ref: c3d7782a0cbb0aee91edae9b2850d053f27a6f0e
dir: /kern/devfs-posix.c/
#include "u.h"
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <dirent.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h> /* for remove, rename */
#include <limits.h>
#ifndef NAME_MAX
# define NAME_MAX 256
#endif
#include "lib.h"
#include "dat.h"
#include "fns.h"
#include "error.h"
typedef struct Ufsinfo Ufsinfo;
struct Ufsinfo
{
int mode;
int fd;
int uid;
int gid;
DIR* dir;
vlong offset;
QLock oq;
char* path;
char nextname[NAME_MAX];
};
static Qid fsqid(struct stat *);
static char* catpath(char*, char*);
static ulong fsdirread(Chan*, uchar*, int, ulong);
static int fsomode(int);
static char*
lastelem(char *s)
{
char *t;
if((t = strrchr(s, '/')) == nil)
return s;
if(t[1] == 0)
return t;
return t+1;
}
static Chan*
fsattach(char *spec)
{
Chan *c;
struct stat stbuf;
static int devno;
Ufsinfo *uif;
if(stat("/", &stbuf) < 0)
error(strerror(errno));
c = devattach('U', spec);
uif = mallocz(sizeof(Ufsinfo), 1);
uif->mode = stbuf.st_mode;
uif->uid = stbuf.st_uid;
uif->gid = stbuf.st_gid;
uif->path = strdup("/");
c->aux = uif;
c->dev = devno++;
c->qid.type = QTDIR;
/*print("fsattach %s\n", chanpath(c));*/
return c;
}
static Chan*
fsclone(Chan *c, Chan *nc)
{
Ufsinfo *uif;
uif = mallocz(sizeof(Ufsinfo), 1);
*uif = *(Ufsinfo*)c->aux;
uif->path = strdup(uif->path);
nc->aux = uif;
return nc;
}
static int
fswalk1(Chan *c, char *name)
{
struct stat stbuf;
Ufsinfo *uif;
char *path;
/*print("** fs walk '%s' -> %s\n", path, name); */
uif = c->aux;
path = catpath(uif->path, name);
if(stat(path, &stbuf) < 0){
free(path);
return 0;
}
free(uif->path);
uif->path = path;
uif->mode = stbuf.st_mode;
uif->uid = stbuf.st_uid;
uif->gid = stbuf.st_gid;
c->qid = fsqid(&stbuf);
return 1;
}
static Walkqid*
fswalk(Chan *c, Chan *nc, char **name, int nname)
{
int i;
Walkqid *wq;
if(nc != nil)
panic("fswalk: nc != nil");
wq = smalloc(sizeof(Walkqid)+(nname-1)*sizeof(Qid));
nc = devclone(c);
fsclone(c, nc);
wq->clone = nc;
for(i=0; i<nname; i++){
if(fswalk1(nc, name[i]) == 0)
break;
wq->qid[i] = nc->qid;
}
if(i != nname){
cclose(nc);
wq->clone = nil;
}
wq->nqid = i;
return wq;
}
static int
fsstat(Chan *c, uchar *buf, int n)
{
Dir d;
struct stat stbuf;
Ufsinfo *uif;
if(n < BIT16SZ)
error(Eshortstat);
uif = c->aux;
if(stat(uif->path, &stbuf) < 0)
error(strerror(errno));
d.name = lastelem(uif->path);
d.uid = eve;
d.gid = eve;
d.muid = eve;
d.qid = c->qid;
d.mode = (c->qid.type<<24)|(stbuf.st_mode&0777);
d.atime = stbuf.st_atime;
d.mtime = stbuf.st_mtime;
d.length = stbuf.st_size;
d.type = 'U';
d.dev = c->dev;
return convD2M(&d, buf, n);
}
static Chan*
fsopen(Chan *c, int mode)
{
Ufsinfo *uif;
int omode;
omode = openmode(mode);
uif = c->aux;
if(c->qid.type & QTDIR) {
if(omode != OREAD)
error(Eperm);
if((uif->dir = opendir(uif->path)) == NULL)
error(strerror(errno));
}
else {
int m = fsomode(omode & 3);
if(mode & OTRUNC)
m |= O_TRUNC;
if((uif->fd = open(uif->path, m, 0666)) < 0)
error(strerror(errno));
}
uif->offset = 0;
c->offset = 0;
c->mode = omode;
c->flag |= COPEN;
return c;
}
static Chan*
fscreate(Chan *c, char *name, int mode, ulong perm)
{
struct stat stbuf;
Ufsinfo *uif;
char *path;
DIR *dir;
int fd, omode;
omode = openmode(mode & ~OEXCL);
uif = c->aux;
path = catpath(uif->path, name);
if(waserror()){
free(path);
nexterror();
}
fd = -1;
dir = NULL;
if(perm & DMDIR) {
if(omode != OREAD)
error(Eperm);
if(mkdir(path, uif->mode & perm & 0777) < 0){
if(errno != EEXIST || mode & OEXCL)
error(strerror(errno));
}
if((dir = opendir(path)) == NULL)
error(strerror(errno));
if(waserror()){
closedir(dir);
nexterror();
}
}
else {
int m = fsomode(omode & 3) | O_CREAT | O_TRUNC;
if(mode & OEXCL)
m |= O_EXCL;
if((fd = open(path, m, uif->mode & perm & 0777)) < 0)
error(strerror(errno));
if(waserror()){
close(fd);
nexterror();
}
}
if(stat(path, &stbuf) < 0)
error(strerror(errno));
c->qid = fsqid(&stbuf);
uif->fd = fd;
uif->dir = dir;
poperror();
free(uif->path);
uif->path = path;
uif->offset = 0;
poperror();
c->offset = 0;
c->mode = omode;
c->flag |= COPEN;
return c;
}
static void
fsclose(Chan *c)
{
Ufsinfo *uif;
uif = c->aux;
if(c->flag & COPEN) {
if(c->qid.type & QTDIR)
closedir(uif->dir);
else
close(uif->fd);
c->flag &= ~COPEN;
if(c->flag & CRCLOSE) {
devtab[c->type]->remove(c);
return;
}
}
free(uif->path);
free(uif);
}
static long
fsread(Chan *c, void *va, long n, vlong offset)
{
int fd;
vlong r;
Ufsinfo *uif;
/*print("fsread %s\n", chanpath(c));*/
if(c->qid.type & QTDIR)
return fsdirread(c, va, n, offset);
uif = c->aux;
qlock(&uif->oq);
if(waserror()) {
qunlock(&uif->oq);
nexterror();
}
fd = uif->fd;
if(uif->offset != offset) {
r = lseek(fd, offset, 0);
if(r < 0)
error(strerror(errno));
uif->offset = offset;
}
n = read(fd, va, n);
if(n < 0)
error(strerror(errno));
uif->offset += n;
qunlock(&uif->oq);
poperror();
return n;
}
static long
fswrite(Chan *c, void *va, long n, vlong offset)
{
int fd;
vlong r;
Ufsinfo *uif;
uif = c->aux;
qlock(&uif->oq);
if(waserror()) {
qunlock(&uif->oq);
nexterror();
}
fd = uif->fd;
if(uif->offset != offset) {
r = lseek(fd, offset, 0);
if(r < 0)
error(strerror(errno));
uif->offset = offset;
}
n = write(fd, va, n);
if(n < 0)
error(strerror(errno));
uif->offset += n;
qunlock(&uif->oq);
poperror();
return n;
}
static void
fsremove(Chan *c)
{
int n;
Ufsinfo *uif;
if(waserror()){
fsclose(c);
nexterror();
}
uif = c->aux;
if(c->qid.type & QTDIR)
n = rmdir(uif->path);
else
n = remove(uif->path);
if(n < 0)
error(strerror(errno));
poperror();
fsclose(c);
}
int
fswstat(Chan *c, uchar *buf, int n)
{
Dir d;
struct stat stbuf;
char strs[NAME_MAX*3];
Ufsinfo *uif;
/*
* wstat is supposed to be atomic.
* we check all the things we can before trying anything.
* still, if we are told to truncate a file and rename it and only
* one works, we're screwed. in such cases we leave things
* half broken and return an error. it's hardly perfect.
*/
if(convM2D(buf, n, &d, strs) != n)
error(Ebadstat);
uif = c->aux;
if(stat(uif->path, &stbuf) < 0)
error(strerror(errno));
/*
* try things in increasing order of harm to the file.
* mtime should come after truncate so that if you
* do both the mtime actually takes effect, but i'd rather
* leave truncate until last.
* (see above comment about atomicity).
*/
if(~d.mode != 0 && (int)(d.mode&0777) != (int)(stbuf.st_mode&0777)) {
if(chmod(uif->path, d.mode&0777) < 0)
error(strerror(errno));
uif->mode &= ~0777;
uif->mode |= d.mode&0777;
}
if(~d.atime != 0 || ~d.mtime != 0){
struct timeval t[2];
t[0].tv_sec = ~d.atime != 0 ? d.atime : stbuf.st_atime;
t[0].tv_usec = 0;
t[1].tv_sec = ~d.mtime != 0 ? d.mtime : stbuf.st_mtime;
t[1].tv_usec = 0;
utimes(uif->path, t);
}
if(d.name[0] && strcmp(d.name, lastelem(uif->path)) != 0) {
char *base, *newpath;
base = strdup(uif->path);
*lastelem(base) = 0;
newpath = catpath(base, d.name);
free(base);
if(waserror()){
free(newpath);
nexterror();
}
if(stat(newpath, &stbuf) >= 0)
error(Eexist);
if(rename(uif->path, newpath) < 0)
error(strerror(errno));
free(uif->path);
uif->path = newpath;
poperror();
}
/*
p = name2pass(gid, d.gid);
if(p == 0)
error(Eunknown);
if(p->id != stbuf.st_gid) {
if(chown(old, stbuf.st_uid, p->id) < 0)
error(strerror(errno));
uif->gid = p->id;
}
*/
if((uvlong)d.length != (uvlong)~0 && truncate(uif->path, d.length) < 0)
error(strerror(errno));
return n;
}
static Qid
fsqid(struct stat *st)
{
Qid q;
q.type = 0;
if((st->st_mode&S_IFMT) == S_IFDIR)
q.type = QTDIR;
q.path = (uvlong)st->st_dev<<32 | st->st_ino;
q.vers = st->st_mtime;
return q;
}
static char*
catpath(char *base, char *ext)
{
char *path;
int n, m;
n = strlen(base);
m = strlen(ext);
path = malloc(n+m+2);
memmove(path, base, n);
if(n > 0 && path[n-1] != '/')
path[n++] = '/';
memmove(path+n, ext, m+1);
return path;
}
static int
isdots(char *name)
{
if(name[0] != '.')
return 0;
if(name[1] == '\0')
return 1;
if(name[1] != '.')
return 0;
if(name[2] == '\0')
return 1;
return 0;
}
static int
p9readdir(char *name, Ufsinfo *uif)
{
struct dirent *de;
if(uif->nextname[0]){
strcpy(name, uif->nextname);
uif->nextname[0] = 0;
return 1;
}
de = readdir(uif->dir);
if(de == NULL)
return 0;
strcpy(name, de->d_name);
return 1;
}
static ulong
fsdirread(Chan *c, uchar *va, int count, ulong offset)
{
int i;
Dir d;
long n;
char de[NAME_MAX];
struct stat stbuf;
Ufsinfo *uif;
/*print("fsdirread %s\n", chanpath(c));*/
i = 0;
uif = c->aux;
errno = 0;
if(uif->offset != offset) {
if(offset != 0)
error("bad offset in fsdirread");
uif->offset = offset; /* sync offset */
uif->nextname[0] = 0;
rewinddir(uif->dir);
}
while(i+BIT16SZ < count) {
char *p;
if(!p9readdir(de, uif))
break;
if(de[0]==0 || isdots(de))
continue;
d.name = de;
p = catpath(uif->path, de);
if(stat(p, &stbuf) < 0) {
/* fprint(2, "dir: bad path %s\n", path); */
/* but continue... probably a bad symlink */
memset(&stbuf, 0, sizeof stbuf);
}
free(p);
d.uid = eve;
d.gid = eve;
d.muid = eve;
d.qid = fsqid(&stbuf);
d.mode = (d.qid.type<<24)|(stbuf.st_mode&0777);
d.atime = stbuf.st_atime;
d.mtime = stbuf.st_mtime;
d.length = stbuf.st_size;
d.type = 'U';
d.dev = c->dev;
n = convD2M(&d, (uchar*)va+i, count-i);
if(n == BIT16SZ){
strcpy(uif->nextname, de);
break;
}
i += n;
}
/*print("got %d\n", i);*/
uif->offset += i;
return i;
}
static int
fsomode(int m)
{
switch(m) {
case OREAD:
case OEXEC:
return O_RDONLY;
case OWRITE:
return O_WRONLY;
case ORDWR:
return O_RDWR;
}
error(Ebadarg);
return 0;
}
Dev fsdevtab = {
'U',
"fs",
devreset,
devinit,
devshutdown,
fsattach,
fswalk,
fsstat,
fsopen,
fscreate,
fsclose,
fsread,
devbread,
fswrite,
devbwrite,
fsremove,
fswstat,
};