core/rtkit.cpp

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   2
   3 /***
   4         Copyright 2009 Lennart Poettering
   5         Copyright 2010 David Henningsson <diwic@ubuntu.com>
   6         Copyright 2021 Chris Robinson
   7
   8         Permission is hereby granted, free of charge, to any person
   9         obtaining a copy of this software and associated documentation files
  10         (the "Software"), to deal in the Software without restriction,
  11         including without limitation the rights to use, copy, modify, merge,
  12         publish, distribute, sublicense, and/or sell copies of the Software,
  13         and to permit persons to whom the Software is furnished to do so,
  14         subject to the following conditions:
  15
  16         The above copyright notice and this permission notice shall be
  17         included in all copies or substantial portions of the Software.
  18
  19         THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  20         EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  21         MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  22         NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  23         BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  24         ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  25         CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26         SOFTWARE.
  27 ***/
  28
  29 #include "config.h"
  30
  31 #include "rtkit.h"
  32
  33 #include <errno.h>
  34
  35 #ifndef _GNU_SOURCE
  36 #define _GNU_SOURCE
  37 #endif
  38
  39 #include <memory>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #include <sys/types.h>
  43 #include <sys/syscall.h>
  44 #ifdef __FreeBSD__
  45 #include <sys/thr.h>
  46 #endif
  47
  48
  49 namespace dbus {
  50
  51 constexpr int TypeString{'s'};
  52 constexpr int TypeVariant{'v'};
  53 constexpr int TypeInt32{'i'};
  54 constexpr int TypeUInt32{'u'};
  55 constexpr int TypeInt64{'x'};
  56 constexpr int TypeUInt64{'t'};
  57 constexpr int TypeInvalid{'\0'};
  58
  59 struct MessageDeleter {
  60     void operator()(DBusMessage *m) { dbus_message_unref(m); }
  61 };
  62 using MessagePtr = std::unique_ptr<DBusMessage,MessageDeleter>;
  63
  64 } // namespace dbus
  65
  66 namespace {
  67
  68 inline pid_t _gettid()
  69 {
  70 #ifdef __linux__
  71     return static_cast<pid_t>(syscall(SYS_gettid));
  72 #elif defined(__FreeBSD__)
  73     long pid{};
  74     thr_self(&pid);
  75     return static_cast<pid_t>(pid);
  76 #else
  77 #warning gettid not available
  78     return 0;
  79 #endif
  80 }
  81
  82 int translate_error(const char *name)
  83 {
  84     if(strcmp(name, DBUS_ERROR_NO_MEMORY) == 0)
  85         return -ENOMEM;
  86     if(strcmp(name, DBUS_ERROR_SERVICE_UNKNOWN) == 0
  87         || strcmp(name, DBUS_ERROR_NAME_HAS_NO_OWNER) == 0)
  88         return -ENOENT;
  89     if(strcmp(name, DBUS_ERROR_ACCESS_DENIED) == 0
  90         || strcmp(name, DBUS_ERROR_AUTH_FAILED) == 0)
  91         return -EACCES;
  92     return -EIO;
  93 }
  94
  95 int rtkit_get_int_property(DBusConnection *connection, const char *propname, long long *propval)
  96 {
  97     dbus::MessagePtr m{dbus_message_new_method_call(RTKIT_SERVICE_NAME, RTKIT_OBJECT_PATH,
  98         "org.freedesktop.DBus.Properties", "Get")};
  99     if(!m) return -ENOMEM;
 100
 101     const char *interfacestr = RTKIT_SERVICE_NAME;
 102     auto ready = dbus_message_append_args(m.get(),
 103         dbus::TypeString, &interfacestr,
 104         dbus::TypeString, &propname,
 105         dbus::TypeInvalid);
 106     if(!ready) return -ENOMEM;
 107
 108     dbus::Error error;
 109     dbus::MessagePtr r{dbus_connection_send_with_reply_and_block(connection, m.get(), -1,
 110         &error.get())};
 111     if(!r) return translate_error(error->name);
 112
 113     if(dbus_set_error_from_message(&error.get(), r.get()))
 114         return translate_error(error->name);
 115
 116     int ret{-EBADMSG};
 117     DBusMessageIter iter{};
 118     dbus_message_iter_init(r.get(), &iter);
 119     while(int curtype{dbus_message_iter_get_arg_type(&iter)})
 120     {
 121         if(curtype == dbus::TypeVariant)
 122         {
 123             DBusMessageIter subiter{};
 124             dbus_message_iter_recurse(&iter, &subiter);
 125
 126             while((curtype=dbus_message_iter_get_arg_type(&subiter)) != dbus::TypeInvalid)
 127             {
 128                 if(curtype == dbus::TypeInt32)
 129                 {
 130                     dbus_int32_t i32{};
 131                     dbus_message_iter_get_basic(&subiter, &i32);
 132                     *propval = i32;
 133                     ret = 0;
 134                 }
 135
 136                 if(curtype == dbus::TypeInt64)
 137                 {
 138                     dbus_int64_t i64{};
 139                     dbus_message_iter_get_basic(&subiter, &i64);
 140                     *propval = i64;
 141                     ret = 0;
 142                 }
 143
 144                 dbus_message_iter_next(&subiter);
 145             }
 146         }
 147         dbus_message_iter_next(&iter);
 148     }
 149
 150     return ret;
 151 }
 152
 153 } // namespace
 154
 155 int rtkit_get_max_realtime_priority(DBusConnection *connection)
 156 {
 157     long long retval{};
 158     int err{rtkit_get_int_property(connection, "MaxRealtimePriority", &retval)};
 159     return err < 0 ? err : static_cast<int>(retval);
 160 }
 161
 162 int rtkit_get_min_nice_level(DBusConnection *connection, int *min_nice_level)
 163 {
 164     long long retval{};
 165     int err{rtkit_get_int_property(connection, "MinNiceLevel", &retval)};
 166     if(err >= 0) *min_nice_level = static_cast<int>(retval);
 167     return err;
 168 }
 169
 170 long long rtkit_get_rttime_usec_max(DBusConnection *connection)
 171 {
 172     long long retval{};
 173     int err{rtkit_get_int_property(connection, "RTTimeUSecMax", &retval)};
 174     return err < 0 ? err : retval;
 175 }
 176
 177 int rtkit_make_realtime(DBusConnection *connection, pid_t thread, int priority)
 178 {
 179     if(thread == 0)
 180         thread = _gettid();
 181     if(thread == 0)
 182         return -ENOTSUP;
 183
 184     dbus::MessagePtr m{dbus_message_new_method_call(RTKIT_SERVICE_NAME, RTKIT_OBJECT_PATH,
 185         "org.freedesktop.RealtimeKit1", "MakeThreadRealtime")};
 186     if(!m) return -ENOMEM;
 187
 188     auto u64 = static_cast<dbus_uint64_t>(thread);
 189     auto u32 = static_cast<dbus_uint32_t>(priority);
 190     auto ready = dbus_message_append_args(m.get(),
 191         dbus::TypeUInt64, &u64,
 192         dbus::TypeUInt32, &u32,
 193         dbus::TypeInvalid);
 194     if(!ready) return -ENOMEM;
 195
 196     dbus::Error error;
 197     dbus::MessagePtr r{dbus_connection_send_with_reply_and_block(connection, m.get(), -1,
 198         &error.get())};
 199     if(!r) return translate_error(error->name);
 200
 201     if(dbus_set_error_from_message(&error.get(), r.get()))
 202         return translate_error(error->name);
 203
 204     return 0;
 205 }
 206
 207 int rtkit_make_high_priority(DBusConnection *connection, pid_t thread, int nice_level)
 208 {
 209     if(thread == 0)
 210         thread = _gettid();
 211     if(thread == 0)
 212         return -ENOTSUP;
 213
 214     dbus::MessagePtr m{dbus_message_new_method_call(RTKIT_SERVICE_NAME, RTKIT_OBJECT_PATH,
 215         "org.freedesktop.RealtimeKit1", "MakeThreadHighPriority")};
 216     if(!m) return -ENOMEM;
 217
 218     auto u64 = static_cast<dbus_uint64_t>(thread);
 219     auto s32 = static_cast<dbus_int32_t>(nice_level);
 220     auto ready = dbus_message_append_args(m.get(),
 221         dbus::TypeUInt64, &u64,
 222         dbus::TypeInt32, &s32,
 223         dbus::TypeInvalid);
 224     if(!ready) return -ENOMEM;
 225
 226     dbus::Error error;
 227     dbus::MessagePtr r{dbus_connection_send_with_reply_and_block(connection, m.get(), -1,
 228         &error.get())};
 229     if(!r) return translate_error(error->name);
 230
 231     if(dbus_set_error_from_message(&error.get(), r.get()))
 232         return translate_error(error->name);
 233
 234     return 0;
 235 }