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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>
int vfs_request_create(struct vfs_request req_) {
struct vfs_request *req;
process_transition(process_current, PS_WAITS4FS);
process_current->waits4fs.queue_next = NULL;
// the request is owned by the caller
process_current->waits4fs.req = req_;
req = &process_current->waits4fs.req;
if (!req->backend || !req->backend->potential_handlers)
return vfs_request_finish(req, -1);
switch (req->backend->type) {
case VFS_BACK_ROOT:
return vfs_root_handler(req);
case VFS_BACK_USER: {
struct process **iter = &req->backend->queue;
while (*iter != NULL) // find free spot in queue
iter = &(*iter)->waits4fs.queue_next;
*iter = req->caller;
vfs_backend_accept(req->backend);
return -1; // isn't passed to the caller process anyways
}
default:
panic_invalid_state();
}
}
int vfs_backend_accept(struct vfs_backend *backend) {
struct vfs_request *req;
struct process *handler = backend->handler;
struct fs_wait_response res = {0};
int len;
if (!backend->handler) return -1;
assert(handler->state == PS_WAITS4REQUEST);
assert(!handler->handled_req);
if (!backend->queue) return -1;
// TODO wouldn't it be better to directly store vfs_requests in the queue?
req = &backend->queue->waits4fs.req;
backend->queue = backend->queue->waits4fs.queue_next;
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->handler = NULL;
regs_savereturn(&handler->regs, 0);
return 0;
fail:
panic_unimplemented(); // TODO
}
int vfs_request_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
handle_t handle = process_find_handle(req->caller);
if (handle < 0)
panic_invalid_state(); // we check for free handles before the open() call
req->caller->handles[handle] = (struct handle){
.type = HANDLE_FILE,
.file = {
.backend = req->backend,
.id = ret,
},
};
ret = handle;
}
if (req->input.kern)
kfree(req->input.buf_kern);
assert(req->caller->state == PS_WAITS4FS || req->caller->state == PS_WAITS4IRQ);
process_transition(req->caller, PS_RUNNING);
regs_savereturn(&req->caller->regs, ret);
return ret;
}
void vfs_request_cancel(struct vfs_request *req, int ret) {
if (req->input.kern)
kfree(req->input.buf_kern);
// ret must always be negative, so it won't be confused with a success
if (ret > 0) ret = -ret;
if (ret == 0) ret = -1;
regs_savereturn(&req->caller->regs, ret);
process_transition(req->caller, PS_RUNNING);
}
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