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#pragma once
#include <kernel/types.h>
#include <stdbool.h>
#include <stddef.h>
/* describes something which can act as an access function */
struct VfsBackend {
/* amount of using references
* VfsMount
* VfsReq
* Handle
* once it reaches 0, it'll never increase */
size_t usehcnt; /* VfsMount */
/* amount of providing references
* Proc
* 0 - orphaned, will never increase */
size_t provhcnt;
VfsReq *queue;
bool is_user;
union {
struct {
Proc *handler;
} user;
struct {
void (*accept)(VfsReq *);
void (*cleanup)(VfsBackend *);
void *data;
} kern;
};
};
/* describes an in-progress vfs call */
struct VfsReq {
enum vfs_op type;
struct {
bool kern; // if false: use .buf ; if true: use .buf_kern
union {
char __user *buf;
char *buf_kern;
};
size_t len;
} input;
struct {
char __user *buf;
size_t len;
} output;
// TODO why doesn't this just have a reference to the handle?
void __user *id; // handle.file.id
long offset;
int flags;
/* if caller != NULL, owned by it - don't free, the allocation will be reused
* if caller == NULL, free on finish */
Proc *caller;
VfsBackend *backend;
VfsReq *queue_next;
VfsReq *postqueue_next; /* used by kernel backends */
/* only one of these queues is in use at a given moment, they could
* be merged into a single field */
};
/** Assigns the vfs_request to the caller, and dispatches the call */
void vfsreq_create(VfsReq);
void vfsreq_finish(VfsReq*, char __user *stored, long ret, int flags, Proc *handler);
static inline void vfsreq_finish_short(VfsReq *req, long ret) {
vfsreq_finish(req, (void __user *)ret, ret, 0, NULL);
}
/** Try to accept an enqueued request */
void vfs_backend_tryaccept(VfsBackend *);
// TODO the bool arg is confusing. maybe this should just be a function
// that verified the refcount and potentially frees the backend
void vfs_backend_refdown(VfsBackend *, bool use);
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