"); /* needs to fit for stat */
eg = up->env->egrp;
qlock(&eg->l);
for(le = nil, e = eg->entries; e != nil; le = e, e = e->next)
if(strcmp(e->var, name) == 0) {
qunlock(&eg->l);
error(Eexist);
}
e = smalloc(sizeof(Evalue));
e->var = smalloc(strlen(name)+1);
strcpy(e->var, name);
e->val = 0;
e->len = 0;
e->qid.path = ++eg->path;
if (le == nil)
eg->entries = e;
else
le->next = e;
e->qid.vers = 0;
c->qid = e->qid;
eg->vers++;
qunlock(&eg->l);
c->offset = 0;
c->flag |= COPEN;
c->mode = mode;
}
static void
envclose(Chan * c)
{
if(c->flag & CRCLOSE)
envremove(c);
}
static long
envread(Chan *c, void *a, long n, vlong offset)
{
Egrp *eg;
Evalue *e;
if(c->qid.type & QTDIR)
return devdirread(c, a, n, 0, 0, envgen);
eg = up->env->egrp;
qlock(&eg->l);
for(e = eg->entries; e != nil; e = e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil) {
qunlock(&eg->l);
error(Enonexist);
}
if(offset > e->len) /* protects against overflow converting vlong to ulong */
n = 0;
else if(offset + n > e->len)
n = e->len - offset;
if(n <= 0)
n = 0;
else
memmove(a, e->val+offset, n);
qunlock(&eg->l);
return n;
}
static long
envwrite(Chan *c, void *a, long n, vlong offset)
{
char *s;
int ve;
Egrp *eg;
Evalue *e;
if(n <= 0)
return 0;
eg = up->env->egrp;
qlock(&eg->l);
for(e = eg->entries; e != nil; e = e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil) {
qunlock(&eg->l);
error(Enonexist);
}
ve = offset+n;
if(ve > e->len) {
s = smalloc(ve);
memmove(s, e->val, e->len);
if(e->val)
free(e->val);
e->val = s;
e->len = ve;
}
memmove(e->val+offset, a, n);
e->qid.vers++;
qunlock(&eg->l);
return n;
}
static void
envremove(Chan *c)
{
Egrp *eg;
Evalue *e, **l;
if(c->qid.type & QTDIR)
error(Eperm);
eg = up->env->egrp;
qlock(&eg->l);
for(l = &eg->entries; *l != nil; l = &(*l)->next)
if((*l)->qid.path == c->qid.path)
break;
e = *l;
if(e == nil) {
qunlock(&eg->l);
error(Enonexist);
}
*l = e->next;
eg->vers++;
qunlock(&eg->l);
free(e->var);
if(e->val != nil)
free(e->val);
free(e);
}
Dev envdevtab = {
'e',
"env",
devinit,
envattach,
envwalk,
envstat,
envopen,
envcreate,
envclose,
envread,
devbread,
envwrite,
devbwrite,
envremove,
devwstat
};
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