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#include <camellia/errno.h>
#include <camellia/flags.h>
#include <kernel/malloc.h>
#include <kernel/panic.h>
#include <kernel/proc.h>
#include <kernel/vfs/request.h>
#include <shared/mem.h>
/** Checks if the request flags don't contradict each other.
* While this could be done by caller of vfsreq_dispatchcopy, as currently
* there's only one of them per operation, doing this here means that any
* potential future callers can't forget those checks.
* Doing this so late is kinda inefficient but I don't really care. */
static bool
vfsreq_isvalid(VfsReq *r)
{
/* Notable omissions:
* - Simplifying the path for open(). Already done when resolving the mount.
* - Checking the handle permissions. We don't have access to it.
* */
if (r->type == VFSOP_OPEN && !(r->flags & OPEN_WRITE) && (r->flags & OPEN_CREATE)) {
return false;
}
// XXX if i add a handle field to vfs_request, check ->readable ->writeable here
return true;
}
void
vfsreq_dispatchcopy(VfsReq tmpl)
{
VfsReq *req;
VfsBackend *backend;
/* allocate memory for the request and move it there */
req = kmalloc(sizeof *req, "VfsReq");
memcpy(req, &tmpl, sizeof *req);
backend = req->backend;
if (backend) {
assert(backend->usehcnt > 0);
backend->usehcnt++;
}
if (req->caller) {
proc_setstate(req->caller, PS_WAITS4FS);
req->caller->reqslot = req;
}
/* Check request validity. Doing this after the memcpy means that it
* doesn't need to be special cased in vfsreq_finish. */
if (!vfsreq_isvalid(req)) {
vfsreq_finish_short(req, -EINVAL);
return;
}
assert(req->queue_next == NULL);
assert(req->postqueue_next == NULL);
if (backend == NULL) {
/* null mount - probably never had a real backend */
vfsreq_finish_short(req, -ENOENT);
} else if (backend->is_user) {
vfsback_useraccept(req);
} else { /* kernel backend */
assert(backend->kern.accept);
backend->kern.accept(req);
}
}
void
vfsreq_finish(VfsReq *req, char __user *stored, long ret, int flags, Proc *handler)
{
if (req->type == VFSOP_OPEN && ret >= 0) {
Handle *h;
if (!(flags & FSR_DELEGATE)) {
/* default behavior - create a new handle for the file, wrap the id */
h = handle_init(HANDLE_FILE);
h->backend = req->backend;
req->backend->usehcnt++;
h->file_id = stored;
h->readable = OPEN_READABLE(req->flags);
h->writeable = OPEN_WRITEABLE(req->flags);
} else {
/* delegating - moving a handle to the caller */
assert(handler);
h = hs_take(handler->hs, ret);
if (h) {
h->readable = h->readable && OPEN_READABLE(req->flags);
h->writeable = h->writeable && OPEN_WRITEABLE(req->flags);
}
}
if (h) {
// TODO write tests for caller getting killed while opening a file
if (!req->caller) panic_unimplemented();
ret = hs_put(req->caller->hs, h);
if (ret < 0) ret = -EMFILE;
} else {
ret = -1;
}
}
if (req->type == VFSOP_READ && ret >= 0) {
assert((size_t)ret <= req->output.len);
}
if (req->input.kern) {
kfree(req->input.buf_kern);
}
if (req->backend) {
vfsback_userdown(req->backend);
}
assert(req->queue_next == NULL);
assert(req->postqueue_next == NULL);
if (req->caller) {
assert(req->caller->state == PS_WAITS4FS);
regs_savereturn(&req->caller->regs, ret);
proc_setstate(req->caller, PS_RUNNING);
}
kfree(req);
}
void
vfsback_useraccept(VfsReq *req)
{
VfsBackend *backend;
Proc *handler;
struct ufs_request res = {0};
int len;
assert(req != NULL);
backend = req->backend;
assert(backend);
assert(backend->is_user);
if (backend->provhcnt == 0) {
vfsreq_finish_short(req, -EPIPE);
return;
} else if (backend->user.handler == NULL) {
/* queue the request up */
// TODO use postqueue
VfsReq **it = &backend->queue;
while (*it != NULL) { /* find a free spot in queue */
it = &(*it)->queue_next;
}
*it = req;
return;
}
handler = backend->user.handler;
assert(handler->state == PS_WAITS4REQUEST);
// the pcpy calls aren't present in all kernel backends
// it's a way to tell apart kernel and user backends apart
// TODO check validity of memory regions somewhere else
if (req->input.buf) {
__user void *buf = handler->awaited_req.buf;
len = min(req->input.len, handler->awaited_req.max_len);
if (req->input.kern) {
pcpy_to(handler, buf, req->input.buf_kern, len);
} else {
len = pcpy_bi(
handler, buf,
req->caller, req->input.buf, len
);
}
} else {
len = req->output.len;
}
res.len = len;
res.capacity = req->output.len;
res.id = req->id;
res.offset = req->offset;
res.flags = req->flags;
res.op = req->type;
if (pcpy_to(handler, handler->awaited_req.res, &res, sizeof res) < sizeof(res))
{
panic_unimplemented();
}
Handle *h;
hid_t hid = hs_hinit(handler->hs, HANDLE_FS_REQ, &h);
if (hid < 0) panic_unimplemented();
h->req = req;
proc_setstate(handler, PS_RUNNING);
regs_savereturn(&handler->regs, hid);
req->backend->user.handler = NULL;
}
static void
vfsback_checkfree(VfsBackend *b)
{
if (b->usehcnt == 0 && b->provhcnt == 0) {
assert(!b->queue);
kfree(b);
}
}
void
vfsback_userdown(VfsBackend *b)
{
assert(b);
assert(0 < b->usehcnt);
b->usehcnt--;
if (b->usehcnt == 0) {
if (!b->is_user && b->kern.cleanup) {
b->kern.cleanup(b);
}
if (b->is_user && b->user.handler) {
/* tell the process that the filesystem won't receive any more
* requests */
Proc *p = b->user.handler;
b->user.handler = NULL;
assert(p->state == PS_WAITS4REQUEST);
regs_savereturn(&p->regs, -EPIPE);
proc_setstate(p, PS_RUNNING);
}
}
vfsback_checkfree(b);
}
void
vfsback_provdown(VfsBackend *b)
{
assert(b);
assert(0 < b->provhcnt);
b->provhcnt--;
if (b->provhcnt == 0) {
/* discard everything in the queue */
VfsReq *q = b->queue;
while (q) {
VfsReq *q2 = q->queue_next;
q->queue_next = NULL;
vfsreq_finish_short(q, -EPIPE);
q = q2;
}
b->queue = NULL;
}
vfsback_checkfree(b);
}
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