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 #include "dwarf_prototypes.h"
  40
  41 #ifndef OS_HAVE_PROCESS_DATA
  42 int
  43 os_process_init(struct process *proc)
  44 {
  45         return 0;
  46 }
  47
  48 void
  49 os_process_destroy(struct process *proc)
  50 {
  51 }
  52
  53 int
  54 os_process_clone(struct process *retp, struct process *proc)
  55 {
  56         return 0;
  57 }
  58
  59 int
  60 os_process_exec(struct process *proc)
  61 {
  62         return 0;
  63 }
  64 #endif
  65
  66 #ifndef ARCH_HAVE_PROCESS_DATA
  67 int
  68 arch_process_init(struct process *proc)
  69 {
  70         return 0;
  71 }
  72
  73 void
  74 arch_process_destroy(struct process *proc)
  75 {
  76 }
  77
  78 int
  79 arch_process_clone(struct process *retp, struct process *proc)
  80 {
  81         return 0;
  82 }
  83
  84 int
  85 arch_process_exec(struct process *proc)
  86 {
  87         return 0;
  88 }
  89 #endif
  90
  91 #ifndef ARCH_HAVE_DYNLINK_DONE
  92 void
  93 arch_dynlink_done(struct process *proc)
  94 {
  95 }
  96 #endif
  97
  98 static int add_process(struct process *proc, int was_exec);
  99 static void unlist_process(struct process *proc);
 100
 101 static void
 102 destroy_unwind(struct process *proc)
 103 {
 104 #if defined(HAVE_LIBUNWIND)
 105         if (proc->unwind_priv != NULL)
 106                 _UPT_destroy(proc->unwind_priv);
 107         if (proc->unwind_as != NULL)
 108                 unw_destroy_addr_space(proc->unwind_as);
 109 #endif /* defined(HAVE_LIBUNWIND) */
 110
 111 #if defined(HAVE_LIBDW)
 112         if (proc->dwfl != NULL)
 113                 dwfl_end(proc->dwfl);
 114 #endif /* defined(HAVE_LIBDW) */
 115 }
 116
 117 static int
 118 process_bare_init(struct process *proc, const char *filename,
 119                   pid_t pid, int was_exec)
 120 {
 121         if (!was_exec) {
 122                 memset(proc, 0, sizeof(*proc));
 123
 124                 proc->filename = strdup(filename);
 125                 if (proc->filename == NULL) {
 126                 fail:
 127                         free(proc->filename);
 128                         if (proc->breakpoints != NULL) {
 129                                 dict_destroy(proc->breakpoints,
 130                                              NULL, NULL, NULL);
 131                                 free(proc->breakpoints);
 132                                 proc->breakpoints = NULL;
 133                         }
 134                         return -1;
 135                 }
 136         }
 137
 138         /* Add process so that we know who the leader is.  */
 139         proc->pid = pid;
 140         if (add_process(proc, was_exec) < 0)
 141                 goto fail;
 142         if (proc->leader == NULL) {
 143         unlist_and_fail:
 144                 if (!was_exec)
 145                         unlist_process(proc);
 146                 goto fail;
 147         }
 148
 149         if (proc->leader == proc) {
 150                 proc->breakpoints = malloc(sizeof(*proc->breakpoints));
 151                 if (proc->breakpoints == NULL)
 152                         goto unlist_and_fail;
 153                 DICT_INIT(proc->breakpoints,
 154                           arch_addr_t, struct breakpoint *,
 155                           arch_addr_hash, arch_addr_eq, NULL);
 156         } else {
 157                 proc->breakpoints = NULL;
 158         }
 159
 160 #if defined(HAVE_LIBUNWIND)
 161         if (options.bt_depth > 0) {
 162                 proc->unwind_priv = _UPT_create(pid);
 163                 proc->unwind_as = unw_create_addr_space(&_UPT_accessors, 0);
 164
 165                 if (proc->unwind_priv == NULL || proc->unwind_as == NULL) {
 166                         fprintf(stderr,
 167                                 "Couldn't initialize unwinding "
 168                                 "for process %d\n", proc->pid);
 169                         destroy_unwind(proc);
 170                         proc->unwind_priv = NULL;
 171                         proc->unwind_as = NULL;
 172                 }
 173         }
 174 #endif /* defined(HAVE_LIBUNWIND) */
 175
 176 #if defined(HAVE_LIBDW)
 177         proc->dwfl = NULL; /* Initialize for leader only on first library.  */
 178 #endif /* defined(HAVE_LIBDW) */
 179
 180         return 0;
 181 }
 182
 183 static void
 184 process_bare_destroy(struct process *proc, int was_exec)
 185 {
 186         dict_destroy(proc->breakpoints, NULL, NULL, NULL);
 187         free(proc->breakpoints);
 188         if (!was_exec) {
 189                 free(proc->filename);
 190                 unlist_process(proc);
 191                 destroy_unwind(proc);
 192         }
 193 }
 194
 195 static int
 196 process_init_main(struct process *proc)
 197 {
 198         if (breakpoints_init(proc) < 0) {
 199                 fprintf(stderr, "failed to init breakpoints %d\n",
 200                         proc->pid);
 201                 return -1;
 202         }
 203
 204         return 0;
 205 }
 206
 207 int
 208 process_init(struct process *proc, const char *filename, pid_t pid)
 209 {
 210         if (process_bare_init(proc, filename, pid, 0) < 0) {
 211         fail:
 212                 fprintf(stderr, "failed to initialize process %d: %s\n",
 213                         pid, strerror(errno));
 214                 return -1;
 215         }
 216
 217         if (os_process_init(proc) < 0) {
 218                 process_bare_destroy(proc, 0);
 219                 goto fail;
 220         }
 221
 222         if (arch_process_init(proc) < 0) {
 223                 os_process_destroy(proc);
 224                 process_bare_destroy(proc, 0);
 225                 goto fail;
 226         }
 227
 228         if (proc->leader != proc) {
 229                 proc->e_machine = proc->leader->e_machine;
 230                 proc->e_class = proc->leader->e_class;
 231                 get_arch_dep(proc);
 232         } else if (process_init_main(proc) < 0) {
 233                 process_bare_destroy(proc, 0);
 234                 goto fail;
 235         }
 236         return 0;
 237 }
 238
 239 static enum callback_status
 240 destroy_breakpoint_cb(struct process *proc, struct breakpoint *bp, void *data)
 241 {
 242         breakpoint_destroy(bp);
 243         free(bp);
 244         return CBS_CONT;
 245 }
 246
 247 // XXX see comment in handle_event.c
 248 void callstack_pop(struct process *proc);
 249
 250 static void
 251 private_process_destroy(struct process *proc, int was_exec)
 252 {
 253         /* Pop remaining stack elements.  */
 254         while (proc->callstack_depth > 0) {
 255                 /* When this is called just before a process is
 256                  * destroyed, the breakpoints should either have been
 257                  * retracted by now, or were killed by exec.  In any
 258                  * case, it's safe to pretend that there are no
 259                  * breakpoints associated with the stack elements, so
 260                  * that stack_pop doesn't attempt to destroy them.  */
 261                 size_t i = proc->callstack_depth - 1;
 262                 if (!proc->callstack[i].is_syscall)
 263                         proc->callstack[i].return_addr = 0;
 264
 265                 callstack_pop(proc);
 266         }
 267
 268         if (!was_exec)
 269                 free(proc->filename);
 270
 271         /* Libraries and symbols.  This is only relevant in
 272          * leader.  */
 273         struct library *lib;
 274         for (lib = proc->libraries; lib != NULL; ) {
 275                 struct library *next = lib->next;
 276                 library_destroy(lib);
 277                 free(lib);
 278                 lib = next;
 279         }
 280         proc->libraries = NULL;
 281
 282         /* Breakpoints.  */
 283         if (proc->breakpoints != NULL) {
 284                 proc_each_breakpoint(proc, NULL, destroy_breakpoint_cb, NULL);
 285                 dict_destroy(proc->breakpoints, NULL, NULL, NULL);
 286                 free(proc->breakpoints);
 287                 proc->breakpoints = NULL;
 288         }
 289
 290         destroy_unwind(proc);
 291 }
 292
 293 void
 294 process_destroy(struct process *proc)
 295 {
 296         arch_process_destroy(proc);
 297         os_process_destroy(proc);
 298         private_process_destroy(proc, 0);
 299 }
 300
 301 int
 302 process_exec(struct process *proc)
 303 {
 304         /* Call exec handlers first, before we destroy the main
 305          * state.  */
 306         if (arch_process_exec(proc) < 0
 307             || os_process_exec(proc) < 0)
 308                 return -1;
 309
 310         private_process_destroy(proc, 1);
 311
 312         if (process_bare_init(proc, NULL, proc->pid, 1) < 0)
 313                 return -1;
 314         if (process_init_main(proc) < 0) {
 315                 process_bare_destroy(proc, 1);
 316                 return -1;
 317         }
 318         return 0;
 319 }
 320
 321 struct process *
 322 open_program(const char *filename, pid_t pid)
 323 {
 324         assert(pid != 0);
 325         struct process *proc = malloc(sizeof(*proc));
 326         if (proc == NULL || process_init(proc, filename, pid) < 0) {
 327                 free(proc);
 328                 return NULL;
 329         }
 330         return proc;
 331 }
 332
 333 struct clone_single_bp_data {
 334         struct process *old_proc;
 335         struct process *new_proc;
 336 };
 337
 338 static enum callback_status
 339 clone_single_bp(arch_addr_t *key, struct breakpoint **bpp, void *u)
 340 {
 341         struct breakpoint *bp = *bpp;
 342         struct clone_single_bp_data *data = u;
 343
 344         struct breakpoint *clone = malloc(sizeof(*clone));
 345         if (clone == NULL
 346             || breakpoint_clone(clone, data->new_proc, bp) < 0) {
 347         fail:
 348                 free(clone);
 349                 return CBS_STOP;
 350         }
 351         if (proc_add_breakpoint(data->new_proc->leader, clone) < 0) {
 352                 breakpoint_destroy(clone);
 353                 goto fail;
 354         }
 355         return CBS_CONT;
 356 }
 357
 358 int
 359 process_clone(struct process *retp, struct process *proc, pid_t pid)
 360 {
 361         if (process_bare_init(retp, proc->filename, pid, 0) < 0) {
 362         fail1:
 363                 fprintf(stderr, "Failed to clone process %d to %d: %s\n",
 364                         proc->pid, pid, strerror(errno));
 365                 return -1;
 366         }
 367
 368         retp->tracesysgood = proc->tracesysgood;
 369         retp->e_machine = proc->e_machine;
 370         retp->e_class = proc->e_class;
 371
 372         /* For non-leader processes, that's all we need to do.  */
 373         if (retp->leader != retp)
 374                 return 0;
 375
 376         /* Clone symbols first so that we can clone and relink
 377          * breakpoints.  */
 378         struct library *lib;
 379         struct library **nlibp = &retp->libraries;
 380         for (lib = proc->leader->libraries; lib != NULL; lib = lib->next) {
 381                 *nlibp = malloc(sizeof(**nlibp));
 382
 383                 if (*nlibp == NULL
 384                     || library_clone(*nlibp, lib) < 0) {
 385                         free(*nlibp);
 386                         *nlibp = NULL;
 387
 388                 fail2:
 389                         process_bare_destroy(retp, 0);
 390
 391                         /* Error when cloning.  Unroll what was done.  */
 392                         for (lib = retp->libraries; lib != NULL; ) {
 393                                 struct library *next = lib->next;
 394                                 library_destroy(lib);
 395                                 free(lib);
 396                                 lib = next;
 397                         }
 398                         goto fail1;
 399                 }
 400
 401                 nlibp = &(*nlibp)->next;
 402         }
 403
 404         /* Now clone breakpoints.  Symbol relinking is done in
 405          * clone_single_bp.  */
 406         struct clone_single_bp_data data = {
 407                 .old_proc = proc,
 408                 .new_proc = retp,
 409         };
 410         if (DICT_EACH(proc->leader->breakpoints,
 411                       arch_addr_t, struct breakpoint *, NULL,
 412                       clone_single_bp, &data) != NULL)
 413                 goto fail2;
 414
 415         /* And finally the call stack.  */
 416         /* XXX clearly the callstack handling should be moved to a
 417          * separate module and this whole business extracted to
 418          * callstack_clone, or callstack_element_clone.  */
 419         memcpy(retp->callstack, proc->callstack, sizeof(retp->callstack));
 420         retp->callstack_depth = proc->callstack_depth;
 421
 422         size_t i;
 423         for (i = 0; i < retp->callstack_depth; ++i) {
 424                 struct callstack_element *elem = &retp->callstack[i];
 425                 struct fetch_context *ctx = elem->fetch_context;
 426                 if (ctx != NULL) {
 427                         struct fetch_context *nctx = fetch_arg_clone(retp, ctx);
 428                         if (nctx == NULL) {
 429                                 size_t j;
 430                         fail3:
 431                                 for (j = 0; j < i; ++j) {
 432                                         nctx = retp->callstack[j].fetch_context;
 433                                         fetch_arg_done(nctx);
 434                                         elem->fetch_context = NULL;
 435                                 }
 436                                 goto fail2;
 437                         }
 438                         elem->fetch_context = nctx;
 439                 }
 440
 441                 if (elem->arguments != NULL) {
 442                         struct value_dict *nargs = malloc(sizeof(*nargs));
 443                         if (nargs == NULL
 444                             || val_dict_clone(nargs, elem->arguments) < 0) {
 445                                 size_t j;
 446                                 for (j = 0; j < i; ++j) {
 447                                         nargs = retp->callstack[j].arguments;
 448                                         val_dict_destroy(nargs);
 449                                         free(nargs);
 450                                         elem->arguments = NULL;
 451                                 }
 452
 453                                 /* Pretend that this round went well,
 454                                  * so that fail3 frees I-th
 455                                  * fetch_context.  */
 456                                 ++i;
 457                                 goto fail3;
 458                         }
 459                         elem->arguments = nargs;
 460                 }
 461
 462                 /* If it's not a syscall, we need to find the
 463                  * corresponding library symbol in the cloned
 464                  * library.  */
 465                 if (!elem->is_syscall && elem->c_un.libfunc != NULL) {
 466                         struct library_symbol *libfunc = elem->c_un.libfunc;
 467                         int rc = proc_find_symbol(retp, libfunc,
 468                                                   NULL, &elem->c_un.libfunc);
 469                         assert(rc == 0);
 470                 }
 471         }
 472
 473         /* At this point, retp is fully initialized, except for OS and
 474          * arch parts, and we can call private_process_destroy.  */
 475         if (os_process_clone(retp, proc) < 0) {
 476                 private_process_destroy(retp, 0);
 477                 return -1;
 478         }
 479         if (arch_process_clone(retp, proc) < 0) {
 480                 os_process_destroy(retp);
 481                 private_process_destroy(retp, 0);
 482                 return -1;
 483         }
 484
 485         return 0;
 486 }
 487
 488 static int
 489 open_one_pid(pid_t pid)
 490 {
 491         debug(DEBUG_PROCESS, "open_one_pid(pid=%d)", pid);
 492
 493         /* Get the filename first.  Should the trace_pid fail, we can
 494          * easily free it, untracing is more work.  */
 495         char *filename = pid2name(pid);
 496         if (filename == NULL || trace_pid(pid) < 0) {
 497         fail:
 498                 free(filename);
 499                 return -1;
 500         }
 501
 502         struct process *proc = open_program(filename, pid);
 503         if (proc == NULL)
 504                 goto fail;
 505         free(filename);
 506         trace_set_options(proc);
 507
 508         return 0;
 509 }
 510
 511 static enum callback_status
 512 start_one_pid(struct process *proc, void *data)
 513 {
 514         continue_process(proc->pid);
 515         return CBS_CONT;
 516 }
 517
 518 static enum callback_status
 519 is_main(struct process *proc, struct library *lib, void *data)
 520 {
 521         return CBS_STOP_IF(lib->type == LT_LIBTYPE_MAIN);
 522 }
 523
 524 void
 525 process_hit_start(struct process *proc)
 526 {
 527         struct process *leader = proc->leader;
 528         assert(leader != NULL);
 529
 530         struct library *mainlib
 531                 = proc_each_library(leader, NULL, is_main, NULL);
 532         assert(mainlib != NULL);
 533         linkmap_init(leader, mainlib->dyn_addr);
 534         arch_dynlink_done(leader);
 535 }
 536
 537 void
 538 open_pid(pid_t pid)
 539 {
 540         debug(DEBUG_PROCESS, "open_pid(pid=%d)", pid);
 541         /* If we are already tracing this guy, we should be seeing all
 542          * his children via normal tracing route.  */
 543         if (pid2proc(pid) != NULL)
 544                 return;
 545
 546         /* First, see if we can attach the requested PID itself.  */
 547         if (open_one_pid(pid) < 0) {
 548                 fprintf(stderr, "Cannot attach to pid %u: %s\n",
 549                         pid, strerror(errno));
 550                 trace_fail_warning(pid);
 551                 return;
 552         }
 553
 554         /* Now attach to all tasks that belong to that PID.  There's a
 555          * race between process_tasks and open_one_pid.  So when we
 556          * fail in open_one_pid below, we just do another round.
 557          * Chances are that by then that PID will have gone away, and
 558          * that's why we have seen the failure.  The processes that we
 559          * manage to open_one_pid are stopped, so we should eventually
 560          * reach a point where process_tasks doesn't give any new
 561          * processes (because there's nobody left to produce
 562          * them).  */
 563         size_t old_ntasks = 0;
 564         int have_all;
 565         while (1) {
 566                 pid_t *tasks;
 567                 size_t ntasks;
 568                 size_t i;
 569
 570                 if (process_tasks(pid, &tasks, &ntasks) < 0) {
 571                         fprintf(stderr, "Cannot obtain tasks of pid %u: %s\n",
 572                                 pid, strerror(errno));
 573                         break;
 574                 }
 575
 576                 have_all = 1;
 577                 for (i = 0; i < ntasks; ++i)
 578                         if (pid2proc(tasks[i]) == NULL
 579                             && open_one_pid(tasks[i]) < 0)
 580                                 have_all = 0;
 581
 582                 free(tasks);
 583
 584                 if (have_all && old_ntasks == ntasks)
 585                         break;
 586                 old_ntasks = ntasks;
 587         }
 588
 589         struct process *leader = pid2proc(pid)->leader;
 590
 591         /* XXX Is there a way to figure out whether _start has
 592          * actually already been hit?  */
 593         process_hit_start(leader);
 594
 595         /* Done.  Continue everyone.  */
 596         each_task(leader, NULL, start_one_pid, NULL);
 597 }
 598
 599 static enum callback_status
 600 find_proc(struct process *proc, void *data)
 601 {
 602         return CBS_STOP_IF(proc->pid == (pid_t)(uintptr_t)data);
 603 }
 604
 605 struct process *
 606 pid2proc(pid_t pid)
 607 {
 608         return each_process(NULL, &find_proc, (void *)(uintptr_t)pid);
 609 }
 610
 611 static struct process *list_of_processes = NULL;
 612
 613 static void
 614 unlist_process(struct process *proc)
 615 {
 616         if (list_of_processes == proc) {
 617                 list_of_processes = list_of_processes->next;
 618                 return;
 619         }
 620
 621         struct process *tmp;
 622         for (tmp = list_of_processes; ; tmp = tmp->next) {
 623                 /* If the following assert fails, the process wasn't
 624                  * in the list.  */
 625                 assert(tmp->next != NULL);
 626
 627                 if (tmp->next == proc) {
 628                         tmp->next = tmp->next->next;
 629                         return;
 630                 }
 631         }
 632 }
 633
 634 struct process *
 635 each_process(struct process *start_after,
 636              enum callback_status(*cb)(struct process *proc, void *data),
 637              void *data)
 638 {
 639         struct process *it = start_after == NULL ? list_of_processes
 640                 : start_after->next;
 641
 642         while (it != NULL) {
 643                 /* Callback might call remove_process.  */
 644                 struct process *next = it->next;
 645                 switch ((*cb)(it, data)) {
 646                 case CBS_FAIL:
 647                         /* XXX handle me */
 648                 case CBS_STOP:
 649                         return it;
 650                 case CBS_CONT:
 651                         break;
 652                 }
 653                 it = next;
 654         }
 655         return NULL;
 656 }
 657
 658 struct process *
 659 each_task(struct process *proc, struct process *start_after,
 660           enum callback_status(*cb)(struct process *proc, void *data),
 661           void *data)
 662 {
 663         assert(proc != NULL);
 664         struct process *it = start_after == NULL ? proc->leader
 665                 : start_after->next;
 666
 667         if (it != NULL) {
 668                 struct process *leader = it->leader;
 669                 while (it != NULL && it->leader == leader) {
 670                         /* Callback might call remove_process.  */
 671                         struct process *next = it->next;
 672                         switch ((*cb)(it, data)) {
 673                         case CBS_FAIL:
 674                                 /* XXX handle me */
 675                         case CBS_STOP:
 676                                 return it;
 677                         case CBS_CONT:
 678                                 break;
 679                         }
 680                         it = next;
 681                 }
 682         }
 683         return NULL;
 684 }
 685
 686 static int
 687 add_process(struct process *proc, int was_exec)
 688 {
 689         struct process **leaderp = &list_of_processes;
 690         if (proc->pid) {
 691                 pid_t tgid = process_leader(proc->pid);
 692                 if (tgid == 0)
 693                         /* Must have been terminated before we managed
 694                          * to fully attach.  */
 695                         return -1;
 696                 if (tgid == proc->pid) {
 697                         proc->leader = proc;
 698                 } else {
 699                         struct process *leader = pid2proc(tgid);
 700                         proc->leader = leader;
 701                         if (leader != NULL)
 702                                 leaderp = &leader->next;
 703                 }
 704         }
 705
 706         if (!was_exec) {
 707                 proc->next = *leaderp;
 708                 *leaderp = proc;
 709         }
 710         return 0;
 711 }
 712
 713 void
 714 change_process_leader(struct process *proc, struct process *leader)
 715 {
 716         struct process **leaderp = &list_of_processes;
 717         if (proc->leader == leader)
 718                 return;
 719
 720         assert(leader != NULL);
 721         unlist_process(proc);
 722         if (proc != leader)
 723                 leaderp = &leader->next;
 724
 725         proc->leader = leader;
 726         proc->next = *leaderp;
 727         *leaderp = proc;
 728 }
 729
 730 static enum callback_status
 731 clear_leader(struct process *proc, void *data)
 732 {
 733         debug(DEBUG_FUNCTION, "detach_task %d from leader %d",
 734               proc->pid, proc->leader->pid);
 735         proc->leader = NULL;
 736         return CBS_CONT;
 737 }
 738
 739 void
 740 remove_process(struct process *proc)
 741 {
 742         debug(DEBUG_FUNCTION, "remove_proc(pid=%d)", proc->pid);
 743
 744         if (proc->leader == proc)
 745                 each_task(proc, NULL, &clear_leader, NULL);
 746
 747         unlist_process(proc);
 748         process_removed(proc);
 749         process_destroy(proc);
 750         free(proc);
 751 }
 752
 753 void
 754 install_event_handler(struct process *proc, struct event_handler *handler)
 755 {
 756         debug(DEBUG_FUNCTION, "install_event_handler(pid=%d, %p)", proc->pid, handler);
 757         assert(proc->event_handler == NULL);
 758         proc->event_handler = handler;
 759 }
 760
 761 void
 762 destroy_event_handler(struct process *proc)
 763 {
 764         struct event_handler *handler = proc->event_handler;
 765         debug(DEBUG_FUNCTION, "destroy_event_handler(pid=%d, %p)", proc->pid, handler);
 766         assert(handler != NULL);
 767         if (handler->destroy != NULL)
 768                 handler->destroy(handler);
 769         free(handler);
 770         proc->event_handler = NULL;
 771 }
 772
 773 static int
 774 breakpoint_for_symbol(struct library_symbol *libsym, struct process *proc)
 775 {
 776         arch_addr_t bp_addr;
 777         assert(proc->leader == proc);
 778
 779         /* Don't enable latent or delayed symbols.  */
 780         if (libsym->latent || libsym->delayed) {
 781                 debug(DEBUG_FUNCTION,
 782                       "delayed and/or latent breakpoint pid=%d, %s@%p",
 783                       proc->pid, libsym->name, libsym->enter_addr);
 784                 return 0;
 785         }
 786
 787         bp_addr = sym2addr(proc, libsym);
 788
 789         /* If there is an artificial breakpoint on the same address,
 790          * its libsym will be NULL, and we can smuggle our libsym
 791          * there.  That artificial breakpoint is there presumably for
 792          * the callbacks, which we don't touch.  If there is a real
 793          * breakpoint, then this is a bug.  ltrace-elf.c should filter
 794          * symbols and ignore extra symbol aliases.
 795          *
 796          * The other direction is more complicated and currently not
 797          * supported.  If a breakpoint has custom callbacks, it might
 798          * be also custom-allocated, and we would really need to swap
 799          * the two: delete the one now in the dictionary, swap values
 800          * around, and put the new breakpoint back in.  */
 801         struct breakpoint *bp;
 802         if (DICT_FIND_VAL(proc->breakpoints, &bp_addr, &bp) == 0) {
 803                 /* MIPS backend makes duplicate requests.  This is
 804                  * likely a bug in the backend.  Currently there's no
 805                  * point assigning more than one symbol to a
 806                  * breakpoint, because when it hits, we won't know
 807                  * what to print out.  But it's easier to fix it here
 808                  * before someone who understands MIPS has the time to
 809                  * look into it.  So turn the sanity check off on
 810                  * MIPS.  References:
 811                  *
 812                  *   http://lists.alioth.debian.org/pipermail/ltrace-devel/2012-November/000764.html
 813                  *   http://lists.alioth.debian.org/pipermail/ltrace-devel/2012-November/000770.html
 814                  */
 815 #ifndef __mips__
 816                 assert(bp->libsym == NULL);
 817                 bp->libsym = libsym;
 818 #endif
 819                 return 0;
 820         }
 821
 822         bp = malloc(sizeof(*bp));
 823         if (bp == NULL
 824             || breakpoint_init(bp, proc, bp_addr, libsym) < 0) {
 825         fail:
 826                 free(bp);
 827                 return -1;
 828         }
 829         if (proc_add_breakpoint(proc, bp) < 0) {
 830                 breakpoint_destroy(bp);
 831                 goto fail;
 832         }
 833
 834         if (breakpoint_turn_on(bp, proc) < 0) {
 835                 proc_remove_breakpoint(proc, bp);
 836                 breakpoint_destroy(bp);
 837                 goto fail;
 838         }
 839
 840         return 0;
 841 }
 842
 843 static enum callback_status
 844 cb_breakpoint_for_symbol(struct library_symbol *libsym, void *data)
 845 {
 846         return CBS_STOP_IF(breakpoint_for_symbol(libsym, data) < 0);
 847 }
 848
 849 static int
 850 proc_activate_latent_symbol(struct process *proc,
 851                             struct library_symbol *libsym)
 852 {
 853         assert(libsym->latent);
 854         libsym->latent = 0;
 855         debug(DEBUG_FUNCTION, "activated latent symbol");
 856         return breakpoint_for_symbol(libsym, proc);
 857 }
 858
 859 int
 860 proc_activate_delayed_symbol(struct process *proc,
 861                              struct library_symbol *libsym)
 862 {
 863         assert(libsym->delayed);
 864         libsym->delayed = 0;
 865         debug(DEBUG_FUNCTION, "activated delayed symbol");
 866         return breakpoint_for_symbol(libsym, proc);
 867 }
 868
 869 static enum callback_status
 870 activate_latent_in(struct process *proc, struct library *lib, void *data)
 871 {
 872         struct library_exported_name *exported;
 873         for (exported = data; exported != NULL; exported = exported->next) {
 874                 struct library_symbol *libsym = NULL;
 875                 while ((libsym = library_each_symbol(lib, libsym,
 876                                                      library_symbol_named_cb,
 877                                                      (void *)exported->name))
 878                        != NULL)
 879                         if (libsym->latent
 880                             && proc_activate_latent_symbol(proc, libsym) < 0)
 881                                 return CBS_FAIL;
 882         }
 883         return CBS_CONT;
 884 }
 885
 886 void
 887 proc_add_library(struct process *proc, struct library *lib)
 888 {
 889         assert(lib->next == NULL);
 890         lib->next = proc->libraries;
 891         proc->libraries = lib;
 892         debug(DEBUG_PROCESS, "added library %s@%p (%s) to %d",
 893               lib->soname, lib->base, lib->pathname, proc->pid);
 894
 895 #if defined(HAVE_LIBDW)
 896         Dwfl *dwfl = NULL;
 897
 898         /* Setup module tracking for libdwfl unwinding.  */
 899         struct process *leader = proc->leader;
 900         dwfl = leader->dwfl;
 901         if (dwfl == NULL) {
 902                 static const Dwfl_Callbacks proc_callbacks = {
 903                         .find_elf = dwfl_linux_proc_find_elf,
 904                         .find_debuginfo = dwfl_standard_find_debuginfo
 905                 };
 906                 dwfl = dwfl_begin(&proc_callbacks);
 907                 if (dwfl == NULL)
 908                         fprintf(stderr,
 909                                 "Couldn't initialize libdwfl unwinding "
 910                                 "for process %d: %s\n", leader->pid,
 911                                 dwfl_errmsg (-1));
 912         }
 913
 914         if (dwfl != NULL) {
 915                 dwfl_report_begin_add(dwfl);
 916                 if (dwfl_report_elf(dwfl, lib->soname,
 917                                     lib->pathname, -1,
 918                                     (GElf_Addr) lib->base,
 919                                     false) == NULL)
 920                         fprintf(stderr,
 921                                 "dwfl_report_elf %s@%p (%s) %d: %s\n",
 922                                 lib->soname, lib->base, lib->pathname,
 923                                 proc->pid, dwfl_errmsg (-1));
 924                 dwfl_report_end(dwfl, NULL, NULL);
 925
 926                 if (options.bt_depth > 0) {
 927                         if (leader->dwfl == NULL) {
 928                                 int r = dwfl_linux_proc_attach(dwfl,
 929                                                                leader->pid,
 930                                                                true);
 931                                 if (r == 0)
 932                                         leader->dwfl = dwfl;
 933                                 else {
 934                                         const char *msg;
 935                                         dwfl_end(dwfl);
 936                                         if (r < 0)
 937                                                 msg = dwfl_errmsg(-1);
 938                                         else
 939                                                 msg = strerror(r);
 940                                         fprintf(stderr, "Couldn't initialize "
 941                                                 "libdwfl (unwinding, prototype "
 942                                                 "import) for process %d: %s\n",
 943                                                 leader->pid, msg);
 944                                 }
 945                         }
 946                 }
 947         }
 948
 949         lib->dwfl = dwfl;
 950
 951 #endif /* defined(HAVE_LIBDW) */
 952
 953         /* Insert breakpoints for all active (non-latent) symbols.  */
 954         struct library_symbol *libsym = NULL;
 955         while ((libsym = library_each_symbol(lib, libsym,
 956                                              cb_breakpoint_for_symbol,
 957                                              proc)) != NULL)
 958                 fprintf(stderr,
 959                         "Couldn't insert breakpoint for %s to %d: %s.\n",
 960                         libsym->name, proc->pid, strerror(errno));
 961
 962         /* Look through export list of the new library and compare it
 963          * with latent symbols of all libraries (including this
 964          * library itself).  */
 965         struct library *lib2 = NULL;
 966         while ((lib2 = proc_each_library(proc, lib2, activate_latent_in,
 967                                          lib->exported_names)) != NULL)
 968                 fprintf(stderr,
 969                         "Couldn't activate latent symbols for %s in %d: %s.\n",
 970                         lib2->soname, proc->pid, strerror(errno));
 971 }
 972
 973 int
 974 proc_remove_library(struct process *proc, struct library *lib)
 975 {
 976         struct library **libp;
 977         for (libp = &proc->libraries; *libp != NULL; libp = &(*libp)->next)
 978                 if (*libp == lib) {
 979                         *libp = lib->next;
 980                         return 0;
 981                 }
 982         return -1;
 983 }
 984
 985 struct library *
 986 proc_each_library(struct process *proc, struct library *it,
 987                   enum callback_status (*cb)(struct process *proc,
 988                                              struct library *lib, void *data),
 989                   void *data)
 990 {
 991         if (it == NULL)
 992                 it = proc->libraries;
 993         else
 994                 it = it->next;
 995
 996         while (it != NULL) {
 997                 struct library *next = it->next;
 998
 999                 switch (cb(proc, it, data)) {
1000                 case CBS_FAIL:
1001                         /* XXX handle me */
1002                 case CBS_STOP:
1003                         return it;
1004                 case CBS_CONT:
1005                         break;
1006                 }
1007
1008                 it = next;
1009         }
1010
1011         return NULL;
1012 }
1013
1014 static void
1015 check_leader(struct process *proc)
1016 {
1017         /* Only the group leader should be getting the breakpoints and
1018          * thus have ->breakpoint initialized.  */
1019         assert(proc->leader != NULL);
1020         assert(proc->leader == proc);
1021         assert(proc->breakpoints != NULL);
1022 }
1023
1024 int
1025 proc_add_breakpoint(struct process *proc, struct breakpoint *bp)
1026 {
1027         debug(DEBUG_FUNCTION, "proc_add_breakpoint(pid=%d, %s@%p)",
1028               proc->pid, breakpoint_name(bp), bp->addr);
1029         check_leader(proc);
1030
1031         /* XXX We might merge bp->libsym instead of the following
1032          * assert, but that's not necessary right now.  Read the
1033          * comment in breakpoint_for_symbol.  */
1034         assert(dict_find(proc->breakpoints, &bp->addr) == NULL);
1035
1036         if (DICT_INSERT(proc->breakpoints, &bp->addr, &bp) < 0) {
1037                 fprintf(stderr,
1038                         "couldn't enter breakpoint %s@%p to dictionary: %s\n",
1039                         breakpoint_name(bp), bp->addr, strerror(errno));
1040                 return -1;
1041         }
1042
1043         return 0;
1044 }
1045
1046 void
1047 proc_remove_breakpoint(struct process *proc, struct breakpoint *bp)
1048 {
1049         debug(DEBUG_FUNCTION, "proc_remove_breakpoint(pid=%d, %s@%p)",
1050               proc->pid, breakpoint_name(bp), bp->addr);
1051         check_leader(proc);
1052         int rc = DICT_ERASE(proc->breakpoints, &bp->addr, struct breakpoint *,
1053                             NULL, NULL, NULL);
1054         assert(rc == 0);
1055 }
1056
1057 struct each_breakpoint_data
1058 {
1059         struct process *proc;
1060         enum callback_status (*cb)(struct process *proc,
1061                                    struct breakpoint *bp,
1062                                    void *data);
1063         void *cb_data;
1064 };
1065
1066 static enum callback_status
1067 each_breakpoint_cb(arch_addr_t *key, struct breakpoint **bpp, void *d)
1068 {
1069         struct each_breakpoint_data *data = d;
1070         return data->cb(data->proc, *bpp, data->cb_data);
1071 }
1072
1073 arch_addr_t *
1074 proc_each_breakpoint(struct process *proc, arch_addr_t *start,
1075                      enum callback_status (*cb)(struct process *proc,
1076                                                 struct breakpoint *bp,
1077                                                 void *data), void *data)
1078 {
1079         struct each_breakpoint_data dd = {
1080                 .proc = proc,
1081                 .cb = cb,
1082                 .cb_data = data,
1083         };
1084         return DICT_EACH(proc->breakpoints,
1085                          arch_addr_t, struct breakpoint *, start,
1086                          &each_breakpoint_cb, &dd);
1087 }
1088
1089 int
1090 proc_find_symbol(struct process *proc, struct library_symbol *sym,
1091                  struct library **retlib, struct library_symbol **retsym)
1092 {
1093         struct library *lib = sym->lib;
1094         assert(lib != NULL);
1095
1096         struct library *flib
1097                 = proc_each_library(proc, NULL, library_with_key_cb, &lib->key);
1098         if (flib == NULL)
1099                 return -1;
1100
1101         struct library_symbol *fsym
1102                 = library_each_symbol(flib, NULL, library_symbol_named_cb,
1103                                       (char *)sym->name);
1104         if (fsym == NULL)
1105                 return -1;
1106
1107         if (retlib != NULL)
1108                 *retlib = flib;
1109         if (retsym != NULL)
1110                 *retsym = fsym;
1111
1112         return 0;
1113 }
1114
1115 struct library_symbol *
1116 proc_each_symbol(struct process *proc, struct library_symbol *start_after,
1117                  enum callback_status (*cb)(struct library_symbol *, void *),
1118                  void *data)
1119 {
1120         struct library *lib;
1121         for (lib = start_after != NULL ? start_after->lib : proc->libraries;
1122              lib != NULL; lib = lib->next) {
1123                 start_after = library_each_symbol(lib, start_after, cb, data);
1124                 if (start_after != NULL)
1125                         return start_after;
1126         }
1127
1128         return NULL;
1129 }
1130
1131 #define DEF_READER(NAME, SIZE)                                          \
1132         int                                                             \
1133         NAME(struct process *proc, arch_addr_t addr,                    \
1134              uint##SIZE##_t *lp)                                        \
1135         {                                                               \
1136                 union {                                                 \
1137                         uint##SIZE##_t dst;                             \
1138                         char buf[0];                                    \
1139                 } u;                                                    \
1140                 if (umovebytes(proc, addr, &u.buf, sizeof(u.dst))       \
1141                     != sizeof(u.dst))                                   \
1142                         return -1;                                      \
1143                 *lp = u.dst;                                            \
1144                 return 0;                                               \
1145         }
1146
1147 DEF_READER(proc_read_8, 8)
1148 DEF_READER(proc_read_16, 16)
1149 DEF_READER(proc_read_32, 32)
1150 DEF_READER(proc_read_64, 64)
1151
1152 #undef DEF_READER