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#include <camellia/errno.h>
#include <camellia/flags.h>
#include <kernel/mem/alloc.h>
#include <kernel/panic.h>
#include <kernel/proc.h>
#include <kernel/vfs/request.h>
#include <shared/mem.h>
static void vfs_backend_user_accept(VfsReq *req);
void vfsreq_create(VfsReq req_) {
VfsReq *req;
if (req_.caller) {
proc_setstate(req_.caller, PS_WAITS4FS);
if (!req_.caller->reqslot)
req_.caller->reqslot = kmalloc(sizeof *req);
req = req_.caller->reqslot;
/* (re)using a single allocation for all request a process makes */
} else {
req = kmalloc(sizeof *req);
}
memcpy(req, &req_, sizeof *req);
if (req->backend) {
assert(req->backend->usehcnt);
req->backend->usehcnt++;
}
if (req->type == VFSOP_OPEN && !(req->flags & OPEN_WRITE) && (req->flags & OPEN_CREATE)) {
vfsreq_finish_short(req, -EINVAL);
return;
}
// TODO if i add a handle field to vfs_request, check ->readable ->writeable here
if (req->backend && req->backend->provhcnt) {
VfsReq **iter = &req->backend->queue;
while (*iter != NULL) // find free spot in queue
iter = &(*iter)->queue_next;
*iter = req;
vfs_backend_tryaccept(req->backend);
} else {
vfsreq_finish_short(req, -1);
}
}
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 = proc_hid_take(handler, ret);
// TODO don't ignore OPEN_RO
}
if (h) {
// TODO write tests for caller getting killed while opening a file
if (!req->caller) panic_unimplemented();
ret = proc_handle_put(req->caller, h);
if (ret < 0) ret = -EMFILE;
} else {
ret = -1;
}
}
if (req->input.kern)
kfree(req->input.buf_kern);
if (req->backend)
vfs_backend_refdown(req->backend, true);
if (req->caller) {
assert(req->caller->state == PS_WAITS4FS);
regs_savereturn(&req->caller->regs, ret);
proc_setstate(req->caller, PS_RUNNING);
} else {
kfree(req);
}
}
void vfs_backend_tryaccept(VfsBackend *backend) {
VfsReq *req = backend->queue;
if (!req) return;
if (backend->is_user && !backend->user.handler) return;
backend->queue = req->queue_next;
if (backend->is_user) {
vfs_backend_user_accept(req);
} else {
assert(backend->kern.accept);
backend->kern.accept(req);
}
}
static void vfs_backend_user_accept(VfsReq *req) {
Proc *handler;
struct ufs_request res = {0};
int len;
assert(req && req->backend && req->backend->user.handler);
handler = req->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 = proc_handle_init(handler, 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;
return;
}
void vfs_backend_refdown(VfsBackend *b, bool use) {
size_t *field = use ? &b->usehcnt : &b->provhcnt;
assert(b);
assert(0 < *field);
*field -= 1;
if (b->provhcnt == 0 && use == false) {
VfsReq *q = b->queue;
while (q) {
VfsReq *q2 = q->queue_next;
vfsreq_finish_short(q, -1);
q = q2;
}
b->queue = NULL;
}
if (b->usehcnt == 0 && use == true) {
if (!b->is_user && b->kern.cleanup) {
b->kern.cleanup(b);
}
if (b->is_user && b->user.handler) {
Proc *p = b->user.handler;
b->user.handler = NULL;
assert(p->state == PS_WAITS4REQUEST);
regs_savereturn(&p->regs, -EPIPE);
proc_setstate(p, PS_RUNNING);
}
}
if (b->usehcnt == 0 && b->provhcnt == 0) {
assert(!b->queue);
kfree(b);
}
}
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