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         LENGTH = 0x00515300
  28 };
  29
  30 struct tal_hdr {
  31         struct list_node list;
  32         struct prop_hdr *prop;
  33         /* XOR with TAL_PTR_OBFUSTICATOR */
  34         intptr_t parent_child;
  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 length {
  54         struct prop_hdr hdr; /* LENGTH */
  55         size_t len;
  56 };
  57
  58 struct notifier {
  59         struct prop_hdr hdr; /* NOTIFIER */
  60         enum tal_notify_type types;
  61         union {
  62                 void (*notifyfn)(tal_t *, enum tal_notify_type, void *);
  63                 void (*destroy)(tal_t *); /* If NOTIFY_IS_DESTRUCTOR set */
  64                 void (*destroy2)(tal_t *, void *); /* If NOTIFY_EXTRA_ARG */
  65         } u;
  66 };
  67
  68 /* Extra arg */
  69 struct notifier_extra_arg {
  70         struct notifier n;
  71         void *arg;
  72 };
  73
  74 #define EXTRA_ARG(n) (((struct notifier_extra_arg *)(n))->arg)
  75
  76 static struct {
  77         struct tal_hdr hdr;
  78         struct children c;
  79 } null_parent = { { { &null_parent.hdr.list, &null_parent.hdr.list },
  80                     &null_parent.c.hdr, TAL_PTR_OBFUSTICATOR },
  81                   { { CHILDREN, NULL },
  82                     &null_parent.hdr,
  83                     { { &null_parent.c.children.n,
  84                         &null_parent.c.children.n } }
  85                   }
  86 };
  87
  88
  89 static void *(*allocfn)(size_t size) = malloc;
  90 static void *(*resizefn)(void *, size_t size) = realloc;
  91 static void (*freefn)(void *) = free;
  92 static void (*errorfn)(const char *msg) = (void *)abort;
  93 /* Count on non-destrutor notifiers; often stays zero. */
  94 static size_t notifiers = 0;
  95
  96 static inline void COLD call_error(const char *msg)
  97 {
  98         errorfn(msg);
  99 }
 100
 101 static bool get_destroying_bit(intptr_t parent_child)
 102 {
 103         return parent_child & 1;
 104 }
 105
 106 static void set_destroying_bit(intptr_t *parent_child)
 107 {
 108         *parent_child |= 1;
 109 }
 110
 111 static struct children *ignore_destroying_bit(intptr_t parent_child)
 112 {
 113         return (void *)((parent_child ^ TAL_PTR_OBFUSTICATOR) & ~(intptr_t)1);
 114 }
 115
 116 /* This means valgrind can see leaks. */
 117 void tal_cleanup(void)
 118 {
 119         struct tal_hdr *i;
 120
 121         while ((i = list_top(&null_parent.c.children, struct tal_hdr, list))) {
 122                 list_del(&i->list);
 123                 memset(i, 0, sizeof(*i));
 124         }
 125
 126         /* Cleanup any taken pointers. */
 127         take_cleanup();
 128 }
 129
 130 /* We carefully start all real properties with a zero byte. */
 131 static bool is_literal(const struct prop_hdr *prop)
 132 {
 133         return ((char *)prop)[0] != 0;
 134 }
 135
 136 #ifndef NDEBUG
 137 static const void *bounds_start, *bounds_end;
 138
 139 static void update_bounds(const void *new, size_t size)
 140 {
 141         if (unlikely(!bounds_start)) {
 142                 bounds_start = new;
 143                 bounds_end = (char *)new + size;
 144         } else if (new < bounds_start)
 145                 bounds_start = new;
 146         else if ((char *)new + size > (char *)bounds_end)
 147                 bounds_end = (char *)new + size;
 148 }
 149
 150 static bool in_bounds(const void *p)
 151 {
 152         return !p
 153                 || (p >= (void *)&null_parent && p <= (void *)(&null_parent + 1))
 154                 || (p >= bounds_start && p <= bounds_end);
 155 }
 156 #else
 157 static void update_bounds(const void *new, size_t size)
 158 {
 159 }
 160
 161 static bool in_bounds(const void *p)
 162 {
 163         return true;
 164 }
 165 #endif
 166
 167 static void check_bounds(const void *p)
 168 {
 169         if (!in_bounds(p))
 170                 call_error("Not a valid header");
 171 }
 172
 173 static struct tal_hdr *to_tal_hdr(const void *ctx)
 174 {
 175         struct tal_hdr *t;
 176
 177         t = (struct tal_hdr *)((char *)ctx - sizeof(struct tal_hdr));
 178         check_bounds(t);
 179         check_bounds(ignore_destroying_bit(t->parent_child));
 180         check_bounds(t->list.next);
 181         check_bounds(t->list.prev);
 182         if (t->prop && !is_literal(t->prop))
 183                 check_bounds(t->prop);
 184         return t;
 185 }
 186
 187 static struct tal_hdr *to_tal_hdr_or_null(const void *ctx)
 188 {
 189         if (!ctx)
 190                 return &null_parent.hdr;
 191         return to_tal_hdr(ctx);
 192 }
 193
 194 static void *from_tal_hdr(const struct tal_hdr *hdr)
 195 {
 196         return (void *)(hdr + 1);
 197 }
 198
 199 #ifdef TAL_DEBUG
 200 static void *from_tal_hdr_or_null(struct tal_hdr *hdr)
 201 {
 202         if (hdr == &null_parent.hdr)
 203                 return NULL;
 204         return from_tal_hdr(hdr);
 205 }
 206
 207 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 208 {
 209         tal_check(from_tal_hdr_or_null(tal), "TAL_DEBUG ");
 210         return tal;
 211 }
 212 #else
 213 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 214 {
 215         return tal;
 216 }
 217 #endif
 218
 219 static void notify(const struct tal_hdr *ctx,
 220                    enum tal_notify_type type, const void *info,
 221                    int saved_errno)
 222 {
 223         const struct prop_hdr *p;
 224
 225         for (p = ctx->prop; p; p = p->next) {
 226                 struct notifier *n;
 227
 228                 if (is_literal(p))
 229                         break;
 230                 if (p->type != NOTIFIER)
 231                         continue;
 232                 n = (struct notifier *)p;
 233                 if (n->types & type) {
 234                         errno = saved_errno;
 235                         if (n->types & NOTIFY_IS_DESTRUCTOR) {
 236                                 if (n->types & NOTIFY_EXTRA_ARG)
 237                                         n->u.destroy2(from_tal_hdr(ctx),
 238                                                       EXTRA_ARG(n));
 239                                 else
 240                                         n->u.destroy(from_tal_hdr(ctx));
 241                         } else
 242                                 n->u.notifyfn(from_tal_hdr(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         /* Already being destroyed?  Don't loop. */
 394         if (unlikely(get_destroying_bit(t->parent_child)))
 395                 return;
 396
 397         set_destroying_bit(&t->parent_child);
 398
 399         /* Call free notifiers. */
 400         notify(t, TAL_NOTIFY_FREE, (tal_t *)orig, saved_errno);
 401
 402         /* Now free children and groups. */
 403         prop = find_property_ptr(t, CHILDREN);
 404         if (prop) {
 405                 struct tal_hdr *i;
 406                 struct children *c = (struct children *)*prop;
 407
 408                 while ((i = list_top(&c->children, struct tal_hdr, list))) {
 409                         list_del(&i->list);
 410                         del_tree(i, orig, saved_errno);
 411                 }
 412         }
 413
 414         /* Finally free our properties. */
 415         for (p = t->prop; p && !is_literal(p); p = next) {
 416                 next = p->next;
 417                 /* LENGTH is appended, so don't free separately! */
 418                 if (p->type != LENGTH)
 419                         freefn(p);
 420         }
 421         freefn(t);
 422 }
 423
 424 static size_t extra_for_length(size_t size)
 425 {
 426         size_t extra;
 427         const size_t align = ALIGNOF(struct length);
 428
 429         /* Round up size, and add tailer. */
 430         extra = ((size + align-1) & ~(align-1)) - size;
 431         extra += sizeof(struct length);
 432         return extra;
 433 }
 434
 435 void *tal_alloc_(const tal_t *ctx, size_t size,
 436                  bool clear, bool add_length, const char *label)
 437 {
 438         size_t req_size = size;
 439         struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
 440
 441 #ifdef CCAN_TAL_DEBUG
 442         /* Always record length if debugging. */
 443         add_length = true;
 444 #endif
 445         if (add_length)
 446                 size += extra_for_length(size);
 447
 448         child = allocate(sizeof(struct tal_hdr) + size);
 449         if (!child)
 450                 return NULL;
 451         if (clear)
 452                 memset(from_tal_hdr(child), 0, req_size);
 453         child->prop = (void *)label;
 454
 455         if (add_length) {
 456                 struct length *lprop;
 457                 lprop = (struct length *)((char *)(child+1) + size) - 1;
 458                 init_property(&lprop->hdr, child, LENGTH);
 459                 lprop->len = req_size;
 460         }
 461         if (!add_child(parent, child)) {
 462                 freefn(child);
 463                 return NULL;
 464         }
 465         debug_tal(parent);
 466         if (notifiers)
 467                 notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(child), 0);
 468         return from_tal_hdr(debug_tal(child));
 469 }
 470
 471 static bool adjust_size(size_t *size, size_t count)
 472 {
 473         const size_t extra = sizeof(struct tal_hdr) + sizeof(struct length)*2;
 474
 475         /* Multiplication wrap */
 476         if (count && unlikely(*size * count / *size != count))
 477                 goto overflow;
 478
 479         *size *= count;
 480
 481         /* Make sure we don't wrap adding header/tailer. */
 482         if (*size + extra < extra)
 483                 goto overflow;
 484         return true;
 485 overflow:
 486         call_error("allocation size overflow");
 487         return false;
 488 }
 489
 490 void *tal_alloc_arr_(const tal_t *ctx, size_t size, size_t count, bool clear,
 491                      bool add_length, const char *label)
 492 {
 493         if (!adjust_size(&size, count))
 494                 return NULL;
 495
 496         return tal_alloc_(ctx, size, clear, add_length, label);
 497 }
 498
 499 void *tal_free(const tal_t *ctx)
 500 {
 501         if (ctx) {
 502                 struct tal_hdr *t;
 503                 int saved_errno = errno;
 504                 t = debug_tal(to_tal_hdr(ctx));
 505                 if (notifiers)
 506                         notify(ignore_destroying_bit(t->parent_child)->parent,
 507                                TAL_NOTIFY_DEL_CHILD, ctx, saved_errno);
 508                 list_del(&t->list);
 509                 del_tree(t, ctx, saved_errno);
 510                 errno = saved_errno;
 511         }
 512         return NULL;
 513 }
 514
 515 void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
 516 {
 517         if (ctx) {
 518                 struct tal_hdr *newpar, *t, *old_parent;
 519
 520                 newpar = debug_tal(to_tal_hdr_or_null(new_parent));
 521                 t = debug_tal(to_tal_hdr(ctx));
 522
 523                 /* Unlink it from old parent. */
 524                 list_del(&t->list);
 525                 old_parent = ignore_destroying_bit(t->parent_child)->parent;
 526
 527                 if (unlikely(!add_child(newpar, t))) {
 528                         /* We can always add to old parent, becuase it has a
 529                          * children property already. */
 530                         if (!add_child(old_parent, t))
 531                                 abort();
 532                         return NULL;
 533                 }
 534                 debug_tal(newpar);
 535                 if (notifiers)
 536                         notify(t, TAL_NOTIFY_STEAL, new_parent, 0);
 537         }
 538         return (void *)ctx;
 539 }
 540
 541 bool tal_add_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 542 {
 543         tal_t *t = debug_tal(to_tal_hdr(ctx));
 544         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
 545                                      (void *)destroy, NULL);
 546 }
 547
 548 bool tal_add_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
 549                           void *arg)
 550 {
 551         tal_t *t = debug_tal(to_tal_hdr(ctx));
 552         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR
 553                                      |NOTIFY_EXTRA_ARG,
 554                                      (void *)destroy, arg);
 555 }
 556
 557 /* We could support notifiers with an extra arg, but we didn't add to API */
 558 bool tal_add_notifier_(const tal_t *ctx, enum tal_notify_type types,
 559                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 560 {
 561         tal_t *t = debug_tal(to_tal_hdr(ctx));
 562         struct notifier *n;
 563
 564         assert(types);
 565         assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
 566                           | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
 567                           | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
 568                           | TAL_NOTIFY_ADD_NOTIFIER
 569                           | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
 570
 571         /* Don't call notifier about itself: set types after! */
 572         n = add_notifier_property(t, 0, callback, NULL);
 573         if (unlikely(!n))
 574                 return false;
 575
 576         if (notifiers)
 577                 notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback, 0);
 578
 579         n->types = types;
 580         if (types != TAL_NOTIFY_FREE)
 581                 notifiers++;
 582         return true;
 583 }
 584
 585 bool tal_del_notifier_(const tal_t *ctx,
 586                        void (*callback)(tal_t *, enum tal_notify_type, void *),
 587                        bool match_extra_arg, void *extra_arg)
 588 {
 589         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 590         enum tal_notify_type types;
 591
 592         types = del_notifier_property(t, callback, match_extra_arg, extra_arg);
 593         if (types) {
 594                 notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback, 0);
 595                 if (types != TAL_NOTIFY_FREE)
 596                         notifiers--;
 597                 return true;
 598         }
 599         return false;
 600 }
 601
 602 bool tal_del_destructor_(const tal_t *ctx, void (*destroy)(void *me))
 603 {
 604         return tal_del_notifier_(ctx, (void *)destroy, false, NULL);
 605 }
 606
 607 bool tal_del_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
 608                           void *arg)
 609 {
 610         return tal_del_notifier_(ctx, (void *)destroy, true, arg);
 611 }
 612
 613 bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
 614 {
 615         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 616         struct prop_hdr **prop = find_property_ptr(t, NAME);
 617
 618         /* Get rid of any old name */
 619         if (prop) {
 620                 struct name *name = (struct name *)*prop;
 621                 if (is_literal(&name->hdr))
 622                         *prop = NULL;
 623                 else {
 624                         *prop = name->hdr.next;
 625                         freefn(name);
 626                 }
 627         }
 628
 629         if (literal && name[0]) {
 630                 struct prop_hdr **p;
 631
 632                 /* Append literal. */
 633                 for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
 634                 *p = (struct prop_hdr *)name;
 635         } else if (!add_name_property(t, name))
 636                 return false;
 637
 638         debug_tal(t);
 639         if (notifiers)
 640                 notify(t, TAL_NOTIFY_RENAME, name, 0);
 641         return true;
 642 }
 643
 644 const char *tal_name(const tal_t *t)
 645 {
 646         struct name *n;
 647
 648         n = find_property(debug_tal(to_tal_hdr(t)), NAME);
 649         if (!n)
 650                 return NULL;
 651
 652         if (is_literal(&n->hdr))
 653                 return (const char *)n;
 654         return n->name;
 655 }
 656
 657 size_t tal_len(const tal_t *ptr)
 658 {
 659         struct length *l;
 660
 661         if (!ptr)
 662                 return 0;
 663
 664         l = find_property(debug_tal(to_tal_hdr(ptr)), LENGTH);
 665         if (!l)
 666                 return 0;
 667         return l->len;
 668 }
 669
 670 /* Start one past first child: make stopping natural in circ. list. */
 671 static struct tal_hdr *first_child(struct tal_hdr *parent)
 672 {
 673         struct children *child;
 674
 675         child = find_property(parent, CHILDREN);
 676         if (!child)
 677                 return NULL;
 678
 679         return list_top(&child->children, struct tal_hdr, list);
 680 }
 681
 682 tal_t *tal_first(const tal_t *root)
 683 {
 684         struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
 685
 686         c = first_child(t);
 687         if (!c)
 688                 return NULL;
 689         return from_tal_hdr(c);
 690 }
 691
 692 tal_t *tal_next(const tal_t *prev)
 693 {
 694         struct tal_hdr *next, *prevhdr = debug_tal(to_tal_hdr(prev));
 695         struct list_head *head;
 696
 697         head = &ignore_destroying_bit(prevhdr->parent_child)->children;
 698         next = list_next(head, prevhdr, list);
 699         if (!next)
 700                 return NULL;
 701         return from_tal_hdr(next);
 702 }
 703
 704 tal_t *tal_parent(const tal_t *ctx)
 705 {
 706         struct tal_hdr *t;
 707
 708         if (!ctx)
 709                 return NULL;
 710
 711         t = debug_tal(to_tal_hdr(ctx));
 712         if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
 713                 return NULL;
 714         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
 715 }
 716
 717 bool tal_resize_(tal_t **ctxp, size_t size, size_t count, bool clear)
 718 {
 719         struct tal_hdr *old_t, *t;
 720         struct children *child;
 721         struct prop_hdr **lenp;
 722         struct length len;
 723         size_t extra = 0;
 724
 725         old_t = debug_tal(to_tal_hdr(*ctxp));
 726
 727         if (!adjust_size(&size, count))
 728                 return false;
 729
 730         lenp = find_property_ptr(old_t, LENGTH);
 731         if (lenp) {
 732                 /* Copy here, in case we're shrinking! */
 733                 len = *(struct length *)*lenp;
 734                 extra = extra_for_length(size);
 735         } else /* If we don't have an old length, we can't clear! */
 736                 assert(!clear);
 737
 738         t = resizefn(old_t, sizeof(struct tal_hdr) + size + extra);
 739         if (!t) {
 740                 call_error("Reallocation failure");
 741                 return false;
 742         }
 743
 744         /* Copy length to end. */
 745         if (lenp) {
 746                 struct length *new_len;
 747
 748                 /* Clear between old end and new end. */
 749                 if (clear && size > len.len) {
 750                         char *old_end = (char *)(t + 1) + len.len;
 751                         memset(old_end, 0, size - len.len);
 752                 }
 753
 754                 new_len = (struct length *)((char *)(t + 1) + size
 755                                             + extra - sizeof(len));
 756                 len.len = size;
 757                 *new_len = len;
 758
 759                 /* Be careful replacing next ptr; could be old hdr. */
 760                 if (lenp == &old_t->prop)
 761                         t->prop = &new_len->hdr;
 762                 else
 763                         *lenp = &new_len->hdr;
 764         }
 765
 766         update_bounds(t, sizeof(struct tal_hdr) + size + extra);
 767
 768         /* If it didn't move, we're done! */
 769         if (t != old_t) {
 770                 /* Fix up linked list pointers. */
 771                 t->list.next->prev = t->list.prev->next = &t->list;
 772
 773                 /* Fix up child property's parent pointer. */
 774                 child = find_property(t, CHILDREN);
 775                 if (child) {
 776                         assert(child->parent == old_t);
 777                         child->parent = t;
 778                 }
 779                 *ctxp = from_tal_hdr(debug_tal(t));
 780                 if (notifiers)
 781                         notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t), 0);
 782         }
 783         if (notifiers)
 784                 notify(t, TAL_NOTIFY_RESIZE, (void *)size, 0);
 785
 786         return true;
 787 }
 788
 789 bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
 790 {
 791         struct length *l;
 792         size_t old_len;
 793         bool ret = false;
 794
 795         l = find_property(debug_tal(to_tal_hdr(*ctxp)), LENGTH);
 796         old_len = l->len;
 797
 798         /* Check for additive overflow */
 799         if (old_len + count * size < old_len) {
 800                 call_error("dup size overflow");
 801                 goto out;
 802         }
 803
 804         /* Don't point src inside thing we're expanding! */
 805         assert(src < *ctxp
 806                || (char *)src >= (char *)(*ctxp) + old_len);
 807
 808         if (!tal_resize_(ctxp, size, old_len/size + count, false))
 809                 goto out;
 810
 811         memcpy((char *)*ctxp + old_len, src, count * size);
 812         ret = true;
 813
 814 out:
 815         if (taken(src))
 816                 tal_free(src);
 817         return ret;
 818 }
 819
 820 void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
 821                size_t n, size_t extra, bool add_length,
 822                const char *label)
 823 {
 824         void *ret;
 825         size_t nbytes = size;
 826
 827         if (!adjust_size(&nbytes, n)) {
 828                 if (taken(p))
 829                         tal_free(p);
 830                 return NULL;
 831         }
 832
 833         /* Beware addition overflow! */
 834         if (n + extra < n) {
 835                 call_error("dup size overflow");
 836                 if (taken(p))
 837                         tal_free(p);
 838                 return NULL;
 839         }
 840
 841         if (taken(p)) {
 842                 if (unlikely(!p))
 843                         return NULL;
 844                 if (unlikely(!tal_resize_((void **)&p, size, n + extra, false)))
 845                         return tal_free(p);
 846                 if (unlikely(!tal_steal(ctx, p)))
 847                         return tal_free(p);
 848                 return (void *)p;
 849         }
 850
 851         ret = tal_alloc_arr_(ctx, size, n + extra, false, add_length, label);
 852         if (ret)
 853                 memcpy(ret, p, nbytes);
 854         return ret;
 855 }
 856
 857 void tal_set_backend(void *(*alloc_fn)(size_t size),
 858                      void *(*resize_fn)(void *, size_t size),
 859                      void (*free_fn)(void *),
 860                      void (*error_fn)(const char *msg))
 861 {
 862         if (alloc_fn)
 863                 allocfn = alloc_fn;
 864         if (resize_fn)
 865                 resizefn = resize_fn;
 866         if (free_fn)
 867                 freefn = free_fn;
 868         if (error_fn)
 869                 errorfn = error_fn;
 870 }
 871
 872 #ifdef CCAN_TAL_DEBUG
 873 static void dump_node(unsigned int indent, const struct tal_hdr *t)
 874 {
 875         unsigned int i;
 876         const struct prop_hdr *p;
 877
 878         for (i = 0; i < indent; i++)
 879                 printf("  ");
 880         printf("%p", t);
 881         for (p = t->prop; p; p = p->next) {
 882                 struct children *c;
 883                 struct name *n;
 884                 struct notifier *no;
 885                 struct length *l;
 886                 if (is_literal(p)) {
 887                         printf(" \"%s\"", (const char *)p);
 888                         break;
 889                 }
 890                 switch (p->type) {
 891                 case CHILDREN:
 892                         c = (struct children *)p;
 893                         printf(" CHILDREN(%p):parent=%p,children={%p,%p}\n",
 894                                p, c->parent,
 895                                c->children.n.prev, c->children.n.next);
 896                         break;
 897                 case NAME:
 898                         n = (struct name *)p;
 899                         printf(" NAME(%p):%s", p, n->name);
 900                         break;
 901                 case NOTIFIER:
 902                         no = (struct notifier *)p;
 903                         printf(" NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
 904                         break;
 905                 case LENGTH:
 906                         l = (struct length *)p;
 907                         printf(" LENGTH(%p):len=%zu", p, l->len);
 908                         break;
 909                 default:
 910                         printf(" **UNKNOWN(%p):%i**", p, p->type);
 911                 }
 912         }
 913         printf("\n");
 914 }
 915
 916 static void tal_dump_(unsigned int level, const struct tal_hdr *t)
 917 {
 918         struct children *children;
 919
 920         dump_node(level, t);
 921
 922         children = find_property(t, CHILDREN);
 923         if (children) {
 924                 struct tal_hdr *i;
 925
 926                 list_for_each(&children->children, i, list)
 927                         tal_dump_(level + 1, i);
 928         }
 929 }
 930
 931 void tal_dump(void)
 932 {
 933         tal_dump_(0, &null_parent.hdr);
 934 }
 935 #endif /* CCAN_TAL_DEBUG */
 936
 937 #ifndef NDEBUG
 938 static bool check_err(struct tal_hdr *t, const char *errorstr,
 939                       const char *errmsg)
 940 {
 941         if (errorstr) {
 942                 /* Try not to malloc: it may be corrupted. */
 943                 char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
 944                 sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
 945                 call_error(msg);
 946         }
 947         return false;
 948 }
 949
 950 static bool check_node(struct children *parent_child,
 951                        struct tal_hdr *t, const char *errorstr)
 952 {
 953         struct prop_hdr *p;
 954         struct name *name = NULL;
 955         struct children *children = NULL;
 956         struct length *length = NULL;
 957
 958         if (!in_bounds(t))
 959                 return check_err(t, errorstr, "invalid pointer");
 960
 961         if (ignore_destroying_bit(t->parent_child) != parent_child)
 962                 return check_err(t, errorstr, "incorrect parent");
 963
 964         for (p = t->prop; p; p = p->next) {
 965                 if (is_literal(p)) {
 966                         if (name)
 967                                 return check_err(t, errorstr,
 968                                                  "has extra literal");
 969                         break;
 970                 }
 971                 if (!in_bounds(p))
 972                         return check_err(t, errorstr,
 973                                          "has bad property pointer");
 974
 975                 switch (p->type) {
 976                 case CHILDREN:
 977                         if (children)
 978                                 return check_err(t, errorstr,
 979                                                  "has two child nodes");
 980                         children = (struct children *)p;
 981                         break;
 982                 case LENGTH:
 983                         if (length)
 984                                 return check_err(t, errorstr,
 985                                                  "has two lengths");
 986                         length = (struct length *)p;
 987                         break;
 988                 case NOTIFIER:
 989                         break;
 990                 case NAME:
 991                         if (name)
 992                                 return check_err(t, errorstr,
 993                                                  "has two names");
 994                         name = (struct name *)p;
 995                         break;
 996                 default:
 997                         return check_err(t, errorstr, "has unknown property");
 998                 }
 999         }
1000         if (children) {
1001                 struct tal_hdr *i;
1002
1003                 if (!list_check(&children->children, errorstr))
1004                         return false;
1005                 list_for_each(&children->children, i, list) {
1006                         if (!check_node(children, i, errorstr))
1007                                 return false;
1008                 }
1009         }
1010         return true;
1011 }
1012
1013 bool tal_check(const tal_t *ctx, const char *errorstr)
1014 {
1015         struct tal_hdr *t = to_tal_hdr_or_null(ctx);
1016
1017         return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
1018 }
1019 #else /* NDEBUG */
1020 bool tal_check(const tal_t *ctx, const char *errorstr)
1021 {
1022         return true;
1023 }
1024 #endif