zircon/kernel/syscalls/port.cpp

// Copyright 2016 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include <err.h>
#include <inttypes.h>
#include <trace.h>

#include <lib/ktrace.h>
#include <object/handle.h>
#include <object/port_dispatcher.h>
#include <object/process_dispatcher.h>

#include <fbl/alloc_checker.h>
#include <fbl/ref_ptr.h>

#include <zircon/syscalls/policy.h>
#include <zircon/types.h>

#include "priv.h"

#define LOCAL_TRACE 0

// zx_status_t zx_port_create
zx_status_t sys_port_create(uint32_t options, user_out_handle* out) {
    LTRACEF("options %u\n", options);
    auto up = ProcessDispatcher::GetCurrent();
    zx_status_t result = up->EnforceBasicPolicy(ZX_POL_NEW_PORT);
    if (result != ZX_OK)
        return result;

    KernelHandle<PortDispatcher> handle;
    zx_rights_t rights;

    result = PortDispatcher::Create(options, &handle, &rights);
    if (result != ZX_OK)
        return result;

    uint32_t koid = (uint32_t)handle.dispatcher()->get_koid();

    result = out->make(ktl::move(handle), rights);

    ktrace(TAG_PORT_CREATE, koid, 0, 0, 0);
    return result;
}

// zx_status_t zx_port_queue
zx_status_t sys_port_queue(zx_handle_t handle, user_in_ptr<const zx_port_packet_t> packet_in) {
    LTRACEF("handle %x\n", handle);

    auto up = ProcessDispatcher::GetCurrent();

    fbl::RefPtr<PortDispatcher> port;
    zx_status_t status = up->GetDispatcherWithRights(handle, ZX_RIGHT_WRITE, &port);
    if (status != ZX_OK)
        return status;

    zx_port_packet_t packet;
    status = packet_in.copy_from_user(&packet);
    if (status != ZX_OK)
        return status;

    return port->QueueUser(packet);
}

// zx_status_t zx_port_wait
zx_status_t sys_port_wait(zx_handle_t handle, zx_time_t deadline,
                          user_out_ptr<zx_port_packet_t> packet_out) {
    LTRACEF("handle %x\n", handle);

    auto up = ProcessDispatcher::GetCurrent();

    fbl::RefPtr<PortDispatcher> port;
    zx_status_t status = up->GetDispatcherWithRights(handle, ZX_RIGHT_READ, &port);
    if (status != ZX_OK)
        return status;

    const Deadline slackDeadline(deadline, up->GetTimerSlackPolicy());

    ktrace(TAG_PORT_WAIT, (uint32_t)port->get_koid(), 0, 0, 0);

    zx_port_packet_t pp;
    zx_status_t st = port->Dequeue(slackDeadline, &pp);

    ktrace(TAG_PORT_WAIT_DONE, (uint32_t)port->get_koid(), st, 0, 0);

    if (st != ZX_OK)
        return st;

    status = packet_out.copy_to_user(pp);
    if (status != ZX_OK)
        return status;

    return ZX_OK;
}

// zx_status_t zx_port_cancel
zx_status_t sys_port_cancel(zx_handle_t handle, zx_handle_t source, uint64_t key) {
    auto up = ProcessDispatcher::GetCurrent();

    fbl::RefPtr<PortDispatcher> port;
    zx_status_t status = up->GetDispatcherWithRights(handle, ZX_RIGHT_WRITE, &port);
    if (status != ZX_OK)
        return status;

    {
        Guard<BrwLockPi, BrwLockPi::Reader> guard{up->handle_table_lock()};
        Handle* watched = up->GetHandleLocked(source);
        if (!watched)
            return ZX_ERR_BAD_HANDLE;
        if (!watched->HasRights(ZX_RIGHT_WAIT))
            return ZX_ERR_ACCESS_DENIED;

        auto dispatcher = watched->dispatcher();
        if (!dispatcher->is_waitable())
            return ZX_ERR_NOT_SUPPORTED;

        bool had_observer = dispatcher->CancelByKey(watched, port.get(), key);
        bool packet_removed = port->CancelQueued(watched, key);
        return (had_observer || packet_removed) ? ZX_OK : ZX_ERR_NOT_FOUND;
    }
}