tal: Make tal_resize() easier to use.

[ccan] / ccan / tal / tal.h

diff --git a/ccan/tal/tal.h b/ccan/tal/tal.h
index 24db0864332a721f5aabc4750d19a2af15aea993..28726c324cedd9ec4c150bcd02f369c6e6180905 100644 (file)
--- a/ccan/tal/tal.h
+++ b/ccan/tal/tal.h
@@ -5,6 +5,7 @@
 #include <ccan/compiler/compiler.h>
 #include <ccan/likely/likely.h>
 #include <ccan/typesafe_cb/typesafe_cb.h>
+#include <ccan/str/str.h>
 #include <stdlib.h>
 #include <stdbool.h>
 #include <stdarg.h>
@@ -34,9 +35,16 @@ typedef void tal_t;
  * @ctx: NULL, or tal allocated object to be parent.
  * @type: the type to allocate.
  *
- * Allocates a specific type, with a given parent context.
+ * Allocates a specific type, with a given parent context.  The name
+ * of the object is a string of the type, but if CCAN_TAL_DEBUG is
+ * defined it also contains the file and line which allocated it.
+ *
+ * Example:
+ *     int *p = tal(NULL, int);
+ *     *p = 1;
  */
-#define tal(ctx, type) tal_arr((ctx), type, 1)
+#define tal(ctx, type) \
+       ((type *)tal_alloc_((ctx), sizeof(type), false, TAL_LABEL(type, "")))
 
 /**
  * talz - zeroing allocator function
@@ -44,8 +52,13 @@ typedef void tal_t;
  * @type: the type to allocate.
  *
  * Equivalent to tal() followed by memset() to zero.
+ *
+ * Example:
+ *     p = talz(NULL, int);
+ *     assert(*p == 0);
  */
-#define talz(ctx, type) tal_arrz((ctx), type, 1)
+#define talz(ctx, type) \
+       ((type *)tal_alloc_((ctx), sizeof(type), true, TAL_LABEL(type, "")))
 
 /**
  * tal_free - free a tal-allocated pointer.
@@ -53,6 +66,11 @@ typedef void tal_t;
  *
  * This calls the destructors for p (if any), then does the same for all its
  * children (recursively) before finally freeing the memory.
+ *
+ * Note: errno is preserved by this call.
+ *
+ * Example:
+ *     tal_free(p);
  */
 void tal_free(const tal_t *p);
 
@@ -61,29 +79,42 @@ void tal_free(const tal_t *p);
  * @ctx: NULL, or tal allocated object to be parent.
  * @type: the type to allocate.
  * @count: the number to allocate.
+ *
+ * Example:
+ *     p = tal_arr(NULL, int, 2);
+ *     p[0] = 0;
+ *     p[1] = 1;
  */
 #define tal_arr(ctx, type, count) \
-       ((type *)tal_alloc_((ctx), tal_sizeof_(sizeof(type), (count)), false))
+       ((type *)tal_alloc_((ctx), tal_sizeof_(sizeof(type), (count)), false, \
+                           TAL_LABEL(type, "[]")))
 
 /**
  * tal_arrz - allocate an array of zeroed objects.
  * @ctx: NULL, or tal allocated object to be parent.
  * @type: the type to allocate.
  * @count: the number to allocate.
+ *
+ * Example:
+ *     p = tal_arrz(NULL, int, 2);
+ *     assert(p[0] == 0 && p[1] == 0);
  */
 #define tal_arrz(ctx, type, count) \
-       ((type *)tal_alloc_((ctx), tal_sizeof_(sizeof(type), (count)), true))
+       ((type *)tal_alloc_((ctx), tal_sizeof_(sizeof(type), (count)), true, \
+                           TAL_LABEL(type, "[]")))
 
 /**
- * tal_resize - enlarge or reduce a tal_arr(z).
- * @p: The tal allocated array to resize.
+ * tal_resize - enlarge or reduce a tal_arr[z].
+ * @p: A pointer to the tal allocated array to resize.
  * @count: the number to allocate.
  *
- * This returns the new pointer, or NULL (and destroys the old one)
- * on failure.
+ * This returns true on success (and may move *@p), or false on failure.
+ *
+ * Example:
+ *     tal_resize(&p, 100);
  */
 #define tal_resize(p, count) \
-       ((tal_typeof(p) tal_realloc_((p), tal_sizeof_(sizeof(*p), (count)))))
+       tal_resize_((void **)(p), tal_sizeof_(sizeof**(p), (count)))
 
 /**
  * tal_steal - change the parent of a tal-allocated pointer.
@@ -93,7 +124,7 @@ void tal_free(const tal_t *p);
  * This may need to perform an allocation, in which case it may fail; thus
  * it can return NULL, otherwise returns @ptr.
  *
- * Weird macro avoids gcc's 'warning: value computed is not used'.
+ * Note: weird macro avoids gcc's 'warning: value computed is not used'.
  */
 #if HAVE_STATEMENT_EXPR
 #define tal_steal(ctx, ptr) \
@@ -152,7 +183,7 @@ tal_t *tal_next(const tal_t *root, const tal_t *prev);
  * tal_parent - get the parent of a tal object.
  * @ctx: The tal allocated object.
  *
- * Returns the parent, which may be NULL.
+ * Returns the parent, which may be NULL.  Returns NULL if @ctx is NULL.
  */
 tal_t *tal_parent(const tal_t *ctx);
 
@@ -246,6 +277,19 @@ void tal_dump(void);
 #endif
 
 /* Internal support functions */
+#ifndef TAL_LABEL
+#ifdef CCAN_TAL_NO_LABELS
+#define TAL_LABEL(type, arr) NULL
+#else
+#ifdef CCAN_TAL_DEBUG
+#define TAL_LABEL(type, arr) \
+       __FILE__ ":" stringify(__LINE__) ":" stringify(type) arr
+#else
+#define TAL_LABEL(type, arr) stringify(type) arr
+#endif /* CCAN_TAL_DEBUG */
+#endif
+#endif
+
 #if HAVE_BUILTIN_CONSTANT_P
 #define TAL_IS_LITERAL(str) __builtin_constant_p(str)
 #else
@@ -275,11 +319,11 @@ static inline size_t tal_sizeof_(size_t size, size_t count)
 #define tal_typeof(ptr)
 #endif
 
-void *tal_alloc_(const tal_t *ctx, size_t bytes, bool clear);
+void *tal_alloc_(const tal_t *ctx, size_t bytes, bool clear, const char *label);
 
 tal_t *tal_steal_(const tal_t *new_parent, const tal_t *t);
 
-void *tal_realloc_(tal_t *ctx, size_t size);
+bool tal_resize_(tal_t **ctxp, size_t size);
 
 bool tal_add_destructor_(tal_t *ctx, void (*destroy)(void *me));