proc.c

   1 /*
   2  * This file is part of ltrace.
   3  * Copyright (C) 2011,2012,2013,2014 Petr Machata, Red Hat Inc.
   4  * Copyright (C) 2010 Joe Damato
   5  * Copyright (C) 1998,2009 Juan Cespedes
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * 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, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  20  * 02110-1301 USA
  21  */
  22
  23 #include "config.h"
  24
  25 #include <sys/types.h>
  26 #include <assert.h>
  27 #include <errno.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31
  32 #include "backend.h"
  33 #include "breakpoint.h"
  34 #include "debug.h"
  35 #include "fetch.h"
  36 #include "options.h"
  37 #include "proc.h"
  38 #include "value_dict.h"
  39
  40 #ifndef OS_HAVE_PROCESS_DATA
  41 int
  42 os_process_init(struct process *proc)
  43 {
  44         return 0;
  45 }
  46
  47 void
  48 os_process_destroy(struct process *proc)
  49 {
  50 }
  51
  52 int
  53 os_process_clone(struct process *retp, struct process *proc)
  54 {
  55         return 0;
  56 }
  57
  58 int
  59 os_process_exec(struct process *proc)
  60 {
  61         return 0;
  62 }
  63 #endif
  64
  65 #ifndef ARCH_HAVE_PROCESS_DATA
  66 int
  67 arch_process_init(struct process *proc)
  68 {
  69         return 0;
  70 }
  71
  72 void
  73 arch_process_destroy(struct process *proc)
  74 {
  75 }
  76
  77 int
  78 arch_process_clone(struct process *retp, struct process *proc)
  79 {
  80         return 0;
  81 }
  82
  83 int
  84 arch_process_exec(struct process *proc)
  85 {
  86         return 0;
  87 }
  88 #endif
  89
  90 #ifndef ARCH_HAVE_DYNLINK_DONE
  91 void
  92 arch_dynlink_done(struct process *proc)
  93 {
  94 }
  95 #endif
  96
  97 static int add_process(struct process *proc, int was_exec);
  98 static void unlist_process(struct process *proc);
  99
 100 static void
 101 destroy_unwind(struct process *proc)
 102 {
 103 #if defined(HAVE_LIBUNWIND)
 104         if (proc->unwind_priv != NULL)
 105                 _UPT_destroy(proc->unwind_priv);
 106         if (proc->unwind_as != NULL)
 107                 unw_destroy_addr_space(proc->unwind_as);
 108 #endif /* defined(HAVE_LIBUNWIND) */
 109
 110 #if defined(HAVE_LIBDW)
 111         if (proc->dwfl != NULL)
 112                 dwfl_end(proc->dwfl);
 113 #endif /* defined(HAVE_LIBDW) */
 114 }
 115
 116 static int
 117 process_bare_init(struct process *proc, const char *filename,
 118                   pid_t pid, int was_exec)
 119 {
 120         if (!was_exec) {
 121                 memset(proc, 0, sizeof(*proc));
 122
 123                 proc->filename = strdup(filename);
 124                 if (proc->filename == NULL) {
 125                 fail:
 126                         free(proc->filename);
 127                         if (proc->breakpoints != NULL) {
 128                                 dict_destroy(proc->breakpoints,
 129                                              NULL, NULL, NULL);
 130                                 free(proc->breakpoints);
 131                                 proc->breakpoints = NULL;
 132                         }
 133                         return -1;
 134                 }
 135         }
 136
 137         /* Add process so that we know who the leader is.  */
 138         proc->pid = pid;
 139         if (add_process(proc, was_exec) < 0)
 140                 goto fail;
 141         if (proc->leader == NULL) {
 142         unlist_and_fail:
 143                 if (!was_exec)
 144                         unlist_process(proc);
 145                 goto fail;
 146         }
 147
 148         if (proc->leader == proc) {
 149                 proc->breakpoints = malloc(sizeof(*proc->breakpoints));
 150                 if (proc->breakpoints == NULL)
 151                         goto unlist_and_fail;
 152                 DICT_INIT(proc->breakpoints,
 153                           arch_addr_t, struct breakpoint *,
 154                           arch_addr_hash, arch_addr_eq, NULL);
 155         } else {
 156                 proc->breakpoints = NULL;
 157         }
 158
 159 #if defined(HAVE_LIBUNWIND)
 160         if (options.bt_depth > 0) {
 161                 proc->unwind_priv = _UPT_create(pid);
 162                 proc->unwind_as = unw_create_addr_space(&_UPT_accessors, 0);
 163
 164                 if (proc->unwind_priv == NULL || proc->unwind_as == NULL) {
 165                         fprintf(stderr,
 166                                 "Couldn't initialize unwinding "
 167                                 "for process %d\n", proc->pid);
 168                         destroy_unwind(proc);
 169                         proc->unwind_priv = NULL;
 170                         proc->unwind_as = NULL;
 171                 }
 172         }
 173 #endif /* defined(HAVE_LIBUNWIND) */
 174
 175 #if defined(HAVE_LIBDW)
 176         proc->dwfl = NULL; /* Initialize for leader only on first library.  */
 177 #endif /* defined(HAVE_LIBDW) */
 178
 179         return 0;
 180 }
 181
 182 static void
 183 process_bare_destroy(struct process *proc, int was_exec)
 184 {
 185         dict_destroy(proc->breakpoints, NULL, NULL, NULL);
 186         free(proc->breakpoints);
 187         if (!was_exec) {
 188                 free(proc->filename);
 189                 unlist_process(proc);
 190                 destroy_unwind(proc);
 191         }
 192 }
 193
 194 static int
 195 process_init_main(struct process *proc)
 196 {
 197         if (breakpoints_init(proc) < 0) {
 198                 fprintf(stderr, "failed to init breakpoints %d\n",
 199                         proc->pid);
 200                 return -1;
 201         }
 202
 203         return 0;
 204 }
 205
 206 int
 207 process_init(struct process *proc, const char *filename, pid_t pid)
 208 {
 209         if (process_bare_init(proc, filename, pid, 0) < 0) {
 210         fail:
 211                 fprintf(stderr, "failed to initialize process %d: %s\n",
 212                         pid, strerror(errno));
 213                 return -1;
 214         }
 215
 216         if (os_process_init(proc) < 0) {
 217                 process_bare_destroy(proc, 0);
 218                 goto fail;
 219         }
 220
 221         if (arch_process_init(proc) < 0) {
 222                 os_process_destroy(proc);
 223                 process_bare_destroy(proc, 0);
 224                 goto fail;
 225         }
 226
 227         if (proc->leader != proc)
 228                 return 0;
 229         if (process_init_main(proc) < 0) {
 230                 process_bare_destroy(proc, 0);
 231                 goto fail;
 232         }
 233         return 0;
 234 }
 235
 236 static enum callback_status
 237 destroy_breakpoint_cb(struct process *proc, struct breakpoint *bp, void *data)
 238 {
 239         breakpoint_destroy(bp);
 240         free(bp);
 241         return CBS_CONT;
 242 }
 243
 244 // XXX see comment in handle_event.c
 245 void callstack_pop(struct process *proc);
 246
 247 static void
 248 private_process_destroy(struct process *proc, int was_exec)
 249 {
 250         /* Pop remaining stack elements.  */
 251         while (proc->callstack_depth > 0) {
 252                 /* When this is called just before a process is
 253                  * destroyed, the breakpoints should either have been
 254                  * retracted by now, or were killed by exec.  In any
 255                  * case, it's safe to pretend that there are no
 256                  * breakpoints associated with the stack elements, so
 257                  * that stack_pop doesn't attempt to destroy them.  */
 258                 size_t i = proc->callstack_depth - 1;
 259                 if (!proc->callstack[i].is_syscall)
 260                         proc->callstack[i].return_addr = 0;
 261
 262                 callstack_pop(proc);
 263         }
 264
 265         if (!was_exec)
 266                 free(proc->filename);
 267
 268         /* Libraries and symbols.  This is only relevant in
 269          * leader.  */
 270         struct library *lib;
 271         for (lib = proc->libraries; lib != NULL; ) {
 272                 struct library *next = lib->next;
 273                 library_destroy(lib);
 274                 free(lib);
 275                 lib = next;
 276         }
 277         proc->libraries = NULL;
 278
 279         /* Breakpoints.  */
 280         if (proc->breakpoints != NULL) {
 281                 proc_each_breakpoint(proc, NULL, destroy_breakpoint_cb, NULL);
 282                 dict_destroy(proc->breakpoints, NULL, NULL, NULL);
 283                 free(proc->breakpoints);
 284                 proc->breakpoints = NULL;
 285         }
 286
 287         destroy_unwind(proc);
 288 }
 289
 290 void
 291 process_destroy(struct process *proc)
 292 {
 293         arch_process_destroy(proc);
 294         os_process_destroy(proc);
 295         private_process_destroy(proc, 0);
 296 }
 297
 298 int
 299 process_exec(struct process *proc)
 300 {
 301         /* Call exec handlers first, before we destroy the main
 302          * state.  */
 303         if (arch_process_exec(proc) < 0
 304             || os_process_exec(proc) < 0)
 305                 return -1;
 306
 307         private_process_destroy(proc, 1);
 308
 309         if (process_bare_init(proc, NULL, proc->pid, 1) < 0)
 310                 return -1;
 311         if (process_init_main(proc) < 0) {
 312                 process_bare_destroy(proc, 1);
 313                 return -1;
 314         }
 315         return 0;
 316 }
 317
 318 struct process *
 319 open_program(const char *filename, pid_t pid)
 320 {
 321         assert(pid != 0);
 322         struct process *proc = malloc(sizeof(*proc));
 323         if (proc == NULL || process_init(proc, filename, pid) < 0) {
 324                 free(proc);
 325                 return NULL;
 326         }
 327         return proc;
 328 }
 329
 330 struct clone_single_bp_data {
 331         struct process *old_proc;
 332         struct process *new_proc;
 333 };
 334
 335 static enum callback_status
 336 clone_single_bp(arch_addr_t *key, struct breakpoint **bpp, void *u)
 337 {
 338         struct breakpoint *bp = *bpp;
 339         struct clone_single_bp_data *data = u;
 340
 341         struct breakpoint *clone = malloc(sizeof(*clone));
 342         if (clone == NULL
 343             || breakpoint_clone(clone, data->new_proc, bp) < 0) {
 344         fail:
 345                 free(clone);
 346                 return CBS_STOP;
 347         }
 348         if (proc_add_breakpoint(data->new_proc->leader, clone) < 0) {
 349                 breakpoint_destroy(clone);
 350                 goto fail;
 351         }
 352         return CBS_CONT;
 353 }
 354
 355 int
 356 process_clone(struct process *retp, struct process *proc, pid_t pid)
 357 {
 358         if (process_bare_init(retp, proc->filename, pid, 0) < 0) {
 359         fail1:
 360                 fprintf(stderr, "Failed to clone process %d to %d: %s\n",
 361                         proc->pid, pid, strerror(errno));
 362                 return -1;
 363         }
 364
 365         retp->tracesysgood = proc->tracesysgood;
 366         retp->e_machine = proc->e_machine;
 367         retp->e_class = proc->e_class;
 368
 369         /* For non-leader processes, that's all we need to do.  */
 370         if (retp->leader != retp)
 371                 return 0;
 372
 373         /* Clone symbols first so that we can clone and relink
 374          * breakpoints.  */
 375         struct library *lib;
 376         struct library **nlibp = &retp->libraries;
 377         for (lib = proc->leader->libraries; lib != NULL; lib = lib->next) {
 378                 *nlibp = malloc(sizeof(**nlibp));
 379
 380                 if (*nlibp == NULL
 381                     || library_clone(*nlibp, lib) < 0) {
 382                         free(*nlibp);
 383                         *nlibp = NULL;
 384
 385                 fail2:
 386                         process_bare_destroy(retp, 0);
 387
 388                         /* Error when cloning.  Unroll what was done.  */
 389                         for (lib = retp->libraries; lib != NULL; ) {
 390                                 struct library *next = lib->next;
 391                                 library_destroy(lib);
 392                                 free(lib);
 393                                 lib = next;
 394                         }
 395                         goto fail1;
 396                 }
 397
 398                 nlibp = &(*nlibp)->next;
 399         }
 400
 401         /* Now clone breakpoints.  Symbol relinking is done in
 402          * clone_single_bp.  */
 403         struct clone_single_bp_data data = {
 404                 .old_proc = proc,
 405                 .new_proc = retp,
 406         };
 407         if (DICT_EACH(proc->leader->breakpoints,
 408                       arch_addr_t, struct breakpoint *, NULL,
 409                       clone_single_bp, &data) != NULL)
 410                 goto fail2;
 411
 412         /* And finally the call stack.  */
 413         /* XXX clearly the callstack handling should be moved to a
 414          * separate module and this whole business extracted to
 415          * callstack_clone, or callstack_element_clone.  */
 416         memcpy(retp->callstack, proc->callstack, sizeof(retp->callstack));
 417         retp->callstack_depth = proc->callstack_depth;
 418
 419         size_t i;
 420         for (i = 0; i < retp->callstack_depth; ++i) {
 421                 struct callstack_element *elem = &retp->callstack[i];
 422                 struct fetch_context *ctx = elem->fetch_context;
 423                 if (ctx != NULL) {
 424                         struct fetch_context *nctx = fetch_arg_clone(retp, ctx);
 425                         if (nctx == NULL) {
 426                                 size_t j;
 427                         fail3:
 428                                 for (j = 0; j < i; ++j) {
 429                                         nctx = retp->callstack[j].fetch_context;
 430                                         fetch_arg_done(nctx);
 431                                         elem->fetch_context = NULL;
 432                                 }
 433                                 goto fail2;
 434                         }
 435                         elem->fetch_context = nctx;
 436                 }
 437
 438                 if (elem->arguments != NULL) {
 439                         struct value_dict *nargs = malloc(sizeof(*nargs));
 440                         if (nargs == NULL
 441                             || val_dict_clone(nargs, elem->arguments) < 0) {
 442                                 size_t j;
 443                                 for (j = 0; j < i; ++j) {
 444                                         nargs = retp->callstack[j].arguments;
 445                                         val_dict_destroy(nargs);
 446                                         free(nargs);
 447                                         elem->arguments = NULL;
 448                                 }
 449
 450                                 /* Pretend that this round went well,
 451                                  * so that fail3 frees I-th
 452                                  * fetch_context.  */
 453                                 ++i;
 454                                 goto fail3;
 455                         }
 456                         elem->arguments = nargs;
 457                 }
 458
 459                 /* If it's not a syscall, we need to find the
 460                  * corresponding library symbol in the cloned
 461                  * library.  */
 462                 if (!elem->is_syscall && elem->c_un.libfunc != NULL) {
 463                         struct library_symbol *libfunc = elem->c_un.libfunc;
 464                         int rc = proc_find_symbol(retp, libfunc,
 465                                                   NULL, &elem->c_un.libfunc);
 466                         assert(rc == 0);
 467                 }
 468         }
 469
 470         /* At this point, retp is fully initialized, except for OS and
 471          * arch parts, and we can call private_process_destroy.  */
 472         if (os_process_clone(retp, proc) < 0) {
 473                 private_process_destroy(retp, 0);
 474                 return -1;
 475         }
 476         if (arch_process_clone(retp, proc) < 0) {
 477                 os_process_destroy(retp);
 478                 private_process_destroy(retp, 0);
 479                 return -1;
 480         }
 481
 482         return 0;
 483 }
 484
 485 static int
 486 open_one_pid(pid_t pid)
 487 {
 488         debug(DEBUG_PROCESS, "open_one_pid(pid=%d)", pid);
 489
 490         /* Get the filename first.  Should the trace_pid fail, we can
 491          * easily free it, untracing is more work.  */
 492         char *filename = pid2name(pid);
 493         if (filename == NULL || trace_pid(pid) < 0) {
 494         fail:
 495                 free(filename);
 496                 return -1;
 497         }
 498
 499         struct process *proc = open_program(filename, pid);
 500         if (proc == NULL)
 501                 goto fail;
 502         free(filename);
 503         trace_set_options(proc);
 504
 505         return 0;
 506 }
 507
 508 static enum callback_status
 509 start_one_pid(struct process *proc, void *data)
 510 {
 511         continue_process(proc->pid);
 512         return CBS_CONT;
 513 }
 514
 515 static enum callback_status
 516 is_main(struct process *proc, struct library *lib, void *data)
 517 {
 518         return CBS_STOP_IF(lib->type == LT_LIBTYPE_MAIN);
 519 }
 520
 521 void
 522 process_hit_start(struct process *proc)
 523 {
 524         struct process *leader = proc->leader;
 525         assert(leader != NULL);
 526
 527         struct library *mainlib
 528                 = proc_each_library(leader, NULL, is_main, NULL);
 529         assert(mainlib != NULL);
 530         linkmap_init(leader, mainlib->dyn_addr);
 531         arch_dynlink_done(leader);
 532 }
 533
 534 void
 535 open_pid(pid_t pid)
 536 {
 537         debug(DEBUG_PROCESS, "open_pid(pid=%d)", pid);
 538         /* If we are already tracing this guy, we should be seeing all
 539          * his children via normal tracing route.  */
 540         if (pid2proc(pid) != NULL)
 541                 return;
 542
 543         /* First, see if we can attach the requested PID itself.  */
 544         if (open_one_pid(pid) < 0) {
 545                 fprintf(stderr, "Cannot attach to pid %u: %s\n",
 546                         pid, strerror(errno));
 547                 trace_fail_warning(pid);
 548                 return;
 549         }
 550
 551         /* Now attach to all tasks that belong to that PID.  There's a
 552          * race between process_tasks and open_one_pid.  So when we
 553          * fail in open_one_pid below, we just do another round.
 554          * Chances are that by then that PID will have gone away, and
 555          * that's why we have seen the failure.  The processes that we
 556          * manage to open_one_pid are stopped, so we should eventually
 557          * reach a point where process_tasks doesn't give any new
 558          * processes (because there's nobody left to produce
 559          * them).  */
 560         size_t old_ntasks = 0;
 561         int have_all;
 562         while (1) {
 563                 pid_t *tasks;
 564                 size_t ntasks;
 565                 size_t i;
 566
 567                 if (process_tasks(pid, &tasks, &ntasks) < 0) {
 568                         fprintf(stderr, "Cannot obtain tasks of pid %u: %s\n",
 569                                 pid, strerror(errno));
 570                         break;
 571                 }
 572
 573                 have_all = 1;
 574                 for (i = 0; i < ntasks; ++i)
 575                         if (pid2proc(tasks[i]) == NULL
 576                             && open_one_pid(tasks[i]) < 0)
 577                                 have_all = 0;
 578
 579                 free(tasks);
 580
 581                 if (have_all && old_ntasks == ntasks)
 582                         break;
 583                 old_ntasks = ntasks;
 584         }
 585
 586         struct process *leader = pid2proc(pid)->leader;
 587
 588         /* XXX Is there a way to figure out whether _start has
 589          * actually already been hit?  */
 590         process_hit_start(leader);
 591
 592         /* Done.  Continue everyone.  */
 593         each_task(leader, NULL, start_one_pid, NULL);
 594 }
 595
 596 static enum callback_status
 597 find_proc(struct process *proc, void *data)
 598 {
 599         return CBS_STOP_IF(proc->pid == (pid_t)(uintptr_t)data);
 600 }
 601
 602 struct process *
 603 pid2proc(pid_t pid)
 604 {
 605         return each_process(NULL, &find_proc, (void *)(uintptr_t)pid);
 606 }
 607
 608 static struct process *list_of_processes = NULL;
 609
 610 static void
 611 unlist_process(struct process *proc)
 612 {
 613         if (list_of_processes == proc) {
 614                 list_of_processes = list_of_processes->next;
 615                 return;
 616         }
 617
 618         struct process *tmp;
 619         for (tmp = list_of_processes; ; tmp = tmp->next) {
 620                 /* If the following assert fails, the process wasn't
 621                  * in the list.  */
 622                 assert(tmp->next != NULL);
 623
 624                 if (tmp->next == proc) {
 625                         tmp->next = tmp->next->next;
 626                         return;
 627                 }
 628         }
 629 }
 630
 631 struct process *
 632 each_process(struct process *start_after,
 633              enum callback_status(*cb)(struct process *proc, void *data),
 634              void *data)
 635 {
 636         struct process *it = start_after == NULL ? list_of_processes
 637                 : start_after->next;
 638
 639         while (it != NULL) {
 640                 /* Callback might call remove_process.  */
 641                 struct process *next = it->next;
 642                 switch ((*cb)(it, data)) {
 643                 case CBS_FAIL:
 644                         /* XXX handle me */
 645                 case CBS_STOP:
 646                         return it;
 647                 case CBS_CONT:
 648                         break;
 649                 }
 650                 it = next;
 651         }
 652         return NULL;
 653 }
 654
 655 struct process *
 656 each_task(struct process *proc, struct process *start_after,
 657           enum callback_status(*cb)(struct process *proc, void *data),
 658           void *data)
 659 {
 660         assert(proc != NULL);
 661         struct process *it = start_after == NULL ? proc->leader
 662                 : start_after->next;
 663
 664         if (it != NULL) {
 665                 struct process *leader = it->leader;
 666                 while (it != NULL && it->leader == leader) {
 667                         /* Callback might call remove_process.  */
 668                         struct process *next = it->next;
 669                         switch ((*cb)(it, data)) {
 670                         case CBS_FAIL:
 671                                 /* XXX handle me */
 672                         case CBS_STOP:
 673                                 return it;
 674                         case CBS_CONT:
 675                                 break;
 676                         }
 677                         it = next;
 678                 }
 679         }
 680         return NULL;
 681 }
 682
 683 static int
 684 add_process(struct process *proc, int was_exec)
 685 {
 686         struct process **leaderp = &list_of_processes;
 687         if (proc->pid) {
 688                 pid_t tgid = process_leader(proc->pid);
 689                 if (tgid == 0)
 690                         /* Must have been terminated before we managed
 691                          * to fully attach.  */
 692                         return -1;
 693                 if (tgid == proc->pid) {
 694                         proc->leader = proc;
 695                 } else {
 696                         struct process *leader = pid2proc(tgid);
 697                         proc->leader = leader;
 698                         if (leader != NULL)
 699                                 leaderp = &leader->next;
 700                 }
 701         }
 702
 703         if (!was_exec) {
 704                 proc->next = *leaderp;
 705                 *leaderp = proc;
 706         }
 707         return 0;
 708 }
 709
 710 void
 711 change_process_leader(struct process *proc, struct process *leader)
 712 {
 713         struct process **leaderp = &list_of_processes;
 714         if (proc->leader == leader)
 715                 return;
 716
 717         assert(leader != NULL);
 718         unlist_process(proc);
 719         if (proc != leader)
 720                 leaderp = &leader->next;
 721
 722         proc->leader = leader;
 723         proc->next = *leaderp;
 724         *leaderp = proc;
 725 }
 726
 727 static enum callback_status
 728 clear_leader(struct process *proc, void *data)
 729 {
 730         debug(DEBUG_FUNCTION, "detach_task %d from leader %d",
 731               proc->pid, proc->leader->pid);
 732         proc->leader = NULL;
 733         return CBS_CONT;
 734 }
 735
 736 void
 737 remove_process(struct process *proc)
 738 {
 739         debug(DEBUG_FUNCTION, "remove_proc(pid=%d)", proc->pid);
 740
 741         if (proc->leader == proc)
 742                 each_task(proc, NULL, &clear_leader, NULL);
 743
 744         unlist_process(proc);
 745         process_removed(proc);
 746         process_destroy(proc);
 747         free(proc);
 748 }
 749
 750 void
 751 install_event_handler(struct process *proc, struct event_handler *handler)
 752 {
 753         debug(DEBUG_FUNCTION, "install_event_handler(pid=%d, %p)", proc->pid, handler);
 754         assert(proc->event_handler == NULL);
 755         proc->event_handler = handler;
 756 }
 757
 758 void
 759 destroy_event_handler(struct process *proc)
 760 {
 761         struct event_handler *handler = proc->event_handler;
 762         debug(DEBUG_FUNCTION, "destroy_event_handler(pid=%d, %p)", proc->pid, handler);
 763         assert(handler != NULL);
 764         if (handler->destroy != NULL)
 765                 handler->destroy(handler);
 766         free(handler);
 767         proc->event_handler = NULL;
 768 }
 769
 770 static int
 771 breakpoint_for_symbol(struct library_symbol *libsym, struct process *proc)
 772 {
 773         arch_addr_t bp_addr;
 774         assert(proc->leader == proc);
 775
 776         /* Don't enable latent or delayed symbols.  */
 777         if (libsym->latent || libsym->delayed) {
 778                 debug(DEBUG_FUNCTION,
 779                       "delayed and/or latent breakpoint pid=%d, %s@%p",
 780                       proc->pid, libsym->name, libsym->enter_addr);
 781                 return 0;
 782         }
 783
 784         bp_addr = sym2addr(proc, libsym);
 785
 786         /* If there is an artificial breakpoint on the same address,
 787          * its libsym will be NULL, and we can smuggle our libsym
 788          * there.  That artificial breakpoint is there presumably for
 789          * the callbacks, which we don't touch.  If there is a real
 790          * breakpoint, then this is a bug.  ltrace-elf.c should filter
 791          * symbols and ignore extra symbol aliases.
 792          *
 793          * The other direction is more complicated and currently not
 794          * supported.  If a breakpoint has custom callbacks, it might
 795          * be also custom-allocated, and we would really need to swap
 796          * the two: delete the one now in the dictionary, swap values
 797          * around, and put the new breakpoint back in.  */
 798         struct breakpoint *bp;
 799         if (DICT_FIND_VAL(proc->breakpoints, &bp_addr, &bp) == 0) {
 800                 /* MIPS backend makes duplicate requests.  This is
 801                  * likely a bug in the backend.  Currently there's no
 802                  * point assigning more than one symbol to a
 803                  * breakpoint, because when it hits, we won't know
 804                  * what to print out.  But it's easier to fix it here
 805                  * before someone who understands MIPS has the time to
 806                  * look into it.  So turn the sanity check off on
 807                  * MIPS.  References:
 808                  *
 809                  *   http://lists.alioth.debian.org/pipermail/ltrace-devel/2012-November/000764.html
 810                  *   http://lists.alioth.debian.org/pipermail/ltrace-devel/2012-November/000770.html
 811                  */
 812 #ifndef __mips__
 813                 assert(bp->libsym == NULL);
 814                 bp->libsym = libsym;
 815 #endif
 816                 return 0;
 817         }
 818
 819         bp = malloc(sizeof(*bp));
 820         if (bp == NULL
 821             || breakpoint_init(bp, proc, bp_addr, libsym) < 0) {
 822         fail:
 823                 free(bp);
 824                 return -1;
 825         }
 826         if (proc_add_breakpoint(proc, bp) < 0) {
 827                 breakpoint_destroy(bp);
 828                 goto fail;
 829         }
 830
 831         if (breakpoint_turn_on(bp, proc) < 0) {
 832                 proc_remove_breakpoint(proc, bp);
 833                 breakpoint_destroy(bp);
 834                 goto fail;
 835         }
 836
 837         return 0;
 838 }
 839
 840 static enum callback_status
 841 cb_breakpoint_for_symbol(struct library_symbol *libsym, void *data)
 842 {
 843         return CBS_STOP_IF(breakpoint_for_symbol(libsym, data) < 0);
 844 }
 845
 846 static int
 847 proc_activate_latent_symbol(struct process *proc,
 848                             struct library_symbol *libsym)
 849 {
 850         assert(libsym->latent);
 851         libsym->latent = 0;
 852         debug(DEBUG_FUNCTION, "activated latent symbol");
 853         return breakpoint_for_symbol(libsym, proc);
 854 }
 855
 856 int
 857 proc_activate_delayed_symbol(struct process *proc,
 858                              struct library_symbol *libsym)
 859 {
 860         assert(libsym->delayed);
 861         libsym->delayed = 0;
 862         debug(DEBUG_FUNCTION, "activated delayed symbol");
 863         return breakpoint_for_symbol(libsym, proc);
 864 }
 865
 866 static enum callback_status
 867 activate_latent_in(struct process *proc, struct library *lib, void *data)
 868 {
 869         struct library_exported_name *exported;
 870         for (exported = data; exported != NULL; exported = exported->next) {
 871                 struct library_symbol *libsym = NULL;
 872                 while ((libsym = library_each_symbol(lib, libsym,
 873                                                      library_symbol_named_cb,
 874                                                      (void *)exported->name))
 875                        != NULL)
 876                         if (libsym->latent
 877                             && proc_activate_latent_symbol(proc, libsym) < 0)
 878                                 return CBS_FAIL;
 879         }
 880         return CBS_CONT;
 881 }
 882
 883 void
 884 proc_add_library(struct process *proc, struct library *lib)
 885 {
 886         assert(lib->next == NULL);
 887         lib->next = proc->libraries;
 888         proc->libraries = lib;
 889         debug(DEBUG_PROCESS, "added library %s@%p (%s) to %d",
 890               lib->soname, lib->base, lib->pathname, proc->pid);
 891
 892 #if defined(HAVE_LIBDW)
 893         if (options.bt_depth > 0) {
 894                 /* Setup module tracking for libdwfl unwinding.  */
 895                 struct process *leader = proc->leader;
 896                 Dwfl *dwfl = leader->dwfl;
 897                 if (dwfl == NULL) {
 898                         static const Dwfl_Callbacks proc_callbacks = {
 899                                 .find_elf = dwfl_linux_proc_find_elf,
 900                                 .find_debuginfo = dwfl_standard_find_debuginfo
 901                         };
 902                         dwfl = dwfl_begin(&proc_callbacks);
 903                         if (dwfl == NULL)
 904                                 fprintf(stderr,
 905                                         "Couldn't initialize libdwfl unwinding "
 906                                         "for process %d: %s\n", leader->pid,
 907                                         dwfl_errmsg (-1));
 908                 }
 909
 910                 if (dwfl != NULL) {
 911                         dwfl_report_begin_add(dwfl);
 912                         if (dwfl_report_elf(dwfl, lib->soname,
 913                                             lib->pathname, -1,
 914                                             (GElf_Addr) lib->base,
 915                                             false) == NULL)
 916                                 fprintf(stderr,
 917                                         "dwfl_report_elf %s@%p (%s) %d: %s\n",
 918                                         lib->soname, lib->base, lib->pathname,
 919                                         proc->pid, dwfl_errmsg (-1));
 920                         dwfl_report_end(dwfl, NULL, NULL);
 921
 922                         if (leader->dwfl == NULL) {
 923                                 int r = dwfl_linux_proc_attach(dwfl,
 924                                                                leader->pid,
 925                                                                true);
 926                                 if (r == 0)
 927                                         leader->dwfl = dwfl;
 928                                 else {
 929                                         const char *msg;
 930                                         dwfl_end(dwfl);
 931                                         if (r < 0)
 932                                                 msg = dwfl_errmsg(-1);
 933                                         else
 934                                                 msg = strerror(r);
 935                                         fprintf(stderr, "Couldn't initialize "
 936                                                 "libdwfl unwinding for "
 937                                                 "process %d: %s\n",
 938                                                 leader->pid, msg);
 939                                 }
 940                         }
 941                 }
 942         }
 943 #endif /* defined(HAVE_LIBDW) */
 944
 945         /* Insert breakpoints for all active (non-latent) symbols.  */
 946         struct library_symbol *libsym = NULL;
 947         while ((libsym = library_each_symbol(lib, libsym,
 948                                              cb_breakpoint_for_symbol,
 949                                              proc)) != NULL)
 950                 fprintf(stderr,
 951                         "Couldn't insert breakpoint for %s to %d: %s.\n",
 952                         libsym->name, proc->pid, strerror(errno));
 953
 954         /* Look through export list of the new library and compare it
 955          * with latent symbols of all libraries (including this
 956          * library itself).  */
 957         struct library *lib2 = NULL;
 958         while ((lib2 = proc_each_library(proc, lib2, activate_latent_in,
 959                                          lib->exported_names)) != NULL)
 960                 fprintf(stderr,
 961                         "Couldn't activate latent symbols for %s in %d: %s.\n",
 962                         lib2->soname, proc->pid, strerror(errno));
 963 }
 964
 965 int
 966 proc_remove_library(struct process *proc, struct library *lib)
 967 {
 968         struct library **libp;
 969         for (libp = &proc->libraries; *libp != NULL; libp = &(*libp)->next)
 970                 if (*libp == lib) {
 971                         *libp = lib->next;
 972                         return 0;
 973                 }
 974         return -1;
 975 }
 976
 977 struct library *
 978 proc_each_library(struct process *proc, struct library *it,
 979                   enum callback_status (*cb)(struct process *proc,
 980                                              struct library *lib, void *data),
 981                   void *data)
 982 {
 983         if (it == NULL)
 984                 it = proc->libraries;
 985         else
 986                 it = it->next;
 987
 988         while (it != NULL) {
 989                 struct library *next = it->next;
 990
 991                 switch (cb(proc, it, data)) {
 992                 case CBS_FAIL:
 993                         /* XXX handle me */
 994                 case CBS_STOP:
 995                         return it;
 996                 case CBS_CONT:
 997                         break;
 998                 }
 999
1000                 it = next;
1001         }
1002
1003         return NULL;
1004 }
1005
1006 static void
1007 check_leader(struct process *proc)
1008 {
1009         /* Only the group leader should be getting the breakpoints and
1010          * thus have ->breakpoint initialized.  */
1011         assert(proc->leader != NULL);
1012         assert(proc->leader == proc);
1013         assert(proc->breakpoints != NULL);
1014 }
1015
1016 int
1017 proc_add_breakpoint(struct process *proc, struct breakpoint *bp)
1018 {
1019         debug(DEBUG_FUNCTION, "proc_add_breakpoint(pid=%d, %s@%p)",
1020               proc->pid, breakpoint_name(bp), bp->addr);
1021         check_leader(proc);
1022
1023         /* XXX We might merge bp->libsym instead of the following
1024          * assert, but that's not necessary right now.  Read the
1025          * comment in breakpoint_for_symbol.  */
1026         assert(dict_find(proc->breakpoints, &bp->addr) == NULL);
1027
1028         if (DICT_INSERT(proc->breakpoints, &bp->addr, &bp) < 0) {
1029                 fprintf(stderr,
1030                         "couldn't enter breakpoint %s@%p to dictionary: %s\n",
1031                         breakpoint_name(bp), bp->addr, strerror(errno));
1032                 return -1;
1033         }
1034
1035         return 0;
1036 }
1037
1038 void
1039 proc_remove_breakpoint(struct process *proc, struct breakpoint *bp)
1040 {
1041         debug(DEBUG_FUNCTION, "proc_remove_breakpoint(pid=%d, %s@%p)",
1042               proc->pid, breakpoint_name(bp), bp->addr);
1043         check_leader(proc);
1044         int rc = DICT_ERASE(proc->breakpoints, &bp->addr, struct breakpoint *,
1045                             NULL, NULL, NULL);
1046         assert(rc == 0);
1047 }
1048
1049 struct each_breakpoint_data
1050 {
1051         struct process *proc;
1052         enum callback_status (*cb)(struct process *proc,
1053                                    struct breakpoint *bp,
1054                                    void *data);
1055         void *cb_data;
1056 };
1057
1058 static enum callback_status
1059 each_breakpoint_cb(arch_addr_t *key, struct breakpoint **bpp, void *d)
1060 {
1061         struct each_breakpoint_data *data = d;
1062         return data->cb(data->proc, *bpp, data->cb_data);
1063 }
1064
1065 arch_addr_t *
1066 proc_each_breakpoint(struct process *proc, arch_addr_t *start,
1067                      enum callback_status (*cb)(struct process *proc,
1068                                                 struct breakpoint *bp,
1069                                                 void *data), void *data)
1070 {
1071         struct each_breakpoint_data dd = {
1072                 .proc = proc,
1073                 .cb = cb,
1074                 .cb_data = data,
1075         };
1076         return DICT_EACH(proc->breakpoints,
1077                          arch_addr_t, struct breakpoint *, start,
1078                          &each_breakpoint_cb, &dd);
1079 }
1080
1081 int
1082 proc_find_symbol(struct process *proc, struct library_symbol *sym,
1083                  struct library **retlib, struct library_symbol **retsym)
1084 {
1085         struct library *lib = sym->lib;
1086         assert(lib != NULL);
1087
1088         struct library *flib
1089                 = proc_each_library(proc, NULL, library_with_key_cb, &lib->key);
1090         if (flib == NULL)
1091                 return -1;
1092
1093         struct library_symbol *fsym
1094                 = library_each_symbol(flib, NULL, library_symbol_named_cb,
1095                                       (char *)sym->name);
1096         if (fsym == NULL)
1097                 return -1;
1098
1099         if (retlib != NULL)
1100                 *retlib = flib;
1101         if (retsym != NULL)
1102                 *retsym = fsym;
1103
1104         return 0;
1105 }
1106
1107 struct library_symbol *
1108 proc_each_symbol(struct process *proc, struct library_symbol *start_after,
1109                  enum callback_status (*cb)(struct library_symbol *, void *),
1110                  void *data)
1111 {
1112         struct library *lib;
1113         for (lib = start_after != NULL ? start_after->lib : proc->libraries;
1114              lib != NULL; lib = lib->next) {
1115                 start_after = library_each_symbol(lib, start_after, cb, data);
1116                 if (start_after != NULL)
1117                         return start_after;
1118         }
1119
1120         return NULL;
1121 }
1122
1123 #define DEF_READER(NAME, SIZE)                                          \
1124         int                                                             \
1125         NAME(struct process *proc, arch_addr_t addr,                    \
1126              uint##SIZE##_t *lp)                                        \
1127         {                                                               \
1128                 union {                                                 \
1129                         uint##SIZE##_t dst;                             \
1130                         char buf[0];                                    \
1131                 } u;                                                    \
1132                 if (umovebytes(proc, addr, &u.buf, sizeof(u.dst))       \
1133                     != sizeof(u.dst))                                   \
1134                         return -1;                                      \
1135                 *lp = u.dst;                                            \
1136                 return 0;                                               \
1137         }
1138
1139 DEF_READER(proc_read_8, 8)
1140 DEF_READER(proc_read_16, 16)
1141 DEF_READER(proc_read_32, 32)
1142 DEF_READER(proc_read_64, 64)
1143
1144 #undef DEF_READER