git.ozlabs.org Git - ccan/blob - ccan/tal/tal.c

   1 /* Licensed under BSD-MIT - see LICENSE file for details */
   2 #include <ccan/tal/tal.h>
   3 #include <ccan/compiler/compiler.h>
   4 #include <ccan/list/list.h>
   5 #include <ccan/take/take.h>
   6 #include <ccan/alignof/alignof.h>
   7 #include <assert.h>
   8 #include <stdio.h>
   9 #include <stddef.h>
  10 #include <string.h>
  11 #include <limits.h>
  12 #include <errno.h>
  13
  14 //#define TAL_DEBUG 1
  15
  16 #define NOTIFY_IS_DESTRUCTOR 512
  17
  18 /* 32-bit type field, first byte 0 in either endianness. */
  19 enum prop_type {
  20         CHILDREN = 0x00c1d500,
  21         NAME = 0x00111100,
  22         NOTIFIER = 0x00071f00,
  23         LENGTH = 0x00515300
  24 };
  25
  26 struct tal_hdr {
  27         struct list_node list;
  28         struct prop_hdr *prop;
  29         struct children *parent_child;
  30 };
  31
  32 struct prop_hdr {
  33         enum prop_type type;
  34         struct prop_hdr *next;
  35 };
  36
  37 struct children {
  38         struct prop_hdr hdr; /* CHILDREN */
  39         struct tal_hdr *parent;
  40         struct list_head children; /* Head of siblings. */
  41 };
  42
  43 struct name {
  44         struct prop_hdr hdr; /* NAME */
  45         char name[];
  46 };
  47
  48 struct length {
  49         struct prop_hdr hdr; /* LENGTH */
  50         size_t count;
  51 };
  52
  53 struct notifier {
  54         struct prop_hdr hdr; /* NOTIFIER */
  55         enum tal_notify_type types;
  56         union {
  57                 void (*notifyfn)(tal_t *, enum tal_notify_type, void *);
  58                 void (*destroy)(tal_t *); /* If NOTIFY_IS_DESTRUCTOR set */
  59         } u;
  60 };
  61
  62 static struct {
  63         struct tal_hdr hdr;
  64         struct children c;
  65 } null_parent = { { { &null_parent.hdr.list, &null_parent.hdr.list },
  66                     &null_parent.c.hdr, NULL },
  67                   { { CHILDREN, NULL },
  68                     &null_parent.hdr,
  69                     { { &null_parent.c.children.n,
  70                         &null_parent.c.children.n } }
  71                   }
  72 };
  73
  74
  75 static void *(*allocfn)(size_t size) = malloc;
  76 static void *(*resizefn)(void *, size_t size) = realloc;
  77 static void (*freefn)(void *) = free;
  78 static void (*errorfn)(const char *msg) = (void *)abort;
  79 static bool initialized = false;
  80 /* Count on non-destrutor notifiers; often stays zero. */
  81 static size_t notifiers = 0;
  82
  83 static inline void COLD call_error(const char *msg)
  84 {
  85         errorfn(msg);
  86 }
  87
  88 static bool get_destroying_bit(struct children *parent_child)
  89 {
  90         return (size_t)parent_child & 1;
  91 }
  92
  93 static void set_destroying_bit(struct children **parent_child)
  94 {
  95         *parent_child = (void *)((size_t)*parent_child | 1);
  96 }
  97
  98 static struct children *ignore_destroying_bit(struct children *parent_child)
  99 {
 100         return (void *)((size_t)parent_child & ~(size_t)1);
 101 }
 102
 103 /* This means valgrind can see leaks. */
 104 static void tal_cleanup(void)
 105 {
 106         struct tal_hdr *i;
 107
 108         while ((i = list_top(&null_parent.c.children, struct tal_hdr, list)))
 109                 list_del(&i->list);
 110
 111         /* Cleanup any taken pointers. */
 112         take_cleanup();
 113 }
 114
 115 /* For allocation failures inside ccan/take */
 116 static void take_alloc_failed(const void *p)
 117 {
 118         tal_free(p);
 119 }
 120
 121 /* We carefully start all real properties with a zero byte. */
 122 static bool is_literal(const struct prop_hdr *prop)
 123 {
 124         return ((char *)prop)[0] != 0;
 125 }
 126
 127 #ifndef NDEBUG
 128 static const void *bounds_start, *bounds_end;
 129
 130 static void update_bounds(const void *new, size_t size)
 131 {
 132         if (unlikely(!bounds_start)) {
 133                 bounds_start = new;
 134                 bounds_end = (char *)new + size;
 135         } else if (new < bounds_start)
 136                 bounds_start = new;
 137         else if ((char *)new + size > (char *)bounds_end)
 138                 bounds_end = (char *)new + size;
 139 }
 140
 141 static bool in_bounds(const void *p)
 142 {
 143         return !p
 144                 || (p >= (void *)&null_parent && p <= (void *)(&null_parent + 1))
 145                 || (p >= bounds_start && p <= bounds_end);
 146 }
 147 #else
 148 static void update_bounds(const void *new, size_t size)
 149 {
 150 }
 151
 152 static bool in_bounds(const void *p)
 153 {
 154         return true;
 155 }
 156 #endif
 157
 158 static void check_bounds(const void *p)
 159 {
 160         if (!in_bounds(p))
 161                 call_error("Not a valid header");
 162 }
 163
 164 static struct tal_hdr *to_tal_hdr(const void *ctx)
 165 {
 166         struct tal_hdr *t;
 167
 168         t = (struct tal_hdr *)((char *)ctx - sizeof(struct tal_hdr));
 169         check_bounds(t);
 170         check_bounds(ignore_destroying_bit(t->parent_child));
 171         check_bounds(t->list.next);
 172         check_bounds(t->list.prev);
 173         if (t->prop && !is_literal(t->prop))
 174                 check_bounds(t->prop);
 175         return t;
 176 }
 177
 178 static struct tal_hdr *to_tal_hdr_or_null(const void *ctx)
 179 {
 180         if (!ctx)
 181                 return &null_parent.hdr;
 182         return to_tal_hdr(ctx);
 183 }
 184
 185 static void *from_tal_hdr(const struct tal_hdr *hdr)
 186 {
 187         return (void *)(hdr + 1);
 188 }
 189
 190 #ifdef TAL_DEBUG
 191 static void *from_tal_hdr_or_null(struct tal_hdr *hdr)
 192 {
 193         if (hdr == &null_parent.hdr)
 194                 return NULL;
 195         return from_tal_hdr(hdr);
 196 }
 197
 198 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 199 {
 200         tal_check(from_tal_hdr_or_null(tal), "TAL_DEBUG ");
 201         return tal;
 202 }
 203 #else
 204 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 205 {
 206         return tal;
 207 }
 208 #endif
 209
 210 static void notify(const struct tal_hdr *ctx,
 211                    enum tal_notify_type type, const void *info)
 212 {
 213         const struct prop_hdr *p;
 214
 215         for (p = ctx->prop; p; p = p->next) {
 216                 struct notifier *n;
 217
 218                 if (is_literal(p))
 219                         break;
 220                 if (p->type != NOTIFIER)
 221                         continue;
 222                 n = (struct notifier *)p;
 223                 if (n->types & type) {
 224                         if (n->types & NOTIFY_IS_DESTRUCTOR)
 225                                 n->u.destroy(from_tal_hdr(ctx));
 226                         else
 227                                 n->u.notifyfn(from_tal_hdr(ctx), type,
 228                                               (void *)info);
 229                 }
 230         }
 231 }
 232
 233 static void *allocate(size_t size)
 234 {
 235         void *ret = allocfn(size);
 236         if (!ret)
 237                 call_error("allocation failed");
 238         else
 239                 update_bounds(ret, size);
 240         return ret;
 241 }
 242
 243 static struct prop_hdr **find_property_ptr(const struct tal_hdr *t,
 244                                            enum prop_type type)
 245 {
 246         struct prop_hdr **p;
 247
 248         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 249                 if (is_literal(*p)) {
 250                         if (type == NAME)
 251                                 return p;
 252                         break;
 253                 }
 254                 if ((*p)->type == type)
 255                         return p;
 256         }
 257         return NULL;
 258 }
 259
 260 static void *find_property(const struct tal_hdr *parent, enum prop_type type)
 261 {
 262         struct prop_hdr **p = find_property_ptr(parent, type);
 263
 264         if (p)
 265                 return *p;
 266         return NULL;
 267 }
 268
 269 static void init_property(struct prop_hdr *hdr,
 270                           struct tal_hdr *parent,
 271                           enum prop_type type)
 272 {
 273         hdr->type = type;
 274         hdr->next = parent->prop;
 275         parent->prop = hdr;
 276 }
 277
 278 static struct notifier *add_notifier_property(struct tal_hdr *t,
 279                                               enum tal_notify_type types,
 280                                               void (*fn)(void *,
 281                                                          enum tal_notify_type,
 282                                                          void *))
 283 {
 284         struct notifier *prop = allocate(sizeof(*prop));
 285         if (prop) {
 286                 init_property(&prop->hdr, t, NOTIFIER);
 287                 prop->types = types;
 288                 prop->u.notifyfn = fn;
 289         }
 290         return prop;
 291 }
 292
 293 static enum tal_notify_type del_notifier_property(struct tal_hdr *t,
 294                                                   void (*fn)(tal_t *,
 295                                                              enum tal_notify_type,
 296                                                              void *))
 297 {
 298         struct prop_hdr **p;
 299
 300         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 301                 struct notifier *n;
 302
 303                 if (is_literal(*p))
 304                         break;
 305                 if ((*p)->type != NOTIFIER)
 306                         continue;
 307                 n = (struct notifier *)*p;
 308                 if (n->u.notifyfn == fn) {
 309                         enum tal_notify_type types = n->types;
 310                         *p = (*p)->next;
 311                         freefn(n);
 312                         return types & ~NOTIFY_IS_DESTRUCTOR;
 313                 }
 314         }
 315         return 0;
 316 }
 317
 318 static struct name *add_name_property(struct tal_hdr *t, const char *name)
 319 {
 320         struct name *prop;
 321
 322         prop = allocate(sizeof(*prop) + strlen(name) + 1);
 323         if (prop) {
 324                 init_property(&prop->hdr, t, NAME);
 325                 strcpy(prop->name, name);
 326         }
 327         return prop;
 328 }
 329
 330 static struct children *add_child_property(struct tal_hdr *parent,
 331                                            struct tal_hdr *child)
 332 {
 333         struct children *prop = allocate(sizeof(*prop));
 334         if (prop) {
 335                 init_property(&prop->hdr, parent, CHILDREN);
 336                 prop->parent = parent;
 337                 list_head_init(&prop->children);
 338         }
 339         return prop;
 340 }
 341
 342 static bool add_child(struct tal_hdr *parent, struct tal_hdr *child)
 343 {
 344         struct children *children = find_property(parent, CHILDREN);
 345
 346         if (!children) {
 347                 if (unlikely(!initialized)) {
 348                         atexit(tal_cleanup);
 349                         take_allocfail(take_alloc_failed);
 350                         initialized = true;
 351                 }
 352                 children = add_child_property(parent, child);
 353                 if (!children)
 354                         return false;
 355         }
 356         list_add(&children->children, &child->list);
 357         child->parent_child = children;
 358         return true;
 359 }
 360
 361 static void del_tree(struct tal_hdr *t, const tal_t *orig)
 362 {
 363         struct prop_hdr **prop, *p, *next;
 364
 365         /* Already being destroyed?  Don't loop. */
 366         if (unlikely(get_destroying_bit(t->parent_child)))
 367                 return;
 368
 369         set_destroying_bit(&t->parent_child);
 370
 371         /* Call free notifiers. */
 372         notify(t, TAL_NOTIFY_FREE, (tal_t *)orig);
 373
 374         /* Now free children and groups. */
 375         prop = find_property_ptr(t, CHILDREN);
 376         if (prop) {
 377                 struct tal_hdr *i;
 378                 struct children *c = (struct children *)*prop;
 379
 380                 while ((i = list_top(&c->children, struct tal_hdr, list))) {
 381                         list_del(&i->list);
 382                         del_tree(i, orig);
 383                 }
 384         }
 385
 386         /* Finally free our properties. */
 387         for (p = t->prop; p && !is_literal(p); p = next) {
 388                 next = p->next;
 389                 /* LENGTH is appended, so don't free separately! */
 390                 if (p->type != LENGTH)
 391                         freefn(p);
 392         }
 393         freefn(t);
 394 }
 395
 396 void *tal_alloc_(const tal_t *ctx, size_t size, bool clear, const char *label)
 397 {
 398         struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
 399
 400         child = allocate(sizeof(struct tal_hdr) + size);
 401         if (!child)
 402                 return NULL;
 403         if (clear)
 404                 memset(from_tal_hdr(child), 0, size);
 405         child->prop = (void *)label;
 406         if (!add_child(parent, child)) {
 407                 freefn(child);
 408                 return NULL;
 409         }
 410         debug_tal(parent);
 411         if (notifiers)
 412                 notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(child));
 413         return from_tal_hdr(debug_tal(child));
 414 }
 415
 416 static bool adjust_size(size_t *size, size_t count)
 417 {
 418         const size_t extra = sizeof(struct tal_hdr) + sizeof(struct length)*2;
 419
 420         /* Multiplication wrap */
 421         if (count && unlikely(*size * count / *size != count))
 422                 goto overflow;
 423
 424         *size *= count;
 425
 426         /* Make sure we don't wrap adding header/tailer. */
 427         if (*size + extra < extra)
 428                 goto overflow;
 429         return true;
 430 overflow:
 431         call_error("allocation size overflow");
 432         return false;
 433 }
 434
 435 static size_t extra_for_length(size_t size)
 436 {
 437         size_t extra;
 438         const size_t align = ALIGNOF(struct length);
 439
 440         /* Round up size, and add tailer. */
 441         extra = ((size + align-1) & ~(align-1)) - size;
 442         extra += sizeof(struct length);
 443         return extra;
 444 }
 445
 446 void *tal_alloc_arr_(const tal_t *ctx, size_t size, size_t count, bool clear,
 447                      bool add_count, const char *label)
 448 {
 449         void *ret;
 450
 451         if (!adjust_size(&size, count))
 452                 return NULL;
 453
 454         if (add_count)
 455                 size += extra_for_length(size);
 456
 457         ret = tal_alloc_(ctx, size, clear, label);
 458         if (unlikely(!ret))
 459                 return ret;
 460
 461         if (add_count) {
 462                 struct length *lprop;
 463                 lprop = (struct length *)((char *)ret + size) - 1;
 464                 init_property(&lprop->hdr, to_tal_hdr(ret), LENGTH);
 465                 lprop->count = count;
 466         }
 467         return ret;
 468 }
 469
 470 void *tal_free(const tal_t *ctx)
 471 {
 472         if (ctx) {
 473                 struct tal_hdr *t;
 474                 int saved_errno = errno;
 475                 t = debug_tal(to_tal_hdr(ctx));
 476                 if (notifiers)
 477                         notify(ignore_destroying_bit(t->parent_child)->parent,
 478                                TAL_NOTIFY_DEL_CHILD, ctx);
 479                 list_del(&t->list);
 480                 del_tree(t, ctx);
 481                 errno = saved_errno;
 482         }
 483         return NULL;
 484 }
 485
 486 void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
 487 {
 488         if (ctx) {
 489                 struct tal_hdr *newpar, *t, *old_parent;
 490
 491                 newpar = debug_tal(to_tal_hdr_or_null(new_parent));
 492                 t = debug_tal(to_tal_hdr(ctx));
 493
 494                 /* Unlink it from old parent. */
 495                 list_del(&t->list);
 496                 old_parent = ignore_destroying_bit(t->parent_child)->parent;
 497
 498                 if (unlikely(!add_child(newpar, t))) {
 499                         /* We can always add to old parent, becuase it has a
 500                          * children property already. */
 501                         if (!add_child(old_parent, t))
 502                                 abort();
 503                         return NULL;
 504                 }
 505                 debug_tal(newpar);
 506                 if (notifiers)
 507                         notify(t, TAL_NOTIFY_STEAL, new_parent);
 508         }
 509         return (void *)ctx;
 510 }
 511
 512 bool tal_add_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 513 {
 514         tal_t *t = debug_tal(to_tal_hdr(ctx));
 515         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
 516                                      (void *)destroy);
 517 }
 518
 519 bool tal_add_notifier_(const tal_t *ctx, enum tal_notify_type types,
 520                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 521 {
 522         tal_t *t = debug_tal(to_tal_hdr(ctx));
 523         struct notifier *n;
 524
 525         assert(types);
 526         assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
 527                           | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
 528                           | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
 529                           | TAL_NOTIFY_ADD_NOTIFIER
 530                           | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
 531
 532         /* Don't call notifier about itself: set types after! */
 533         n = add_notifier_property(t, 0, callback);
 534         if (unlikely(!n))
 535                 return false;
 536
 537         if (notifiers)
 538                 notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback);
 539
 540         n->types = types;
 541         if (types != TAL_NOTIFY_FREE)
 542                 notifiers++;
 543         return true;
 544 }
 545
 546 bool tal_del_notifier_(const tal_t *ctx,
 547                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 548 {
 549         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 550         enum tal_notify_type types;
 551
 552         types = del_notifier_property(t, callback);
 553         if (types) {
 554                 notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback);
 555                 if (types != TAL_NOTIFY_FREE)
 556                         notifiers--;
 557                 return true;
 558         }
 559         return false;
 560 }
 561
 562 bool tal_del_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 563 {
 564         return tal_del_notifier_(ctx, (void *)destroy);
 565 }
 566
 567 bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
 568 {
 569         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 570         struct prop_hdr **prop = find_property_ptr(t, NAME);
 571
 572         /* Get rid of any old name */
 573         if (prop) {
 574                 struct name *name = (struct name *)*prop;
 575                 if (is_literal(&name->hdr))
 576                         *prop = NULL;
 577                 else {
 578                         *prop = name->hdr.next;
 579                         freefn(name);
 580                 }
 581         }
 582
 583         if (literal && name[0]) {
 584                 struct prop_hdr **p;
 585
 586                 /* Append literal. */
 587                 for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
 588                 *p = (struct prop_hdr *)name;
 589         } else if (!add_name_property(t, name))
 590                 return false;
 591
 592         debug_tal(t);
 593         if (notifiers)
 594                 notify(t, TAL_NOTIFY_RENAME, name);
 595         return true;
 596 }
 597
 598 const char *tal_name(const tal_t *t)
 599 {
 600         struct name *n;
 601
 602         n = find_property(debug_tal(to_tal_hdr(t)), NAME);
 603         if (!n)
 604                 return NULL;
 605
 606         if (is_literal(&n->hdr))
 607                 return (const char *)n;
 608         return n->name;
 609 }
 610
 611 size_t tal_count(const tal_t *ptr)
 612 {
 613         struct length *l;
 614
 615         l = find_property(debug_tal(to_tal_hdr(ptr)), LENGTH);
 616         if (!l)
 617                 return 0;
 618         return l->count;
 619 }
 620
 621 /* Start one past first child: make stopping natural in circ. list. */
 622 static struct tal_hdr *first_child(struct tal_hdr *parent)
 623 {
 624         struct children *child;
 625
 626         child = find_property(parent, CHILDREN);
 627         if (!child)
 628                 return NULL;
 629
 630         return list_top(&child->children, struct tal_hdr, list);
 631 }
 632
 633 tal_t *tal_first(const tal_t *root)
 634 {
 635         struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
 636
 637         c = first_child(t);
 638         if (!c)
 639                 return NULL;
 640         return from_tal_hdr(c);
 641 }
 642
 643 tal_t *tal_next(const tal_t *root, const tal_t *prev)
 644 {
 645         struct tal_hdr *c, *t = debug_tal(to_tal_hdr(prev)), *top;
 646
 647         /* Children? */
 648         c = first_child(t);
 649         if (c)
 650                 return from_tal_hdr(c);
 651
 652         top = to_tal_hdr_or_null(root);
 653         do {
 654                 struct tal_hdr *next;
 655                 struct list_node *end;
 656
 657                 end = &ignore_destroying_bit(t->parent_child)->children.n;
 658
 659                 next = list_entry(t->list.next, struct tal_hdr, list);
 660                 if (&next->list != end)
 661                         return from_tal_hdr(next);
 662
 663                 /* OK, go back to parent. */
 664                 t = ignore_destroying_bit(t->parent_child)->parent;
 665         } while (t != top);
 666
 667         return NULL;
 668 }
 669
 670 tal_t *tal_parent(const tal_t *ctx)
 671 {
 672         struct tal_hdr *t;
 673
 674         if (!ctx)
 675                 return NULL;
 676
 677         t = debug_tal(to_tal_hdr(ctx));
 678         if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
 679                 return NULL;
 680         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
 681 }
 682
 683 bool tal_resize_(tal_t **ctxp, size_t size, size_t count)
 684 {
 685         struct tal_hdr *old_t, *t;
 686         struct children *child;
 687         struct prop_hdr **lenp;
 688         struct length len;
 689         size_t extra = 0;
 690
 691         old_t = debug_tal(to_tal_hdr(*ctxp));
 692
 693         if (!adjust_size(&size, count))
 694                 return false;
 695
 696         lenp = find_property_ptr(old_t, LENGTH);
 697         if (lenp) {
 698                 /* Copy here, in case we're shrinking! */
 699                 len = *(struct length *)*lenp;
 700                 extra = extra_for_length(size);
 701         }
 702
 703         t = resizefn(old_t, sizeof(struct tal_hdr) + size + extra);
 704         if (!t) {
 705                 call_error("Reallocation failure");
 706                 return false;
 707         }
 708
 709         /* Copy length to end. */
 710         if (lenp) {
 711                 struct length *new_len;
 712
 713                 new_len = (struct length *)((char *)(t + 1) + size);
 714                 len.count = count;
 715                 *new_len = len;
 716
 717                 /* Be careful replacing next ptr; could be old hdr. */
 718                 if (lenp == &old_t->prop)
 719                         t->prop = &new_len->hdr;
 720                 else
 721                         *lenp = &new_len->hdr;
 722         }
 723
 724         update_bounds(t, sizeof(struct tal_hdr) + size + extra);
 725
 726         /* If it didn't move, we're done! */
 727         if (t != old_t) {
 728                 /* Fix up linked list pointers. */
 729                 t->list.next->prev = t->list.prev->next = &t->list;
 730
 731                 /* Fix up child property's parent pointer. */
 732                 child = find_property(t, CHILDREN);
 733                 if (child) {
 734                         assert(child->parent == old_t);
 735                         child->parent = t;
 736                 }
 737                 *ctxp = from_tal_hdr(debug_tal(t));
 738                 if (notifiers)
 739                         notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t));
 740         }
 741         if (notifiers)
 742                 notify(t, TAL_NOTIFY_RESIZE, (void *)size);
 743
 744         return true;
 745 }
 746
 747 bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
 748 {
 749         struct length *l;
 750         size_t old_count;
 751         bool ret = false;
 752
 753         l = find_property(debug_tal(to_tal_hdr(*ctxp)), LENGTH);
 754         old_count = l->count;
 755
 756         /* Check for additive overflow */
 757         if (old_count + count < count) {
 758                 call_error("dup size overflow");
 759                 goto out;
 760         }
 761
 762         /* Don't point src inside thing we're expanding! */
 763         assert(src < *ctxp
 764                || (char *)src >= (char *)(*ctxp) + (size * old_count));
 765
 766         if (!tal_resize_(ctxp, size, old_count + count))
 767                 goto out;
 768
 769         memcpy((char *)*ctxp + size * old_count, src, count * size);
 770         ret = true;
 771
 772 out:
 773         if (taken(src))
 774                 tal_free(src);
 775         return ret;
 776 }
 777
 778 void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
 779                size_t n, size_t extra, bool add_count,
 780                const char *label)
 781 {
 782         void *ret;
 783         size_t nbytes = size;
 784
 785         if (!adjust_size(&nbytes, n)) {
 786                 if (taken(p))
 787                         tal_free(p);
 788                 return NULL;
 789         }
 790
 791         /* Beware addition overflow! */
 792         if (n + extra < n) {
 793                 call_error("dup size overflow");
 794                 if (taken(p))
 795                         tal_free(p);
 796                 return NULL;
 797         }
 798
 799         if (taken(p)) {
 800                 if (unlikely(!p))
 801                         return NULL;
 802                 if (unlikely(!tal_resize_((void **)&p, size, n + extra)))
 803                         return tal_free(p);
 804                 if (unlikely(!tal_steal(ctx, p)))
 805                         return tal_free(p);
 806                 return (void *)p;
 807         }
 808
 809         ret = tal_alloc_arr_(ctx, size, n + extra, false, add_count, label);
 810         if (ret)
 811                 memcpy(ret, p, nbytes);
 812         return ret;
 813 }
 814
 815 void tal_set_backend(void *(*alloc_fn)(size_t size),
 816                      void *(*resize_fn)(void *, size_t size),
 817                      void (*free_fn)(void *),
 818                      void (*error_fn)(const char *msg))
 819 {
 820         if (alloc_fn)
 821                 allocfn = alloc_fn;
 822         if (resize_fn)
 823                 resizefn = resize_fn;
 824         if (free_fn)
 825                 freefn = free_fn;
 826         if (error_fn)
 827                 errorfn = error_fn;
 828 }
 829
 830 #ifdef CCAN_TAL_DEBUG
 831 static void dump_node(unsigned int indent, const struct tal_hdr *t)
 832 {
 833         unsigned int i;
 834         const struct prop_hdr *p;
 835
 836         for (i = 0; i < indent; i++)
 837                 printf("  ");
 838         printf("%p", t);
 839         for (p = t->prop; p; p = p->next) {
 840                 struct children *c;
 841                 struct name *n;
 842                 struct notifier *no;
 843                 struct length *l;
 844                 if (is_literal(p)) {
 845                         printf(" \"%s\"", (const char *)p);
 846                         break;
 847                 }
 848                 switch (p->type) {
 849                 case CHILDREN:
 850                         c = (struct children *)p;
 851                         printf(" CHILDREN(%p):parent=%p,children={%p,%p}\n",
 852                                p, c->parent,
 853                                c->children.n.prev, c->children.n.next);
 854                         break;
 855                 case NAME:
 856                         n = (struct name *)p;
 857                         printf(" NAME(%p):%s", p, n->name);
 858                         break;
 859                 case NOTIFIER:
 860                         no = (struct notifier *)p;
 861                         printf(" NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
 862                         break;
 863                 case LENGTH:
 864                         l = (struct length *)p;
 865                         printf(" LENGTH(%p):count=%zu", p, l->count);
 866                         break;
 867                 default:
 868                         printf(" **UNKNOWN(%p):%i**", p, p->type);
 869                 }
 870         }
 871         printf("\n");
 872 }
 873
 874 static void tal_dump_(unsigned int level, const struct tal_hdr *t)
 875 {
 876         struct children *children;
 877
 878         dump_node(level, t);
 879
 880         children = find_property(t, CHILDREN);
 881         if (children) {
 882                 struct tal_hdr *i;
 883
 884                 list_for_each(&children->children, i, list)
 885                         tal_dump_(level + 1, i);
 886         }
 887 }
 888
 889 void tal_dump(void)
 890 {
 891         tal_dump_(0, &null_parent.hdr);
 892 }
 893 #endif /* CCAN_TAL_DEBUG */
 894
 895 #ifndef NDEBUG
 896 static bool check_err(struct tal_hdr *t, const char *errorstr,
 897                       const char *errmsg)
 898 {
 899         if (errorstr) {
 900                 /* Try not to malloc: it may be corrupted. */
 901                 char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
 902                 sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
 903                 call_error(msg);
 904         }
 905         return false;
 906 }
 907
 908 static bool check_node(struct children *parent_child,
 909                        struct tal_hdr *t, const char *errorstr)
 910 {
 911         struct prop_hdr *p;
 912         struct name *name = NULL;
 913         struct children *children = NULL;
 914         struct length *length = NULL;
 915
 916         if (!in_bounds(t))
 917                 return check_err(t, errorstr, "invalid pointer");
 918
 919         if (ignore_destroying_bit(t->parent_child) != parent_child)
 920                 return check_err(t, errorstr, "incorrect parent");
 921
 922         for (p = t->prop; p; p = p->next) {
 923                 if (is_literal(p)) {
 924                         if (name)
 925                                 return check_err(t, errorstr,
 926                                                  "has extra literal");
 927                         name = (struct name *)p;
 928                         break;
 929                 }
 930                 if (!in_bounds(p))
 931                         return check_err(t, errorstr,
 932                                          "has bad property pointer");
 933
 934                 switch (p->type) {
 935                 case CHILDREN:
 936                         if (children)
 937                                 return check_err(t, errorstr,
 938                                                  "has two child nodes");
 939                         children = (struct children *)p;
 940                         break;
 941                 case LENGTH:
 942                         if (length)
 943                                 return check_err(t, errorstr,
 944                                                  "has two lengths");
 945                         length = (struct length *)p;
 946                         break;
 947                 case NOTIFIER:
 948                         break;
 949                 case NAME:
 950                         if (name)
 951                                 return check_err(t, errorstr,
 952                                                  "has two names");
 953                         name = (struct name *)p;
 954                         break;
 955                 default:
 956                         return check_err(t, errorstr, "has unknown property");
 957                 }
 958         }
 959         if (children) {
 960                 struct tal_hdr *i;
 961
 962                 if (!list_check(&children->children, errorstr))
 963                         return false;
 964                 list_for_each(&children->children, i, list) {
 965                         if (!check_node(children, i, errorstr))
 966                                 return false;
 967                 }
 968         }
 969         return true;
 970 }
 971
 972 bool tal_check(const tal_t *ctx, const char *errorstr)
 973 {
 974         struct tal_hdr *t = to_tal_hdr_or_null(ctx);
 975
 976         return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
 977 }
 978 #else /* NDEBUG */
 979 bool tal_check(const tal_t *ctx, const char *errorstr)
 980 {
 981         return true;
 982 }
 983 #endif