text: /* Licensed under BSD-MIT - see LICENSE file for details */
  #include <ccan/tal/tal.h>
  #include <ccan/compiler/compiler.h>
  #include <ccan/list/list.h>
  #include <ccan/alignof/alignof.h>
  #include <assert.h>
  #include <stdio.h>
  #include <stddef.h>
  #include <string.h>
  #include <limits.h>
  #include <stdint.h>
  #include <errno.h>
  
  //#define TAL_DEBUG 1
  
  #define NOTIFY_IS_DESTRUCTOR 512
  #define NOTIFY_EXTRA_ARG 1024
  
  /* This makes our parent_child ptr stand out for to_tal_hdr checks */
  #define TAL_PTR_OBFUSTICATOR ((intptr_t)0x1984200820142016ULL)
  
  /* 32-bit type field, first byte 0 in either endianness. */
  enum prop_type {
  	CHILDREN = 0x00c1d500,
  	NAME = 0x00111100,
  	NOTIFIER = 0x00071f00,
  };
  
  struct tal_hdr {
  	struct list_node list;
  	struct prop_hdr *prop;
  	/* XOR with TAL_PTR_OBFUSTICATOR */
  	intptr_t parent_child;
  	size_t bytelen;
  };
  
  struct prop_hdr {
  	enum prop_type type;
  	struct prop_hdr *next;
  };
  
  struct children {
  	struct prop_hdr hdr; /* CHILDREN */
  	struct tal_hdr *parent;
  	struct list_head children; /* Head of siblings. */
  };
  
  struct name {
  	struct prop_hdr hdr; /* NAME */
  	char name[];
  };
  
  struct notifier {
  	struct prop_hdr hdr; /* NOTIFIER */
  	enum tal_notify_type types;
  	union notifier_cb {
  		void (*notifyfn)(tal_t *, enum tal_notify_type, void *);
  		void (*destroy)(tal_t *); /* If NOTIFY_IS_DESTRUCTOR set */
  		void (*destroy2)(tal_t *, void *); /* If NOTIFY_EXTRA_ARG */
  	} u;
  };
  
  /* Extra arg */
  struct notifier_extra_arg {
  	struct notifier n;
  	void *arg;
  };
  
  #define EXTRA_ARG(n) (((struct notifier_extra_arg *)(n))->arg)
  
  static struct {
  	struct tal_hdr hdr;
  	struct children c;
  } null_parent = { { { &null_parent.hdr.list, &null_parent.hdr.list },
  		    &null_parent.c.hdr, TAL_PTR_OBFUSTICATOR, 0 },
  		  { { CHILDREN, NULL },
  		    &null_parent.hdr,
  		    { { &null_parent.c.children.n,
  			&null_parent.c.children.n } }
  		  }
  };
  
  
  static void *(*allocfn)(size_t size) = malloc;
  static void *(*resizefn)(void *, size_t size) = realloc;
  static void (*freefn)(void *) = free;
  static void (*errorfn)(const char *msg) = (void *)abort;
  /* Count on non-destrutor notifiers; often stays zero. */
  static size_t notifiers = 0;
  
  static inline void COLD call_error(const char *msg)
  {
  	errorfn(msg);
  }
  
  static bool get_destroying_bit(intptr_t parent_child)
  {
  	return parent_child & 1;
  }
  
  static void set_destroying_bit(intptr_t *parent_child)
  {
  	*parent_child |= 1;
  }
  
  static struct children *ignore_destroying_bit(intptr_t parent_child)
  {
  	return (void *)((parent_child ^ TAL_PTR_OBFUSTICATOR) & ~(intptr_t)1);
  }
  
  /* This means valgrind can see leaks. */
  void tal_cleanup(void)
  {
  	struct tal_hdr *i;
  
  	while ((i = list_top(&null_parent.c.children, struct tal_hdr, list))) {
  		list_del(&i->list);
  		memset(i, 0, sizeof(*i));
  	}
  
  	/* Cleanup any taken pointers. */
  	take_cleanup();
  }
  
  /* We carefully start all real properties with a zero byte. */
  static bool is_literal(const struct prop_hdr *prop)
  {
  	return ((char *)prop)[0] != 0;
  }
  
  #ifndef NDEBUG
  static const void *bounds_start, *bounds_end;
  
  static void update_bounds(const void *new, size_t size)
  {
  	if (unlikely(!bounds_start)) {
  		bounds_start = new;
  		bounds_end = (char *)new + size;
  	} else if (new < bounds_start)
  		bounds_start = new;
  	else if ((char *)new + size > (char *)bounds_end)
  		bounds_end = (char *)new + size;
  }
  
  static bool in_bounds(const void *p)
  {
  	return !p
  		|| (p >= (void *)&null_parent && p <= (void *)(&null_parent + 1))
  		|| (p >= bounds_start && p <= bounds_end);
  }
  #else
  static void update_bounds(const void *new, size_t size)
  {
  }
  
  static bool in_bounds(const void *p)
  {
  	return true;
  }
  #endif
  
  static void check_bounds(const void *p)
  {
  	if (!in_bounds(p))
  		call_error("Not a valid header");
  }
  
  static struct tal_hdr *to_tal_hdr(const void *ctx)
  {
  	struct tal_hdr *t;
  
  	t = (struct tal_hdr *)((char *)ctx - sizeof(struct tal_hdr));
  	check_bounds(t);
  	check_bounds(ignore_destroying_bit(t->parent_child));
  	check_bounds(t->list.next);
  	check_bounds(t->list.prev);
  	if (t->prop && !is_literal(t->prop))
  		check_bounds(t->prop);
  	return t;
  }
  
  static struct tal_hdr *to_tal_hdr_or_null(const void *ctx)
  {
  	if (!ctx)
  		return &null_parent.hdr;
  	return to_tal_hdr(ctx);
  }
  
  static void *from_tal_hdr(const struct tal_hdr *hdr)
  {
  	return (void *)(hdr + 1);
  }
  
  static void *from_tal_hdr_or_null(const struct tal_hdr *hdr)
  {
  	if (hdr == &null_parent.hdr)
  		return NULL;
  	return from_tal_hdr(hdr);
  }
  
  #ifdef TAL_DEBUG
  static struct tal_hdr *debug_tal(struct tal_hdr *tal)
  {
  	tal_check(from_tal_hdr_or_null(tal), "TAL_DEBUG ");
  	return tal;
  }
  #else
  static struct tal_hdr *debug_tal(struct tal_hdr *tal)
  {
  	return tal;
  }
  #endif
  
  static void notify(const struct tal_hdr *ctx,
  		   enum tal_notify_type type, const void *info,
  		   int saved_errno)
  {
          const struct prop_hdr *p;
  
          for (p = ctx->prop; p; p = p->next) {
  		struct notifier *n;
  
                  if (is_literal(p))
  			break;
                  if (p->type != NOTIFIER)
  			continue;
  		n = (struct notifier *)p;
  		if (n->types & type) {
  			errno = saved_errno;
  			if (n->types & NOTIFY_IS_DESTRUCTOR) {
  				/* Blatt this notifier in case it tries to
  				 * tal_del_destructor() from inside */
  				union notifier_cb cb = n->u;
  				/* It's a union, so this NULLs destroy2 too! */
  				n->u.destroy = NULL;
  				if (n->types & NOTIFY_EXTRA_ARG)
  					cb.destroy2(from_tal_hdr(ctx),
  						    EXTRA_ARG(n));
  				else
  					cb.destroy(from_tal_hdr(ctx));
  			} else
  				n->u.notifyfn(from_tal_hdr_or_null(ctx), type,
  					      (void *)info);
  		}
  	}
  }
  
  static void *allocate(size_t size)
  {
  	void *ret = allocfn(size);
  	if (!ret)
  		call_error("allocation failed");
  	else
  		update_bounds(ret, size);
  	return ret;
  }
  
  static struct prop_hdr **find_property_ptr(const struct tal_hdr *t,
  					   enum prop_type type)
  {
          struct prop_hdr **p;
  
          for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
                  if (is_literal(*p)) {
                          if (type == NAME)
                                  return p;
                          break;
                  }
                  if ((*p)->type == type)
                          return p;
          }
          return NULL;
  }
  
  static void *find_property(const struct tal_hdr *parent, enum prop_type type)
  {
          struct prop_hdr **p = find_property_ptr(parent, type);
  
          if (p)
                  return *p;
          return NULL;
  }
  
  static void init_property(struct prop_hdr *hdr,
  			  struct tal_hdr *parent,
  			  enum prop_type type)
  {
  	hdr->type = type;
  	hdr->next = parent->prop;
  	parent->prop = hdr;
  }
  
  static struct notifier *add_notifier_property(struct tal_hdr *t,
  					      enum tal_notify_type types,
  					      void (*fn)(void *,
  							 enum tal_notify_type,
  							 void *),
  					      void *extra_arg)
  {
  	struct notifier *prop;
  
  	if (types & NOTIFY_EXTRA_ARG)
  		prop = allocate(sizeof(struct notifier_extra_arg));
  	else
  		prop = allocate(sizeof(struct notifier));
  
  	if (prop) {
  		init_property(&prop->hdr, t, NOTIFIER);
  		prop->types = types;
  		prop->u.notifyfn = fn;
  		if (types & NOTIFY_EXTRA_ARG)
  			EXTRA_ARG(prop) = extra_arg;
  	}
  	return prop;
  }
  
  static enum tal_notify_type del_notifier_property(struct tal_hdr *t,
  						  void (*fn)(tal_t *,
  							     enum tal_notify_type,
  							     void *),
  						  bool match_extra_arg,
  						  void *extra_arg)
  {
          struct prop_hdr **p;
  
          for (p = (struct prop_hdr **)&t->prop; *p; p = &(*p)->next) {
  		struct notifier *n;
  		enum tal_notify_type types;
  
                  if (is_literal(*p))
  			break;
                  if ((*p)->type != NOTIFIER)
  			continue;
  		n = (struct notifier *)*p;
  		if (n->u.notifyfn != fn)
  			continue;
  
  		types = n->types;
  		if ((types & NOTIFY_EXTRA_ARG)
  		    && match_extra_arg
  		    && extra_arg != EXTRA_ARG(n))
  			continue;
  
  		*p = (*p)->next;
  		freefn(n);
  		return types & ~(NOTIFY_IS_DESTRUCTOR|NOTIFY_EXTRA_ARG);
          }
          return 0;
  }
  
  static struct name *add_name_property(struct tal_hdr *t, const char *name)
  {
  	struct name *prop;
  
  	prop = allocate(sizeof(*prop) + strlen(name) + 1);
  	if (prop) {
  		init_property(&prop->hdr, t, NAME);
  		strcpy(prop->name, name);
  	}
  	return prop;
  }
  
  static struct children *add_child_property(struct tal_hdr *parent,
  					   struct tal_hdr *child UNNEEDED)
  {
  	struct children *prop = allocate(sizeof(*prop));
  	if (prop) {
  		init_property(&prop->hdr, parent, CHILDREN);
  		prop->parent = parent;
  		list_head_init(&prop->children);
  	}
  	return prop;
  }
  
  static bool add_child(struct tal_hdr *parent, struct tal_hdr *child)
  {
  	struct children *children = find_property(parent, CHILDREN);
  
          if (!children) {
  		children = add_child_property(parent, child);
  		if (!children)
  			return false;
  	}
  	list_add(&children->children, &child->list);
  	child->parent_child = (intptr_t)children ^ TAL_PTR_OBFUSTICATOR;
  	return true;
  }
  
  static void del_tree(struct tal_hdr *t, const tal_t *orig, int saved_errno)
  {
  	struct prop_hdr **prop, *p, *next;
  
  	assert(!taken(from_tal_hdr(t)));
  
          /* Already being destroyed?  Don't loop. */
          if (unlikely(get_destroying_bit(t->parent_child)))
                  return;
  
          set_destroying_bit(&t->parent_child);
  
  	/* Call free notifiers. */
  	notify(t, TAL_NOTIFY_FREE, (tal_t *)orig, saved_errno);
  
  	/* Now free children and groups. */
  	prop = find_property_ptr(t, CHILDREN);
  	if (prop) {
  		struct tal_hdr *i;
  		struct children *c = (struct children *)*prop;
  
  		while ((i = list_top(&c->children, struct tal_hdr, list))) {
  			list_del(&i->list);
  			del_tree(i, orig, saved_errno);
  		}
  	}
  
          /* Finally free our properties. */
          for (p = t->prop; p && !is_literal(p); p = next) {
                  next = p->next;
  		freefn(p);
          }
          freefn(t);
  }
  
  void *tal_alloc_(const tal_t *ctx, size_t size, bool clear, const char *label)
  {
          struct tal_hdr *child, *parent = debug_tal(to_tal_hdr_or_null(ctx));
  
          child = allocate(sizeof(struct tal_hdr) + size);
  	if (!child)
  		return NULL;
  	if (clear)
  		memset(from_tal_hdr(child), 0, size);
          child->prop = (void *)label;
  	child->bytelen = size;
  
          if (!add_child(parent, child)) {
  		freefn(child);
  		return NULL;
  	}
  	debug_tal(parent);
  	if (notifiers)
  		notify(parent, TAL_NOTIFY_ADD_CHILD, from_tal_hdr(child), 0);
  	return from_tal_hdr(debug_tal(child));
  }
  
  static bool adjust_size(size_t *size, size_t count)
  {
  	const size_t extra = sizeof(struct tal_hdr);
  
  	/* Multiplication wrap */
          if (count && unlikely(*size * count / *size != count))
  		goto overflow;
  
          *size *= count;
  
          /* Make sure we don't wrap adding header. */
          if (*size + extra < extra)
  		goto overflow;
  	return true;
  overflow:
  	call_error("allocation size overflow");
  	return false;
  }
  
  void *tal_alloc_arr_(const tal_t *ctx, size_t size, size_t count, bool clear,
  		     const char *label)
  {
  	if (!adjust_size(&size, count))
  		return NULL;
  
  	return tal_alloc_(ctx, size, clear, label);
  }
  
  void *tal_free(const tal_t *ctx)
  {
          if (ctx) {
  		struct tal_hdr *t;
  		int saved_errno = errno;
  		t = debug_tal(to_tal_hdr(ctx));
  		if (unlikely(get_destroying_bit(t->parent_child)))
  			return NULL;
  		if (notifiers)
  			notify(ignore_destroying_bit(t->parent_child)->parent,
  			       TAL_NOTIFY_DEL_CHILD, ctx, saved_errno);
  		list_del(&t->list);
  		del_tree(t, ctx, saved_errno);
  		errno = saved_errno;
  	}
  	return NULL;
  }
  
  void *tal_steal_(const tal_t *new_parent, const tal_t *ctx)
  {
          if (ctx) {
  		struct tal_hdr *newpar, *t, *old_parent;
  
                  newpar = debug_tal(to_tal_hdr_or_null(new_parent));
                  t = debug_tal(to_tal_hdr(ctx));
  
                  /* Unlink it from old parent. */
  		list_del(&t->list);
  		old_parent = ignore_destroying_bit(t->parent_child)->parent;
  
                  if (unlikely(!add_child(newpar, t))) {
  			/* We can always add to old parent, because it has a
  			 * children property already. */
  			if (!add_child(old_parent, t))
  				abort();
  			return NULL;
  		}
  		debug_tal(newpar);
  		if (notifiers)
  			notify(t, TAL_NOTIFY_STEAL, new_parent, 0);
          }
          return (void *)ctx;
  }
  
  bool tal_add_destructor_(const tal_t *ctx, void (*destroy)(void *me))
  {
  	tal_t *t = debug_tal(to_tal_hdr(ctx));
  	return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR,
  				     (void *)destroy, NULL);
  }
  
  bool tal_add_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
  			  void *arg)
  {
  	tal_t *t = debug_tal(to_tal_hdr(ctx));
  	return add_notifier_property(t, TAL_NOTIFY_FREE|NOTIFY_IS_DESTRUCTOR
  				     |NOTIFY_EXTRA_ARG,
  				     (void *)destroy, arg);
  }
  
  /* We could support notifiers with an extra arg, but we didn't add to API */
  bool tal_add_notifier_(const tal_t *ctx, enum tal_notify_type types,
  		       void (*callback)(tal_t *, enum tal_notify_type, void *))
  {
  	struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
  	struct notifier *n;
  
  	assert(types);
  	assert((types & ~(TAL_NOTIFY_FREE | TAL_NOTIFY_STEAL | TAL_NOTIFY_MOVE
  			  | TAL_NOTIFY_RESIZE | TAL_NOTIFY_RENAME
  			  | TAL_NOTIFY_ADD_CHILD | TAL_NOTIFY_DEL_CHILD
  			  | TAL_NOTIFY_ADD_NOTIFIER
  			  | TAL_NOTIFY_DEL_NOTIFIER)) == 0);
  
  	/* Don't call notifier about itself: set types after! */
          n = add_notifier_property(t, 0, callback, NULL);
  	if (unlikely(!n))
  		return false;
  
  	if (notifiers)
  		notify(t, TAL_NOTIFY_ADD_NOTIFIER, callback, 0);
  
  	n->types = types;
  	if (types != TAL_NOTIFY_FREE)
  		notifiers++;
  	return true;
  }
  
  bool tal_del_notifier_(const tal_t *ctx,
  		       void (*callback)(tal_t *, enum tal_notify_type, void *),
  		       bool match_extra_arg, void *extra_arg)
  {
  	struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ctx));
  	enum tal_notify_type types;
  
          types = del_notifier_property(t, callback, match_extra_arg, extra_arg);
  	if (types) {
  		notify(t, TAL_NOTIFY_DEL_NOTIFIER, callback, 0);
  		if (types != TAL_NOTIFY_FREE)
  			notifiers--;
  		return true;
  	}
  	return false;
  }
  
  bool tal_del_destructor_(const tal_t *ctx, void (*destroy)(void *me))
  {
  	return tal_del_notifier_(ctx, (void *)destroy, false, NULL);
  }
  
  bool tal_del_destructor2_(const tal_t *ctx, void (*destroy)(void *me, void *arg),
  			  void *arg)
  {
  	return tal_del_notifier_(ctx, (void *)destroy, true, arg);
  }
  
  bool tal_set_name_(tal_t *ctx, const char *name, bool literal)
  {
          struct tal_hdr *t = debug_tal(to_tal_hdr(ctx));
          struct prop_hdr **prop = find_property_ptr(t, NAME);
  
          /* Get rid of any old name */
          if (prop) {
                  struct name *name = (struct name *)*prop;
                  if (is_literal(&name->hdr))
                          *prop = NULL;
                  else {
                          *prop = name->hdr.next;
  			freefn(name);
                  }
          }
  
          if (literal && name[0]) {
                  struct prop_hdr **p;
  
                  /* Append literal. */
                  for (p = &t->prop; *p && !is_literal(*p); p = &(*p)->next);
                  *p = (struct prop_hdr *)name;
          } else if (!add_name_property(t, name))
  		return false;
  
  	debug_tal(t);
  	if (notifiers)
  		notify(t, TAL_NOTIFY_RENAME, name, 0);
  	return true;
  }
  
  const char *tal_name(const tal_t *t)
  {
          struct name *n;
  
  	n = find_property(debug_tal(to_tal_hdr(t)), NAME);
  	if (!n)
  		return NULL;
  
  	if (is_literal(&n->hdr))
  		return (const char *)n;
  	return n->name;
  }
  
  size_t tal_bytelen(const tal_t *ptr)
  {
  	/* NULL -> null_parent which has bytelen 0 */
  	struct tal_hdr *t = debug_tal(to_tal_hdr_or_null(ptr));
  
  	return t->bytelen;
  }
  
  /* Start one past first child: make stopping natural in circ. list. */
  static struct tal_hdr *first_child(struct tal_hdr *parent)
  {
  	struct children *child;
  
  	child = find_property(parent, CHILDREN);
          if (!child)
                  return NULL;
  
  	return list_top(&child->children, struct tal_hdr, list);
  }
  
  tal_t *tal_first(const tal_t *root)
  {
          struct tal_hdr *c, *t = debug_tal(to_tal_hdr_or_null(root));
  
  	c = first_child(t);
  	if (!c)
  		return NULL;
  	return from_tal_hdr(c);
  }
  
  tal_t *tal_next(const tal_t *prev)
  {
          struct tal_hdr *next, *prevhdr = debug_tal(to_tal_hdr(prev));
  	struct list_head *head;
  
  	head = &ignore_destroying_bit(prevhdr->parent_child)->children;
  	next = list_next(head, prevhdr, list);
  	if (!next)
  		return NULL;
  	return from_tal_hdr(next);
  }
  
  tal_t *tal_parent(const tal_t *ctx)
  {
          struct tal_hdr *t;
  
  	if (!ctx)
  		return NULL;
  
  	t = debug_tal(to_tal_hdr(ctx));
  	if (ignore_destroying_bit(t->parent_child)->parent == &null_parent.hdr)
  		return NULL;
          return from_tal_hdr(ignore_destroying_bit(t->parent_child)->parent);
  }
  
  bool tal_resize_(tal_t **ctxp, size_t size, size_t count, bool clear)
  {
          struct tal_hdr *old_t, *t;
          struct children *child;
  
          old_t = debug_tal(to_tal_hdr(*ctxp));
  
  	if (!adjust_size(&size, count))
  		return false;
  
          t = resizefn(old_t, sizeof(struct tal_hdr) + size);
  	if (!t) {
  		call_error("Reallocation failure");
  		return false;
  	}
  
  	/* Clear between old end and new end. */
  	if (clear && size > t->bytelen) {
  		char *old_end = (char *)(t + 1) + t->bytelen;
  		memset(old_end, 0, size - t->bytelen);
  	}
  
  	/* Update length. */
  	t->bytelen = size;
  	update_bounds(t, sizeof(struct tal_hdr) + size);
  
  	/* If it didn't move, we're done! */
          if (t != old_t) {
  		/* Fix up linked list pointers. */
  		t->list.next->prev = t->list.prev->next = &t->list;
  
  		/* Copy take() property. */
  		if (taken(from_tal_hdr(old_t)))
  			take(from_tal_hdr(t));
  
  		/* Fix up child property's parent pointer. */
  		child = find_property(t, CHILDREN);
  		if (child) {
  			assert(child->parent == old_t);
  			child->parent = t;
  		}
  		*ctxp = from_tal_hdr(debug_tal(t));
  		if (notifiers)
  			notify(t, TAL_NOTIFY_MOVE, from_tal_hdr(old_t), 0);
  	}
  	if (notifiers)
  		notify(t, TAL_NOTIFY_RESIZE, (void *)size, 0);
  
  	return true;
  }
  
  bool tal_expand_(tal_t **ctxp, const void *src, size_t size, size_t count)
  {
  	size_t old_len;
  	bool ret = false;
  
  	old_len = debug_tal(to_tal_hdr(*ctxp))->bytelen;
  
  	/* Check for additive overflow */
  	if (old_len + count * size < old_len) {
  		call_error("dup size overflow");
  		goto out;
  	}
  
  	/* Don't point src inside thing we're expanding! */
  	assert(src < *ctxp
  	       || (char *)src >= (char *)(*ctxp) + old_len);
  
  	if (!tal_resize_(ctxp, size, old_len/size + count, false))
  		goto out;
  
  	memcpy((char *)*ctxp + old_len, src, count * size);
  	ret = true;
  
  out:
  	if (taken(src))
  		tal_free(src);
  	return ret;
  }
  
  void *tal_dup_(const tal_t *ctx, const void *p, size_t size,
  	       size_t n, size_t extra, bool nullok, const char *label)
  {
  	void *ret;
  	size_t nbytes = size;
  
  	if (nullok && p == NULL) {
  		/* take(NULL) works. */
  		(void)taken(p);
  		return NULL;
  	}
  	
  	if (!adjust_size(&nbytes, n)) {
  		if (taken(p))
  			tal_free(p);
  		return NULL;
  	}
  
  	/* Beware addition overflow! */
  	if (n + extra < n) {
  		call_error("dup size overflow");
  		if (taken(p))
  			tal_free(p);
  		return NULL;
  	}
  
  	if (taken(p)) {
  		if (unlikely(!p))
  			return NULL;
  		if (unlikely(!tal_resize_((void **)&p, size, n + extra, false)))
  			return tal_free(p);
  		if (unlikely(!tal_steal(ctx, p)))
  			return tal_free(p);
  		return (void *)p;
  	}
  
  	ret = tal_alloc_arr_(ctx, size, n + extra, false, label);
  	if (ret)
  		memcpy(ret, p, nbytes);
  	return ret;
  }
  
  void *tal_dup_talarr_(const tal_t *ctx, const tal_t *src TAKES, const char *label)
  {
  	return tal_dup_(ctx, src, 1, tal_bytelen(src), 0, true, label);
  }
  
  void tal_set_backend(void *(*alloc_fn)(size_t size),
  		     void *(*resize_fn)(void *, size_t size),
  		     void (*free_fn)(void *),
  		     void (*error_fn)(const char *msg))
  {
  	if (alloc_fn)
  		allocfn = alloc_fn;
  	if (resize_fn)
  		resizefn = resize_fn;
  	if (free_fn)
  		freefn = free_fn;
  	if (error_fn)
  		errorfn = error_fn;
  }
  
  #ifdef CCAN_TAL_DEBUG
  static void dump_node(unsigned int indent, const struct tal_hdr *t)
  {
  	unsigned int i;
          const struct prop_hdr *p;
  
  	for (i = 0; i < indent; i++)
  		fprintf(stderr, "  ");
  	fprintf(stderr, "%p len=%zu", t, t->bytelen);
          for (p = t->prop; p; p = p->next) {
  		struct children *c;
  		struct name *n;
  		struct notifier *no;
                  if (is_literal(p)) {
  			fprintf(stderr, " \"%s\"", (const char *)p);
  			break;
  		}
  		switch (p->type) {
  		case CHILDREN:
  			c = (struct children *)p;
  			fprintf(stderr, " CHILDREN(%p):parent=%p,children={%p,%p}",
  			       p, c->parent,
  			       c->children.n.prev, c->children.n.next);
  			break;
  		case NAME:
  			n = (struct name *)p;
  			fprintf(stderr, " NAME(%p):%s", p, n->name);
  			break;
  		case NOTIFIER:
  			no = (struct notifier *)p;
  			fprintf(stderr, " NOTIFIER(%p):fn=%p", p, no->u.notifyfn);
  			break;
  		default:
  			fprintf(stderr, " **UNKNOWN(%p):%i**", p, p->type);
  		}
  	}
  	fprintf(stderr, "\n");
  }
  
  static void tal_dump_(unsigned int level, const struct tal_hdr *t)
  {
          struct children *children;
  
  	dump_node(level, t);
  
  	children = find_property(t, CHILDREN);
  	if (children) {
  		struct tal_hdr *i;
  
  		list_for_each(&children->children, i, list)
  			tal_dump_(level + 1, i);
  	}
  }
  
  void tal_dump(void)
  {
  	tal_dump_(0, &null_parent.hdr);
  }
  #endif /* CCAN_TAL_DEBUG */
  
  #ifndef NDEBUG
  static bool check_err(struct tal_hdr *t, const char *errorstr,
  		      const char *errmsg)
  {
  	if (errorstr) {
  		/* Try not to malloc: it may be corrupted. */
  		char msg[strlen(errorstr) + 20 + strlen(errmsg) + 1];
  		sprintf(msg, "%s:%p %s", errorstr, from_tal_hdr(t), errmsg);
  		call_error(msg);
  	}
  	return false;
  }
  
  static bool check_node(struct children *parent_child,
  		       struct tal_hdr *t, const char *errorstr)
  {
  	struct prop_hdr *p;
  	struct name *name = NULL;
  	struct children *children = NULL;
  
  	if (!in_bounds(t))
  		return check_err(t, errorstr, "invalid pointer");
  
  	if (ignore_destroying_bit(t->parent_child) != parent_child)
  		return check_err(t, errorstr, "incorrect parent");
  
  	for (p = t->prop; p; p = p->next) {
  		if (is_literal(p)) {
  			if (name)
  				return check_err(t, errorstr,
  						 "has extra literal");
  			break;
  		}
  		if (!in_bounds(p))
  			return check_err(t, errorstr,
  					 "has bad property pointer");
  
  		switch (p->type) {
  		case CHILDREN:
  			if (children)
  				return check_err(t, errorstr,
  						 "has two child nodes");
  			children = (struct children *)p;
  			break;
  		case NOTIFIER:
  			break;
  		case NAME:
  			if (name)
  				return check_err(t, errorstr,
  						 "has two names");
  			name = (struct name *)p;
  			break;
  		default:
  			return check_err(t, errorstr, "has unknown property");
  		}
  	}
  	if (children) {
  		struct tal_hdr *i;
  
  		if (!list_check(&children->children, errorstr))
  			return false;
  		list_for_each(&children->children, i, list) {
  			if (!check_node(children, i, errorstr))
  				return false;
  		}
  	}
  	return true;
  }
  
  bool tal_check(const tal_t *ctx, const char *errorstr)
  {
  	struct tal_hdr *t = to_tal_hdr_or_null(ctx);
  
  	return check_node(ignore_destroying_bit(t->parent_child), t, errorstr);
  }
  #else /* NDEBUG */
  bool tal_check(const tal_t *ctx, const char *errorstr)
  {
  	return true;
  }
  #endif
  