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>

5 files changed, 482 insertions, 0 deletions

diff --git a/lib/ccan/compiler/LICENSE b/lib/ccan/compiler/LICENSE
new file mode 100644
index 0000000000..cca7fc278f
--- /dev/null
+++ b/lib/ccan/compiler/LICENSE
@@ -0,0 +1,165 @@
+		   GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+
+  This version of the GNU Lesser General Public License incorporates
+the terms and conditions of version 3 of the GNU General Public
+License, supplemented by the additional permissions listed below.
+
+  0. Additional Definitions.
+
+  As used herein, "this License" refers to version 3 of the GNU Lesser
+General Public License, and the "GNU GPL" refers to version 3 of the GNU
+General Public License.
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+other than an Application or a Combined Work as defined below.
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+  1. Exception to Section 3 of the GNU GPL.
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+  You may convey a covered work under sections 3 and 4 of this License
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+  2. Conveying Modified Versions.
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+  If you modify a copy of the Library, and, in your modifications, a
+facility refers to a function or data to be supplied by an Application
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+   b) under the GNU GPL, with none of the additional permissions of
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+   on the Library, uncombined with any other library facilities,
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+   is a work based on the Library, and explaining where to find the
+   accompanying uncombined form of the same work.
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+  6. Revised Versions of the GNU Lesser General Public License.
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+  The Free Software Foundation may publish revised and/or new versions
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diff --git a/lib/ccan/compiler/_info b/lib/ccan/compiler/_info
new file mode 100644
index 0000000000..c55ba22f08
--- /dev/null
+++ b/lib/ccan/compiler/_info
@@ -0,0 +1,64 @@
+#include <string.h>
+#include <stdio.h>
+#include "config.h"
+
+/**
+ * compiler - macros for common compiler extensions
+ *
+ * Abstracts away some compiler hints.  Currently these include:
+ * - COLD
+ *	For functions not called in fast paths (aka. cold functions)
+ * - PRINTF_FMT
+ *	For functions which take printf-style parameters.
+ * - IDEMPOTENT
+ *	For functions which return the same value for same parameters.
+ * - NEEDED
+ *	For functions and variables which must be emitted even if unused.
+ * - UNNEEDED
+ *	For functions and variables which need not be emitted if unused.
+ * - UNUSED
+ *	For parameters which are not used.
+ * - IS_COMPILE_CONSTANT
+ *	For using different tradeoffs for compiletime vs runtime evaluation.
+ *
+ * License: LGPL (3 or any later version)
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ *
+ * Example:
+ *	#include <ccan/compiler/compiler.h>
+ *	#include <stdio.h>
+ *	#include <stdarg.h>
+ *
+ *	// Example of a (slow-path) logging function.
+ *	static int log_threshold = 2;
+ *	static void COLD PRINTF_FMT(2,3)
+ *		logger(int level, const char *fmt, ...)
+ *	{
+ *		va_list ap;
+ *		va_start(ap, fmt);
+ *		if (level >= log_threshold)
+ *			vfprintf(stderr, fmt, ap);
+ *		va_end(ap);
+ *	}
+ *
+ *	int main(int argc, char *argv[])
+ *	{
+ *		if (argc != 1) {
+ *			logger(3, "Don't want %i arguments!\n", argc-1);
+ *			return 1;
+ *		}
+ *		return 0;
+ *	}
+ */
+int main(int argc, char *argv[])
+{
+	/* Expect exactly one argument */
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	return 1;
+}
diff --git a/lib/ccan/compiler/compiler.h b/lib/ccan/compiler/compiler.h
new file mode 100644
index 0000000000..74e0f1835c
--- /dev/null
+++ b/lib/ccan/compiler/compiler.h
@@ -0,0 +1,216 @@
+#ifndef CCAN_COMPILER_H
+#define CCAN_COMPILER_H
+#include "config.h"
+
+#ifndef COLD
+#if HAVE_ATTRIBUTE_COLD
+/**
+ * COLD - a function is unlikely to be called.
+ *
+ * Used to mark an unlikely code path and optimize appropriately.
+ * It is usually used on logging or error routines.
+ *
+ * Example:
+ * static void COLD moan(const char *reason)
+ * {
+ *	fprintf(stderr, "Error: %s (%s)\n", reason, strerror(errno));
+ * }
+ */
+#define COLD __attribute__((cold))
+#else
+#define COLD
+#endif
+#endif
+
+#ifndef NORETURN
+#if HAVE_ATTRIBUTE_NORETURN
+/**
+ * NORETURN - a function does not return
+ *
+ * Used to mark a function which exits; useful for suppressing warnings.
+ *
+ * Example:
+ * static void NORETURN fail(const char *reason)
+ * {
+ *	fprintf(stderr, "Error: %s (%s)\n", reason, strerror(errno));
+ *	exit(1);
+ * }
+ */
+#define NORETURN __attribute__((noreturn))
+#else
+#define NORETURN
+#endif
+#endif
+
+#ifndef PRINTF_FMT
+#if HAVE_ATTRIBUTE_PRINTF
+/**
+ * PRINTF_FMT - a function takes printf-style arguments
+ * @nfmt: the 1-based number of the function's format argument.
+ * @narg: the 1-based number of the function's first variable argument.
+ *
+ * This allows the compiler to check your parameters as it does for printf().
+ *
+ * Example:
+ * void PRINTF_FMT(2,3) my_printf(const char *prefix, const char *fmt, ...);
+ */
+#define PRINTF_FMT(nfmt, narg) \
+	__attribute__((format(__printf__, nfmt, narg)))
+#else
+#define PRINTF_FMT(nfmt, narg)
+#endif
+#endif
+
+#ifndef IDEMPOTENT
+#if HAVE_ATTRIBUTE_CONST
+/**
+ * IDEMPOTENT - a function's return depends only on its argument
+ *
+ * This allows the compiler to assume that the function will return the exact
+ * same value for the exact same arguments.  This implies that the function
+ * must not use global variables, or dereference pointer arguments.
+ */
+#define IDEMPOTENT __attribute__((const))
+#else
+#define IDEMPOTENT
+#endif
+#endif
+
+#if HAVE_ATTRIBUTE_UNUSED
+#ifndef UNNEEDED
+/**
+ * UNNEEDED - a variable/function may not be needed
+ *
+ * This suppresses warnings about unused variables or functions, but tells
+ * the compiler that if it is unused it need not emit it into the source code.
+ *
+ * Example:
+ * // With some preprocessor options, this is unnecessary.
+ * static UNNEEDED int counter;
+ *
+ * // With some preprocessor options, this is unnecessary.
+ * static UNNEEDED void add_to_counter(int add)
+ * {
+ *	counter += add;
+ * }
+ */
+#define UNNEEDED __attribute__((unused))
+#endif
+
+#ifndef NEEDED
+#if HAVE_ATTRIBUTE_USED
+/**
+ * NEEDED - a variable/function is needed
+ *
+ * This suppresses warnings about unused variables or functions, but tells
+ * the compiler that it must exist even if it (seems) unused.
+ *
+ * Example:
+ *	// Even if this is unused, these are vital for debugging.
+ *	static NEEDED int counter;
+ *	static NEEDED void dump_counter(void)
+ *	{
+ *		printf("Counter is %i\n", counter);
+ *	}
+ */
+#define NEEDED __attribute__((used))
+#else
+/* Before used, unused functions and vars were always emitted. */
+#define NEEDED __attribute__((unused))
+#endif
+#endif
+
+#ifndef UNUSED
+/**
+ * UNUSED - a parameter is unused
+ *
+ * Some compilers (eg. gcc with -W or -Wunused) warn about unused
+ * function parameters.  This suppresses such warnings and indicates
+ * to the reader that it's deliberate.
+ *
+ * Example:
+ *	// This is used as a callback, so needs to have this prototype.
+ *	static int some_callback(void *unused UNUSED)
+ *	{
+ *		return 0;
+ *	}
+ */
+#define UNUSED __attribute__((unused))
+#endif
+#else
+#ifndef UNNEEDED
+#define UNNEEDED
+#endif
+#ifndef NEEDED
+#define NEEDED
+#endif
+#ifndef UNUSED
+#define UNUSED
+#endif
+#endif
+
+#ifndef IS_COMPILE_CONSTANT
+#if HAVE_BUILTIN_CONSTANT_P
+/**
+ * IS_COMPILE_CONSTANT - does the compiler know the value of this expression?
+ * @expr: the expression to evaluate
+ *
+ * When an expression manipulation is complicated, it is usually better to
+ * implement it in a function.  However, if the expression being manipulated is
+ * known at compile time, it is better to have the compiler see the entire
+ * expression so it can simply substitute the result.
+ *
+ * This can be done using the IS_COMPILE_CONSTANT() macro.
+ *
+ * Example:
+ *	enum greek { ALPHA, BETA, GAMMA, DELTA, EPSILON };
+ *
+ *	// Out-of-line version.
+ *	const char *greek_name(enum greek greek);
+ *
+ *	// Inline version.
+ *	static inline const char *_greek_name(enum greek greek)
+ *	{
+ *		switch (greek) {
+ *		case ALPHA: return "alpha";
+ *		case BETA: return "beta";
+ *		case GAMMA: return "gamma";
+ *		case DELTA: return "delta";
+ *		case EPSILON: return "epsilon";
+ *		default: return "**INVALID**";
+ *		}
+ *	}
+ *
+ *	// Use inline if compiler knows answer.  Otherwise call function
+ *	// to avoid copies of the same code everywhere.
+ *	#define greek_name(g)						\
+ *		 (IS_COMPILE_CONSTANT(greek) ? _greek_name(g) : greek_name(g))
+ */
+#define IS_COMPILE_CONSTANT(expr) __builtin_constant_p(expr)
+#else
+/* If we don't know, assume it's not. */
+#define IS_COMPILE_CONSTANT(expr) 0
+#endif
+#endif
+
+#ifndef WARN_UNUSED_RESULT
+#if HAVE_WARN_UNUSED_RESULT
+/**
+ * WARN_UNUSED_RESULT - warn if a function return value is unused.
+ *
+ * Used to mark a function where it is extremely unlikely that the caller
+ * can ignore the result, eg realloc().
+ *
+ * Example:
+ * // buf param may be freed by this; need return value!
+ * static char *WARN_UNUSED_RESULT enlarge(char *buf, unsigned *size)
+ * {
+ *	return realloc(buf, (*size) *= 2);
+ * }
+ */
+#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+#else
+#define WARN_UNUSED_RESULT
+#endif
+#endif
+#endif /* CCAN_COMPILER_H */
diff --git a/lib/ccan/compiler/test/compile_fail-printf.c b/lib/ccan/compiler/test/compile_fail-printf.c
new file mode 100644
index 0000000000..8f34ae5a12
--- /dev/null
+++ b/lib/ccan/compiler/test/compile_fail-printf.c
@@ -0,0 +1,22 @@
+#include <ccan/compiler/compiler.h>
+
+static void PRINTF_FMT(2,3) my_printf(int x, const char *fmt, ...)
+{
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i = 0;
+
+	my_printf(1, "Not a pointer "
+#ifdef FAIL
+		  "%p",
+#if !HAVE_ATTRIBUTE_PRINTF
+#error "Unfortunately we don't fail if !HAVE_ATTRIBUTE_PRINTF."
+#endif
+#else
+		  "%i",
+#endif
+		  i);
+	return 0;
+}
diff --git a/lib/ccan/compiler/test/run-is_compile_constant.c b/lib/ccan/compiler/test/run-is_compile_constant.c
new file mode 100644
index 0000000000..a66f2e13e6
--- /dev/null
+++ b/lib/ccan/compiler/test/run-is_compile_constant.c
@@ -0,0 +1,15 @@
+#include <ccan/compiler/compiler.h>
+#include <ccan/tap/tap.h>
+
+int main(int argc, char *argv[])
+{
+	plan_tests(2);
+
+	ok1(!IS_COMPILE_CONSTANT(argc));
+#if HAVE_BUILTIN_CONSTANT_P
+	ok1(IS_COMPILE_CONSTANT(7));
+#else
+	pass("If !HAVE_BUILTIN_CONSTANT_P, IS_COMPILE_CONSTANT always false");
+#endif
+	return exit_status();
+}