gdb/inf-ptrace.c

   1 /* Low-level child interface to ptrace.
   2
   3    Copyright (C) 1988-2018 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "command.h"
  22 #include "inferior.h"
  23 #include "inflow.h"
  24 #include "terminal.h"
  25 #include "gdbcore.h"
  26 #include "regcache.h"
  27 #include "nat/gdb_ptrace.h"
  28 #include "gdb_wait.h"
  29 #include <signal.h>
  30
  31 #include "inf-ptrace.h"
  32 #include "inf-child.h"
  33 #include "gdbthread.h"
  34 #include "nat/fork-inferior.h"
  35 #include "utils.h"
  36
  37 \f
  38
  39 /* A unique_ptr helper to unpush a target.  */
  40
  41 struct target_unpusher
  42 {
  43   void operator() (struct target_ops *ops) const
  44   {
  45     unpush_target (ops);
  46   }
  47 };
  48
  49 /* A unique_ptr that unpushes a target on destruction.  */
  50
  51 typedef std::unique_ptr<struct target_ops, target_unpusher> target_unpush_up;
  52
  53 \f
  54
  55 #ifdef PT_GET_PROCESS_STATE
  56
  57 /* Target hook for follow_fork.  On entry and at return inferior_ptid is
  58    the ptid of the followed inferior.  */
  59
  60 static int
  61 inf_ptrace_follow_fork (struct target_ops *ops, int follow_child,
  62                         int detach_fork)
  63 {
  64   if (!follow_child)
  65     {
  66       struct thread_info *tp = inferior_thread ();
  67       pid_t child_pid = ptid_get_pid (tp->pending_follow.value.related_pid);
  68
  69       /* Breakpoints have already been detached from the child by
  70          infrun.c.  */
  71
  72       if (ptrace (PT_DETACH, child_pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
  73         perror_with_name (("ptrace"));
  74     }
  75
  76   return 0;
  77 }
  78
  79 static int
  80 inf_ptrace_insert_fork_catchpoint (struct target_ops *self, int pid)
  81 {
  82   return 0;
  83 }
  84
  85 static int
  86 inf_ptrace_remove_fork_catchpoint (struct target_ops *self, int pid)
  87 {
  88   return 0;
  89 }
  90
  91 #endif /* PT_GET_PROCESS_STATE */
  92 \f
  93
  94 /* Prepare to be traced.  */
  95
  96 static void
  97 inf_ptrace_me (void)
  98 {
  99   /* "Trace me, Dr. Memory!"  */
 100   if (ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3) 0, 0) < 0)
 101     trace_start_error_with_name ("ptrace");
 102 }
 103
 104 /* Start a new inferior Unix child process.  EXEC_FILE is the file to
 105    run, ALLARGS is a string containing the arguments to the program.
 106    ENV is the environment vector to pass.  If FROM_TTY is non-zero, be
 107    chatty about it.  */
 108
 109 static void
 110 inf_ptrace_create_inferior (struct target_ops *ops,
 111                             const char *exec_file, const std::string &allargs,
 112                             char **env, int from_tty)
 113 {
 114   pid_t pid;
 115   ptid_t ptid;
 116
 117   /* Do not change either targets above or the same target if already present.
 118      The reason is the target stack is shared across multiple inferiors.  */
 119   int ops_already_pushed = target_is_pushed (ops);
 120
 121   target_unpush_up unpusher;
 122   if (! ops_already_pushed)
 123     {
 124       /* Clear possible core file with its process_stratum.  */
 125       push_target (ops);
 126       unpusher.reset (ops);
 127     }
 128
 129   pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
 130                        NULL, NULL, NULL);
 131
 132   ptid = pid_to_ptid (pid);
 133   /* We have something that executes now.  We'll be running through
 134      the shell at this point (if startup-with-shell is true), but the
 135      pid shouldn't change.  */
 136   add_thread_silent (ptid);
 137
 138   unpusher.release ();
 139
 140   gdb_startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED);
 141
 142   /* On some targets, there must be some explicit actions taken after
 143      the inferior has been started up.  */
 144   target_post_startup_inferior (ptid);
 145 }
 146
 147 #ifdef PT_GET_PROCESS_STATE
 148
 149 static void
 150 inf_ptrace_post_startup_inferior (struct target_ops *self, ptid_t pid)
 151 {
 152   ptrace_event_t pe;
 153
 154   /* Set the initial event mask.  */
 155   memset (&pe, 0, sizeof pe);
 156   pe.pe_set_event |= PTRACE_FORK;
 157   if (ptrace (PT_SET_EVENT_MASK, ptid_get_pid (pid),
 158               (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
 159     perror_with_name (("ptrace"));
 160 }
 161
 162 #endif
 163
 164 /* Clean up a rotting corpse of an inferior after it died.  */
 165
 166 static void
 167 inf_ptrace_mourn_inferior (struct target_ops *ops)
 168 {
 169   int status;
 170
 171   /* Wait just one more time to collect the inferior's exit status.
 172      Do not check whether this succeeds though, since we may be
 173      dealing with a process that we attached to.  Such a process will
 174      only report its exit status to its original parent.  */
 175   waitpid (ptid_get_pid (inferior_ptid), &status, 0);
 176
 177   inf_child_mourn_inferior (ops);
 178 }
 179
 180 /* Attach to the process specified by ARGS.  If FROM_TTY is non-zero,
 181    be chatty about it.  */
 182
 183 static void
 184 inf_ptrace_attach (struct target_ops *ops, const char *args, int from_tty)
 185 {
 186   char *exec_file;
 187   pid_t pid;
 188   struct inferior *inf;
 189
 190   /* Do not change either targets above or the same target if already present.
 191      The reason is the target stack is shared across multiple inferiors.  */
 192   int ops_already_pushed = target_is_pushed (ops);
 193
 194   pid = parse_pid_to_attach (args);
 195
 196   if (pid == getpid ())         /* Trying to masturbate?  */
 197     error (_("I refuse to debug myself!"));
 198
 199   target_unpush_up unpusher;
 200   if (! ops_already_pushed)
 201     {
 202       /* target_pid_to_str already uses the target.  Also clear possible core
 203          file with its process_stratum.  */
 204       push_target (ops);
 205       unpusher.reset (ops);
 206     }
 207
 208   if (from_tty)
 209     {
 210       exec_file = get_exec_file (0);
 211
 212       if (exec_file)
 213         printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
 214                            target_pid_to_str (pid_to_ptid (pid)));
 215       else
 216         printf_unfiltered (_("Attaching to %s\n"),
 217                            target_pid_to_str (pid_to_ptid (pid)));
 218
 219       gdb_flush (gdb_stdout);
 220     }
 221
 222 #ifdef PT_ATTACH
 223   errno = 0;
 224   ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
 225   if (errno != 0)
 226     perror_with_name (("ptrace"));
 227 #else
 228   error (_("This system does not support attaching to a process"));
 229 #endif
 230
 231   inf = current_inferior ();
 232   inferior_appeared (inf, pid);
 233   inf->attach_flag = 1;
 234   inferior_ptid = pid_to_ptid (pid);
 235
 236   /* Always add a main thread.  If some target extends the ptrace
 237      target, it should decorate the ptid later with more info.  */
 238   thread_info *thr = add_thread_silent (inferior_ptid);
 239   /* Don't consider the thread stopped until we've processed its
 240      initial SIGSTOP stop.  */
 241   set_executing (thr->ptid, true);
 242
 243   unpusher.release ();
 244 }
 245
 246 #ifdef PT_GET_PROCESS_STATE
 247
 248 static void
 249 inf_ptrace_post_attach (struct target_ops *self, int pid)
 250 {
 251   ptrace_event_t pe;
 252
 253   /* Set the initial event mask.  */
 254   memset (&pe, 0, sizeof pe);
 255   pe.pe_set_event |= PTRACE_FORK;
 256   if (ptrace (PT_SET_EVENT_MASK, pid,
 257               (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
 258     perror_with_name (("ptrace"));
 259 }
 260
 261 #endif
 262
 263 /* Detach from the inferior.  If FROM_TTY is non-zero, be chatty about it.  */
 264
 265 static void
 266 inf_ptrace_detach (struct target_ops *ops, inferior *inf, int from_tty)
 267 {
 268   pid_t pid = ptid_get_pid (inferior_ptid);
 269
 270   target_announce_detach (from_tty);
 271
 272 #ifdef PT_DETACH
 273   /* We'd better not have left any breakpoints in the program or it'll
 274      die when it hits one.  Also note that this may only work if we
 275      previously attached to the inferior.  It *might* work if we
 276      started the process ourselves.  */
 277   errno = 0;
 278   ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0);
 279   if (errno != 0)
 280     perror_with_name (("ptrace"));
 281 #else
 282   error (_("This system does not support detaching from a process"));
 283 #endif
 284
 285   inf_ptrace_detach_success (ops, inf);
 286 }
 287
 288 /* See inf-ptrace.h.  */
 289
 290 void
 291 inf_ptrace_detach_success (struct target_ops *ops, inferior *inf)
 292 {
 293   inferior_ptid = null_ptid;
 294   detach_inferior (inf);
 295
 296   inf_child_maybe_unpush_target (ops);
 297 }
 298
 299 /* Kill the inferior.  */
 300
 301 static void
 302 inf_ptrace_kill (struct target_ops *ops)
 303 {
 304   pid_t pid = ptid_get_pid (inferior_ptid);
 305   int status;
 306
 307   if (pid == 0)
 308     return;
 309
 310   ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
 311   waitpid (pid, &status, 0);
 312
 313   target_mourn_inferior (inferior_ptid);
 314 }
 315
 316 /* Return which PID to pass to ptrace in order to observe/control the
 317    tracee identified by PTID.  */
 318
 319 pid_t
 320 get_ptrace_pid (ptid_t ptid)
 321 {
 322   pid_t pid;
 323
 324   /* If we have an LWPID to work with, use it.  Otherwise, we're
 325      dealing with a non-threaded program/target.  */
 326   pid = ptid_get_lwp (ptid);
 327   if (pid == 0)
 328     pid = ptid_get_pid (ptid);
 329   return pid;
 330 }
 331
 332 /* Resume execution of thread PTID, or all threads if PTID is -1.  If
 333    STEP is nonzero, single-step it.  If SIGNAL is nonzero, give it
 334    that signal.  */
 335
 336 static void
 337 inf_ptrace_resume (struct target_ops *ops,
 338                    ptid_t ptid, int step, enum gdb_signal signal)
 339 {
 340   pid_t pid;
 341   int request;
 342
 343   if (ptid_equal (minus_one_ptid, ptid))
 344     /* Resume all threads.  Traditionally ptrace() only supports
 345        single-threaded processes, so simply resume the inferior.  */
 346     pid = ptid_get_pid (inferior_ptid);
 347   else
 348     pid = get_ptrace_pid (ptid);
 349
 350   if (catch_syscall_enabled () > 0)
 351     request = PT_SYSCALL;
 352   else
 353     request = PT_CONTINUE;
 354
 355   if (step)
 356     {
 357       /* If this system does not support PT_STEP, a higher level
 358          function will have called single_step() to transmute the step
 359          request into a continue request (by setting breakpoints on
 360          all possible successor instructions), so we don't have to
 361          worry about that here.  */
 362       request = PT_STEP;
 363     }
 364
 365   /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
 366      where it was.  If GDB wanted it to start some other way, we have
 367      already written a new program counter value to the child.  */
 368   errno = 0;
 369   ptrace (request, pid, (PTRACE_TYPE_ARG3)1, gdb_signal_to_host (signal));
 370   if (errno != 0)
 371     perror_with_name (("ptrace"));
 372 }
 373
 374 /* Wait for the child specified by PTID to do something.  Return the
 375    process ID of the child, or MINUS_ONE_PTID in case of error; store
 376    the status in *OURSTATUS.  */
 377
 378 static ptid_t
 379 inf_ptrace_wait (struct target_ops *ops,
 380                  ptid_t ptid, struct target_waitstatus *ourstatus, int options)
 381 {
 382   pid_t pid;
 383   int status, save_errno;
 384
 385   do
 386     {
 387       set_sigint_trap ();
 388
 389       do
 390         {
 391           pid = waitpid (ptid_get_pid (ptid), &status, 0);
 392           save_errno = errno;
 393         }
 394       while (pid == -1 && errno == EINTR);
 395
 396       clear_sigint_trap ();
 397
 398       if (pid == -1)
 399         {
 400           fprintf_unfiltered (gdb_stderr,
 401                               _("Child process unexpectedly missing: %s.\n"),
 402                               safe_strerror (save_errno));
 403
 404           /* Claim it exited with unknown signal.  */
 405           ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
 406           ourstatus->value.sig = GDB_SIGNAL_UNKNOWN;
 407           return inferior_ptid;
 408         }
 409
 410       /* Ignore terminated detached child processes.  */
 411       if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
 412         pid = -1;
 413     }
 414   while (pid == -1);
 415
 416 #ifdef PT_GET_PROCESS_STATE
 417   if (WIFSTOPPED (status))
 418     {
 419       ptrace_state_t pe;
 420       pid_t fpid;
 421
 422       if (ptrace (PT_GET_PROCESS_STATE, pid,
 423                   (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
 424         perror_with_name (("ptrace"));
 425
 426       switch (pe.pe_report_event)
 427         {
 428         case PTRACE_FORK:
 429           ourstatus->kind = TARGET_WAITKIND_FORKED;
 430           ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
 431
 432           /* Make sure the other end of the fork is stopped too.  */
 433           fpid = waitpid (pe.pe_other_pid, &status, 0);
 434           if (fpid == -1)
 435             perror_with_name (("waitpid"));
 436
 437           if (ptrace (PT_GET_PROCESS_STATE, fpid,
 438                       (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
 439             perror_with_name (("ptrace"));
 440
 441           gdb_assert (pe.pe_report_event == PTRACE_FORK);
 442           gdb_assert (pe.pe_other_pid == pid);
 443           if (fpid == ptid_get_pid (inferior_ptid))
 444             {
 445               ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
 446               return pid_to_ptid (fpid);
 447             }
 448
 449           return pid_to_ptid (pid);
 450         }
 451     }
 452 #endif
 453
 454   store_waitstatus (ourstatus, status);
 455   return pid_to_ptid (pid);
 456 }
 457
 458 /* Transfer data via ptrace into process PID's memory from WRITEBUF, or
 459    from process PID's memory into READBUF.  Start at target address ADDR
 460    and transfer up to LEN bytes.  Exactly one of READBUF and WRITEBUF must
 461    be non-null.  Return the number of transferred bytes.  */
 462
 463 static ULONGEST
 464 inf_ptrace_peek_poke (pid_t pid, gdb_byte *readbuf,
 465                       const gdb_byte *writebuf,
 466                       ULONGEST addr, ULONGEST len)
 467 {
 468   ULONGEST n;
 469   unsigned int chunk;
 470
 471   /* We transfer aligned words.  Thus align ADDR down to a word
 472      boundary and determine how many bytes to skip at the
 473      beginning.  */
 474   ULONGEST skip = addr & (sizeof (PTRACE_TYPE_RET) - 1);
 475   addr -= skip;
 476
 477   for (n = 0;
 478        n < len;
 479        n += chunk, addr += sizeof (PTRACE_TYPE_RET), skip = 0)
 480     {
 481       /* Restrict to a chunk that fits in the current word.  */
 482       chunk = std::min (sizeof (PTRACE_TYPE_RET) - skip, len - n);
 483
 484       /* Use a union for type punning.  */
 485       union
 486       {
 487         PTRACE_TYPE_RET word;
 488         gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
 489       } buf;
 490
 491       /* Read the word, also when doing a partial word write.  */
 492       if (readbuf != NULL || chunk < sizeof (PTRACE_TYPE_RET))
 493         {
 494           errno = 0;
 495           buf.word = ptrace (PT_READ_I, pid,
 496                              (PTRACE_TYPE_ARG3)(uintptr_t) addr, 0);
 497           if (errno != 0)
 498             break;
 499           if (readbuf != NULL)
 500             memcpy (readbuf + n, buf.byte + skip, chunk);
 501         }
 502       if (writebuf != NULL)
 503         {
 504           memcpy (buf.byte + skip, writebuf + n, chunk);
 505           errno = 0;
 506           ptrace (PT_WRITE_D, pid, (PTRACE_TYPE_ARG3)(uintptr_t) addr,
 507                   buf.word);
 508           if (errno != 0)
 509             {
 510               /* Using the appropriate one (I or D) is necessary for
 511                  Gould NP1, at least.  */
 512               errno = 0;
 513               ptrace (PT_WRITE_I, pid, (PTRACE_TYPE_ARG3)(uintptr_t) addr,
 514                       buf.word);
 515               if (errno != 0)
 516                 break;
 517             }
 518         }
 519     }
 520
 521   return n;
 522 }
 523
 524 /* Implement the to_xfer_partial target_ops method.  */
 525
 526 static enum target_xfer_status
 527 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
 528                          const char *annex, gdb_byte *readbuf,
 529                          const gdb_byte *writebuf,
 530                          ULONGEST offset, ULONGEST len, ULONGEST *xfered_len)
 531 {
 532   pid_t pid = get_ptrace_pid (inferior_ptid);
 533
 534   switch (object)
 535     {
 536     case TARGET_OBJECT_MEMORY:
 537 #ifdef PT_IO
 538       /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
 539          request that promises to be much more efficient in reading
 540          and writing data in the traced process's address space.  */
 541       {
 542         struct ptrace_io_desc piod;
 543
 544         /* NOTE: We assume that there are no distinct address spaces
 545            for instruction and data.  However, on OpenBSD 3.9 and
 546            later, PIOD_WRITE_D doesn't allow changing memory that's
 547            mapped read-only.  Since most code segments will be
 548            read-only, using PIOD_WRITE_D will prevent us from
 549            inserting breakpoints, so we use PIOD_WRITE_I instead.  */
 550         piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
 551         piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
 552         piod.piod_offs = (void *) (long) offset;
 553         piod.piod_len = len;
 554
 555         errno = 0;
 556         if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
 557           {
 558             /* Return the actual number of bytes read or written.  */
 559             *xfered_len = piod.piod_len;
 560             return (piod.piod_len == 0) ? TARGET_XFER_EOF : TARGET_XFER_OK;
 561           }
 562         /* If the PT_IO request is somehow not supported, fallback on
 563            using PT_WRITE_D/PT_READ_D.  Otherwise we will return zero
 564            to indicate failure.  */
 565         if (errno != EINVAL)
 566           return TARGET_XFER_EOF;
 567       }
 568 #endif
 569       *xfered_len = inf_ptrace_peek_poke (pid, readbuf, writebuf,
 570                                           offset, len);
 571       return *xfered_len != 0 ? TARGET_XFER_OK : TARGET_XFER_EOF;
 572
 573     case TARGET_OBJECT_UNWIND_TABLE:
 574       return TARGET_XFER_E_IO;
 575
 576     case TARGET_OBJECT_AUXV:
 577 #if defined (PT_IO) && defined (PIOD_READ_AUXV)
 578       /* OpenBSD 4.5 has a new PIOD_READ_AUXV operation for the PT_IO
 579          request that allows us to read the auxilliary vector.  Other
 580          BSD's may follow if they feel the need to support PIE.  */
 581       {
 582         struct ptrace_io_desc piod;
 583
 584         if (writebuf)
 585           return TARGET_XFER_E_IO;
 586         piod.piod_op = PIOD_READ_AUXV;
 587         piod.piod_addr = readbuf;
 588         piod.piod_offs = (void *) (long) offset;
 589         piod.piod_len = len;
 590
 591         errno = 0;
 592         if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
 593           {
 594             /* Return the actual number of bytes read or written.  */
 595             *xfered_len = piod.piod_len;
 596             return (piod.piod_len == 0) ? TARGET_XFER_EOF : TARGET_XFER_OK;
 597           }
 598       }
 599 #endif
 600       return TARGET_XFER_E_IO;
 601
 602     case TARGET_OBJECT_WCOOKIE:
 603       return TARGET_XFER_E_IO;
 604
 605     default:
 606       return TARGET_XFER_E_IO;
 607     }
 608 }
 609
 610 /* Return non-zero if the thread specified by PTID is alive.  */
 611
 612 static int
 613 inf_ptrace_thread_alive (struct target_ops *ops, ptid_t ptid)
 614 {
 615   /* ??? Is kill the right way to do this?  */
 616   return (kill (ptid_get_pid (ptid), 0) != -1);
 617 }
 618
 619 /* Print status information about what we're accessing.  */
 620
 621 static void
 622 inf_ptrace_files_info (struct target_ops *ignore)
 623 {
 624   struct inferior *inf = current_inferior ();
 625
 626   printf_filtered (_("\tUsing the running image of %s %s.\n"),
 627                    inf->attach_flag ? "attached" : "child",
 628                    target_pid_to_str (inferior_ptid));
 629 }
 630
 631 static const char *
 632 inf_ptrace_pid_to_str (struct target_ops *ops, ptid_t ptid)
 633 {
 634   return normal_pid_to_str (ptid);
 635 }
 636
 637 #if defined (PT_IO) && defined (PIOD_READ_AUXV)
 638
 639 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
 640    Return 0 if *READPTR is already at the end of the buffer.
 641    Return -1 if there is insufficient buffer for a whole entry.
 642    Return 1 if an entry was read into *TYPEP and *VALP.  */
 643
 644 static int
 645 inf_ptrace_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
 646                        gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
 647 {
 648   struct type *int_type = builtin_type (target_gdbarch ())->builtin_int;
 649   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 650   const int sizeof_auxv_type = TYPE_LENGTH (int_type);
 651   const int sizeof_auxv_val = TYPE_LENGTH (ptr_type);
 652   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 653   gdb_byte *ptr = *readptr;
 654
 655   if (endptr == ptr)
 656     return 0;
 657
 658   if (endptr - ptr < 2 * sizeof_auxv_val)
 659     return -1;
 660
 661   *typep = extract_unsigned_integer (ptr, sizeof_auxv_type, byte_order);
 662   ptr += sizeof_auxv_val;       /* Alignment.  */
 663   *valp = extract_unsigned_integer (ptr, sizeof_auxv_val, byte_order);
 664   ptr += sizeof_auxv_val;
 665
 666   *readptr = ptr;
 667   return 1;
 668 }
 669
 670 #endif
 671
 672 /* Create a prototype ptrace target.  The client can override it with
 673    local methods.  */
 674
 675 struct target_ops *
 676 inf_ptrace_target (void)
 677 {
 678   struct target_ops *t = inf_child_target ();
 679
 680   t->to_attach = inf_ptrace_attach;
 681   t->to_detach = inf_ptrace_detach;
 682   t->to_resume = inf_ptrace_resume;
 683   t->to_wait = inf_ptrace_wait;
 684   t->to_files_info = inf_ptrace_files_info;
 685   t->to_kill = inf_ptrace_kill;
 686   t->to_create_inferior = inf_ptrace_create_inferior;
 687 #ifdef PT_GET_PROCESS_STATE
 688   t->to_follow_fork = inf_ptrace_follow_fork;
 689   t->to_insert_fork_catchpoint = inf_ptrace_insert_fork_catchpoint;
 690   t->to_remove_fork_catchpoint = inf_ptrace_remove_fork_catchpoint;
 691   t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
 692   t->to_post_attach = inf_ptrace_post_attach;
 693 #endif
 694   t->to_mourn_inferior = inf_ptrace_mourn_inferior;
 695   t->to_thread_alive = inf_ptrace_thread_alive;
 696   t->to_pid_to_str = inf_ptrace_pid_to_str;
 697   t->to_xfer_partial = inf_ptrace_xfer_partial;
 698 #if defined (PT_IO) && defined (PIOD_READ_AUXV)
 699   t->to_auxv_parse = inf_ptrace_auxv_parse;
 700 #endif
 701
 702   return t;
 703 }
 704 \f