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/alignof/alignof.h>
   6 #include <assert.h>
   7 #include <stdio.h>
   8 #include <stddef.h>
   9 #include <string.h>
  10 #include <limits.h>
  11 #include <stdint.h>
  12 #include <errno.h>
  13
  14 //#define TAL_DEBUG 1
  15
  16 #define NOTIFY_IS_DESTRUCTOR 512
  17 #define NOTIFY_EXTRA_ARG 1024
  18
  19 /* This makes our parent_child ptr stand out for to_tal_hdr checks */
  20 #define TAL_PTR_OBFUSTICATOR ((intptr_t)0x1984200820142016ULL)
  21
  22 /* 32-bit type field, first byte 0 in either endianness. */
  23 enum prop_type {
  24         CHILDREN = 0x00c1d500,
  25         NAME = 0x00111100,
  26         NOTIFIER = 0x00071f00,
  27 };
  28
  29 struct tal_hdr {
  30         struct list_node list;
  31         struct prop_hdr *prop;
  32         /* XOR with TAL_PTR_OBFUSTICATOR */
  33         intptr_t parent_child;
  34         size_t bytelen;
  35 };
  36
  37 struct prop_hdr {
  38         enum prop_type type;
  39         struct prop_hdr *next;
  40 };
  41
  42 struct children {
  43         struct prop_hdr hdr; /* CHILDREN */
  44         struct tal_hdr *parent;
  45         struct list_head children; /* Head of siblings. */
  46 };
  47
  48 struct name {
  49         struct prop_hdr hdr; /* NAME */
  50         char name[];
  51 };
  52
  53 struct notifier {
  54         struct prop_hdr hdr; /* NOTIFIER */
  55         enum tal_notify_type types;
  56         union notifier_cb {
  57                 void (*notifyfn)(tal_t *, enum tal_notify_type, void *);
  58                 void (*destroy)(tal_t *); /* If NOTIFY_IS_DESTRUCTOR set */
  59                 void (*destroy2)(tal_t *, void *); /* If NOTIFY_EXTRA_ARG */
  60         } u;
  61 };
  62
  63 /* Extra arg */
  64 struct notifier_extra_arg {
  65         struct notifier n;
  66         void *arg;
  67 };
  68
  69 #define EXTRA_ARG(n) (((struct notifier_extra_arg *)(n))->arg)
  70
  71 static struct {
  72         struct tal_hdr hdr;
  73         struct children c;
  74 } null_parent = { { { &null_parent.hdr.list, &null_parent.hdr.list },
  75                     &null_parent.c.hdr, TAL_PTR_OBFUSTICATOR, 0 },
  76                   { { CHILDREN, NULL },
  77                     &null_parent.hdr,
  78                     { { &null_parent.c.children.n,
  79                         &null_parent.c.children.n } }
  80                   }
  81 };
  82
  83
  84 static void *(*allocfn)(size_t size) = malloc;
  85 static void *(*resizefn)(void *, size_t size) = realloc;
  86 static void (*freefn)(void *) = free;
  87 static void (*errorfn)(const char *msg) = (void *)abort;
  88 /* Count on non-destrutor notifiers; often stays zero. */
  89 static size_t notifiers = 0;
  90
  91 static inline void COLD call_error(const char *msg)
  92 {
  93         errorfn(msg);
  94 }
  95
  96 static bool get_destroying_bit(intptr_t parent_child)
  97 {
  98         return parent_child & 1;
  99 }
 100
 101 static void set_destroying_bit(intptr_t *parent_child)
 102 {
 103         *parent_child |= 1;
 104 }
 105
 106 static struct children *ignore_destroying_bit(intptr_t parent_child)
 107 {
 108         return (void *)((parent_child ^ TAL_PTR_OBFUSTICATOR) & ~(intptr_t)1);
 109 }
 110
 111 /* This means valgrind can see leaks. */
 112 void tal_cleanup(void)
 113 {
 114         struct tal_hdr *i;
 115
 116         while ((i = list_top(&null_parent.c.children, struct tal_hdr, list))) {
 117                 list_del(&i->list);
 118                 memset(i, 0, sizeof(*i));
 119         }
 120
 121         /* Cleanup any taken pointers. */
 122         take_cleanup();
 123 }
 124
 125 /* We carefully start all real properties with a zero byte. */
 126 static bool is_literal(const struct prop_hdr *prop)
 127 {
 128         return ((char *)prop)[0] != 0;
 129 }
 130
 131 #ifndef NDEBUG
 132 static const void *bounds_start, *bounds_end;
 133
 134 static void update_bounds(const void *new, size_t size)
 135 {
 136         if (unlikely(!bounds_start)) {
 137                 bounds_start = new;
 138                 bounds_end = (char *)new + size;
 139         } else if (new < bounds_start)
 140                 bounds_start = new;
 141         else if ((char *)new + size > (char *)bounds_end)
 142                 bounds_end = (char *)new + size;
 143 }
 144
 145 static bool in_bounds(const void *p)
 146 {
 147         return !p
 148                 || (p >= (void *)&null_parent && p <= (void *)(&null_parent + 1))
 149                 || (p >= bounds_start && p <= bounds_end);
 150 }
 151 #else
 152 static void update_bounds(const void *new, size_t size)
 153 {
 154 }
 155
 156 static bool in_bounds(const void *p)
 157 {
 158         return true;
 159 }
 160 #endif
 161
 162 static void check_bounds(const void *p)
 163 {
 164         if (!in_bounds(p))
 165                 call_error("Not a valid header");
 166 }
 167
 168 static struct tal_hdr *to_tal_hdr(const void *ctx)
 169 {
 170         struct tal_hdr *t;
 171
 172         t = (struct tal_hdr *)((char *)ctx - sizeof(struct tal_hdr));
 173         check_bounds(t);
 174         check_bounds(ignore_destroying_bit(t->parent_child));
 175         check_bounds(t->list.next);
 176         check_bounds(t->list.prev);
 177         if (t->prop && !is_literal(t->prop))
 178                 check_bounds(t->prop);
 179         return t;
 180 }
 181
 182 static struct tal_hdr *to_tal_hdr_or_null(const void *ctx)
 183 {
 184         if (!ctx)
 185                 return &null_parent.hdr;
 186         return to_tal_hdr(ctx);
 187 }
 188
 189 static void *from_tal_hdr(const struct tal_hdr *hdr)
 190 {
 191         return (void *)(hdr + 1);
 192 }
 193
 194 static void *from_tal_hdr_or_null(const struct tal_hdr *hdr)
 195 {
 196         if (hdr == &null_parent.hdr)
 197                 return NULL;
 198         return from_tal_hdr(hdr);
 199 }
 200
 201 #ifdef TAL_DEBUG
 202 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 203 {
 204         tal_check(from_tal_hdr_or_null(tal), "TAL_DEBUG ");
 205         return tal;
 206 }
 207 #else
 208 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 209 {
 210         return tal;
 211 }
 212 #endif
 213
 214 static void notify(const struct tal_hdr *ctx,
 215                    enum tal_notify_type type, const void *info,
 216                    int saved_errno)
 217 {
 218         const struct prop_hdr *p;
 219
 220         for (p = ctx->prop; p; p = p->next) {
 221                 struct notifier *n;
 222
 223                 if (is_literal(p))
 224                         break;
 225                 if (p->type != NOTIFIER)
 226                         continue;
 227                 n = (struct notifier *)p;
 228                 if (n->types & type) {
 229                         errno = saved_errno;
 230                         if (n->types & NOTIFY_IS_DESTRUCTOR) {
 231                                 /* Blatt this notifier in case it tries to
 232                                  * tal_del_destructor() from inside */
 233                                 union notifier_cb cb = n->u;
 234                                 /* It's a union, so this NULLs destroy2 too! */
 235                                 n->u.destroy = NULL;
 236                                 if (n->types & NOTIFY_EXTRA_ARG)
 237                                         cb.destroy2(from_tal_hdr(ctx),
 238                                                     EXTRA_ARG(n));
 239                                 else
 240                                         cb.destroy(from_tal_hdr(ctx));
 241                         } else
 242                                 n->u.notifyfn(from_tal_hdr_or_null(ctx), type,
 243                                               (void *)info);
 244                 }
 245         }
 246 }
 247
 248 static void *allocate(size_t size)
 249 {
 250         void *ret = allocfn(size);
 251         if (!ret)
 252                 call_error("allocation failed");
 253         else
 254                 update_bounds(ret, size);
 255         return ret;
 256 }
 257
 258 static struct prop_hdr **find_property_ptr(const struct tal_hdr *t,
 259                                            enum prop_type type)
 260 {
 261         struct prop_hdr **p;
 262
 263         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 264                 if (is_literal(*p)) {
 265                         if (type == NAME)
 266                                 return p;
 267                         break;
 268                 }
 269                 if ((*p)->type == type)
 270                         return p;
 271         }
 272         return NULL;
 273 }
 274
 275 static void *find_property(const struct tal_hdr *parent, enum prop_type type)
 276 {
 277         struct prop_hdr **p = find_property_ptr(parent, type);
 278
 279         if (p)
 280                 return *p;
 281         return NULL;
 282 }
 283
 284 static void init_property(struct prop_hdr *hdr,
 285                           struct tal_hdr *parent,
 286                           enum prop_type type)
 287 {
 288         hdr->type = type;
 289         hdr->next = parent->prop;
 290         parent->prop = hdr;
 291 }
 292
 293 static struct notifier *add_notifier_property(struct tal_hdr *t,
 294                                               enum tal_notify_type types,
 295                                               void (*fn)(void *,
 296                                                          enum tal_notify_type,
 297                                                          void *),
 298                                               void *extra_arg)
 299 {
 300         struct notifier *prop;
 301
 302         if (types & NOTIFY_EXTRA_ARG)
 303                 prop = allocate(sizeof(struct notifier_extra_arg));
 304         else
 305                 prop = allocate(sizeof(struct notifier));
 306
 307         if (prop) {
 308                 init_property(&prop->hdr, t, NOTIFIER);
 309                 prop->types = types;
 310                 prop->u.notifyfn = fn;
 311                 if (types & NOTIFY_EXTRA_ARG)
 312                         EXTRA_ARG(prop) = extra_arg;
 313         }
 314         return prop;
 315 }
 316
 317 static enum tal_notify_type del_notifier_property(struct tal_hdr *t,
 318                                                   void (*fn)(tal_t *,
 319                                                              enum tal_notify_type,
 320                                                              void *),
 321                                                   bool match_extra_arg,
 322                                                   void *extra_arg)
 323 {
 324         struct prop_hdr **p;
 325
 326         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 327                 struct notifier *n;
 328                 enum tal_notify_type types;
 329
 330                 if (is_literal(*p))
 331                         break;
 332                 if ((*p)->type != NOTIFIER)
 333                         continue;
 334                 n = (struct notifier *)*p;
 335                 if (n->u.notifyfn != fn)
 336                         continue;
 337
 338                 types = n->types;
 339                 if ((types & NOTIFY_EXTRA_ARG)
 340                     && match_extra_arg
 341                     && extra_arg != EXTRA_ARG(n))
 342                         continue;
 343
 344                 *p = (*p)->next;
 345                 freefn(n);
 346                 return types & ~(NOTIFY_IS_DESTRUCTOR|NOTIFY_EXTRA_ARG);
 347         }
 348         return 0;
 349 }
 350
 351 static struct name *add_name_property(struct tal_hdr *t, const char *name)
 352 {
 353         struct name *prop;
 354
 355         prop = allocate(sizeof(*prop) + strlen(name) + 1);
 356         if (prop) {
 357                 init_property(&prop->hdr, t, NAME);
 358                 strcpy(prop->name, name);
 359         }
 360         return prop;
 361 }
 362
 363 static struct children *add_child_property(struct tal_hdr *parent,
 364                                            struct tal_hdr *child UNNEEDED)
 365 {
 366         struct children *prop = allocate(sizeof(*prop));
 367         if (prop) {
 368                 init_property(&prop->hdr, parent, CHILDREN);
 369                 prop->parent = parent;
 370                 list_head_init(&prop->children);
 371         }
 372         return prop;
 373 }
 374
 375 static bool add_child(struct tal_hdr *parent, struct tal_hdr *child)
 376 {
 377         struct children *children = find_property(parent, CHILDREN);
 378
 379         if (!children) {
 380                 children = add_child_property(parent, child);
 381                 if (!children)
 382                         return false;
 383         }
 384         list_add(&children->children, &child->list);
 385         child->parent_child = (intptr_t)children ^ TAL_PTR_OBFUSTICATOR;
 386         return true;
 387 }
 388
 389 static void del_tree(struct tal_hdr *t, const tal_t *orig, int saved_errno)
 390 {
 391         struct prop_hdr **prop, *p, *next;
 392
 393         assert(!taken(from_tal_hdr(t)));
 394
 395         /* Already being destroyed?  Don't loop. */
 396         if (unlikely(get_destroying_bit(t->parent_child)))
 397                 return;
 398
 399         set_destroying_bit(&t->parent_child);
 400
 401         /* Call free notifiers. */
 402         notify(t, TAL_NOTIFY_FREE, (tal_t *)orig, saved_errno);
 403
 404         /* Now free children and groups. */
 405         prop = find_property_ptr(t, CHILDREN);
 406         if (prop) {
 407                 struct tal_hdr *i;
 408                 struct children *c = (struct children *)*prop;
 409
 410                 while ((i = list_top(&c->children, struct tal_hdr, list))) {
 411                         list_del(&i->list);
 412                         del_tree(i, orig, saved_errno);
 413                 }
 414         }
 415
 416         /* Finally free our properties. */
 417         for (p = t->prop; p && !is_literal(p); p = next) {
 418                 next = p->next;
 419                 freefn(p);
 420         }
 421         freefn(t);
 422 }
 423
 424 void *tal_alloc_(const tal_t *ctx, size_t size, bool clear, const char *label)
 425 {
 426         struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
 427
 428         child = allocate(sizeof(struct tal_hdr) + size);
 429         if (!child)
 430                 return NULL;
 431         if (clear)
 432                 memset(from_tal_hdr(child), 0, size);
 433         child->prop = (void *)label;
 434         child->bytelen = size;
 435
 436         if (!add_child(parent, child)) {
 437                 freefn(child);
 438                 return NULL;
 439         }
 440         debug_tal(parent);
 441         if (notifiers)
 442                 notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(child), 0);
 443         return from_tal_hdr(debug_tal(child));
 444 }
 445
 446 static bool adjust_size(size_t *size, size_t count)
 447 {
 448         const size_t extra = sizeof(struct tal_hdr);
 449
 450         /* Multiplication wrap */
 451         if (count && unlikely(*size * count / *size != count))
 452                 goto overflow;
 453
 454         *size *= count;
 455
 456         /* Make sure we don't wrap adding header. */
 457         if (*size + extra < extra)
 458                 goto overflow;
 459         return true;
 460 overflow:
 461         call_error("allocation size overflow");
 462         return false;
 463 }
 464
 465 void *tal_alloc_arr_(const tal_t *ctx, size_t size, size_t count, bool clear,
 466                      const char *label)
 467 {
 468         if (!adjust_size(&size, count))
 469                 return NULL;
 470
 471         return tal_alloc_(ctx, size, clear, label);
 472 }
 473
 474 void *tal_free(const tal_t *ctx)
 475 {
 476         if (ctx) {
 477                 struct tal_hdr *t;
 478                 int saved_errno = errno;
 479                 t = debug_tal(to_tal_hdr(ctx));
 480                 if (unlikely(get_destroying_bit(t->parent_child)))
 481                         return NULL;
 482                 if (notifiers)
 483                         notify(ignore_destroying_bit(t->parent_child)->parent,
 484                                TAL_NOTIFY_DEL_CHILD, ctx, saved_errno);
 485                 list_del(&t->list);
 486                 del_tree(t, ctx, saved_errno);
 487                 errno = saved_errno;
 488         }
 489         return NULL;
 490 }
 491
 492 void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
 493 {
 494         if (ctx) {
 495                 struct tal_hdr *newpar, *t, *old_parent;
 496
 497                 newpar = debug_tal(to_tal_hdr_or_null(new_parent));
 498                 t = debug_tal(to_tal_hdr(ctx));
 499
 500                 /* Unlink it from old parent. */
 501                 list_del(&t->list);
 502                 old_parent = ignore_destroying_bit(t->parent_child)->parent;
 503
 504                 if (unlikely(!add_child(newpar, t))) {
 505                         /* We can always add to old parent, because it has a
 506                          * children property already. */
 507                         if (!add_child(old_parent, t))
 508                                 abort();
 509                         return NULL;
 510                 }
 511                 debug_tal(newpar);
 512                 if (notifiers)
 513                         notify(t, TAL_NOTIFY_STEAL, new_parent, 0);
 514         }
 515         return (void *)ctx;
 516 }
 517
 518 bool tal_add_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 519 {
 520         tal_t *t = debug_tal(to_tal_hdr(ctx));
 521         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
 522                                      (void *)destroy, NULL);
 523 }
 524
 525 bool tal_add_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
 526                           void *arg)
 527 {
 528         tal_t *t = debug_tal(to_tal_hdr(ctx));
 529         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR
 530                                      |NOTIFY_EXTRA_ARG,
 531                                      (void *)destroy, arg);
 532 }
 533
 534 /* We could support notifiers with an extra arg, but we didn't add to API */
 535 bool tal_add_notifier_(const tal_t *ctx, enum tal_notify_type types,
 536                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 537 {
 538         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
 539         struct notifier *n;
 540
 541         assert(types);
 542         assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
 543                           | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
 544                           | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
 545                           | TAL_NOTIFY_ADD_NOTIFIER
 546                           | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
 547
 548         /* Don't call notifier about itself: set types after! */
 549         n = add_notifier_property(t, 0, callback, NULL);
 550         if (unlikely(!n))
 551                 return false;
 552
 553         if (notifiers)
 554                 notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback, 0);
 555
 556         n->types = types;
 557         if (types != TAL_NOTIFY_FREE)
 558                 notifiers++;
 559         return true;
 560 }
 561
 562 bool tal_del_notifier_(const tal_t *ctx,
 563                        void (*callback)(tal_t *, enum tal_notify_type, void *),
 564                        bool match_extra_arg, void *extra_arg)
 565 {
 566         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
 567         enum tal_notify_type types;
 568
 569         types = del_notifier_property(t, callback, match_extra_arg, extra_arg);
 570         if (types) {
 571                 notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback, 0);
 572                 if (types != TAL_NOTIFY_FREE)
 573                         notifiers--;
 574                 return true;
 575         }
 576         return false;
 577 }
 578
 579 bool tal_del_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 580 {
 581         return tal_del_notifier_(ctx, (void *)destroy, false, NULL);
 582 }
 583
 584 bool tal_del_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
 585                           void *arg)
 586 {
 587         return tal_del_notifier_(ctx, (void *)destroy, true, arg);
 588 }
 589
 590 bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
 591 {
 592         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 593         struct prop_hdr **prop = find_property_ptr(t, NAME);
 594
 595         /* Get rid of any old name */
 596         if (prop) {
 597                 struct name *name = (struct name *)*prop;
 598                 if (is_literal(&name->hdr))
 599                         *prop = NULL;
 600                 else {
 601                         *prop = name->hdr.next;
 602                         freefn(name);
 603                 }
 604         }
 605
 606         if (literal && name[0]) {
 607                 struct prop_hdr **p;
 608
 609                 /* Append literal. */
 610                 for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
 611                 *p = (struct prop_hdr *)name;
 612         } else if (!add_name_property(t, name))
 613                 return false;
 614
 615         debug_tal(t);
 616         if (notifiers)
 617                 notify(t, TAL_NOTIFY_RENAME, name, 0);
 618         return true;
 619 }
 620
 621 const char *tal_name(const tal_t *t)
 622 {
 623         struct name *n;
 624
 625         n = find_property(debug_tal(to_tal_hdr(t)), NAME);
 626         if (!n)
 627                 return NULL;
 628
 629         if (is_literal(&n->hdr))
 630                 return (const char *)n;
 631         return n->name;
 632 }
 633
 634 size_t tal_bytelen(const tal_t *ptr)
 635 {
 636         /* NULL -> null_parent which has bytelen 0 */
 637         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ptr));
 638
 639         return t->bytelen;
 640 }
 641
 642 /* Start one past first child: make stopping natural in circ. list. */
 643 static struct tal_hdr *first_child(struct tal_hdr *parent)
 644 {
 645         struct children *child;
 646
 647         child = find_property(parent, CHILDREN);
 648         if (!child)
 649                 return NULL;
 650
 651         return list_top(&child->children, struct tal_hdr, list);
 652 }
 653
 654 tal_t *tal_first(const tal_t *root)
 655 {
 656         struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
 657
 658         c = first_child(t);
 659         if (!c)
 660                 return NULL;
 661         return from_tal_hdr(c);
 662 }
 663
 664 tal_t *tal_next(const tal_t *prev)
 665 {
 666         struct tal_hdr *next, *prevhdr = debug_tal(to_tal_hdr(prev));
 667         struct list_head *head;
 668
 669         head = &ignore_destroying_bit(prevhdr->parent_child)->children;
 670         next = list_next(head, prevhdr, list);
 671         if (!next)
 672                 return NULL;
 673         return from_tal_hdr(next);
 674 }
 675
 676 tal_t *tal_parent(const tal_t *ctx)
 677 {
 678         struct tal_hdr *t;
 679
 680         if (!ctx)
 681                 return NULL;
 682
 683         t = debug_tal(to_tal_hdr(ctx));
 684         if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
 685                 return NULL;
 686         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
 687 }
 688
 689 bool tal_resize_(tal_t **ctxp, size_t size, size_t count, bool clear)
 690 {
 691         struct tal_hdr *old_t, *t;
 692         struct children *child;
 693
 694         old_t = debug_tal(to_tal_hdr(*ctxp));
 695
 696         if (!adjust_size(&size, count))
 697                 return false;
 698
 699         t = resizefn(old_t, sizeof(struct tal_hdr) + size);
 700         if (!t) {
 701                 call_error("Reallocation failure");
 702                 return false;
 703         }
 704
 705         /* Clear between old end and new end. */
 706         if (clear && size > t->bytelen) {
 707                 char *old_end = (char *)(t + 1) + t->bytelen;
 708                 memset(old_end, 0, size - t->bytelen);
 709         }
 710
 711         /* Update length. */
 712         t->bytelen = size;
 713         update_bounds(t, sizeof(struct tal_hdr) + size);
 714
 715         /* If it didn't move, we're done! */
 716         if (t != old_t) {
 717                 /* Fix up linked list pointers. */
 718                 t->list.next->prev = t->list.prev->next = &t->list;
 719
 720                 /* Copy take() property. */
 721                 if (taken(from_tal_hdr(old_t)))
 722                         take(from_tal_hdr(t));
 723
 724                 /* Fix up child property's parent pointer. */
 725                 child = find_property(t, CHILDREN);
 726                 if (child) {
 727                         assert(child->parent == old_t);
 728                         child->parent = t;
 729                 }
 730                 *ctxp = from_tal_hdr(debug_tal(t));
 731                 if (notifiers)
 732                         notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t), 0);
 733         }
 734         if (notifiers)
 735                 notify(t, TAL_NOTIFY_RESIZE, (void *)size, 0);
 736
 737         return true;
 738 }
 739
 740 bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
 741 {
 742         size_t old_len;
 743         bool ret = false;
 744
 745         old_len = debug_tal(to_tal_hdr(*ctxp))->bytelen;
 746
 747         /* Check for additive overflow */
 748         if (old_len + count * size < old_len) {
 749                 call_error("dup size overflow");
 750                 goto out;
 751         }
 752
 753         /* Don't point src inside thing we're expanding! */
 754         assert(src < *ctxp
 755                || (char *)src >= (char *)(*ctxp) + old_len);
 756
 757         if (!tal_resize_(ctxp, size, old_len/size + count, false))
 758                 goto out;
 759
 760         memcpy((char *)*ctxp + old_len, src, count * size);
 761         ret = true;
 762
 763 out:
 764         if (taken(src))
 765                 tal_free(src);
 766         return ret;
 767 }
 768
 769 void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
 770                size_t n, size_t extra, const char *label)
 771 {
 772         void *ret;
 773         size_t nbytes = size;
 774
 775         if (!adjust_size(&nbytes, n)) {
 776                 if (taken(p))
 777                         tal_free(p);
 778                 return NULL;
 779         }
 780
 781         /* Beware addition overflow! */
 782         if (n + extra < n) {
 783                 call_error("dup size overflow");
 784                 if (taken(p))
 785                         tal_free(p);
 786                 return NULL;
 787         }
 788
 789         if (taken(p)) {
 790                 if (unlikely(!p))
 791                         return NULL;
 792                 if (unlikely(!tal_resize_((void **)&p, size, n + extra, false)))
 793                         return tal_free(p);
 794                 if (unlikely(!tal_steal(ctx, p)))
 795                         return tal_free(p);
 796                 return (void *)p;
 797         }
 798
 799         ret = tal_alloc_arr_(ctx, size, n + extra, false, label);
 800         if (ret)
 801                 memcpy(ret, p, nbytes);
 802         return ret;
 803 }
 804
 805 void tal_set_backend(void *(*alloc_fn)(size_t size),
 806                      void *(*resize_fn)(void *, size_t size),
 807                      void (*free_fn)(void *),
 808                      void (*error_fn)(const char *msg))
 809 {
 810         if (alloc_fn)
 811                 allocfn = alloc_fn;
 812         if (resize_fn)
 813                 resizefn = resize_fn;
 814         if (free_fn)
 815                 freefn = free_fn;
 816         if (error_fn)
 817                 errorfn = error_fn;
 818 }
 819
 820 #ifdef CCAN_TAL_DEBUG
 821 static void dump_node(unsigned int indent, const struct tal_hdr *t)
 822 {
 823         unsigned int i;
 824         const struct prop_hdr *p;
 825
 826         for (i = 0; i < indent; i++)
 827                 fprintf(stderr, "  ");
 828         fprintf(stderr, "%p len=%zu", t, t->bytelen);
 829         for (p = t->prop; p; p = p->next) {
 830                 struct children *c;
 831                 struct name *n;
 832                 struct notifier *no;
 833                 if (is_literal(p)) {
 834                         fprintf(stderr, " \"%s\"", (const char *)p);
 835                         break;
 836                 }
 837                 switch (p->type) {
 838                 case CHILDREN:
 839                         c = (struct children *)p;
 840                         fprintf(stderr, " CHILDREN(%p):parent=%p,children={%p,%p}",
 841                                p, c->parent,
 842                                c->children.n.prev, c->children.n.next);
 843                         break;
 844                 case NAME:
 845                         n = (struct name *)p;
 846                         fprintf(stderr, " NAME(%p):%s", p, n->name);
 847                         break;
 848                 case NOTIFIER:
 849                         no = (struct notifier *)p;
 850                         fprintf(stderr, " NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
 851                         break;
 852                 default:
 853                         fprintf(stderr, " **UNKNOWN(%p):%i**", p, p->type);
 854                 }
 855         }
 856         fprintf(stderr, "\n");
 857 }
 858
 859 static void tal_dump_(unsigned int level, const struct tal_hdr *t)
 860 {
 861         struct children *children;
 862
 863         dump_node(level, t);
 864
 865         children = find_property(t, CHILDREN);
 866         if (children) {
 867                 struct tal_hdr *i;
 868
 869                 list_for_each(&children->children, i, list)
 870                         tal_dump_(level + 1, i);
 871         }
 872 }
 873
 874 void tal_dump(void)
 875 {
 876         tal_dump_(0, &null_parent.hdr);
 877 }
 878 #endif /* CCAN_TAL_DEBUG */
 879
 880 #ifndef NDEBUG
 881 static bool check_err(struct tal_hdr *t, const char *errorstr,
 882                       const char *errmsg)
 883 {
 884         if (errorstr) {
 885                 /* Try not to malloc: it may be corrupted. */
 886                 char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
 887                 sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
 888                 call_error(msg);
 889         }
 890         return false;
 891 }
 892
 893 static bool check_node(struct children *parent_child,
 894                        struct tal_hdr *t, const char *errorstr)
 895 {
 896         struct prop_hdr *p;
 897         struct name *name = NULL;
 898         struct children *children = NULL;
 899
 900         if (!in_bounds(t))
 901                 return check_err(t, errorstr, "invalid pointer");
 902
 903         if (ignore_destroying_bit(t->parent_child) != parent_child)
 904                 return check_err(t, errorstr, "incorrect parent");
 905
 906         for (p = t->prop; p; p = p->next) {
 907                 if (is_literal(p)) {
 908                         if (name)
 909                                 return check_err(t, errorstr,
 910                                                  "has extra literal");
 911                         break;
 912                 }
 913                 if (!in_bounds(p))
 914                         return check_err(t, errorstr,
 915                                          "has bad property pointer");
 916
 917                 switch (p->type) {
 918                 case CHILDREN:
 919                         if (children)
 920                                 return check_err(t, errorstr,
 921                                                  "has two child nodes");
 922                         children = (struct children *)p;
 923                         break;
 924                 case NOTIFIER:
 925                         break;
 926                 case NAME:
 927                         if (name)
 928                                 return check_err(t, errorstr,
 929                                                  "has two names");
 930                         name = (struct name *)p;
 931                         break;
 932                 default:
 933                         return check_err(t, errorstr, "has unknown property");
 934                 }
 935         }
 936         if (children) {
 937                 struct tal_hdr *i;
 938
 939                 if (!list_check(&children->children, errorstr))
 940                         return false;
 941                 list_for_each(&children->children, i, list) {
 942                         if (!check_node(children, i, errorstr))
 943                                 return false;
 944                 }
 945         }
 946         return true;
 947 }
 948
 949 bool tal_check(const tal_t *ctx, const char *errorstr)
 950 {
 951         struct tal_hdr *t = to_tal_hdr_or_null(ctx);
 952
 953         return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
 954 }
 955 #else /* NDEBUG */
 956 bool tal_check(const tal_t *ctx, const char *errorstr)
 957 {
 958         return true;
 959 }
 960 #endif