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

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