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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>
// dispatches a VFS operation to the correct process
int vfs_request_create(struct vfs_request req_) {
struct vfs_request *req;
int ret;
process_current->state = PS_WAITS4FS;
// the request is owned by the caller
process_current->pending_req = req_;
req = &process_current->pending_req;
if (!req->backend)
return vfs_request_finish(req, -1);
switch (req->backend->type) {
case VFS_BACK_ROOT:
ret = vfs_root_handler(req);
ret = vfs_request_finish(req, ret);
return ret;
case VFS_BACK_USER:
if (req->backend->handler == NULL) {
// backend isn't ready yet, join the queue
assert(req->backend->queue == NULL); // TODO implement a proper queue
req->backend->queue = process_current;
process_switch_any();
} else {
vfs_request_pass2handler(req);
}
default:
panic();
}
}
_Noreturn void vfs_request_pass2handler(struct vfs_request *req) {
struct process *handler = req->backend->handler;
int len;
assert(handler);
assert(handler->state == PS_WAITS4REQUEST);
assert(!handler->handled_req);
handler->state = PS_RUNNING;
handler->handled_req = req;
if (!virt_cpy_from(handler->pages,
&len, handler->awaited_req.len, sizeof len))
goto fail; // can't read buffer length
if (len > req->input.len) {
// input bigger than buffer
// TODO what should be done during e.g. open() calls? truncating doesn't seem right
len = req->input.len;
}
if (req->input.kern) {
if (!virt_cpy_to(handler->pages,
handler->awaited_req.buf, req->input.buf_kern, len))
goto fail; // can't copy buffer
} else {
if (!virt_cpy(handler->pages, handler->awaited_req.buf,
req->caller->pages, req->input.buf, len))
goto fail; // can't copy buffer
}
if (!virt_cpy_to(handler->pages,
handler->awaited_req.len, &len, sizeof len))
goto fail; // can't copy new length
if (!virt_cpy_to(handler->pages,
handler->awaited_req.id, &req->id, sizeof req->id))
goto fail; // can't copy id
regs_savereturn(&handler->regs, req->type);
process_switch(handler);
fail:
panic(); // TODO
}
int vfs_request_finish(struct vfs_request *req, int ret) {
struct process *caller = req->caller;
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();
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);
req->caller->state = PS_RUNNING;
regs_savereturn(&req->caller->regs, ret);
kfree(req);
return ret;
}
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