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 <assert.h>
   7 #include <stdio.h>
   8 #include <stdarg.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 };
  24
  25 struct tal_hdr {
  26         struct list_node list;
  27         struct prop_hdr *prop;
  28         struct children *parent_child;
  29 };
  30
  31 struct prop_hdr {
  32         enum prop_type type;
  33         struct prop_hdr *next;
  34 };
  35
  36 struct children {
  37         struct prop_hdr hdr; /* CHILDREN */
  38         struct tal_hdr *parent;
  39         struct list_head children; /* Head of siblings. */
  40 };
  41
  42 struct name {
  43         struct prop_hdr hdr; /* NAME */
  44         char name[];
  45 };
  46
  47 struct notifier {
  48         struct prop_hdr hdr; /* NOTIFIER */
  49         enum tal_notify_type types;
  50         union {
  51                 void (*notifyfn)(tal_t *, enum tal_notify_type, void *);
  52                 void (*destroy)(tal_t *); /* If NOTIFY_IS_DESTRUCTOR set */
  53         } u;
  54 };
  55
  56 static struct {
  57         struct tal_hdr hdr;
  58         struct children c;
  59 } null_parent = { { { &null_parent.hdr.list, &null_parent.hdr.list },
  60                     &null_parent.c.hdr, NULL },
  61                   { { CHILDREN, NULL },
  62                     &null_parent.hdr,
  63                     { { &null_parent.c.children.n,
  64                         &null_parent.c.children.n } }
  65                   }
  66 };
  67
  68
  69 static void *(*allocfn)(size_t size) = malloc;
  70 static void *(*resizefn)(void *, size_t size) = realloc;
  71 static void (*freefn)(void *) = free;
  72 static void (*errorfn)(const char *msg) = (void *)abort;
  73
  74 static inline void COLD call_error(const char *msg)
  75 {
  76         errorfn(msg);
  77 }
  78
  79 static bool get_destroying_bit(struct children *parent_child)
  80 {
  81         return (size_t)parent_child & 1;
  82 }
  83
  84 static void set_destroying_bit(struct children **parent_child)
  85 {
  86         *parent_child = (void *)((size_t)*parent_child | 1);
  87 }
  88
  89 static struct children *ignore_destroying_bit(struct children *parent_child)
  90 {
  91         return (void *)((size_t)parent_child & ~(size_t)1);
  92 }
  93
  94 static bool initialized = false;
  95
  96 /* This means valgrind can see leaks. */
  97 static void tal_cleanup(void)
  98 {
  99         struct tal_hdr *i;
 100
 101         while ((i = list_top(&null_parent.c.children, struct tal_hdr, list)))
 102                 list_del(&i->list);
 103
 104         /* Cleanup any taken pointers. */
 105         take_cleanup();
 106 }
 107
 108 /* For allocation failures inside ccan/take */
 109 static void take_alloc_failed(const void *p)
 110 {
 111         tal_free(p);
 112 }
 113
 114 /* We carefully start all real properties with a zero byte. */
 115 static bool is_literal(const struct prop_hdr *prop)
 116 {
 117         return ((char *)prop)[0] != 0;
 118 }
 119
 120 #ifndef NDEBUG
 121 static const void *bounds_start, *bounds_end;
 122
 123 static void update_bounds(const void *new, size_t size)
 124 {
 125         if (unlikely(!bounds_start)) {
 126                 bounds_start = new;
 127                 bounds_end = (char *)new + size;
 128         } else if (new < bounds_start)
 129                 bounds_start = new;
 130         else if ((char *)new + size > (char *)bounds_end)
 131                 bounds_end = (char *)new + size;
 132 }
 133
 134 static bool in_bounds(const void *p)
 135 {
 136         return !p
 137                 || (p >= (void *)&null_parent && p <= (void *)(&null_parent + 1))
 138                 || (p >= bounds_start && p <= bounds_end);
 139 }
 140 #else
 141 static void update_bounds(const void *new, size_t size)
 142 {
 143 }
 144
 145 static bool in_bounds(const void *p)
 146 {
 147         return true;
 148 }
 149 #endif
 150
 151 static void check_bounds(const void *p)
 152 {
 153         if (!in_bounds(p))
 154                 call_error("Not a valid header");
 155 }
 156
 157 static struct tal_hdr *to_tal_hdr(const void *ctx)
 158 {
 159         struct tal_hdr *t;
 160
 161         t = (struct tal_hdr *)((char *)ctx - sizeof(struct tal_hdr));
 162         check_bounds(t);
 163         check_bounds(ignore_destroying_bit(t->parent_child));
 164         check_bounds(t->list.next);
 165         check_bounds(t->list.prev);
 166         if (t->prop && !is_literal(t->prop))
 167                 check_bounds(t->prop);
 168         return t;
 169 }
 170
 171 static struct tal_hdr *to_tal_hdr_or_null(const void *ctx)
 172 {
 173         if (!ctx)
 174                 return &null_parent.hdr;
 175         return to_tal_hdr(ctx);
 176 }
 177
 178 static void *from_tal_hdr(const struct tal_hdr *hdr)
 179 {
 180         return (void *)(hdr + 1);
 181 }
 182
 183 #ifdef TAL_DEBUG
 184 static void *from_tal_hdr_or_null(struct tal_hdr *hdr)
 185 {
 186         if (hdr == &null_parent.hdr)
 187                 return NULL;
 188         return from_tal_hdr(hdr);
 189 }
 190
 191 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 192 {
 193         tal_check(from_tal_hdr_or_null(tal), "TAL_DEBUG ");
 194         return tal;
 195 }
 196 #else
 197 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
 198 {
 199         return tal;
 200 }
 201 #endif
 202
 203 static void notify(const struct tal_hdr *ctx,
 204                    enum tal_notify_type type, const void *info)
 205 {
 206         const struct prop_hdr *p;
 207
 208         for (p = ctx->prop; p; p = p->next) {
 209                 struct notifier *n;
 210
 211                 if (is_literal(p))
 212                         break;
 213                 if (p->type != NOTIFIER)
 214                         continue;
 215                 n = (struct notifier *)p;
 216                 if (n->types & type) {
 217                         if (n->types & NOTIFY_IS_DESTRUCTOR)
 218                                 n->u.destroy(from_tal_hdr(ctx));
 219                         else
 220                                 n->u.notifyfn(from_tal_hdr(ctx), type,
 221                                               (void *)info);
 222                 }
 223         }
 224 }
 225
 226 static void *allocate(size_t size)
 227 {
 228         void *ret;
 229
 230         /* Don't hand silly sizes to malloc. */
 231         if (size >> (CHAR_BIT*sizeof(size) - 1)) {
 232                 call_error("allocation size overflow");
 233                 return NULL;
 234         }
 235
 236         ret = allocfn(size);
 237         if (!ret)
 238                 call_error("allocation failed");
 239         else
 240                 update_bounds(ret, size);
 241         return ret;
 242 }
 243
 244 static struct prop_hdr **find_property_ptr(const struct tal_hdr *t,
 245                                            enum prop_type type)
 246 {
 247         struct prop_hdr **p;
 248
 249         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 250                 if (is_literal(*p)) {
 251                         if (type == NAME)
 252                                 return p;
 253                         break;
 254                 }
 255                 if ((*p)->type == type)
 256                         return p;
 257         }
 258         return NULL;
 259 }
 260
 261 static void *find_property(const struct tal_hdr *parent, enum prop_type type)
 262 {
 263         struct prop_hdr **p = find_property_ptr(parent, type);
 264
 265         if (p)
 266                 return *p;
 267         return NULL;
 268 }
 269
 270 static void init_property(struct prop_hdr *hdr,
 271                           struct tal_hdr *parent,
 272                           enum prop_type type)
 273 {
 274         hdr->type = type;
 275         hdr->next = parent->prop;
 276         parent->prop = hdr;
 277 }
 278
 279 static struct notifier *add_notifier_property(struct tal_hdr *t,
 280                                               enum tal_notify_type types,
 281                                               void (*fn)(void *,
 282                                                          enum tal_notify_type,
 283                                                          void *))
 284 {
 285         struct notifier *prop = allocate(sizeof(*prop));
 286         if (prop) {
 287                 init_property(&prop->hdr, t, NOTIFIER);
 288                 prop->types = types;
 289                 prop->u.notifyfn = fn;
 290         }
 291         return prop;
 292 }
 293
 294 static bool del_notifier_property(struct tal_hdr *t,
 295                                   void (*fn)(tal_t *,
 296                                              enum tal_notify_type, void *))
 297 {
 298         struct prop_hdr **p;
 299
 300         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
 301                 struct notifier *n;
 302
 303                 if (is_literal(*p))
 304                         break;
 305                 if ((*p)->type != NOTIFIER)
 306                         continue;
 307                 n = (struct notifier *)*p;
 308                 if (n->u.notifyfn == fn) {
 309                         *p = (*p)->next;
 310                         freefn(n);
 311                         return true;
 312                 }
 313         }
 314         return false;
 315 }
 316
 317 static struct name *add_name_property(struct tal_hdr *t, const char *name)
 318 {
 319         struct name *prop;
 320
 321         prop = allocate(sizeof(*prop) + strlen(name) + 1);
 322         if (prop) {
 323                 init_property(&prop->hdr, t, NAME);
 324                 strcpy(prop->name, name);
 325         }
 326         return prop;
 327 }
 328
 329 static struct children *add_child_property(struct tal_hdr *parent,
 330                                            struct tal_hdr *child)
 331 {
 332         struct children *prop = allocate(sizeof(*prop));
 333         if (prop) {
 334                 init_property(&prop->hdr, parent, CHILDREN);
 335                 prop->parent = parent;
 336                 list_head_init(&prop->children);
 337         }
 338         return prop;
 339 }
 340
 341 static bool add_child(struct tal_hdr *parent, struct tal_hdr *child)
 342 {
 343         struct children *children = find_property(parent, CHILDREN);
 344
 345         if (!children) {
 346                 if (unlikely(!initialized)) {
 347                         atexit(tal_cleanup);
 348                         take_allocfail(take_alloc_failed);
 349                         initialized = true;
 350                 }
 351                 children = add_child_property(parent, child);
 352                 if (!children)
 353                         return false;
 354         }
 355         list_add(&children->children, &child->list);
 356         child->parent_child = children;
 357         return true;
 358 }
 359
 360 static void del_tree(struct tal_hdr *t, const tal_t *orig)
 361 {
 362         struct prop_hdr **prop, *p, *next;
 363
 364         /* Already being destroyed?  Don't loop. */
 365         if (unlikely(get_destroying_bit(t->parent_child)))
 366                 return;
 367
 368         set_destroying_bit(&t->parent_child);
 369
 370         /* Call free notifiers. */
 371         notify(t, TAL_NOTIFY_FREE, (tal_t *)orig);
 372
 373         /* Now free children and groups. */
 374         prop = find_property_ptr(t, CHILDREN);
 375         if (prop) {
 376                 struct tal_hdr *i;
 377                 struct children *c = (struct children *)*prop;
 378
 379                 while ((i = list_top(&c->children, struct tal_hdr, list))) {
 380                         list_del(&i->list);
 381                         del_tree(i, orig);
 382                 }
 383         }
 384
 385         /* Finally free our properties. */
 386         for (p = t->prop; p && !is_literal(p); p = next) {
 387                 next = p->next;
 388                 freefn(p);
 389         }
 390         freefn(t);
 391 }
 392
 393 void *tal_alloc_(const tal_t *ctx, size_t size, bool clear, const char *label)
 394 {
 395         struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
 396
 397         child = allocate(sizeof(struct tal_hdr) + size);
 398         if (!child)
 399                 return NULL;
 400         if (clear)
 401                 memset(from_tal_hdr(child), 0, size);
 402         child->prop = (void *)label;
 403         if (!add_child(parent, child)) {
 404                 freefn(child);
 405                 return NULL;
 406         }
 407         debug_tal(parent);
 408         notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(debug_tal(child)));
 409         return from_tal_hdr(debug_tal(child));
 410 }
 411
 412 void *tal_free(const tal_t *ctx)
 413 {
 414         if (ctx) {
 415                 struct tal_hdr *t;
 416                 int saved_errno = errno;
 417                 t = debug_tal(to_tal_hdr(ctx));
 418                 notify(ignore_destroying_bit(t->parent_child)->parent,
 419                        TAL_NOTIFY_DEL_CHILD, ctx);
 420                 list_del(&t->list);
 421                 del_tree(t, ctx);
 422                 errno = saved_errno;
 423         }
 424         return NULL;
 425 }
 426
 427 void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
 428 {
 429         if (ctx) {
 430                 struct tal_hdr *newpar, *t, *old_parent;
 431
 432                 newpar = debug_tal(to_tal_hdr_or_null(new_parent));
 433                 t = debug_tal(to_tal_hdr(ctx));
 434
 435                 /* Unlink it from old parent. */
 436                 list_del(&t->list);
 437                 old_parent = ignore_destroying_bit(t->parent_child)->parent;
 438
 439                 if (unlikely(!add_child(newpar, t))) {
 440                         /* We can always add to old parent, becuase it has a
 441                          * children property already. */
 442                         if (!add_child(old_parent, t))
 443                                 abort();
 444                         return NULL;
 445                 }
 446                 debug_tal(newpar);
 447                 notify(t, TAL_NOTIFY_STEAL, new_parent);
 448         }
 449         return (void *)ctx;
 450 }
 451
 452 bool tal_add_destructor_(tal_t *ctx, void (*destroy)(void *me))
 453 {
 454         tal_t *t = debug_tal(to_tal_hdr(ctx));
 455         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
 456                                      (void *)destroy);
 457 }
 458
 459 bool tal_add_notifier_(tal_t *ctx, enum tal_notify_type types,
 460                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 461 {
 462         tal_t *t = debug_tal(to_tal_hdr(ctx));
 463         struct notifier *n;
 464
 465         assert(types);
 466         assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
 467                           | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
 468                           | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
 469                           | TAL_NOTIFY_ADD_NOTIFIER
 470                           | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
 471
 472         /* Don't call notifier about itself: set types after! */
 473         n = add_notifier_property(t, 0, callback);
 474         if (unlikely(!n))
 475                 return false;
 476
 477         notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback);
 478         n->types = types;
 479         return true;
 480 }
 481
 482 bool tal_del_notifier_(tal_t *ctx,
 483                        void (*callback)(tal_t *, enum tal_notify_type, void *))
 484 {
 485         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 486         bool ret;
 487
 488         ret = del_notifier_property(t, callback);
 489         if (ret)
 490                 notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback);
 491         return ret;
 492 }
 493
 494 bool tal_del_destructor_(tal_t *ctx, void (*destroy)(void *me))
 495 {
 496         return tal_del_notifier_(ctx, (void *)destroy);
 497 }
 498
 499 bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
 500 {
 501         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
 502         struct prop_hdr **prop = find_property_ptr(t, NAME);
 503
 504         /* Get rid of any old name */
 505         if (prop) {
 506                 struct name *name = (struct name *)*prop;
 507                 if (is_literal(&name->hdr))
 508                         *prop = NULL;
 509                 else {
 510                         *prop = name->hdr.next;
 511                         freefn(name);
 512                 }
 513         }
 514
 515         if (literal && name[0]) {
 516                 struct prop_hdr **p;
 517
 518                 /* Append literal. */
 519                 for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
 520                 *p = (struct prop_hdr *)name;
 521         } else if (!add_name_property(t, name))
 522                 return false;
 523
 524         debug_tal(t);
 525         notify(t, TAL_NOTIFY_RENAME, name);
 526         return true;
 527 }
 528
 529 const char *tal_name(const tal_t *t)
 530 {
 531         struct name *n;
 532
 533         n = find_property(debug_tal(to_tal_hdr(t)), NAME);
 534         if (!n)
 535                 return NULL;
 536
 537         if (is_literal(&n->hdr))
 538                 return (const char *)n;
 539         return n->name;
 540 }
 541
 542 /* Start one past first child: make stopping natural in circ. list. */
 543 static struct tal_hdr *first_child(struct tal_hdr *parent)
 544 {
 545         struct children *child;
 546
 547         child = find_property(parent, CHILDREN);
 548         if (!child)
 549                 return NULL;
 550
 551         return list_top(&child->children, struct tal_hdr, list);
 552 }
 553
 554 tal_t *tal_first(const tal_t *root)
 555 {
 556         struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
 557
 558         c = first_child(t);
 559         if (!c)
 560                 return NULL;
 561         return from_tal_hdr(c);
 562 }
 563
 564 tal_t *tal_next(const tal_t *root, const tal_t *prev)
 565 {
 566         struct tal_hdr *c, *t = debug_tal(to_tal_hdr(prev)), *top;
 567
 568         /* Children? */
 569         c = first_child(t);
 570         if (c)
 571                 return from_tal_hdr(c);
 572
 573         top = to_tal_hdr_or_null(root);
 574         do {
 575                 struct tal_hdr *next;
 576                 struct list_node *end;
 577
 578                 end = &ignore_destroying_bit(t->parent_child)->children.n;
 579
 580                 next = list_entry(t->list.next, struct tal_hdr, list);
 581                 if (&next->list != end)
 582                         return from_tal_hdr(next);
 583
 584                 /* OK, go back to parent. */
 585                 t = ignore_destroying_bit(t->parent_child)->parent;
 586         } while (t != top);
 587
 588         return NULL;
 589 }
 590
 591 tal_t *tal_parent(const tal_t *ctx)
 592 {
 593         struct tal_hdr *t;
 594
 595         if (!ctx)
 596                 return NULL;
 597
 598         t = debug_tal(to_tal_hdr(ctx));
 599         if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
 600                 return NULL;
 601         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
 602 }
 603
 604 bool tal_resize_(tal_t **ctxp, size_t size)
 605 {
 606         struct tal_hdr *old_t, *t;
 607         struct children *child;
 608
 609         old_t = debug_tal(to_tal_hdr(*ctxp));
 610
 611         /* Don't hand silly sizes to realloc. */
 612         if (size >> (CHAR_BIT*sizeof(size) - 1)) {
 613                 call_error("Reallocation size overflow");
 614                 return false;
 615         }
 616
 617         t = resizefn(old_t, size + sizeof(struct tal_hdr));
 618         if (!t) {
 619                 call_error("Reallocation failure");
 620                 return false;
 621         }
 622
 623         /* If it didn't move, we're done! */
 624         if (t != old_t) {
 625                 update_bounds(t, size + sizeof(struct tal_hdr));
 626
 627                 /* Fix up linked list pointers. */
 628                 if (list_entry(t->list.next, struct tal_hdr, list) != old_t)
 629                         t->list.next->prev = t->list.prev->next = &t->list;
 630
 631                 /* Fix up child property's parent pointer. */
 632                 child = find_property(t, CHILDREN);
 633                 if (child) {
 634                         assert(child->parent == old_t);
 635                         child->parent = t;
 636                 }
 637                 *ctxp = from_tal_hdr(debug_tal(t));
 638                 notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t));
 639         }
 640         notify(t, TAL_NOTIFY_RESIZE, (void *)size);
 641
 642         return true;
 643 }
 644
 645 char *tal_strdup(const tal_t *ctx, const char *p)
 646 {
 647         /* We have to let through NULL for take(). */
 648         return tal_dup(ctx, char, p, p ? strlen(p) + 1: 1, 0);
 649 }
 650
 651 char *tal_strndup(const tal_t *ctx, const char *p, size_t n)
 652 {
 653         size_t len;
 654         char *ret;
 655
 656         /* We have to let through NULL for take(). */
 657         if (likely(p)) {
 658                 len = strlen(p);
 659                 if (len > n)
 660                         len = n;
 661         } else
 662                 len = n;
 663
 664         ret = tal_dup(ctx, char, p, len, 1);
 665         if (ret)
 666                 ret[len] = '\0';
 667         return ret;
 668 }
 669
 670 void *tal_dup_(const tal_t *ctx, const void *p, size_t n, size_t extra,
 671                const char *label)
 672 {
 673         void *ret;
 674
 675         /* Beware overflow! */
 676         if (n + extra < n || n + extra + sizeof(struct tal_hdr) < n) {
 677                 call_error("dup size overflow");
 678                 if (taken(p))
 679                         tal_free(p);
 680                 return NULL;
 681         }
 682
 683         if (taken(p)) {
 684                 if (unlikely(!p))
 685                         return NULL;
 686                 if (unlikely(!tal_resize_((void **)&p, n + extra)))
 687                         return tal_free(p);
 688                 if (unlikely(!tal_steal(ctx, p)))
 689                         return tal_free(p);
 690                 return (void *)p;
 691         }
 692         ret = tal_alloc_(ctx, n + extra, false, label);
 693         if (ret)
 694                 memcpy(ret, p, n);
 695         return ret;
 696 }
 697
 698 char *tal_asprintf(const tal_t *ctx, const char *fmt, ...)
 699 {
 700         va_list ap;
 701         char *ret;
 702
 703         va_start(ap, fmt);
 704         ret = tal_vasprintf(ctx, fmt, ap);
 705         va_end(ap);
 706
 707         return ret;
 708 }
 709
 710 char *tal_vasprintf(const tal_t *ctx, const char *fmt, va_list ap)
 711 {
 712         size_t max;
 713         char *buf;
 714         int ret;
 715
 716         if (!fmt && taken(fmt))
 717                 return NULL;
 718
 719         /* A decent guess to start. */
 720         max = strlen(fmt) * 2;
 721         buf = tal_arr(ctx, char, max);
 722         while (buf) {
 723                 va_list ap2;
 724
 725                 va_copy(ap2, ap);
 726                 ret = vsnprintf(buf, max, fmt, ap2);
 727                 va_end(ap2);
 728
 729                 if (ret < max)
 730                         break;
 731                 if (!tal_resize(&buf, max *= 2))
 732                         buf = tal_free(buf);
 733         }
 734         if (taken(fmt))
 735                 tal_free(fmt);
 736         return buf;
 737 }
 738
 739 void tal_set_backend(void *(*alloc_fn)(size_t size),
 740                      void *(*resize_fn)(void *, size_t size),
 741                      void (*free_fn)(void *),
 742                      void (*error_fn)(const char *msg))
 743 {
 744         if (alloc_fn)
 745                 allocfn = alloc_fn;
 746         if (resize_fn)
 747                 resizefn = resize_fn;
 748         if (free_fn)
 749                 freefn = free_fn;
 750         if (error_fn)
 751                 errorfn = error_fn;
 752 }
 753
 754 #ifdef CCAN_TAL_DEBUG
 755 static void dump_node(unsigned int indent, const struct tal_hdr *t)
 756 {
 757         unsigned int i;
 758         const struct prop_hdr *p;
 759
 760         for (i = 0; i < indent; i++)
 761                 printf("  ");
 762         printf("%p", t);
 763         for (p = t->prop; p; p = p->next) {
 764                 struct children *c;
 765                 struct name *n;
 766                 struct notifier *no;
 767                 if (is_literal(p)) {
 768                         printf(" \"%s\"", (const char *)p);
 769                         break;
 770                 }
 771                 switch (p->type) {
 772                 case CHILDREN:
 773                         c = (struct children *)p;
 774                         printf(" CHILDREN(%p):parent=%p,children={%p,%p}\n",
 775                                p, c->parent,
 776                                c->children.n.prev, c->children.n.next);
 777                         break;
 778                 case NAME:
 779                         n = (struct name *)p;
 780                         printf(" NAME(%p):%s", p, n->name);
 781                         break;
 782                 case NOTIFIER:
 783                         no = (struct notifier *)p;
 784                         printf(" NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
 785                         break;
 786                 default:
 787                         printf(" **UNKNOWN(%p):%i**", p, p->type);
 788                 }
 789         }
 790         printf("\n");
 791 }
 792
 793 static void tal_dump_(unsigned int level, const struct tal_hdr *t)
 794 {
 795         struct children *children;
 796
 797         dump_node(level, t);
 798
 799         children = find_property(t, CHILDREN);
 800         if (children) {
 801                 struct tal_hdr *i;
 802
 803                 list_for_each(&children->children, i, list)
 804                         tal_dump_(level + 1, i);
 805         }
 806 }
 807
 808 void tal_dump(void)
 809 {
 810         tal_dump_(0, &null_parent.hdr);
 811 }
 812 #endif /* CCAN_TAL_DEBUG */
 813
 814 #ifndef NDEBUG
 815 static bool check_err(struct tal_hdr *t, const char *errorstr,
 816                       const char *errmsg)
 817 {
 818         if (errorstr) {
 819                 /* Try not to malloc: it may be corrupted. */
 820                 char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
 821                 sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
 822                 call_error(msg);
 823         }
 824         return false;
 825 }
 826
 827 static bool check_node(struct children *parent_child,
 828                        struct tal_hdr *t, const char *errorstr)
 829 {
 830         struct prop_hdr *p;
 831         struct name *name = NULL;
 832         struct children *children = NULL;
 833
 834         if (!in_bounds(t))
 835                 return check_err(t, errorstr, "invalid pointer");
 836
 837         if (ignore_destroying_bit(t->parent_child) != parent_child)
 838                 return check_err(t, errorstr, "incorrect parent");
 839
 840         for (p = t->prop; p; p = p->next) {
 841                 if (is_literal(p)) {
 842                         if (name)
 843                                 return check_err(t, errorstr,
 844                                                  "has extra literal");
 845                         name = (struct name *)p;
 846                         break;
 847                 }
 848                 if (!in_bounds(p))
 849                         return check_err(t, errorstr,
 850                                          "has bad property pointer");
 851
 852                 switch (p->type) {
 853                 case CHILDREN:
 854                         if (children)
 855                                 return check_err(t, errorstr,
 856                                                  "has two child nodes");
 857                         children = (struct children *)p;
 858                         break;
 859                 case NOTIFIER:
 860                         break;
 861                 case NAME:
 862                         if (name)
 863                                 return check_err(t, errorstr,
 864                                                  "has two names");
 865                         name = (struct name *)p;
 866                         break;
 867                 default:
 868                         return check_err(t, errorstr, "has unknown property");
 869                 }
 870         }
 871         if (children) {
 872                 struct tal_hdr *i;
 873
 874                 if (!list_check(&children->children, errorstr))
 875                         return false;
 876                 list_for_each(&children->children, i, list) {
 877                         if (!check_node(children, i, errorstr))
 878                                 return false;
 879                 }
 880         }
 881         return true;
 882 }
 883
 884 bool tal_check(const tal_t *ctx, const char *errorstr)
 885 {
 886         struct tal_hdr *t = to_tal_hdr_or_null(ctx);
 887
 888         return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
 889 }
 890 #else /* NDEBUG */
 891 bool tal_check(const tal_t *ctx, const char *errorstr)
 892 {
 893         return true;
 894 }
 895 #endif