ref: 80e484d564586d035af62709835cd6ed65a05d38
dir: /kern/devenv.c/
#include "u.h"
#include "lib.h"
#include "dat.h"
#include "fns.h"
#include "error.h"
enum
{
Maxenvsize = 16300,
};
static Egrp *envgrp(Chan *c);
static int envwriteable(Chan *c);
static void initunix();
static Egrp unixegrp; /* unix environment group */
static Evalue*
envlookup(Egrp *eg, char *name, ulong qidpath)
{
Evalue *e;
int i;
for(i=0; i<eg->nent; i++){
e = eg->ent[i];
if(e->qid.path == qidpath || (name && e->name[0]==name[0] && strcmp(e->name, name) == 0))
return e;
}
return nil;
}
static int
envgen(Chan *c, char *name, Dirtab *_1, int _2, int s, Dir *dp)
{
Egrp *eg;
Evalue *e;
if(s == DEVDOTDOT){
devdir(c, c->qid, "#e", 0, eve, DMDIR|0775, dp);
return 1;
}
eg = envgrp(c);
rlock(&eg->lk);
e = 0;
if(name)
e = envlookup(eg, name, -1);
else if(s < eg->nent)
e = eg->ent[s];
if(e == 0) {
runlock(&eg->lk);
return -1;
}
/* make sure name string continues to exist after we release lock */
kstrcpy(up->genbuf, e->name, sizeof up->genbuf);
devdir(c, e->qid, up->genbuf, e->len, eve, 0666, dp);
runlock(&eg->lk);
return 1;
}
static Chan*
envattach(char *spec)
{
Chan *c;
if(spec && *spec) {
error(Ebadarg);
}
initunix();
c = devattach('e', spec);
c->aux = &unixegrp;
return c;
}
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 = envgrp(c)->vers;
return devstat(c, db, n, 0, 0, envgen);
}
static Chan*
envopen(Chan *c, int omode)
{
Egrp *eg;
Evalue *e;
int trunc;
eg = envgrp(c);
if(c->qid.type & QTDIR) {
if(omode != OREAD)
error(Eperm);
}
else {
trunc = omode & OTRUNC;
if(omode != OREAD && !envwriteable(c))
error(Eperm);
if(trunc)
wlock(&eg->lk);
else
rlock(&eg->lk);
e = envlookup(eg, nil, c->qid.path);
if(e == 0) {
if(trunc)
wunlock(&eg->lk);
else
runlock(&eg->lk);
error(Enonexist);
}
if(trunc && e->value) {
e->qid.vers++;
free(e->value);
e->value = 0;
e->len = 0;
}
if(trunc)
wunlock(&eg->lk);
else
runlock(&eg->lk);
}
c->mode = openmode(omode);
c->flag |= COPEN;
c->offset = 0;
return c;
}
static Chan*
envcreate(Chan *c, char *name, int omode, ulong _)
{
Egrp *eg;
Evalue *e;
Evalue **ent;
if(c->qid.type != QTDIR)
error(Eperm);
if(strlen(name) >= sizeof up->genbuf)
error("name too long"); /* protect envgen */
omode = openmode(omode);
eg = envgrp(c);
wlock(&eg->lk);
if(waserror()) {
wunlock(&eg->lk);
nexterror();
}
if(envlookup(eg, name, -1))
error(Eexist);
e = smalloc(sizeof(Evalue));
e->name = smalloc(strlen(name)+1);
strcpy(e->name, name);
if(eg->nent == eg->ment){
eg->ment += 32;
ent = smalloc(sizeof(eg->ent[0])*eg->ment);
if(eg->nent)
memmove(ent, eg->ent, sizeof(eg->ent[0])*eg->nent);
free(eg->ent);
eg->ent = ent;
}
e->qid.path = ++eg->path;
e->qid.vers = 0;
eg->vers++;
eg->ent[eg->nent++] = e;
c->qid = e->qid;
wunlock(&eg->lk);
poperror();
c->offset = 0;
c->mode = omode;
c->flag |= COPEN;
return c;
}
static void
envremove(Chan *c)
{
int i;
Egrp *eg;
Evalue *e;
if(c->qid.type & QTDIR)
error(Eperm);
eg = envgrp(c);
wlock(&eg->lk);
e = 0;
for(i=0; i<eg->nent; i++){
if(eg->ent[i]->qid.path == c->qid.path){
e = eg->ent[i];
eg->nent--;
eg->ent[i] = eg->ent[eg->nent];
eg->vers++;
break;
}
}
wunlock(&eg->lk);
if(e == 0)
error(Enonexist);
free(e->name);
if(e->value)
free(e->value);
free(e);
}
static void
envclose(Chan *c)
{
/*
* 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)
envremove(c);
}
static long
envread(Chan *c, void *a, long n, vlong off)
{
Egrp *eg;
Evalue *e;
ulong offset = off;
if(c->qid.type & QTDIR)
return devdirread(c, a, n, 0, 0, envgen);
eg = envgrp(c);
rlock(&eg->lk);
e = envlookup(eg, nil, c->qid.path);
if(e == 0) {
runlock(&eg->lk);
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->value+offset, n);
runlock(&eg->lk);
return n;
}
static long
envwrite(Chan *c, void *a, long n, vlong off)
{
char *s;
ulong len;
Egrp *eg;
Evalue *e;
ulong offset = off;
if(n <= 0)
return 0;
if(offset > Maxenvsize || n > (Maxenvsize - offset))
error(Etoobig);
eg = envgrp(c);
wlock(&eg->lk);
e = envlookup(eg, nil, c->qid.path);
if(e == 0) {
wunlock(&eg->lk);
error(Enonexist);
}
len = offset+n;
if(len > e->len) {
s = smalloc(len);
if(e->value){
memmove(s, e->value, e->len);
free(e->value);
}
e->value = s;
e->len = len;
}
memmove(e->value+offset, a, n);
e->qid.vers++;
eg->vers++;
wunlock(&eg->lk);
return n;
}
Dev envdevtab = {
'e',
"env",
devreset,
devinit,
devshutdown,
envattach,
envwalk,
envstat,
envopen,
envcreate,
envclose,
envread,
devbread,
envwrite,
devbwrite,
envremove,
devwstat,
};
extern char **environ;
static void
initunix()
{
Egrp *eg = &unixegrp;
Evalue **ent, *e;
char *eq, **envp, *line;
int n;
wlock(&eg->lk);
if(eg->path > 0 || eg->ment > 0 || !environ){
// already initialized or nothing in environent
wunlock(&eg->lk);
return;
}
for(envp = environ; *envp != nil; envp++)
eg->ment++;
ent = smalloc(sizeof(eg->ent[0])*eg->ment);
eg->ent = ent;
for(envp = environ; *envp != nil; envp++){
line = *envp;
n = strlen(line);
eq = strchr(line, '=');
if(eq == nil)
eq = &line[n];
e = smalloc(sizeof(Evalue));
e->name = smalloc(eq-line+1);
strncpy(e->name, line, eq-line);
if(eq[0] != '\0')
eq++;
e->len = line+n-eq;
e->value = smalloc(e->len);
memmove(e->value, eq, e->len);
e->qid.path = ++eg->path;
e->qid.vers = 0;
eg->vers++;
eg->ent[eg->nent++] = e;
}
wunlock(&eg->lk);
}
void
envcpy(Egrp *to, Egrp *from)
{
int i;
Evalue *ne, *e;
rlock(&from->lk);
to->ment = (from->nent+31)&~31;
to->ent = smalloc(to->ment*sizeof(to->ent[0]));
for(i=0; i<from->nent; i++){
e = from->ent[i];
ne = smalloc(sizeof(Evalue));
ne->name = smalloc(strlen(e->name)+1);
strcpy(ne->name, e->name);
if(e->value){
ne->value = smalloc(e->len);
memmove(ne->value, e->value, e->len);
ne->len = e->len;
}
ne->qid.path = ++to->path;
to->ent[i] = ne;
}
to->nent = from->nent;
runlock(&from->lk);
}
void
closeegrp(Egrp *eg)
{
int i;
Evalue *e;
if(decref(&eg->ref) == 0){
for(i=0; i<eg->nent; i++){
e = eg->ent[i];
free(e->name);
if(e->value)
free(e->value);
free(e);
}
free(eg->ent);
free(eg);
}
}
static Egrp*
envgrp(Chan *c)
{
if(c->aux == nil)
return &unixegrp;
return c->aux;
}
static int
envwriteable(Chan *c)
{
return iseve() || c->aux == nil;
}