Handout

kernel/debug/assert.h

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+// vim: set noet ts=4 sw=4:
+
+/*! \file
+ * \brief Contains several macros usable for making assertions
+ *
+ * Depending on the type of assertion (either static or at runtime), a failing
+ * assertion will trigger an error. For static assertion, this error will be
+ * shown at compile time and abort compilation. Runtime assertions will trigger
+ * a message containing details about the error occurred and will make the CPU
+ * die.
+ */
+
+/*!
+ * \defgroup debug Debugging functions
+ */
+
+#pragma once
+#include "../types.h"
+
+#ifndef STRINGIFY
+/*! \def STRINGIFY(S)
+ * \brief Converts a macro parameter into a string
+ * \ingroup debug
+ * \param S Expression to be converted
+ * \return stringified version of S
+ */
+#define STRINGIFY(S) #S
+#endif
+
+/*! \def assert_size(TYPE, SIZE)
+ * \brief Statically ensure (at compile time) that a data type (or variable)
+ * has the expected size.
+ *
+ * \ingroup debug
+ * \param TYPE The type to be checked
+ * \param SIZE Expected size in bytes
+ */
+#define assert_size(TYPE, SIZE) \
+	static_assert(sizeof(TYPE) == (SIZE), "Wrong size for " STRINGIFY(TYPE))
+
+/*! \def assert(EXP)
+ * \brief Ensure (at execution time) an expression evaluates to `true`, print
+ * an error message and stop the CPU otherwise.
+ *
+ * \ingroup debug
+ * \param EXP The expression to be checked
+ */
+#ifdef NDEBUG
+#define assert(EXP) ((void)0)
+#else
+#define assert(EXP)                                                         \
+	do {                                                                    \
+		if (__builtin_expect(!(EXP), 0)) {                                  \
+			assertion_failed(STRINGIFY(EXP), __func__, __FILE__, __LINE__); \
+		}                                                                   \
+	} while (false)
+
+/*! \brief Handles a failed assertion
+ *
+ * This function will print a message containing further information about the
+ * failed assertion and stops the current CPU permanently.
+ *
+ * \note This function should never be called directly, but only via the macro
+ * `assert`.
+ *
+ *
+ * \param exp Expression that did not hold
+ * \param func Name of the function in which the assertion failed
+ * \param file Name of the file in which the assertion failed
+ * \param line Line in which the assertion failed
+ */
+[[noreturn]] void assertion_failed(const char* exp, const char* func,
+								   const char* file, int line);
+#endif