tal: make sure tal_free() preserves errno.

[ccan] / ccan / tal / tal.h

diff --git a/ccan/tal/tal.h b/ccan/tal/tal.h
index d511e88aa7b637c7dc8d98b1cccf3ad923025c92..a12e0dc476ba6acb773e2e65d0b2de68a1c8f234 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>
@@ -17,14 +18,29 @@
  */
 typedef void tal_t;
 
+/**
+ * TAL_TAKE - fake tal_t to indicate function will own arguments.
+ *
+ * Various functions take a context on which to allocate: if you use
+ * TAL_TAKE there instead, it means that the argument(s) are actually
+ * tal objects.  The returned value will share the same parent; it may
+ * even be the same pointer as the arguments.  The arguments themselves
+ * will be reused, freed, or made a child of the return value: they are
+ * no longer valid for external use.
+ */
+#define TAL_TAKE ((tal_t *)-2L)
+
 /**
  * tal - basic allocator function
  * @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.
  */
-#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
@@ -33,7 +49,8 @@ typedef void tal_t;
  *
  * Equivalent to tal() followed by memset() to zero.
  */
-#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.
@@ -41,6 +58,8 @@ 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.
  */
 void tal_free(const tal_t *p);
 
@@ -51,7 +70,8 @@ void tal_free(const tal_t *p);
  * @count: the number to allocate.
  */
 #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.
@@ -60,7 +80,8 @@ void tal_free(const tal_t *p);
  * @count: the number to allocate.
  */
 #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).
@@ -140,28 +161,29 @@ 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);
 
 /**
  * tal_memdup - duplicate memory.
- * @ctx: NULL, or tal allocated object to be parent.
+ * @ctx: NULL, or tal allocated object to be parent (or TAL_TAKE).
  * @p: the memory to copy
  * @n: the number of bytes.
+ *
  */
 void *tal_memdup(const tal_t *ctx, const void *p, size_t n);
 
 /**
- * tal_strdup - duplicate a string.
- * @ctx: NULL, or tal allocated object to be parent.
+ * tal_strdup - duplicate a string
+ * @ctx: NULL, or tal allocated object to be parent (or TAL_TAKE).
  * @p: the string to copy
  */
 char *tal_strdup(const tal_t *ctx, const char *p);
 
 /**
  * tal_strndup - duplicate a limited amount of a string.
- * @ctx: NULL, or tal allocated object to be parent.
+ * @ctx: NULL, or tal allocated object to be parent (or TAL_TAKE).
  * @p: the string to copy
  * @n: the maximum length to copy.
  *
@@ -171,16 +193,22 @@ char *tal_strndup(const tal_t *ctx, const char *p, size_t n);
 
 /**
  * tal_asprintf - allocate a formatted string
- * @ctx: NULL, or tal allocated object to be parent.
+ * @ctx: NULL, or tal allocated object to be parent (or TAL_TAKE).
  * @fmt: the printf-style format.
+ *
+ * If @ctx is TAL_TAKE, @fmt is freed and its parent will be the parent
+ * of the return value.
  */
 char *tal_asprintf(const tal_t *ctx, const char *fmt, ...) PRINTF_FMT(2,3);
 
 /**
  * tal_vasprintf - allocate a formatted string (va_list version)
- * @ctx: NULL, or tal allocated object to be parent.
+ * @ctx: NULL, or tal allocated object to be parent (or TAL_TAKE).
  * @fmt: the printf-style format.
  * @va: the va_list containing the format args.
+ *
+ * If @ctx is TAL_TAKE, @fmt is freed and its parent will be the parent
+ * of the return value.
  */
 char *tal_vasprintf(const tal_t *ctx, const char *fmt, va_list ap)
        PRINTF_FMT(2,0);
@@ -227,6 +255,19 @@ 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
@@ -256,7 +297,7 @@ 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);