From 754c677b0bbf3ea6c7d2a73c93848f1b0d68c91e Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 20 Jun 2011 16:54:15 +0930
Subject: lib: import ccan modules for tdb2

Imported from git://git.ozlabs.org/~ccan/ccan init-1161-g661d41f

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 lib/ccan/cast/cast.h | 129 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 lib/ccan/cast/cast.h

(limited to 'lib/ccan/cast/cast.h')

diff --git a/lib/ccan/cast/cast.h b/lib/ccan/cast/cast.h
new file mode 100644
index 0000000000..daebd85723
--- /dev/null
+++ b/lib/ccan/cast/cast.h
@@ -0,0 +1,129 @@
+#ifndef CCAN_CAST_H
+#define CCAN_CAST_H
+#include "config.h"
+#include <stdint.h>
+#include <ccan/build_assert/build_assert.h>
+
+/**
+ * cast_signed - cast a (const) char * to/from (const) signed/unsigned char *.
+ * @type: some char * variant.
+ * @expr: expression (of some char * variant) to cast.
+ *
+ * Some libraries insist on an unsigned char in various places; cast_signed
+ * makes sure (with suitable compiler) that the expression you are casting
+ * only differs in signed/unsigned, not in type or const-ness.
+ */
+#define cast_signed(type, expr)						\
+	((type)(expr)							\
+	 + BUILD_ASSERT_OR_ZERO(cast_sign_compatible(type, (expr))))
+
+/**
+ * cast_const - remove a const qualifier from a pointer.
+ * @type: some pointer type.
+ * @expr: expression to cast.
+ *
+ * This ensures that you are only removing the const qualifier from an
+ * expression.  The expression must otherwise match @type.
+ *
+ * If @type is a pointer to a pointer, you must use cast_const2 (etc).
+ *
+ * Example:
+ *	// Dumb open-coded strstr variant.
+ *	static char *find_needle(const char *haystack)
+ *	{
+ *		size_t i;
+ *		for (i = 0; i < strlen(haystack); i++)
+ *		if (memcmp("needle", haystack+i, strlen("needle")) == 0)
+ *			return cast_const(char *, haystack+i);
+ *		return NULL;
+ *	}
+ */
+#define cast_const(type, expr)						\
+	((type)((intptr_t)(expr)					\
+		+ BUILD_ASSERT_OR_ZERO(cast_const_compat1((expr), type))))
+
+/**
+ * cast_const2 - remove a const qualifier from a pointer to a pointer.
+ * @type: some pointer to pointer type.
+ * @expr: expression to cast.
+ *
+ * This ensures that you are only removing the const qualifier from an
+ * expression.  The expression must otherwise match @type.
+ */
+#define cast_const2(type, expr)						\
+	((type)((intptr_t)(expr)					\
+		+ BUILD_ASSERT_OR_ZERO(cast_const_compat2((expr), type))))
+
+/**
+ * cast_const3 - remove a const from a pointer to a pointer to a pointer..
+ * @type: some pointer to pointer to pointer type.
+ * @expr: expression to cast.
+ *
+ * This ensures that you are only removing the const qualifier from an
+ * expression.  The expression must otherwise match @type.
+ */
+#define cast_const3(type, expr)						\
+	((type)((intptr_t)(expr)					\
+		+ BUILD_ASSERT_OR_ZERO(cast_const_compat3((expr), type))))
+
+
+/**
+ * cast_static - explicit mimic of implicit cast.
+ * @type: some type.
+ * @expr: expression to cast.
+ *
+ * This ensures that the cast is not to or from a pointer: it can only be
+ * an implicit cast, such as a pointer to a similar const pointer, or between
+ * integral types.
+ */
+#if HAVE_COMPOUND_LITERALS
+#define cast_static(type, expr)			\
+	((struct { type x; }){(expr)}.x)
+#else
+#define cast_static(type, expr)			\
+	((type)(expr))
+#endif
+
+/* Herein lies the gcc magic to evoke compile errors. */
+#if HAVE_BUILTIN_CHOOSE_EXPR && HAVE_BUILTIN_TYPES_COMPATIBLE_P && HAVE_TYPEOF
+#define cast_sign_compatible(t, e) \
+  __builtin_choose_expr(						\
+	  __builtin_types_compatible_p(__typeof__(t), char *) ||	\
+	  __builtin_types_compatible_p(__typeof__(t), signed char *) || \
+	  __builtin_types_compatible_p(__typeof__(t), unsigned char *), \
+	  /* if type is not const qualified */				\
+	  __builtin_types_compatible_p(__typeof__(e), char *) ||	\
+	  __builtin_types_compatible_p(__typeof__(e), signed char *) || \
+	  __builtin_types_compatible_p(__typeof__(e), unsigned char *), \
+	  /* and if it is... */						\
+	  __builtin_types_compatible_p(__typeof__(e), const char *) ||	\
+	  __builtin_types_compatible_p(__typeof__(e), const signed char *) || \
+	  __builtin_types_compatible_p(__typeof__(e), const unsigned char *) ||\
+	  __builtin_types_compatible_p(__typeof__(e), char *) ||	\
+	  __builtin_types_compatible_p(__typeof__(e), signed char *) ||	\
+	  __builtin_types_compatible_p(__typeof__(e), unsigned char *)	\
+	  )
+
+#define cast_const_strip1(expr)			\
+	__typeof__(*(struct { int z; __typeof__(expr) x; }){0}.x)
+#define cast_const_strip2(expr) \
+	__typeof__(**(struct { int z; __typeof__(expr) x; }){0}.x)
+#define cast_const_strip3(expr) \
+	__typeof__(***(struct { int z; __typeof__(expr) x; }){0}.x)
+#define cast_const_compat1(expr, type)					\
+	__builtin_types_compatible_p(cast_const_strip1(expr),		\
+				     cast_const_strip1(type))
+#define cast_const_compat2(expr, type)					\
+	__builtin_types_compatible_p(cast_const_strip2(expr),		\
+				     cast_const_strip2(type))
+#define cast_const_compat3(expr, type)					\
+	__builtin_types_compatible_p(cast_const_strip3(expr),		\
+				     cast_const_strip3(type))
+#else
+#define cast_sign_compatible(type, expr)		\
+	(sizeof(*(type)0) == 1 && sizeof(*(expr)) == 1)
+#define cast_const_compat1(expr, type)		(1)
+#define cast_const_compat2(expr, type)		(1)
+#define cast_const_compat3(expr, type)		(1)
+#endif
+#endif /* CCAN_CAST_H */
-- 
cgit