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#include <kernel/mem/alloc.h>
#include <kernel/mem/virt.h>
#include <kernel/panic.h>
#include <kernel/proc.h>
#include <kernel/vfs/request.h>
#include <kernel/vfs/root.h>
#include <shared/mem.h>
int vfsreq_create(struct vfs_request req_) {
struct vfs_request *req = kmalloc(sizeof *req); // freed in vfsreq_finish
memcpy(req, &req_, sizeof *req);
if (req->backend)
req->backend->refcount++;
if (req->caller) {
process_transition(req->caller, PS_WAITS4FS);
req->caller->waits4fs.req = req;
}
if (!req->backend || !req->backend->potential_handlers)
return vfsreq_finish(req, -1);
struct vfs_request **iter = &req->backend->queue;
while (*iter != NULL) // find free spot in queue
iter = &(*iter)->queue_next;
*iter = req;
return vfs_backend_tryaccept(req->backend);
}
int vfsreq_finish(struct vfs_request *req, int ret) {
if (req->type == VFSOP_OPEN && ret >= 0) {
// open() calls need special handling
// we need to wrap the id returned by the VFS in a handle passed to
// the client
if (req->caller) {
handle_t handle = process_find_handle(req->caller, 0);
if (handle < 0)
panic_invalid_state(); // we check for free handles before the open() call
struct handle *backing = handle_init(HANDLE_FILE);
backing->file.backend = req->backend;
req->backend->refcount++;
backing->file.id = ret;
req->caller->handles[handle] = backing;
ret = handle;
} else {
// caller got killed
// TODO write tests & implement
panic_unimplemented();
}
}
if (req->input.kern)
kfree(req->input.buf_kern);
if (req->caller) {
assert(req->caller->state == PS_WAITS4FS);
regs_savereturn(&req->caller->regs, ret);
process_transition(req->caller, PS_RUNNING);
}
vfs_backend_refdown(req->backend);
kfree(req);
return ret;
}
int vfs_backend_tryaccept(struct vfs_backend *backend) {
struct vfs_request *req = backend->queue;
if (!req) return -1;
/* ensure backend is ready to accept request */
if (backend->is_user) {
if (!backend->user.handler) return -1;
} else {
assert(backend->kern.ready);
if (!backend->kern.ready(backend)) return -1;
}
backend->queue = req->queue_next;
if (backend->is_user) {
return vfs_backend_user_accept(req);
} else {
assert(backend->kern.accept);
return backend->kern.accept(req);
}
}
int vfs_backend_user_accept(struct vfs_request *req) {
struct process *handler;
struct fs_wait_response res = {0};
int len = 0;
assert(req && req->backend && req->backend->user.handler);
handler = req->backend->user.handler;
assert(handler->state == PS_WAITS4REQUEST);
assert(handler->handled_req == NULL);
// the virt_cpy 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) {
len = min(req->input.len, handler->awaited_req.max_len);
if (!virt_cpy(handler->pages, handler->awaited_req.buf,
req->input.kern ? NULL : req->caller->pages, req->input.buf, len))
goto fail; // can't copy buffer
}
res.len = len;
res.capacity = req->output.len;
res.id = req->id;
res.offset = req->offset;
res.op = req->type;
if (!virt_cpy_to(handler->pages,
handler->awaited_req.res, &res, sizeof res))
goto fail; // can't copy response struct
process_transition(handler, PS_RUNNING);
handler->handled_req = req;
req->backend->user.handler = NULL;
regs_savereturn(&handler->regs, 0);
return 0;
fail:
panic_unimplemented(); // TODO
}
void vfs_backend_refdown(struct vfs_backend *b) {
assert(b);
assert(b->refcount > 0);
if (--(b->refcount) > 0) return;
assert(!b->queue);
kfree(b);
}
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