05d52e1dbe5cab4409461c42b2c26ed57b009987
[ccan] / ccan / tal / tal.c
1 /* Licensed under BSD-MIT - see LICENSE file for details */
2 #include <ccan/tal/tal.h>
3 #include <ccan/compiler/compiler.h>
4 #include <ccan/list/list.h>
5 #include <ccan/alignof/alignof.h>
6 #include <assert.h>
7 #include <stdio.h>
8 #include <stddef.h>
9 #include <string.h>
10 #include <limits.h>
11 #include <stdint.h>
12 #include <errno.h>
13
14 //#define TAL_DEBUG 1
15
16 #define NOTIFY_IS_DESTRUCTOR 512
17 #define NOTIFY_EXTRA_ARG 1024
18
19 /* This makes our parent_child ptr stand out for to_tal_hdr checks */
20 #define TAL_PTR_OBFUSTICATOR ((intptr_t)0x1984200820142016ULL)
21
22 /* 32-bit type field, first byte 0 in either endianness. */
23 enum prop_type {
24         CHILDREN = 0x00c1d500,
25         NAME = 0x00111100,
26         NOTIFIER = 0x00071f00,
27 };
28
29 struct tal_hdr {
30         struct list_node list;
31         struct prop_hdr *prop;
32         /* XOR with TAL_PTR_OBFUSTICATOR */
33         intptr_t parent_child;
34         size_t bytelen;
35 };
36
37 struct prop_hdr {
38         enum prop_type type;
39         struct prop_hdr *next;
40 };
41
42 struct children {
43         struct prop_hdr hdr; /* CHILDREN */
44         struct tal_hdr *parent;
45         struct list_head children; /* Head of siblings. */
46 };
47
48 struct name {
49         struct prop_hdr hdr; /* NAME */
50         char name[];
51 };
52
53 struct notifier {
54         struct prop_hdr hdr; /* NOTIFIER */
55         enum tal_notify_type types;
56         union notifier_cb {
57                 void (*notifyfn)(tal_t *, enum tal_notify_type, void *);
58                 void (*destroy)(tal_t *); /* If NOTIFY_IS_DESTRUCTOR set */
59                 void (*destroy2)(tal_t *, void *); /* If NOTIFY_EXTRA_ARG */
60         } u;
61 };
62
63 /* Extra arg */
64 struct notifier_extra_arg {
65         struct notifier n;
66         void *arg;
67 };
68
69 #define EXTRA_ARG(n) (((struct notifier_extra_arg *)(n))->arg)
70
71 static struct {
72         struct tal_hdr hdr;
73         struct children c;
74 } null_parent = { { { &null_parent.hdr.list, &null_parent.hdr.list },
75                     &null_parent.c.hdr, TAL_PTR_OBFUSTICATOR, 0 },
76                   { { CHILDREN, NULL },
77                     &null_parent.hdr,
78                     { { &null_parent.c.children.n,
79                         &null_parent.c.children.n } }
80                   }
81 };
82
83
84 static void *(*allocfn)(size_t size) = malloc;
85 static void *(*resizefn)(void *, size_t size) = realloc;
86 static void (*freefn)(void *) = free;
87 static void (*errorfn)(const char *msg) = (void *)abort;
88 /* Count on non-destrutor notifiers; often stays zero. */
89 static size_t notifiers = 0;
90
91 static inline void COLD call_error(const char *msg)
92 {
93         errorfn(msg);
94 }
95
96 static bool get_destroying_bit(intptr_t parent_child)
97 {
98         return parent_child & 1;
99 }
100
101 static void set_destroying_bit(intptr_t *parent_child)
102 {
103         *parent_child |= 1;
104 }
105
106 static struct children *ignore_destroying_bit(intptr_t parent_child)
107 {
108         return (void *)((parent_child ^ TAL_PTR_OBFUSTICATOR) & ~(intptr_t)1);
109 }
110
111 /* This means valgrind can see leaks. */
112 void tal_cleanup(void)
113 {
114         struct tal_hdr *i;
115
116         while ((i = list_top(&null_parent.c.children, struct tal_hdr, list))) {
117                 list_del(&i->list);
118                 memset(i, 0, sizeof(*i));
119         }
120
121         /* Cleanup any taken pointers. */
122         take_cleanup();
123 }
124
125 /* We carefully start all real properties with a zero byte. */
126 static bool is_literal(const struct prop_hdr *prop)
127 {
128         return ((char *)prop)[0] != 0;
129 }
130
131 #ifndef NDEBUG
132 static const void *bounds_start, *bounds_end;
133
134 static void update_bounds(const void *new, size_t size)
135 {
136         if (unlikely(!bounds_start)) {
137                 bounds_start = new;
138                 bounds_end = (char *)new + size;
139         } else if (new < bounds_start)
140                 bounds_start = new;
141         else if ((char *)new + size > (char *)bounds_end)
142                 bounds_end = (char *)new + size;
143 }
144
145 static bool in_bounds(const void *p)
146 {
147         return !p
148                 || (p >= (void *)&null_parent && p <= (void *)(&null_parent + 1))
149                 || (p >= bounds_start && p <= bounds_end);
150 }
151 #else
152 static void update_bounds(const void *new, size_t size)
153 {
154 }
155
156 static bool in_bounds(const void *p)
157 {
158         return true;
159 }
160 #endif
161
162 static void check_bounds(const void *p)
163 {
164         if (!in_bounds(p))
165                 call_error("Not a valid header");
166 }
167
168 static struct tal_hdr *to_tal_hdr(const void *ctx)
169 {
170         struct tal_hdr *t;
171
172         t = (struct tal_hdr *)((char *)ctx - sizeof(struct tal_hdr));
173         check_bounds(t);
174         check_bounds(ignore_destroying_bit(t->parent_child));
175         check_bounds(t->list.next);
176         check_bounds(t->list.prev);
177         if (t->prop && !is_literal(t->prop))
178                 check_bounds(t->prop);
179         return t;
180 }
181
182 static struct tal_hdr *to_tal_hdr_or_null(const void *ctx)
183 {
184         if (!ctx)
185                 return &null_parent.hdr;
186         return to_tal_hdr(ctx);
187 }
188
189 static void *from_tal_hdr(const struct tal_hdr *hdr)
190 {
191         return (void *)(hdr + 1);
192 }
193
194 static void *from_tal_hdr_or_null(const struct tal_hdr *hdr)
195 {
196         if (hdr == &null_parent.hdr)
197                 return NULL;
198         return from_tal_hdr(hdr);
199 }
200
201 #ifdef TAL_DEBUG
202 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
203 {
204         tal_check(from_tal_hdr_or_null(tal), "TAL_DEBUG ");
205         return tal;
206 }
207 #else
208 static struct tal_hdr *debug_tal(struct tal_hdr *tal)
209 {
210         return tal;
211 }
212 #endif
213
214 static void notify(const struct tal_hdr *ctx,
215                    enum tal_notify_type type, const void *info,
216                    int saved_errno)
217 {
218         const struct prop_hdr *p;
219
220         for (p = ctx->prop; p; p = p->next) {
221                 struct notifier *n;
222
223                 if (is_literal(p))
224                         break;
225                 if (p->type != NOTIFIER)
226                         continue;
227                 n = (struct notifier *)p;
228                 if (n->types & type) {
229                         errno = saved_errno;
230                         if (n->types & NOTIFY_IS_DESTRUCTOR) {
231                                 /* Blatt this notifier in case it tries to
232                                  * tal_del_destructor() from inside */
233                                 union notifier_cb cb = n->u;
234                                 /* It's a union, so this NULLs destroy2 too! */
235                                 n->u.destroy = NULL;
236                                 if (n->types & NOTIFY_EXTRA_ARG)
237                                         cb.destroy2(from_tal_hdr(ctx),
238                                                     EXTRA_ARG(n));
239                                 else
240                                         cb.destroy(from_tal_hdr(ctx));
241                         } else
242                                 n->u.notifyfn(from_tal_hdr_or_null(ctx), type,
243                                               (void *)info);
244                 }
245         }
246 }
247
248 static void *allocate(size_t size)
249 {
250         void *ret = allocfn(size);
251         if (!ret)
252                 call_error("allocation failed");
253         else
254                 update_bounds(ret, size);
255         return ret;
256 }
257
258 static struct prop_hdr **find_property_ptr(const struct tal_hdr *t,
259                                            enum prop_type type)
260 {
261         struct prop_hdr **p;
262
263         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
264                 if (is_literal(*p)) {
265                         if (type == NAME)
266                                 return p;
267                         break;
268                 }
269                 if ((*p)->type == type)
270                         return p;
271         }
272         return NULL;
273 }
274
275 static void *find_property(const struct tal_hdr *parent, enum prop_type type)
276 {
277         struct prop_hdr **p = find_property_ptr(parent, type);
278
279         if (p)
280                 return *p;
281         return NULL;
282 }
283
284 static void init_property(struct prop_hdr *hdr,
285                           struct tal_hdr *parent,
286                           enum prop_type type)
287 {
288         hdr->type = type;
289         hdr->next = parent->prop;
290         parent->prop = hdr;
291 }
292
293 static struct notifier *add_notifier_property(struct tal_hdr *t,
294                                               enum tal_notify_type types,
295                                               void (*fn)(void *,
296                                                          enum tal_notify_type,
297                                                          void *),
298                                               void *extra_arg)
299 {
300         struct notifier *prop;
301
302         if (types & NOTIFY_EXTRA_ARG)
303                 prop = allocate(sizeof(struct notifier_extra_arg));
304         else
305                 prop = allocate(sizeof(struct notifier));
306
307         if (prop) {
308                 init_property(&prop->hdr, t, NOTIFIER);
309                 prop->types = types;
310                 prop->u.notifyfn = fn;
311                 if (types & NOTIFY_EXTRA_ARG)
312                         EXTRA_ARG(prop) = extra_arg;
313         }
314         return prop;
315 }
316
317 static enum tal_notify_type del_notifier_property(struct tal_hdr *t,
318                                                   void (*fn)(tal_t *,
319                                                              enum tal_notify_type,
320                                                              void *),
321                                                   bool match_extra_arg,
322                                                   void *extra_arg)
323 {
324         struct prop_hdr **p;
325
326         for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
327                 struct notifier *n;
328                 enum tal_notify_type types;
329
330                 if (is_literal(*p))
331                         break;
332                 if ((*p)->type != NOTIFIER)
333                         continue;
334                 n = (struct notifier *)*p;
335                 if (n->u.notifyfn != fn)
336                         continue;
337
338                 types = n->types;
339                 if ((types & NOTIFY_EXTRA_ARG)
340                     && match_extra_arg
341                     && extra_arg != EXTRA_ARG(n))
342                         continue;
343
344                 *p = (*p)->next;
345                 freefn(n);
346                 return types & ~(NOTIFY_IS_DESTRUCTOR|NOTIFY_EXTRA_ARG);
347         }
348         return 0;
349 }
350
351 static struct name *add_name_property(struct tal_hdr *t, const char *name)
352 {
353         struct name *prop;
354
355         prop = allocate(sizeof(*prop) + strlen(name) + 1);
356         if (prop) {
357                 init_property(&prop->hdr, t, NAME);
358                 strcpy(prop->name, name);
359         }
360         return prop;
361 }
362
363 static struct children *add_child_property(struct tal_hdr *parent,
364                                            struct tal_hdr *child UNNEEDED)
365 {
366         struct children *prop = allocate(sizeof(*prop));
367         if (prop) {
368                 init_property(&prop->hdr, parent, CHILDREN);
369                 prop->parent = parent;
370                 list_head_init(&prop->children);
371         }
372         return prop;
373 }
374
375 static bool add_child(struct tal_hdr *parent, struct tal_hdr *child)
376 {
377         struct children *children = find_property(parent, CHILDREN);
378
379         if (!children) {
380                 children = add_child_property(parent, child);
381                 if (!children)
382                         return false;
383         }
384         list_add(&children->children, &child->list);
385         child->parent_child = (intptr_t)children ^ TAL_PTR_OBFUSTICATOR;
386         return true;
387 }
388
389 static void del_tree(struct tal_hdr *t, const tal_t *orig, int saved_errno)
390 {
391         struct prop_hdr **prop, *p, *next;
392
393         assert(!taken(from_tal_hdr(t)));
394
395         /* Already being destroyed?  Don't loop. */
396         if (unlikely(get_destroying_bit(t->parent_child)))
397                 return;
398
399         set_destroying_bit(&t->parent_child);
400
401         /* Call free notifiers. */
402         notify(t, TAL_NOTIFY_FREE, (tal_t *)orig, saved_errno);
403
404         /* Now free children and groups. */
405         prop = find_property_ptr(t, CHILDREN);
406         if (prop) {
407                 struct tal_hdr *i;
408                 struct children *c = (struct children *)*prop;
409
410                 while ((i = list_top(&c->children, struct tal_hdr, list))) {
411                         list_del(&i->list);
412                         del_tree(i, orig, saved_errno);
413                 }
414         }
415
416         /* Finally free our properties. */
417         for (p = t->prop; p && !is_literal(p); p = next) {
418                 next = p->next;
419                 freefn(p);
420         }
421         freefn(t);
422 }
423
424 void *tal_alloc_(const tal_t *ctx, size_t size, bool clear, const char *label)
425 {
426         struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
427
428         child = allocate(sizeof(struct tal_hdr) + size);
429         if (!child)
430                 return NULL;
431         if (clear)
432                 memset(from_tal_hdr(child), 0, size);
433         child->prop = (void *)label;
434         child->bytelen = size;
435
436         if (!add_child(parent, child)) {
437                 freefn(child);
438                 return NULL;
439         }
440         debug_tal(parent);
441         if (notifiers)
442                 notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(child), 0);
443         return from_tal_hdr(debug_tal(child));
444 }
445
446 static bool adjust_size(size_t *size, size_t count)
447 {
448         const size_t extra = sizeof(struct tal_hdr);
449
450         /* Multiplication wrap */
451         if (count && unlikely(*size * count / *size != count))
452                 goto overflow;
453
454         *size *= count;
455
456         /* Make sure we don't wrap adding header. */
457         if (*size + extra < extra)
458                 goto overflow;
459         return true;
460 overflow:
461         call_error("allocation size overflow");
462         return false;
463 }
464
465 void *tal_alloc_arr_(const tal_t *ctx, size_t size, size_t count, bool clear,
466                      const char *label)
467 {
468         if (!adjust_size(&size, count))
469                 return NULL;
470
471         return tal_alloc_(ctx, size, clear, label);
472 }
473
474 void *tal_free(const tal_t *ctx)
475 {
476         if (ctx) {
477                 struct tal_hdr *t;
478                 int saved_errno = errno;
479                 t = debug_tal(to_tal_hdr(ctx));
480                 if (unlikely(get_destroying_bit(t->parent_child)))
481                         return NULL;
482                 if (notifiers)
483                         notify(ignore_destroying_bit(t->parent_child)->parent,
484                                TAL_NOTIFY_DEL_CHILD, ctx, saved_errno);
485                 list_del(&t->list);
486                 del_tree(t, ctx, saved_errno);
487                 errno = saved_errno;
488         }
489         return NULL;
490 }
491
492 void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
493 {
494         if (ctx) {
495                 struct tal_hdr *newpar, *t, *old_parent;
496
497                 newpar = debug_tal(to_tal_hdr_or_null(new_parent));
498                 t = debug_tal(to_tal_hdr(ctx));
499
500                 /* Unlink it from old parent. */
501                 list_del(&t->list);
502                 old_parent = ignore_destroying_bit(t->parent_child)->parent;
503
504                 if (unlikely(!add_child(newpar, t))) {
505                         /* We can always add to old parent, because it has a
506                          * children property already. */
507                         if (!add_child(old_parent, t))
508                                 abort();
509                         return NULL;
510                 }
511                 debug_tal(newpar);
512                 if (notifiers)
513                         notify(t, TAL_NOTIFY_STEAL, new_parent, 0);
514         }
515         return (void *)ctx;
516 }
517
518 bool tal_add_destructor_(const tal_t *ctx, void (*destroy)(void *me))
519 {
520         tal_t *t = debug_tal(to_tal_hdr(ctx));
521         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
522                                      (void *)destroy, NULL);
523 }
524
525 bool tal_add_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
526                           void *arg)
527 {
528         tal_t *t = debug_tal(to_tal_hdr(ctx));
529         return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR
530                                      |NOTIFY_EXTRA_ARG,
531                                      (void *)destroy, arg);
532 }
533
534 /* We could support notifiers with an extra arg, but we didn't add to API */
535 bool tal_add_notifier_(const tal_t *ctx, enum tal_notify_type types,
536                        void (*callback)(tal_t *, enum tal_notify_type, void *))
537 {
538         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
539         struct notifier *n;
540
541         assert(types);
542         assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
543                           | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
544                           | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
545                           | TAL_NOTIFY_ADD_NOTIFIER
546                           | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
547
548         /* Don't call notifier about itself: set types after! */
549         n = add_notifier_property(t, 0, callback, NULL);
550         if (unlikely(!n))
551                 return false;
552
553         if (notifiers)
554                 notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback, 0);
555
556         n->types = types;
557         if (types != TAL_NOTIFY_FREE)
558                 notifiers++;
559         return true;
560 }
561
562 bool tal_del_notifier_(const tal_t *ctx,
563                        void (*callback)(tal_t *, enum tal_notify_type, void *),
564                        bool match_extra_arg, void *extra_arg)
565 {
566         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
567         enum tal_notify_type types;
568
569         types = del_notifier_property(t, callback, match_extra_arg, extra_arg);
570         if (types) {
571                 notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback, 0);
572                 if (types != TAL_NOTIFY_FREE)
573                         notifiers--;
574                 return true;
575         }
576         return false;
577 }
578
579 bool tal_del_destructor_(const tal_t *ctx, void (*destroy)(void *me))
580 {
581         return tal_del_notifier_(ctx, (void *)destroy, false, NULL);
582 }
583
584 bool tal_del_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
585                           void *arg)
586 {
587         return tal_del_notifier_(ctx, (void *)destroy, true, arg);
588 }
589
590 bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
591 {
592         struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
593         struct prop_hdr **prop = find_property_ptr(t, NAME);
594
595         /* Get rid of any old name */
596         if (prop) {
597                 struct name *name = (struct name *)*prop;
598                 if (is_literal(&name->hdr))
599                         *prop = NULL;
600                 else {
601                         *prop = name->hdr.next;
602                         freefn(name);
603                 }
604         }
605
606         if (literal && name[0]) {
607                 struct prop_hdr **p;
608
609                 /* Append literal. */
610                 for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
611                 *p = (struct prop_hdr *)name;
612         } else if (!add_name_property(t, name))
613                 return false;
614
615         debug_tal(t);
616         if (notifiers)
617                 notify(t, TAL_NOTIFY_RENAME, name, 0);
618         return true;
619 }
620
621 const char *tal_name(const tal_t *t)
622 {
623         struct name *n;
624
625         n = find_property(debug_tal(to_tal_hdr(t)), NAME);
626         if (!n)
627                 return NULL;
628
629         if (is_literal(&n->hdr))
630                 return (const char *)n;
631         return n->name;
632 }
633
634 size_t tal_bytelen(const tal_t *ptr)
635 {
636         /* NULL -> null_parent which has bytelen 0 */
637         struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ptr));
638
639         return t->bytelen;
640 }
641
642 /* Start one past first child: make stopping natural in circ. list. */
643 static struct tal_hdr *first_child(struct tal_hdr *parent)
644 {
645         struct children *child;
646
647         child = find_property(parent, CHILDREN);
648         if (!child)
649                 return NULL;
650
651         return list_top(&child->children, struct tal_hdr, list);
652 }
653
654 tal_t *tal_first(const tal_t *root)
655 {
656         struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
657
658         c = first_child(t);
659         if (!c)
660                 return NULL;
661         return from_tal_hdr(c);
662 }
663
664 tal_t *tal_next(const tal_t *prev)
665 {
666         struct tal_hdr *next, *prevhdr = debug_tal(to_tal_hdr(prev));
667         struct list_head *head;
668
669         head = &ignore_destroying_bit(prevhdr->parent_child)->children;
670         next = list_next(head, prevhdr, list);
671         if (!next)
672                 return NULL;
673         return from_tal_hdr(next);
674 }
675
676 tal_t *tal_parent(const tal_t *ctx)
677 {
678         struct tal_hdr *t;
679
680         if (!ctx)
681                 return NULL;
682
683         t = debug_tal(to_tal_hdr(ctx));
684         if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
685                 return NULL;
686         return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
687 }
688
689 bool tal_resize_(tal_t **ctxp, size_t size, size_t count, bool clear)
690 {
691         struct tal_hdr *old_t, *t;
692         struct children *child;
693
694         old_t = debug_tal(to_tal_hdr(*ctxp));
695
696         if (!adjust_size(&size, count))
697                 return false;
698
699         t = resizefn(old_t, sizeof(struct tal_hdr) + size);
700         if (!t) {
701                 call_error("Reallocation failure");
702                 return false;
703         }
704
705         /* Clear between old end and new end. */
706         if (clear && size > t->bytelen) {
707                 char *old_end = (char *)(t + 1) + t->bytelen;
708                 memset(old_end, 0, size - t->bytelen);
709         }
710
711         /* Update length. */
712         t->bytelen = size;
713         update_bounds(t, sizeof(struct tal_hdr) + size);
714
715         /* If it didn't move, we're done! */
716         if (t != old_t) {
717                 /* Fix up linked list pointers. */
718                 t->list.next->prev = t->list.prev->next = &t->list;
719
720                 /* Copy take() property. */
721                 if (taken(from_tal_hdr(old_t)))
722                         take(from_tal_hdr(t));
723
724                 /* Fix up child property's parent pointer. */
725                 child = find_property(t, CHILDREN);
726                 if (child) {
727                         assert(child->parent == old_t);
728                         child->parent = t;
729                 }
730                 *ctxp = from_tal_hdr(debug_tal(t));
731                 if (notifiers)
732                         notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t), 0);
733         }
734         if (notifiers)
735                 notify(t, TAL_NOTIFY_RESIZE, (void *)size, 0);
736
737         return true;
738 }
739
740 bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
741 {
742         size_t old_len;
743         bool ret = false;
744
745         old_len = debug_tal(to_tal_hdr(*ctxp))->bytelen;
746
747         /* Check for additive overflow */
748         if (old_len + count * size < old_len) {
749                 call_error("dup size overflow");
750                 goto out;
751         }
752
753         /* Don't point src inside thing we're expanding! */
754         assert(src < *ctxp
755                || (char *)src >= (char *)(*ctxp) + old_len);
756
757         if (!tal_resize_(ctxp, size, old_len/size + count, false))
758                 goto out;
759
760         memcpy((char *)*ctxp + old_len, src, count * size);
761         ret = true;
762
763 out:
764         if (taken(src))
765                 tal_free(src);
766         return ret;
767 }
768
769 void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
770                size_t n, size_t extra, const char *label)
771 {
772         void *ret;
773         size_t nbytes = size;
774
775         if (!adjust_size(&nbytes, n)) {
776                 if (taken(p))
777                         tal_free(p);
778                 return NULL;
779         }
780
781         /* Beware addition overflow! */
782         if (n + extra < n) {
783                 call_error("dup size overflow");
784                 if (taken(p))
785                         tal_free(p);
786                 return NULL;
787         }
788
789         if (taken(p)) {
790                 if (unlikely(!p))
791                         return NULL;
792                 if (unlikely(!tal_resize_((void **)&p, size, n + extra, false)))
793                         return tal_free(p);
794                 if (unlikely(!tal_steal(ctx, p)))
795                         return tal_free(p);
796                 return (void *)p;
797         }
798
799         ret = tal_alloc_arr_(ctx, size, n + extra, false, label);
800         if (ret)
801                 memcpy(ret, p, nbytes);
802         return ret;
803 }
804
805 void tal_set_backend(void *(*alloc_fn)(size_t size),
806                      void *(*resize_fn)(void *, size_t size),
807                      void (*free_fn)(void *),
808                      void (*error_fn)(const char *msg))
809 {
810         if (alloc_fn)
811                 allocfn = alloc_fn;
812         if (resize_fn)
813                 resizefn = resize_fn;
814         if (free_fn)
815                 freefn = free_fn;
816         if (error_fn)
817                 errorfn = error_fn;
818 }
819
820 #ifdef CCAN_TAL_DEBUG
821 static void dump_node(unsigned int indent, const struct tal_hdr *t)
822 {
823         unsigned int i;
824         const struct prop_hdr *p;
825
826         for (i = 0; i < indent; i++)
827                 fprintf(stderr, "  ");
828         fprintf(stderr, "%p len=%zu", t, t->bytelen);
829         for (p = t->prop; p; p = p->next) {
830                 struct children *c;
831                 struct name *n;
832                 struct notifier *no;
833                 if (is_literal(p)) {
834                         fprintf(stderr, " \"%s\"", (const char *)p);
835                         break;
836                 }
837                 switch (p->type) {
838                 case CHILDREN:
839                         c = (struct children *)p;
840                         fprintf(stderr, " CHILDREN(%p):parent=%p,children={%p,%p}",
841                                p, c->parent,
842                                c->children.n.prev, c->children.n.next);
843                         break;
844                 case NAME:
845                         n = (struct name *)p;
846                         fprintf(stderr, " NAME(%p):%s", p, n->name);
847                         break;
848                 case NOTIFIER:
849                         no = (struct notifier *)p;
850                         fprintf(stderr, " NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
851                         break;
852                 default:
853                         fprintf(stderr, " **UNKNOWN(%p):%i**", p, p->type);
854                 }
855         }
856         fprintf(stderr, "\n");
857 }
858
859 static void tal_dump_(unsigned int level, const struct tal_hdr *t)
860 {
861         struct children *children;
862
863         dump_node(level, t);
864
865         children = find_property(t, CHILDREN);
866         if (children) {
867                 struct tal_hdr *i;
868
869                 list_for_each(&children->children, i, list)
870                         tal_dump_(level + 1, i);
871         }
872 }
873
874 void tal_dump(void)
875 {
876         tal_dump_(0, &null_parent.hdr);
877 }
878 #endif /* CCAN_TAL_DEBUG */
879
880 #ifndef NDEBUG
881 static bool check_err(struct tal_hdr *t, const char *errorstr,
882                       const char *errmsg)
883 {
884         if (errorstr) {
885                 /* Try not to malloc: it may be corrupted. */
886                 char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
887                 sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
888                 call_error(msg);
889         }
890         return false;
891 }
892
893 static bool check_node(struct children *parent_child,
894                        struct tal_hdr *t, const char *errorstr)
895 {
896         struct prop_hdr *p;
897         struct name *name = NULL;
898         struct children *children = NULL;
899
900         if (!in_bounds(t))
901                 return check_err(t, errorstr, "invalid pointer");
902
903         if (ignore_destroying_bit(t->parent_child) != parent_child)
904                 return check_err(t, errorstr, "incorrect parent");
905
906         for (p = t->prop; p; p = p->next) {
907                 if (is_literal(p)) {
908                         if (name)
909                                 return check_err(t, errorstr,
910                                                  "has extra literal");
911                         break;
912                 }
913                 if (!in_bounds(p))
914                         return check_err(t, errorstr,
915                                          "has bad property pointer");
916
917                 switch (p->type) {
918                 case CHILDREN:
919                         if (children)
920                                 return check_err(t, errorstr,
921                                                  "has two child nodes");
922                         children = (struct children *)p;
923                         break;
924                 case NOTIFIER:
925                         break;
926                 case NAME:
927                         if (name)
928                                 return check_err(t, errorstr,
929                                                  "has two names");
930                         name = (struct name *)p;
931                         break;
932                 default:
933                         return check_err(t, errorstr, "has unknown property");
934                 }
935         }
936         if (children) {
937                 struct tal_hdr *i;
938
939                 if (!list_check(&children->children, errorstr))
940                         return false;
941                 list_for_each(&children->children, i, list) {
942                         if (!check_node(children, i, errorstr))
943                                 return false;
944                 }
945         }
946         return true;
947 }
948
949 bool tal_check(const tal_t *ctx, const char *errorstr)
950 {
951         struct tal_hdr *t = to_tal_hdr_or_null(ctx);
952
953         return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
954 }
955 #else /* NDEBUG */
956 bool tal_check(const tal_t *ctx, const char *errorstr)
957 {
958         return true;
959 }
960 #endif