gcc/ada/libgnarl/s-osinte__android.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --                   S Y S T E M . O S _ I N T E R F A C E                  --
   6 --                                                                          --
   7 --                                  S p e c                                 --
   8 --                                                                          --
   9 --          Copyright (C) 1995-2023, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This is an Android version of this package which is based on the
  33 --  GNU/Linux version
  34
  35 --  This package encapsulates all direct interfaces to OS services
  36 --  that are needed by the tasking run-time (libgnarl).
  37
  38 --  PLEASE DO NOT add any with-clauses to this package or remove the pragma
  39 --  Preelaborate. This package is designed to be a bottom-level (leaf) package.
  40
  41 with Ada.Unchecked_Conversion;
  42 with Interfaces.C;
  43 with System.Linux;
  44 with System.OS_Constants;
  45 with System.Parameters;
  46
  47 package System.OS_Interface is
  48    pragma Preelaborate;
  49
  50    subtype int            is Interfaces.C.int;
  51    subtype char           is Interfaces.C.char;
  52    subtype short          is Interfaces.C.short;
  53    subtype long           is Interfaces.C.long;
  54    subtype unsigned       is Interfaces.C.unsigned;
  55    subtype unsigned_short is Interfaces.C.unsigned_short;
  56    subtype unsigned_long  is Interfaces.C.unsigned_long;
  57    subtype unsigned_char  is Interfaces.C.unsigned_char;
  58    subtype plain_char     is Interfaces.C.plain_char;
  59    subtype size_t         is Interfaces.C.size_t;
  60
  61    -----------
  62    -- Errno --
  63    -----------
  64
  65    function errno return int;
  66    pragma Import (C, errno, "__get_errno");
  67
  68    EAGAIN    : constant := System.Linux.EAGAIN;
  69    EINTR     : constant := System.Linux.EINTR;
  70    EINVAL    : constant := System.Linux.EINVAL;
  71    ENOMEM    : constant := System.Linux.ENOMEM;
  72    EPERM     : constant := System.Linux.EPERM;
  73    ETIMEDOUT : constant := System.Linux.ETIMEDOUT;
  74
  75    -------------
  76    -- Signals --
  77    -------------
  78
  79    Max_Interrupt : constant := 31;
  80    type Signal is new int range 0 .. Max_Interrupt;
  81    for Signal'Size use int'Size;
  82
  83    SIGHUP     : constant := System.Linux.SIGHUP;
  84    SIGINT     : constant := System.Linux.SIGINT;
  85    SIGQUIT    : constant := System.Linux.SIGQUIT;
  86    SIGILL     : constant := System.Linux.SIGILL;
  87    SIGTRAP    : constant := System.Linux.SIGTRAP;
  88    SIGIOT     : constant := System.Linux.SIGIOT;
  89    SIGABRT    : constant := System.Linux.SIGABRT;
  90    SIGFPE     : constant := System.Linux.SIGFPE;
  91    SIGKILL    : constant := System.Linux.SIGKILL;
  92    SIGBUS     : constant := System.Linux.SIGBUS;
  93    SIGSEGV    : constant := System.Linux.SIGSEGV;
  94    SIGPIPE    : constant := System.Linux.SIGPIPE;
  95    SIGALRM    : constant := System.Linux.SIGALRM;
  96    SIGTERM    : constant := System.Linux.SIGTERM;
  97    SIGUSR1    : constant := System.Linux.SIGUSR1;
  98    SIGUSR2    : constant := System.Linux.SIGUSR2;
  99    SIGCLD     : constant := System.Linux.SIGCLD;
 100    SIGCHLD    : constant := System.Linux.SIGCHLD;
 101    SIGPWR     : constant := System.Linux.SIGPWR;
 102    SIGWINCH   : constant := System.Linux.SIGWINCH;
 103    SIGURG     : constant := System.Linux.SIGURG;
 104    SIGPOLL    : constant := System.Linux.SIGPOLL;
 105    SIGIO      : constant := System.Linux.SIGIO;
 106    SIGLOST    : constant := System.Linux.SIGLOST;
 107    SIGSTOP    : constant := System.Linux.SIGSTOP;
 108    SIGTSTP    : constant := System.Linux.SIGTSTP;
 109    SIGCONT    : constant := System.Linux.SIGCONT;
 110    SIGTTIN    : constant := System.Linux.SIGTTIN;
 111    SIGTTOU    : constant := System.Linux.SIGTTOU;
 112    SIGVTALRM  : constant := System.Linux.SIGVTALRM;
 113    SIGPROF    : constant := System.Linux.SIGPROF;
 114    SIGXCPU    : constant := System.Linux.SIGXCPU;
 115    SIGXFSZ    : constant := System.Linux.SIGXFSZ;
 116    SIGUNUSED  : constant := System.Linux.SIGUNUSED;
 117    SIGSTKFLT  : constant := System.Linux.SIGSTKFLT;
 118
 119    SIGADAABORT : constant := SIGABRT;
 120    --  Change this to use another signal for task abort. SIGTERM might be a
 121    --  good one.
 122
 123    type Signal_Set is array (Natural range <>) of Signal;
 124
 125    Unmasked : constant Signal_Set := (
 126       SIGTRAP,
 127       --  To enable debugging on multithreaded applications, mark SIGTRAP to
 128       --  be kept unmasked.
 129
 130       SIGBUS,
 131
 132       SIGTTIN, SIGTTOU, SIGTSTP,
 133       --  Keep these three signals unmasked so that background processes and IO
 134       --  behaves as normal "C" applications
 135
 136       SIGPROF,
 137       --  To avoid confusing the profiler
 138
 139       SIGKILL, SIGSTOP);
 140       --  These two signals actually can't be masked (POSIX won't allow it)
 141
 142    Reserved : constant Signal_Set := (SIGVTALRM, SIGUNUSED);
 143    --  Not clear why these two signals are reserved. Perhaps they are not
 144    --  supported by this version of GNU/Linux ???
 145
 146    type sigset_t is private;
 147
 148    function sigaddset (set : access sigset_t; sig : Signal) return int;
 149    pragma Import (C, sigaddset, "_sigaddset");
 150
 151    function sigdelset (set : access sigset_t; sig : Signal) return int;
 152    pragma Import (C, sigdelset, "_sigdelset");
 153
 154    function sigfillset (set : access sigset_t) return int;
 155    pragma Import (C, sigfillset, "_sigfillset");
 156
 157    function sigismember (set : access sigset_t; sig : Signal) return int;
 158    pragma Import (C, sigismember, "_sigismember");
 159
 160    function sigemptyset (set : access sigset_t) return int;
 161    pragma Import (C, sigemptyset, "_sigemptyset");
 162
 163    type union_type_3 is new String (1 .. 116);
 164    type siginfo_t is record
 165       si_signo : int;
 166       si_code  : int;
 167       si_errno : int;
 168       X_data   : union_type_3;
 169    end record;
 170    pragma Convention (C, siginfo_t);
 171
 172    type struct_sigaction is record
 173       sa_handler  : System.Address;
 174       sa_mask     : sigset_t;
 175       sa_flags    : Interfaces.C.unsigned_long;
 176       sa_restorer : System.Address;
 177    end record;
 178    pragma Convention (C, struct_sigaction);
 179
 180    type struct_sigaction_ptr is access all struct_sigaction;
 181
 182    SA_SIGINFO : constant := System.Linux.SA_SIGINFO;
 183    SA_ONSTACK : constant := System.Linux.SA_ONSTACK;
 184    SA_NODEFER : constant := System.Linux.SA_NODEFER;
 185    SA_RESTART : constant := System.Linux.SA_RESTART;
 186
 187    SIG_BLOCK   : constant := 0;
 188    SIG_UNBLOCK : constant := 1;
 189    SIG_SETMASK : constant := 2;
 190
 191    SIG_DFL : constant := 0;
 192    SIG_IGN : constant := 1;
 193
 194    function sigaction
 195      (sig  : Signal;
 196       act  : struct_sigaction_ptr;
 197       oact : struct_sigaction_ptr) return int;
 198    pragma Import (C, sigaction, "sigaction");
 199
 200    ----------
 201    -- Time --
 202    ----------
 203
 204    Time_Slice_Supported : constant Boolean := True;
 205    --  Indicates whether time slicing is supported
 206
 207    type timespec is private;
 208
 209    type clockid_t is new int;
 210
 211    function clock_gettime
 212      (clock_id : clockid_t; tp : access timespec) return int;
 213    pragma Import (C, clock_gettime, "clock_gettime");
 214
 215    function clock_getres
 216      (clock_id : clockid_t;
 217       res      : access timespec) return int;
 218    pragma Import (C, clock_getres, "clock_getres");
 219
 220    function To_Duration (TS : timespec) return Duration;
 221    pragma Inline (To_Duration);
 222
 223    function To_Timespec (D : Duration) return timespec;
 224    pragma Inline (To_Timespec);
 225
 226    function sysconf (name : int) return long;
 227    pragma Import (C, sysconf);
 228
 229    SC_CLK_TCK          : constant := 2;
 230    SC_NPROCESSORS_ONLN : constant := 84;
 231
 232    -------------------------
 233    -- Priority Scheduling --
 234    -------------------------
 235
 236    SCHED_OTHER : constant := 0;
 237    SCHED_FIFO  : constant := 1;
 238    SCHED_RR    : constant := 2;
 239
 240    function To_Target_Priority
 241      (Prio : System.Any_Priority)
 242       return Interfaces.C.int is (Interfaces.C.int (Prio));
 243    --  Maps System.Any_Priority to a POSIX priority
 244
 245    -------------
 246    -- Process --
 247    -------------
 248
 249    type pid_t is private;
 250
 251    function kill (pid : pid_t; sig : Signal) return int;
 252    pragma Import (C, kill, "kill");
 253
 254    function getpid return pid_t;
 255    pragma Import (C, getpid, "getpid");
 256
 257    -------------
 258    -- Threads --
 259    -------------
 260
 261    type Thread_Body is access
 262      function (arg : System.Address) return System.Address;
 263    pragma Convention (C, Thread_Body);
 264
 265    function Thread_Body_Access is new
 266      Ada.Unchecked_Conversion (System.Address, Thread_Body);
 267
 268    type pthread_t is new unsigned_long;
 269    subtype Thread_Id is pthread_t;
 270
 271    function To_pthread_t is
 272      new Ada.Unchecked_Conversion (unsigned_long, pthread_t);
 273
 274    type pthread_mutex_t      is limited private;
 275    type pthread_cond_t       is limited private;
 276    type pthread_attr_t       is limited private;
 277    type pthread_mutexattr_t  is limited private;
 278    type pthread_condattr_t   is limited private;
 279    type pthread_key_t        is private;
 280
 281    PTHREAD_CREATE_DETACHED : constant := 1;
 282
 283    PTHREAD_SCOPE_PROCESS : constant := 1;
 284    PTHREAD_SCOPE_SYSTEM  : constant := 0;
 285
 286    --  Read/Write lock not supported on Android.
 287
 288    subtype pthread_rwlock_t     is pthread_mutex_t;
 289    subtype pthread_rwlockattr_t is pthread_mutexattr_t;
 290
 291    -----------
 292    -- Stack --
 293    -----------
 294
 295    type stack_t is record
 296       ss_sp    : System.Address;
 297       ss_flags : int;
 298       ss_size  : size_t;
 299    end record;
 300    pragma Convention (C, stack_t);
 301
 302    function sigaltstack
 303      (ss  : not null access stack_t;
 304       oss : access stack_t) return int;
 305    pragma Import (C, sigaltstack, "sigaltstack");
 306
 307    Alternate_Stack : aliased System.Address;
 308    pragma Import (C, Alternate_Stack, "__gnat_alternate_stack");
 309    --  The alternate signal stack for stack overflows
 310
 311    Alternate_Stack_Size : constant := 16 * 1024;
 312    --  This must be in keeping with init.c:__gnat_alternate_stack
 313
 314    Stack_Base_Available : constant Boolean := False;
 315    --  Indicates whether the stack base is available on this target
 316
 317    function Get_Stack_Base (ignored_thread : pthread_t)
 318      return Address is (Null_Address);
 319    --  This is a dummy procedure to share some GNULLI files
 320
 321    function Get_Page_Size return int;
 322    pragma Import (C, Get_Page_Size, "_getpagesize");
 323    --  Returns the size of a page
 324
 325    PROT_NONE  : constant := 0;
 326    PROT_READ  : constant := 1;
 327    PROT_WRITE : constant := 2;
 328    PROT_EXEC  : constant := 4;
 329    PROT_ALL   : constant := PROT_READ + PROT_WRITE + PROT_EXEC;
 330    PROT_ON    : constant := PROT_READ;
 331    PROT_OFF   : constant := PROT_ALL;
 332
 333    function mprotect (addr : Address; len : size_t; prot : int) return int;
 334    pragma Import (C, mprotect);
 335
 336    ---------------------------------------
 337    -- Nonstandard Thread Initialization --
 338    ---------------------------------------
 339
 340    procedure pthread_init is null;
 341    --  This is a dummy procedure to share some GNULLI files
 342
 343    -------------------------
 344    -- POSIX.1c  Section 3 --
 345    -------------------------
 346
 347    function sigwait (set : access sigset_t; sig : access Signal) return int;
 348    pragma Import (C, sigwait, "sigwait");
 349
 350    function pthread_kill (thread : pthread_t; sig : Signal) return int;
 351    pragma Import (C, pthread_kill, "pthread_kill");
 352
 353    function pthread_sigmask
 354      (how  : int;
 355       set  : access sigset_t;
 356       oset : access sigset_t) return int;
 357    pragma Import (C, pthread_sigmask, "sigprocmask");
 358    --  pthread_sigmask maybe be broken due to mismatch between sigset_t and
 359    --  kernel_sigset_t, substitute sigprocmask temporarily.  ???
 360    --  pragma Import (C, pthread_sigmask, "pthread_sigmask");
 361
 362    --------------------------
 363    -- POSIX.1c  Section 11 --
 364    --------------------------
 365
 366    function pthread_mutexattr_init
 367      (attr : access pthread_mutexattr_t) return int;
 368    pragma Import (C, pthread_mutexattr_init, "pthread_mutexattr_init");
 369
 370    function pthread_mutexattr_destroy
 371      (attr : access pthread_mutexattr_t) return int;
 372    pragma Import (C, pthread_mutexattr_destroy, "pthread_mutexattr_destroy");
 373
 374    function pthread_mutex_init
 375      (mutex : access pthread_mutex_t;
 376       attr  : access pthread_mutexattr_t) return int;
 377    pragma Import (C, pthread_mutex_init, "pthread_mutex_init");
 378
 379    function pthread_mutex_destroy (mutex : access pthread_mutex_t) return int;
 380    pragma Import (C, pthread_mutex_destroy, "pthread_mutex_destroy");
 381
 382    function pthread_mutex_lock (mutex : access pthread_mutex_t) return int;
 383    pragma Import (C, pthread_mutex_lock, "pthread_mutex_lock");
 384
 385    function pthread_mutex_unlock (mutex : access pthread_mutex_t) return int;
 386    pragma Import (C, pthread_mutex_unlock, "pthread_mutex_unlock");
 387
 388    function pthread_condattr_init
 389      (attr : access pthread_condattr_t) return int;
 390    pragma Import (C, pthread_condattr_init, "pthread_condattr_init");
 391
 392    function pthread_condattr_destroy
 393      (attr : access pthread_condattr_t) return int;
 394    pragma Import (C, pthread_condattr_destroy, "pthread_condattr_destroy");
 395
 396    function pthread_cond_init
 397      (cond : access pthread_cond_t;
 398       attr : access pthread_condattr_t) return int;
 399    pragma Import (C, pthread_cond_init, "pthread_cond_init");
 400
 401    function pthread_cond_destroy (cond : access pthread_cond_t) return int;
 402    pragma Import (C, pthread_cond_destroy, "pthread_cond_destroy");
 403
 404    function pthread_cond_signal (cond : access pthread_cond_t) return int;
 405    pragma Import (C, pthread_cond_signal, "pthread_cond_signal");
 406
 407    function pthread_cond_wait
 408      (cond  : access pthread_cond_t;
 409       mutex : access pthread_mutex_t) return int;
 410    pragma Import (C, pthread_cond_wait, "pthread_cond_wait");
 411
 412    function pthread_cond_timedwait
 413      (cond    : access pthread_cond_t;
 414       mutex   : access pthread_mutex_t;
 415       abstime : access timespec) return int;
 416    pragma Import (C, pthread_cond_timedwait, "pthread_cond_timedwait");
 417
 418    --------------------------
 419    -- POSIX.1c  Section 13 --
 420    --------------------------
 421
 422    PTHREAD_PRIO_PROTECT : constant := 0;
 423    PTHREAD_PRIO_INHERIT : constant := 1;
 424
 425    function pthread_mutexattr_setprotocol
 426      (ignored_attr     : access pthread_mutexattr_t;
 427       ignored_protocol : int) return int is (0);
 428
 429    function pthread_mutexattr_setprioceiling
 430      (ignored_attr        : access pthread_mutexattr_t;
 431       ignored_prioceiling : int) return int is (0);
 432
 433    type struct_sched_param is record
 434       sched_priority : int;  --  scheduling priority
 435    end record;
 436    pragma Convention (C, struct_sched_param);
 437
 438    function pthread_setschedparam
 439      (thread : pthread_t;
 440       policy : int;
 441       param  : access struct_sched_param) return int;
 442    pragma Import (C, pthread_setschedparam, "pthread_setschedparam");
 443
 444    function pthread_attr_setscope
 445      (attr  : access pthread_attr_t;
 446       scope : int) return int;
 447    pragma Import (C, pthread_attr_setscope, "pthread_attr_setscope");
 448
 449    function pthread_attr_setschedpolicy
 450      (attr   : access pthread_attr_t;
 451       policy : int) return int;
 452    pragma Import
 453      (C, pthread_attr_setschedpolicy, "pthread_attr_setschedpolicy");
 454
 455    function sched_yield return int;
 456    pragma Import (C, sched_yield, "sched_yield");
 457
 458    ---------------------------
 459    -- P1003.1c - Section 16 --
 460    ---------------------------
 461
 462    function pthread_attr_init
 463      (attributes : access pthread_attr_t) return int;
 464    pragma Import (C, pthread_attr_init, "pthread_attr_init");
 465
 466    function pthread_attr_destroy
 467      (attributes : access pthread_attr_t) return int;
 468    pragma Import (C, pthread_attr_destroy, "pthread_attr_destroy");
 469
 470    function pthread_attr_setdetachstate
 471      (attr        : access pthread_attr_t;
 472       detachstate : int) return int;
 473    pragma Import
 474      (C, pthread_attr_setdetachstate, "pthread_attr_setdetachstate");
 475
 476    function pthread_attr_setstacksize
 477      (attr      : access pthread_attr_t;
 478       stacksize : size_t) return int;
 479    pragma Import (C, pthread_attr_setstacksize, "pthread_attr_setstacksize");
 480
 481    function pthread_create
 482      (thread        : access pthread_t;
 483       attributes    : access pthread_attr_t;
 484       start_routine : Thread_Body;
 485       arg           : System.Address) return int;
 486    pragma Import (C, pthread_create, "pthread_create");
 487
 488    procedure pthread_exit (status : System.Address);
 489    pragma Import (C, pthread_exit, "pthread_exit");
 490
 491    function pthread_self return pthread_t;
 492    pragma Import (C, pthread_self, "pthread_self");
 493
 494    function lwp_self return System.Address;
 495    pragma Import (C, lwp_self, "__gnat_lwp_self");
 496
 497    --------------------------
 498    -- POSIX.1c  Section 17 --
 499    --------------------------
 500
 501    function pthread_setspecific
 502      (key   : pthread_key_t;
 503       value : System.Address) return int;
 504    pragma Import (C, pthread_setspecific, "pthread_setspecific");
 505
 506    function pthread_getspecific (key : pthread_key_t) return System.Address;
 507    pragma Import (C, pthread_getspecific, "pthread_getspecific");
 508
 509    type destructor_pointer is access procedure (arg : System.Address);
 510    pragma Convention (C, destructor_pointer);
 511
 512    function pthread_key_create
 513      (key        : access pthread_key_t;
 514       destructor : destructor_pointer) return int;
 515    pragma Import (C, pthread_key_create, "pthread_key_create");
 516
 517    CPU_SETSIZE : constant := 1_024;
 518    --  Size of the cpu_set_t mask on most linux systems (SUSE 11 uses 4_096).
 519    --  This is kept for backward compatibility (System.Task_Info uses it), but
 520    --  the run-time library does no longer rely on static masks, using
 521    --  dynamically allocated masks instead.
 522
 523    type bit_field is array (1 .. CPU_SETSIZE) of Boolean;
 524    for bit_field'Size use CPU_SETSIZE;
 525    pragma Pack (bit_field);
 526    pragma Convention (C, bit_field);
 527
 528    type cpu_set_t is record
 529       bits : bit_field;
 530    end record;
 531    pragma Convention (C, cpu_set_t);
 532
 533    type cpu_set_t_ptr is access all cpu_set_t;
 534    --  In the run-time library we use this pointer because the size of type
 535    --  cpu_set_t varies depending on the glibc version. Hence, objects of type
 536    --  cpu_set_t are allocated dynamically using the number of processors
 537    --  available in the target machine (value obtained at execution time).
 538
 539    function CPU_ALLOC (count : size_t) return cpu_set_t_ptr;
 540    pragma Import (C, CPU_ALLOC, "__gnat_cpu_alloc");
 541    --  Wrapper around the CPU_ALLOC C macro
 542
 543    function CPU_ALLOC_SIZE (count : size_t) return size_t;
 544    pragma Import (C, CPU_ALLOC_SIZE, "__gnat_cpu_alloc_size");
 545    --  Wrapper around the CPU_ALLOC_SIZE C macro
 546
 547    procedure CPU_FREE (cpuset : cpu_set_t_ptr);
 548    pragma Import (C, CPU_FREE, "__gnat_cpu_free");
 549    --  Wrapper around the CPU_FREE C macro
 550
 551    procedure CPU_ZERO (count : size_t; cpuset : cpu_set_t_ptr);
 552    pragma Import (C, CPU_ZERO, "__gnat_cpu_zero");
 553    --  Wrapper around the CPU_ZERO_S C macro
 554
 555    procedure CPU_SET (cpu : int; count : size_t; cpuset : cpu_set_t_ptr);
 556    pragma Import (C, CPU_SET, "__gnat_cpu_set");
 557    --  Wrapper around the CPU_SET_S C macro
 558
 559    function pthread_setaffinity_np
 560      (thread     : pthread_t;
 561       cpusetsize : size_t;
 562       cpuset     : cpu_set_t_ptr) return int;
 563    pragma Import (C, pthread_setaffinity_np, "pthread_setaffinity_np");
 564    pragma Weak_External (pthread_setaffinity_np);
 565    --  Use a weak symbol because this function may be available or not,
 566    --  depending on the version of the system.
 567
 568    function pthread_attr_setaffinity_np
 569      (attr       : access pthread_attr_t;
 570       cpusetsize : size_t;
 571       cpuset     : cpu_set_t_ptr) return int;
 572    pragma Import (C, pthread_attr_setaffinity_np,
 573                     "pthread_attr_setaffinity_np");
 574    pragma Weak_External (pthread_attr_setaffinity_np);
 575    --  Use a weak symbol because this function may be available or not,
 576    --  depending on the version of the system.
 577
 578 private
 579
 580    type sigset_t is new Interfaces.C.unsigned_long;
 581    pragma Convention (C, sigset_t);
 582    for sigset_t'Alignment use Interfaces.C.unsigned_long'Alignment;
 583
 584    pragma Warnings (Off);
 585    for struct_sigaction use record
 586       sa_handler at Linux.sa_handler_pos range 0 .. Standard'Address_Size - 1;
 587       sa_mask    at Linux.sa_mask_pos range 0 .. sigset_t'Size - 1;
 588       sa_flags   at Linux.sa_flags_pos
 589         range 0 .. Interfaces.C.unsigned_long'Size - 1;
 590    end record;
 591    --  We intentionally leave sa_restorer unspecified and let the compiler
 592    --  append it after the last field, so disable corresponding warning.
 593    pragma Warnings (On);
 594
 595    type pid_t is new int;
 596
 597    type time_t is range -2 ** (System.Parameters.time_t_bits - 1)
 598      .. 2 ** (System.Parameters.time_t_bits - 1) - 1;
 599
 600    type timespec is record
 601       tv_sec  : time_t;
 602       tv_nsec : long;
 603    end record;
 604    pragma Convention (C, timespec);
 605
 606    type unsigned_long_long_t is mod 2 ** 64;
 607    --  Local type only used to get the alignment of this type below
 608
 609    subtype char_array is Interfaces.C.char_array;
 610
 611    type pthread_attr_t is record
 612       Data : char_array (1 .. OS_Constants.PTHREAD_ATTR_SIZE);
 613    end record;
 614    pragma Convention (C, pthread_attr_t);
 615    for pthread_attr_t'Alignment use Interfaces.C.unsigned_long'Alignment;
 616
 617    type pthread_condattr_t is record
 618       Data : char_array (1 .. OS_Constants.PTHREAD_CONDATTR_SIZE);
 619    end record;
 620    pragma Convention (C, pthread_condattr_t);
 621    for pthread_condattr_t'Alignment use Interfaces.C.int'Alignment;
 622
 623    type pthread_mutexattr_t is record
 624       Data : char_array (1 .. OS_Constants.PTHREAD_MUTEXATTR_SIZE);
 625    end record;
 626    pragma Convention (C, pthread_mutexattr_t);
 627    for pthread_mutexattr_t'Alignment use Interfaces.C.int'Alignment;
 628
 629    type pthread_mutex_t is record
 630       Data : char_array (1 .. OS_Constants.PTHREAD_MUTEX_SIZE);
 631    end record;
 632    pragma Convention (C, pthread_mutex_t);
 633    for pthread_mutex_t'Alignment use Interfaces.C.unsigned_long'Alignment;
 634
 635    type pthread_cond_t is record
 636       Data : char_array (1 .. OS_Constants.PTHREAD_COND_SIZE);
 637    end record;
 638    pragma Convention (C, pthread_cond_t);
 639    for pthread_cond_t'Alignment use unsigned_long_long_t'Alignment;
 640
 641    type pthread_key_t is new unsigned;
 642
 643 end System.OS_Interface;