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 {
  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                                 if (n->types & NOTIFY_EXTRA_ARG)
 232                                         n->u.destroy2(from_tal_hdr(ctx),
 233                                                       EXTRA_ARG(n));
 234                                 else
 235                                         n->u.destroy(from_tal_hdr(ctx));
 236                         } else
 237                                 n->u.notifyfn(from_tal_hdr_or_null(ctx), type,
 238                                               (void *)info);
 239                 }
 240         }
 241 }
 242
 243 static void *allocate(size_t size)
 244 {
 245         void *ret = allocfn(size);
 246         if (!ret)
 247                 call_error("allocation failed");
 248         else
 249                 update_bounds(ret, size);
 250         return ret;
 251 }
 252
 253 static struct prop_hdr **find_property_ptr(const struct tal_hdr *t,
 254                                            enum prop_type type)
 255 {
 256         struct prop_hdr **p;
 257
 258         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 259                 if (is_literal(*p)) {
 260                         if (type == NAME)
 261                                 return p;
 262                         break;
 263                 }
 264                 if ((*p)->type == type)
 265                         return p;
 266         }
 267         return NULL;
 268 }
 269
 270 static void *find_property(const struct tal_hdr *parent, enum prop_type type)
 271 {
 272         struct prop_hdr **p = find_property_ptr(parent, type);
 273
 274         if (p)
 275                 return *p;
 276         return NULL;
 277 }
 278
 279 static void init_property(struct prop_hdr *hdr,
 280                           struct tal_hdr *parent,
 281                           enum prop_type type)
 282 {
 283         hdr->type = type;
 284         hdr->next = parent->prop;
 285         parent->prop = hdr;
 286 }
 287
 288 static struct notifier *add_notifier_property(struct tal_hdr *t,
 289                                               enum tal_notify_type types,
 290                                               void (*fn)(void *,
 291                                                          enum tal_notify_type,
 292                                                          void *),
 293                                               void *extra_arg)
 294 {
 295         struct notifier *prop;
 296
 297         if (types & NOTIFY_EXTRA_ARG)
 298                 prop = allocate(sizeof(struct notifier_extra_arg));
 299         else
 300                 prop = allocate(sizeof(struct notifier));
 301
 302         if (prop) {
 303                 init_property(&prop->hdr, t, NOTIFIER);
 304                 prop->types = types;
 305                 prop->u.notifyfn = fn;
 306                 if (types & NOTIFY_EXTRA_ARG)
 307                         EXTRA_ARG(prop) = extra_arg;
 308         }
 309         return prop;
 310 }
 311
 312 static enum tal_notify_type del_notifier_property(struct tal_hdr *t,
 313                                                   void (*fn)(tal_t *,
 314                                                              enum tal_notify_type,
 315                                                              void *),
 316                                                   bool match_extra_arg,
 317                                                   void *extra_arg)
 318 {
 319         struct prop_hdr **p;
 320
 321         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 322                 struct notifier *n;
 323                 enum tal_notify_type types;
 324
 325                 if (is_literal(*p))
 326                         break;
 327                 if ((*p)->type != NOTIFIER)
 328                         continue;
 329                 n = (struct notifier *)*p;
 330                 if (n->u.notifyfn != fn)
 331                         continue;
 332
 333                 types = n->types;
 334                 if ((types & NOTIFY_EXTRA_ARG)
 335                     && match_extra_arg
 336                     && extra_arg != EXTRA_ARG(n))
 337                         continue;
 338
 339                 *p = (*p)->next;
 340                 freefn(n);
 341                 return types & ~(NOTIFY_IS_DESTRUCTOR|NOTIFY_EXTRA_ARG);
 342         }
 343         return 0;
 344 }
 345
 346 static struct name *add_name_property(struct tal_hdr *t, const char *name)
 347 {
 348         struct name *prop;
 349
 350         prop = allocate(sizeof(*prop) + strlen(name) + 1);
 351         if (prop) {
 352                 init_property(&prop->hdr, t, NAME);
 353                 strcpy(prop->name, name);
 354         }
 355         return prop;
 356 }
 357
 358 static struct children *add_child_property(struct tal_hdr *parent,
 359                                            struct tal_hdr *child UNNEEDED)
 360 {
 361         struct children *prop = allocate(sizeof(*prop));
 362         if (prop) {
 363                 init_property(&prop->hdr, parent, CHILDREN);
 364                 prop->parent = parent;
 365                 list_head_init(&prop->children);
 366         }
 367         return prop;
 368 }
 369
 370 static bool add_child(struct tal_hdr *parent, struct tal_hdr *child)
 371 {
 372         struct children *children = find_property(parent, CHILDREN);
 373
 374         if (!children) {
 375                 children = add_child_property(parent, child);
 376                 if (!children)
 377                         return false;
 378         }
 379         list_add(&children->children, &child->list);
 380         child->parent_child = (intptr_t)children ^ TAL_PTR_OBFUSTICATOR;
 381         return true;
 382 }
 383
 384 static void del_tree(struct tal_hdr *t, const tal_t *orig, int saved_errno)
 385 {
 386         struct prop_hdr **prop, *p, *next;
 387
 388         assert(!taken(from_tal_hdr(t)));
 389
 390         /* Already being destroyed?  Don't loop. */
 391         if (unlikely(get_destroying_bit(t->parent_child)))
 392                 return;
 393
 394         set_destroying_bit(&t->parent_child);
 395
 396         /* Call free notifiers. */
 397         notify(t, TAL_NOTIFY_FREE, (tal_t *)orig, saved_errno);
 398
 399         /* Now free children and groups. */
 400         prop = find_property_ptr(t, CHILDREN);
 401         if (prop) {
 402                 struct tal_hdr *i;
 403                 struct children *c = (struct children *)*prop;
 404
 405                 while ((i = list_top(&c->children, struct tal_hdr, list))) {
 406                         list_del(&i->list);
 407                         del_tree(i, orig, saved_errno);
 408                 }
 409         }
 410
 411         /* Finally free our properties. */
 412         for (p = t->prop; p && !is_literal(p); p = next) {
 413                 next = p->next;
 414                 freefn(p);
 415         }
 416         freefn(t);
 417 }
 418
 419 void *tal_alloc_(const tal_t *ctx, size_t size, bool clear, const char *label)
 420 {
 421         struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
 422
 423         child = allocate(sizeof(struct tal_hdr) + size);
 424         if (!child)
 425                 return NULL;
 426         if (clear)
 427                 memset(from_tal_hdr(child), 0, size);
 428         child->prop = (void *)label;
 429         child->bytelen = size;
 430
 431         if (!add_child(parent, child)) {
 432                 freefn(child);
 433                 return NULL;
 434         }
 435         debug_tal(parent);
 436         if (notifiers)
 437                 notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(child), 0);
 438         return from_tal_hdr(debug_tal(child));
 439 }
 440
 441 static bool adjust_size(size_t *size, size_t count)
 442 {
 443         const size_t extra = sizeof(struct tal_hdr);
 444
 445         /* Multiplication wrap */
 446         if (count && unlikely(*size * count / *size != count))
 447                 goto overflow;
 448
 449         *size *= count;
 450
 451         /* Make sure we don't wrap adding header. */
 452         if (*size + extra < extra)
 453                 goto overflow;
 454         return true;
 455 overflow:
 456         call_error("allocation size overflow");
 457         return false;
 458 }
 459
 460 void *tal_alloc_arr_(const tal_t *ctx, size_t size, size_t count, bool clear,
 461                      const char *label)
 462 {
 463         if (!adjust_size(&size, count))
 464                 return NULL;
 465
 466         return tal_alloc_(ctx, size, clear, label);
 467 }
 468
 469 void *tal_free(const tal_t *ctx)
 470 {
 471         if (ctx) {
 472                 struct tal_hdr *t;
 473                 int saved_errno = errno;
 474                 t = debug_tal(to_tal_hdr(ctx));
 475                 if (unlikely(get_destroying_bit(t->parent_child)))
 476                         return NULL;
 477                 if (notifiers)
 478                         notify(ignore_destroying_bit(t->parent_child)->parent,
 479                                TAL_NOTIFY_DEL_CHILD, ctx, saved_errno);
 480                 list_del(&t->list);
 481                 del_tree(t, ctx, saved_errno);
 482                 errno = saved_errno;
 483         }
 484         return NULL;
 485 }
 486
 487 void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
 488 {
 489         if (ctx) {
 490                 struct tal_hdr *newpar, *t, *old_parent;
 491
 492                 newpar = debug_tal(to_tal_hdr_or_null(new_parent));
 493                 t = debug_tal(to_tal_hdr(ctx));
 494
 495                 /* Unlink it from old parent. */
 496                 list_del(&t->list);
 497                 old_parent = ignore_destroying_bit(t->parent_child)->parent;
 498
 499                 if (unlikely(!add_child(newpar, t))) {
 500                         /* We can always add to old parent, because it has a
 501                          * children property already. */
 502                         if (!add_child(old_parent, t))
 503                                 abort();
 504                         return NULL;
 505                 }
 506                 debug_tal(newpar);
 507                 if (notifiers)
 508                         notify(t, TAL_NOTIFY_STEAL, new_parent, 0);
 509         }
 510         return (void *)ctx;
 511 }
 512
 513 bool tal_add_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 514 {
 515         tal_t *t = debug_tal(to_tal_hdr(ctx));
 516         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
 517                                      (void *)destroy, NULL);
 518 }
 519
 520 bool tal_add_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
 521                           void *arg)
 522 {
 523         tal_t *t = debug_tal(to_tal_hdr(ctx));
 524         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR
 525                                      |NOTIFY_EXTRA_ARG,
 526                                      (void *)destroy, arg);
 527 }
 528
 529 /* We could support notifiers with an extra arg, but we didn't add to API */
 530 bool tal_add_notifier_(const tal_t *ctx, enum tal_notify_type types,
 531                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 532 {
 533         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
 534         struct notifier *n;
 535
 536         assert(types);
 537         assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
 538                           | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
 539                           | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
 540                           | TAL_NOTIFY_ADD_NOTIFIER
 541                           | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
 542
 543         /* Don't call notifier about itself: set types after! */
 544         n = add_notifier_property(t, 0, callback, NULL);
 545         if (unlikely(!n))
 546                 return false;
 547
 548         if (notifiers)
 549                 notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback, 0);
 550
 551         n->types = types;
 552         if (types != TAL_NOTIFY_FREE)
 553                 notifiers++;
 554         return true;
 555 }
 556
 557 bool tal_del_notifier_(const tal_t *ctx,
 558                        void (*callback)(tal_t *, enum tal_notify_type, void *),
 559                        bool match_extra_arg, void *extra_arg)
 560 {
 561         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
 562         enum tal_notify_type types;
 563
 564         types = del_notifier_property(t, callback, match_extra_arg, extra_arg);
 565         if (types) {
 566                 notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback, 0);
 567                 if (types != TAL_NOTIFY_FREE)
 568                         notifiers--;
 569                 return true;
 570         }
 571         return false;
 572 }
 573
 574 bool tal_del_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 575 {
 576         return tal_del_notifier_(ctx, (void *)destroy, false, NULL);
 577 }
 578
 579 bool tal_del_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
 580                           void *arg)
 581 {
 582         return tal_del_notifier_(ctx, (void *)destroy, true, arg);
 583 }
 584
 585 bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
 586 {
 587         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 588         struct prop_hdr **prop = find_property_ptr(t, NAME);
 589
 590         /* Get rid of any old name */
 591         if (prop) {
 592                 struct name *name = (struct name *)*prop;
 593                 if (is_literal(&name->hdr))
 594                         *prop = NULL;
 595                 else {
 596                         *prop = name->hdr.next;
 597                         freefn(name);
 598                 }
 599         }
 600
 601         if (literal && name[0]) {
 602                 struct prop_hdr **p;
 603
 604                 /* Append literal. */
 605                 for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
 606                 *p = (struct prop_hdr *)name;
 607         } else if (!add_name_property(t, name))
 608                 return false;
 609
 610         debug_tal(t);
 611         if (notifiers)
 612                 notify(t, TAL_NOTIFY_RENAME, name, 0);
 613         return true;
 614 }
 615
 616 const char *tal_name(const tal_t *t)
 617 {
 618         struct name *n;
 619
 620         n = find_property(debug_tal(to_tal_hdr(t)), NAME);
 621         if (!n)
 622                 return NULL;
 623
 624         if (is_literal(&n->hdr))
 625                 return (const char *)n;
 626         return n->name;
 627 }
 628
 629 size_t tal_bytelen(const tal_t *ptr)
 630 {
 631         /* NULL -> null_parent which has bytelen 0 */
 632         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ptr));
 633
 634         return t->bytelen;
 635 }
 636
 637 /* Start one past first child: make stopping natural in circ. list. */
 638 static struct tal_hdr *first_child(struct tal_hdr *parent)
 639 {
 640         struct children *child;
 641
 642         child = find_property(parent, CHILDREN);
 643         if (!child)
 644                 return NULL;
 645
 646         return list_top(&child->children, struct tal_hdr, list);
 647 }
 648
 649 tal_t *tal_first(const tal_t *root)
 650 {
 651         struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
 652
 653         c = first_child(t);
 654         if (!c)
 655                 return NULL;
 656         return from_tal_hdr(c);
 657 }
 658
 659 tal_t *tal_next(const tal_t *prev)
 660 {
 661         struct tal_hdr *next, *prevhdr = debug_tal(to_tal_hdr(prev));
 662         struct list_head *head;
 663
 664         head = &ignore_destroying_bit(prevhdr->parent_child)->children;
 665         next = list_next(head, prevhdr, list);
 666         if (!next)
 667                 return NULL;
 668         return from_tal_hdr(next);
 669 }
 670
 671 tal_t *tal_parent(const tal_t *ctx)
 672 {
 673         struct tal_hdr *t;
 674
 675         if (!ctx)
 676                 return NULL;
 677
 678         t = debug_tal(to_tal_hdr(ctx));
 679         if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
 680                 return NULL;
 681         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
 682 }
 683
 684 bool tal_resize_(tal_t **ctxp, size_t size, size_t count, bool clear)
 685 {
 686         struct tal_hdr *old_t, *t;
 687         struct children *child;
 688
 689         old_t = debug_tal(to_tal_hdr(*ctxp));
 690
 691         if (!adjust_size(&size, count))
 692                 return false;
 693
 694         t = resizefn(old_t, sizeof(struct tal_hdr) + size);
 695         if (!t) {
 696                 call_error("Reallocation failure");
 697                 return false;
 698         }
 699
 700         /* Clear between old end and new end. */
 701         if (clear && size > t->bytelen) {
 702                 char *old_end = (char *)(t + 1) + t->bytelen;
 703                 memset(old_end, 0, size - t->bytelen);
 704         }
 705
 706         /* Update length. */
 707         t->bytelen = size;
 708         update_bounds(t, sizeof(struct tal_hdr) + size);
 709
 710         /* If it didn't move, we're done! */
 711         if (t != old_t) {
 712                 /* Fix up linked list pointers. */
 713                 t->list.next->prev = t->list.prev->next = &t->list;
 714
 715                 /* Copy take() property. */
 716                 if (taken(from_tal_hdr(old_t)))
 717                         take(from_tal_hdr(t));
 718
 719                 /* Fix up child property's parent pointer. */
 720                 child = find_property(t, CHILDREN);
 721                 if (child) {
 722                         assert(child->parent == old_t);
 723                         child->parent = t;
 724                 }
 725                 *ctxp = from_tal_hdr(debug_tal(t));
 726                 if (notifiers)
 727                         notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t), 0);
 728         }
 729         if (notifiers)
 730                 notify(t, TAL_NOTIFY_RESIZE, (void *)size, 0);
 731
 732         return true;
 733 }
 734
 735 bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
 736 {
 737         size_t old_len;
 738         bool ret = false;
 739
 740         old_len = debug_tal(to_tal_hdr(*ctxp))->bytelen;
 741
 742         /* Check for additive overflow */
 743         if (old_len + count * size < old_len) {
 744                 call_error("dup size overflow");
 745                 goto out;
 746         }
 747
 748         /* Don't point src inside thing we're expanding! */
 749         assert(src < *ctxp
 750                || (char *)src >= (char *)(*ctxp) + old_len);
 751
 752         if (!tal_resize_(ctxp, size, old_len/size + count, false))
 753                 goto out;
 754
 755         memcpy((char *)*ctxp + old_len, src, count * size);
 756         ret = true;
 757
 758 out:
 759         if (taken(src))
 760                 tal_free(src);
 761         return ret;
 762 }
 763
 764 void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
 765                size_t n, size_t extra, const char *label)
 766 {
 767         void *ret;
 768         size_t nbytes = size;
 769
 770         if (!adjust_size(&nbytes, n)) {
 771                 if (taken(p))
 772                         tal_free(p);
 773                 return NULL;
 774         }
 775
 776         /* Beware addition overflow! */
 777         if (n + extra < n) {
 778                 call_error("dup size overflow");
 779                 if (taken(p))
 780                         tal_free(p);
 781                 return NULL;
 782         }
 783
 784         if (taken(p)) {
 785                 if (unlikely(!p))
 786                         return NULL;
 787                 if (unlikely(!tal_resize_((void **)&p, size, n + extra, false)))
 788                         return tal_free(p);
 789                 if (unlikely(!tal_steal(ctx, p)))
 790                         return tal_free(p);
 791                 return (void *)p;
 792         }
 793
 794         ret = tal_alloc_arr_(ctx, size, n + extra, false, label);
 795         if (ret)
 796                 memcpy(ret, p, nbytes);
 797         return ret;
 798 }
 799
 800 void tal_set_backend(void *(*alloc_fn)(size_t size),
 801                      void *(*resize_fn)(void *, size_t size),
 802                      void (*free_fn)(void *),
 803                      void (*error_fn)(const char *msg))
 804 {
 805         if (alloc_fn)
 806                 allocfn = alloc_fn;
 807         if (resize_fn)
 808                 resizefn = resize_fn;
 809         if (free_fn)
 810                 freefn = free_fn;
 811         if (error_fn)
 812                 errorfn = error_fn;
 813 }
 814
 815 #ifdef CCAN_TAL_DEBUG
 816 static void dump_node(unsigned int indent, const struct tal_hdr *t)
 817 {
 818         unsigned int i;
 819         const struct prop_hdr *p;
 820
 821         for (i = 0; i < indent; i++)
 822                 printf("  ");
 823         printf("%p len=%zu", t, t->bytelen);
 824         for (p = t->prop; p; p = p->next) {
 825                 struct children *c;
 826                 struct name *n;
 827                 struct notifier *no;
 828                 if (is_literal(p)) {
 829                         printf(" \"%s\"", (const char *)p);
 830                         break;
 831                 }
 832                 switch (p->type) {
 833                 case CHILDREN:
 834                         c = (struct children *)p;
 835                         printf(" CHILDREN(%p):parent=%p,children={%p,%p}\n",
 836                                p, c->parent,
 837                                c->children.n.prev, c->children.n.next);
 838                         break;
 839                 case NAME:
 840                         n = (struct name *)p;
 841                         printf(" NAME(%p):%s", p, n->name);
 842                         break;
 843                 case NOTIFIER:
 844                         no = (struct notifier *)p;
 845                         printf(" NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
 846                         break;
 847                 default:
 848                         printf(" **UNKNOWN(%p):%i**", p, p->type);
 849                 }
 850         }
 851         printf("\n");
 852 }
 853
 854 static void tal_dump_(unsigned int level, const struct tal_hdr *t)
 855 {
 856         struct children *children;
 857
 858         dump_node(level, t);
 859
 860         children = find_property(t, CHILDREN);
 861         if (children) {
 862                 struct tal_hdr *i;
 863
 864                 list_for_each(&children->children, i, list)
 865                         tal_dump_(level + 1, i);
 866         }
 867 }
 868
 869 void tal_dump(void)
 870 {
 871         tal_dump_(0, &null_parent.hdr);
 872 }
 873 #endif /* CCAN_TAL_DEBUG */
 874
 875 #ifndef NDEBUG
 876 static bool check_err(struct tal_hdr *t, const char *errorstr,
 877                       const char *errmsg)
 878 {
 879         if (errorstr) {
 880                 /* Try not to malloc: it may be corrupted. */
 881                 char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
 882                 sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
 883                 call_error(msg);
 884         }
 885         return false;
 886 }
 887
 888 static bool check_node(struct children *parent_child,
 889                        struct tal_hdr *t, const char *errorstr)
 890 {
 891         struct prop_hdr *p;
 892         struct name *name = NULL;
 893         struct children *children = NULL;
 894
 895         if (!in_bounds(t))
 896                 return check_err(t, errorstr, "invalid pointer");
 897
 898         if (ignore_destroying_bit(t->parent_child) != parent_child)
 899                 return check_err(t, errorstr, "incorrect parent");
 900
 901         for (p = t->prop; p; p = p->next) {
 902                 if (is_literal(p)) {
 903                         if (name)
 904                                 return check_err(t, errorstr,
 905                                                  "has extra literal");
 906                         break;
 907                 }
 908                 if (!in_bounds(p))
 909                         return check_err(t, errorstr,
 910                                          "has bad property pointer");
 911
 912                 switch (p->type) {
 913                 case CHILDREN:
 914                         if (children)
 915                                 return check_err(t, errorstr,
 916                                                  "has two child nodes");
 917                         children = (struct children *)p;
 918                         break;
 919                 case NOTIFIER:
 920                         break;
 921                 case NAME:
 922                         if (name)
 923                                 return check_err(t, errorstr,
 924                                                  "has two names");
 925                         name = (struct name *)p;
 926                         break;
 927                 default:
 928                         return check_err(t, errorstr, "has unknown property");
 929                 }
 930         }
 931         if (children) {
 932                 struct tal_hdr *i;
 933
 934                 if (!list_check(&children->children, errorstr))
 935                         return false;
 936                 list_for_each(&children->children, i, list) {
 937                         if (!check_node(children, i, errorstr))
 938                                 return false;
 939                 }
 940         }
 941         return true;
 942 }
 943
 944 bool tal_check(const tal_t *ctx, const char *errorstr)
 945 {
 946         struct tal_hdr *t = to_tal_hdr_or_null(ctx);
 947
 948         return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
 949 }
 950 #else /* NDEBUG */
 951 bool tal_check(const tal_t *ctx, const char *errorstr)
 952 {
 953         return true;
 954 }
 955 #endif