allen 0.2.0

/*-*- Mode: C; c-basic-offset: 8 -*-*/

/***
        Copyright 2009 Lennart Poettering
        Copyright 2010 David Henningsson <diwic@ubuntu.com>
        Copyright 2021 Chris Robinson

        Permission is hereby granted, free of charge, to any person
        obtaining a copy of this software and associated documentation files
        (the "Software"), to deal in the Software without restriction,
        including without limitation the rights to use, copy, modify, merge,
        publish, distribute, sublicense, and/or sell copies of the Software,
        and to permit persons to whom the Software is furnished to do so,
        subject to the following conditions:

        The above copyright notice and this permission notice shall be
        included in all copies or substantial portions of the Software.

        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
        EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
        MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
        NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
        BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
        ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
        CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
        SOFTWARE.
***/

#include "config.h"

#include "rtkit.h"

#include <errno.h>

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <memory>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#ifdef __linux__
#include <sys/syscall.h>
#elif defined(__FreeBSD__)
#include <sys/thr.h>
#endif


namespace dbus {

constexpr int TypeString{'s'};
constexpr int TypeVariant{'v'};
constexpr int TypeInt32{'i'};
constexpr int TypeUInt32{'u'};
constexpr int TypeInt64{'x'};
constexpr int TypeUInt64{'t'};
constexpr int TypeInvalid{'\0'};

struct MessageDeleter {
    void operator()(DBusMessage *m) { dbus_message_unref(m); }
};
using MessagePtr = std::unique_ptr<DBusMessage,MessageDeleter>;

} // namespace dbus

namespace {

inline pid_t _gettid()
{
#ifdef __linux__
    return static_cast<pid_t>(syscall(SYS_gettid));
#elif defined(__FreeBSD__)
    long pid{};
    thr_self(&pid);
    return static_cast<pid_t>(pid);
#else
#warning gettid not available
    return 0;
#endif
}

int translate_error(const char *name)
{
    if(strcmp(name, DBUS_ERROR_NO_MEMORY) == 0)
        return -ENOMEM;
    if(strcmp(name, DBUS_ERROR_SERVICE_UNKNOWN) == 0
        || strcmp(name, DBUS_ERROR_NAME_HAS_NO_OWNER) == 0)
        return -ENOENT;
    if(strcmp(name, DBUS_ERROR_ACCESS_DENIED) == 0
        || strcmp(name, DBUS_ERROR_AUTH_FAILED) == 0)
        return -EACCES;
    return -EIO;
}

int rtkit_get_int_property(DBusConnection *connection, const char *propname, long long *propval)
{
    dbus::MessagePtr m{dbus_message_new_method_call(RTKIT_SERVICE_NAME, RTKIT_OBJECT_PATH,
        "org.freedesktop.DBus.Properties", "Get")};
    if(!m) return -ENOMEM;

    const char *interfacestr = RTKIT_SERVICE_NAME;
    auto ready = dbus_message_append_args(m.get(),
        dbus::TypeString, &interfacestr,
        dbus::TypeString, &propname,
        dbus::TypeInvalid);
    if(!ready) return -ENOMEM;

    dbus::Error error;
    dbus::MessagePtr r{dbus_connection_send_with_reply_and_block(connection, m.get(), -1,
        &error.get())};
    if(!r) return translate_error(error->name);

    if(dbus_set_error_from_message(&error.get(), r.get()))
        return translate_error(error->name);

    int ret{-EBADMSG};
    DBusMessageIter iter{};
    dbus_message_iter_init(r.get(), &iter);
    while(int curtype{dbus_message_iter_get_arg_type(&iter)})
    {
        if(curtype == dbus::TypeVariant)
        {
            DBusMessageIter subiter{};
            dbus_message_iter_recurse(&iter, &subiter);

            while((curtype=dbus_message_iter_get_arg_type(&subiter)) != dbus::TypeInvalid)
            {
                if(curtype == dbus::TypeInt32)
                {
                    dbus_int32_t i32{};
                    dbus_message_iter_get_basic(&subiter, &i32);
                    *propval = i32;
                    ret = 0;
                }

                if(curtype == dbus::TypeInt64)
                {
                    dbus_int64_t i64{};
                    dbus_message_iter_get_basic(&subiter, &i64);
                    *propval = i64;
                    ret = 0;
                }

                dbus_message_iter_next(&subiter);
            }
        }
        dbus_message_iter_next(&iter);
    }

    return ret;
}

} // namespace

int rtkit_get_max_realtime_priority(DBusConnection *connection)
{
    long long retval{};
    int err{rtkit_get_int_property(connection, "MaxRealtimePriority", &retval)};
    return err < 0 ? err : static_cast<int>(retval);
}

int rtkit_get_min_nice_level(DBusConnection *connection, int *min_nice_level)
{
    long long retval{};
    int err{rtkit_get_int_property(connection, "MinNiceLevel", &retval)};
    if(err >= 0) *min_nice_level = static_cast<int>(retval);
    return err;
}

long long rtkit_get_rttime_usec_max(DBusConnection *connection)
{
    long long retval{};
    int err{rtkit_get_int_property(connection, "RTTimeUSecMax", &retval)};
    return err < 0 ? err : retval;
}

int rtkit_make_realtime(DBusConnection *connection, pid_t thread, int priority)
{
    if(thread == 0)
        thread = _gettid();
    if(thread == 0)
        return -ENOTSUP;

    dbus::MessagePtr m{dbus_message_new_method_call(RTKIT_SERVICE_NAME, RTKIT_OBJECT_PATH,
        "org.freedesktop.RealtimeKit1", "MakeThreadRealtime")};
    if(!m) return -ENOMEM;

    auto u64 = static_cast<dbus_uint64_t>(thread);
    auto u32 = static_cast<dbus_uint32_t>(priority);
    auto ready = dbus_message_append_args(m.get(),
        dbus::TypeUInt64, &u64,
        dbus::TypeUInt32, &u32,
        dbus::TypeInvalid);
    if(!ready) return -ENOMEM;

    dbus::Error error;
    dbus::MessagePtr r{dbus_connection_send_with_reply_and_block(connection, m.get(), -1,
        &error.get())};
    if(!r) return translate_error(error->name);

    if(dbus_set_error_from_message(&error.get(), r.get()))
        return translate_error(error->name);

    return 0;
}

int rtkit_make_high_priority(DBusConnection *connection, pid_t thread, int nice_level)
{
    if(thread == 0)
        thread = _gettid();
    if(thread == 0)
        return -ENOTSUP;

    dbus::MessagePtr m{dbus_message_new_method_call(RTKIT_SERVICE_NAME, RTKIT_OBJECT_PATH,
        "org.freedesktop.RealtimeKit1", "MakeThreadHighPriority")};
    if(!m) return -ENOMEM;

    auto u64 = static_cast<dbus_uint64_t>(thread);
    auto s32 = static_cast<dbus_int32_t>(nice_level);
    auto ready = dbus_message_append_args(m.get(),
        dbus::TypeUInt64, &u64,
        dbus::TypeInt32, &s32,
        dbus::TypeInvalid);
    if(!ready) return -ENOMEM;

    dbus::Error error;
    dbus::MessagePtr r{dbus_connection_send_with_reply_and_block(connection, m.get(), -1,
        &error.get())};
    if(!r) return translate_error(error->name);

    if(dbus_set_error_from_message(&error.get(), r.get()))
        return translate_error(error->name);

    return 0;
}