ta: change API; ta_set_parent() and ta_set_destructor() never fail

The previous change ensured that these cannot fail anymore (much like in
original talloc). Change the APIs to not return a success value anymore,
to "cement" this.

ta/ta.c

@@ -75,19 +75,18 @@ static struct ta_header *get_header(void *ptr)
 }
 
 /* Set the parent allocation of ptr. If parent==NULL, remove the parent.
- * Setting parent==NULL (with ptr!=NULL) always succeeds, and unsets the
- * parent of ptr. Operations ptr==NULL always succeed and do nothing.
- * Returns true on success, false on OOM.
+ * Setting parent==NULL (with ptr!=NULL) unsets the parent of ptr.
+ * With ptr==NULL, the function does nothing.
  *
  * Warning: if ta_parent is a direct or indirect child of ptr, things will go
  *          wrong. The function will apparently succeed, but creates circular
  *          parent links, which are not allowed.
  */
-bool ta_set_parent(void *ptr, void *ta_parent)
+void ta_set_parent(void *ptr, void *ta_parent)
 {
     struct ta_header *ch = get_header(ptr);
     if (!ch)
-        return true;
+        return;
     struct ta_header *new_parent = get_header(ta_parent);
     // Unlink from previous parent
     if (ch->prev)
@@ -114,7 +113,6 @@ bool ta_set_parent(void *ptr, void *ta_parent)
         new_parent->child = ch;
         ch->parent = new_parent;
     }
-    return true;
 }
 
 /* Allocate size bytes of memory. If ta_parent is not NULL, this is used as
@@ -132,10 +130,7 @@ void *ta_alloc_size(void *ta_parent, size_t size)
     *h = (struct ta_header) {.size = size};
     ta_dbg_add(h);
     void *ptr = PTR_FROM_HEADER(h);
-    if (!ta_set_parent(ptr, ta_parent)) {
-        ta_free(ptr);
-        return NULL;
-    }
+    ta_set_parent(ptr, ta_parent);
     return ptr;
 }
 
@@ -152,10 +147,7 @@ void *ta_zalloc_size(void *ta_parent, size_t size)
     *h = (struct ta_header) {.size = size};
     ta_dbg_add(h);
     void *ptr = PTR_FROM_HEADER(h);
-    if (!ta_set_parent(ptr, ta_parent)) {
-        ta_free(ptr);
-        return NULL;
-    }
+    ta_set_parent(ptr, ta_parent);
     return ptr;
 }
 
@@ -252,16 +244,12 @@ void ta_free(void *ptr)
  * almost anything, but it must not attempt to free or realloc ptr. The
  * destructor is run before the allocation's children are freed (also, before
  * their destructors are run).
- *
- * Returns false if ptr==NULL, or on OOM.
  */
-bool ta_set_destructor(void *ptr, void (*destructor)(void *))
+void ta_set_destructor(void *ptr, void (*destructor)(void *))
 {
     struct ta_header *h = get_header(ptr);
-    if (!h)
-        return false;
-    h->destructor = destructor;
-    return true;
+    if (h)
+        h->destructor = destructor;
 }
 
 #ifdef TA_MEMORY_DEBUGGING

ta/ta.h

@@ -50,8 +50,8 @@ void *ta_realloc_size(void *ta_parent, void *ptr, size_t size);
 size_t ta_get_size(void *ptr);
 void ta_free(void *ptr);
 void ta_free_children(void *ptr);
-bool ta_set_destructor(void *ptr, void (*destructor)(void *));
-bool ta_set_parent(void *ptr, void *ta_parent);
+void ta_set_destructor(void *ptr, void (*destructor)(void *));
+void ta_set_parent(void *ptr, void *ta_parent);
 
 // Utility functions
 size_t ta_calc_array_size(size_t element_size, size_t count);
@@ -105,8 +105,6 @@ bool ta_vasprintf_append_buffer(char **str, const char *fmt, va_list ap) TA_PRF(
 // code.
 #define ta_xalloc_size(...)             ta_oom_p(ta_alloc_size(__VA_ARGS__))
 #define ta_xzalloc_size(...)            ta_oom_p(ta_zalloc_size(__VA_ARGS__))
-#define ta_xset_destructor(...)         ta_oom_b(ta_set_destructor(__VA_ARGS__))
-#define ta_xset_parent(...)             ta_oom_b(ta_set_parent(__VA_ARGS__))
 #define ta_xnew_context(...)            ta_oom_p(ta_new_context(__VA_ARGS__))
 #define ta_xstrdup_append(...)          ta_oom_b(ta_strdup_append(__VA_ARGS__))
 #define ta_xstrdup_append_buffer(...)   ta_oom_b(ta_strdup_append_buffer(__VA_ARGS__))
@@ -127,6 +125,10 @@ bool ta_vasprintf_append_buffer(char **str, const char *fmt, va_list ap) TA_PRF(
 #define ta_xnew_array_ptrtype(...)      ta_oom_g(ta_new_array_ptrtype(__VA_ARGS__))
 #define ta_xdup(...)                    ta_oom_g(ta_dup(__VA_ARGS__))
 
+// Cannot fail anymore.
+#define ta_xset_destructor(...)         ta_set_destructor(__VA_ARGS__)
+#define ta_xset_parent(...)             ta_set_parent(__VA_ARGS__)
+
 #define ta_xsteal(ta_parent, ptr) (TA_TYPEOF(ptr))ta_xsteal_(ta_parent, ptr)
 #define ta_xrealloc(ta_parent, ptr, type, count) \
     (type *)ta_xrealloc_size(ta_parent, ptr, ta_calc_array_size(sizeof(type), count))

ta/ta_utils.c

@@ -44,21 +44,11 @@ size_t ta_calc_prealloc_elems(size_t nextidx)
     return (nextidx + 1) * 2;
 }
 
-static void dummy_dtor(void *p){}
-
-/* Create an empty (size 0) TA allocation, which is prepared in a way such that
- * using it as parent with ta_set_parent() always succeed. Calling
- * ta_set_destructor() on it will always succeed as well.
+/* Create an empty (size 0) TA allocation.
  */
 void *ta_new_context(void *ta_parent)
 {
-    void *new = ta_alloc_size(ta_parent, 0);
-    // Force it to allocate an extended header.
-    if (!ta_set_destructor(new, dummy_dtor)) {
-        ta_free(new);
-        new = NULL;
-    }
-    return new;
+    return ta_alloc_size(ta_parent, 0);
 }
 
 /* Set parent of ptr to ta_parent, return the ptr.
@@ -68,8 +58,7 @@ void *ta_new_context(void *ta_parent)
  */
 void *ta_steal_(void *ta_parent, void *ptr)
 {
-    if (!ta_set_parent(ptr, ta_parent))
-        return NULL;
+    ta_set_parent(ptr, ta_parent);
     return ptr;
 }
 
@@ -138,10 +127,7 @@ char *ta_strndup(void *ta_parent, const char *str, size_t n)
         return NULL;
     char *new = NULL;
     strndup_append_at(&new, 0, str, n);
-    if (!ta_set_parent(new, ta_parent)) {
-        ta_free(new);
-        new = NULL;
-    }
+    ta_set_parent(new, ta_parent);
     return new;
 }
 
@@ -229,7 +215,8 @@ char *ta_vasprintf(void *ta_parent, const char *fmt, va_list ap)
 {
     char *res = NULL;
     ta_vasprintf_append_at(&res, 0, fmt, ap);
-    if (!res || !ta_set_parent(res, ta_parent)) {
+    ta_set_parent(res, ta_parent);
+    if (!res) {
         ta_free(res);
         return NULL;
     }
@@ -303,7 +290,7 @@ char *ta_oom_s(char *s)
 
 void *ta_xsteal_(void *ta_parent, void *ptr)
 {
-    ta_oom_b(ta_set_parent(ptr, ta_parent));
+    ta_set_parent(ptr, ta_parent);
     return ptr;
 }