ref: 83246e296ea433b65b9d295b5e08fedd39ff1ab7
dir: /os/port/devenv.c/
/*
* devenv - environment
*/
#include "u.h"
#include "../port/lib.h"
#include "../port/error.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
static void envremove(Chan*);
enum
{
Maxenvsize = 16300,
};
static Egrp confegrp; /* global environment group containing the kernel configuration */
static int
envgen(Chan *c, char*, Dirtab*, int, int s, Dir *dp)
{
Egrp *eg;
Evalue *e;
if(s == DEVDOTDOT){
devdir(c, c->qid, "#e", 0, eve, DMDIR|0775, dp);
return 1;
}
eg = up->env->egrp;
qlock(eg);
for(e = eg->entries; e != nil && s != 0; e = e->next)
s--;
if(e == nil) {
qunlock(eg);
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);
return 1;
}
static Chan*
envattach(char *spec)
{
if(up->env == nil || up->env->egrp == nil)
error(Enodev);
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, u32 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);
for(e = eg->entries; e != nil; e = e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil) {
qunlock(eg);
error(Enonexist);
}
if((mode & OTRUNC) && e->val) {
free(e->val);
e->val = 0;
e->len = 0;
e->qid.vers++;
}
qunlock(eg);
c->mode = openmode(mode);
c->flag |= COPEN;
c->offset = 0;
return c;
}
static void
envcreate(Chan *c, char *name, u32 mode, u32)
{
Egrp *eg;
Evalue *e, **le;
if(c->qid.type != QTDIR)
error(Eperm);
if(strlen(name) >= sizeof(up->genbuf))
error("name too long"); /* needs to fit for stat */
mode = openmode(mode);
eg = up->env->egrp;
qlock(eg);
if(waserror()){
qunlock(eg);
nexterror();
}
for(le = &eg->entries; (e = *le) != nil; le = &e->next)
if(strcmp(e->var, name) == 0)
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;
e->next = nil;
e->qid.vers = 0;
*le = e;
c->qid = e->qid;
eg->vers++;
poperror();
qunlock(eg);
c->offset = 0;
c->flag |= COPEN;
c->mode = mode;
}
static void
envclose(Chan *c)
{
if(c->flag & CRCLOSE)
envremove(c);
}
static s32
envread(Chan *c, void *a, s32 n, s64 offset)
{
Egrp *eg;
Evalue *e;
if(c->qid.type & QTDIR)
return devdirread(c, a, n, 0, 0, envgen);
eg = up->env->egrp;
qlock(eg);
if(waserror()){
qunlock(eg);
nexterror();
}
for(e = eg->entries; e != nil; e = e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil)
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);
poperror();
qunlock(eg);
return n;
}
static s32
envwrite(Chan *c, void *a, s32 n, s64 offset)
{
char *s;
ulong ve;
Egrp *eg;
Evalue *e;
if(n <= 0)
return 0;
ve = offset+n;
if(ve > Maxenvsize)
error(Etoobig);
eg = up->env->egrp;
qlock(eg);
if(waserror()){
qunlock(eg);
nexterror();
}
for(e = eg->entries; e != nil; e = e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil)
error(Enonexist);
if(ve > e->len) {
s = smalloc(ve);
memmove(s, e->val, e->len);
if(e->val != nil)
free(e->val);
e->val = s;
e->len = ve;
}
memmove(e->val+offset, a, n);
e->qid.vers++;
poperror();
qunlock(eg);
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);
for(l = &eg->entries; (e = *l) != nil; l = &e->next)
if(e->qid.path == c->qid.path)
break;
if(e == nil) {
qunlock(eg);
error(Enonexist);
}
*l = e->next;
eg->vers++;
qunlock(eg);
free(e->var);
if(e->val != nil)
free(e->val);
free(e);
}
Dev envdevtab = {
'e',
"env",
devreset,
devinit,
devshutdown,
envattach,
envwalk,
envstat,
envopen,
envcreate,
envclose,
envread,
devbread,
envwrite,
devbwrite,
envremove,
devwstat
};
/*
* kernel interface to environment variables
*/
Egrp*
newegrp(void)
{
Egrp *e;
e = smalloc(sizeof(Egrp));
e->ref = 1;
return e;
}
void
closeegrp(Egrp *e)
{
Evalue *el, *nl;
if(e == nil || decref(e) != 0)
return;
for (el = e->entries; el != nil; el = nl) {
free(el->var);
if (el->val)
free(el->val);
nl = el->next;
free(el);
}
free(e);
}
void
egrpcpy(Egrp *to, Egrp *from)
{
Evalue *e, *ne, **last;
if(from == nil)
return;
last = &to->entries;
qlock(from);
for (e = from->entries; e != nil; e = e->next) {
ne = smalloc(sizeof(Evalue));
ne->var = smalloc(strlen(e->var)+1);
strcpy(ne->var, e->var);
if (e->val) {
ne->val = smalloc(e->len);
memmove(ne->val, e->val, e->len);
ne->len = e->len;
}
ne->qid.path = ++to->path;
*last = ne;
last = &ne->next;
}
qunlock(from);
}
void
ksetenv(char *var, char *val, int)
{
Chan *c;
char buf[2*KNAMELEN];
snprint(buf, sizeof(buf), "#e/%s", var);
if(waserror())
return;
c = namec(buf, Acreate, OWRITE, 0600);
poperror();
if(!waserror()){
if(!waserror()){
devtab[c->type]->write(c, val, strlen(val), 0);
poperror();
}
poperror();
}
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, *ee;
char *p, *q;
int n;
qlock(eg);
if(waserror()) {
qunlock(eg);
nexterror();
}
/* determine size */
n = 0;
e = eg->ent;
for(ee = e + eg->nent; e < ee; e++)
n += strlen(e->name) + e->len + 2;
p = malloc(n + 1);
if(p == nil)
error(Enomem);
q = p;
e = eg->ent;
for(ee = e + eg->nent; e < ee; e++){
strcpy(q, e->name);
q += strlen(q) + 1;
memmove(q, e->value, e->len);
q[e->len] = 0;
/* move up to the first null */
q += strlen(q) + 1;
}
*q = '\0';
qunlock(eg);
poperror();
return p;
}