add assert.h

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 95 insertions, 0 deletions

diff --git a/include/assert.h b/include/assert.h
new file mode 100644
index 0000000..7f44222
--- /dev/null
+++ b/include/assert.h
@@ -0,0 +1,95 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _ASSERT_H
+#define _ASSERT_H
+#include <slibc/version.h>
+
+
+
+/* The `assert` macro shall be redefined according to the the
+ * current state of `NDEBUF` each time <assert.h> is included. */
+#ifdef assert
+# undef assert
+#endif
+
+
+/**
+ * Unless `NDEBUG` is defined, print an error message
+ * and abort the process, if the expression evaluates to
+ * non-zero.
+ * 
+ * POSIX specifies that `assert` shall not evaluate the
+ * expression if `NDEBUG` is defined. This is probably
+ * to save CPU-cycles.
+ */
+#ifdef NDEBUG
+# define assert(expression)   ((void)0)
+#else
+# define assert(expression)  \
+  ((void)((expression) ? 0 : (__assert_fail(#expression, 0, __FILE__, __LINE__, __func__), 0)))
+#endif
+
+
+/**
+ * A compile-time error should occur if the expression
+ * evaluates to zero.
+ * 
+ * @param  expression:scalar    The expression to evaluate.
+ * @param  message:const char*  The message to print on error.
+ */
+#define static_assert _Static_assert
+
+
+/**
+ * Unless `NDEBUG` is defined, print an error message
+ * and abort the process, if `errnum` is non-zero.
+ * 
+ * @param  errnum:int  The error code, describing the error that occurred.
+ * 
+ * `assert_perror` is a GNU extension.
+ */
+#if defined(_SLIBC_SOURCE) || defined(_GNU_SOURCE)
+#ifdef assert_perror
+# undef assert_perror
+#endif
+#ifdef NDEBUG
+# define assert_perror(errnum)  ((void)0)
+#else
+# define assert_perror(errnum)  \
+  ((void)((errnum == 0) ? 0 : (__assert_fail(NULL, errnum, __FILE__, __LINE__, __func__), 0)))
+__USE_GNU
+#endif
+
+
+
+/**
+ * The function that is called if an assertion fails.
+ * 
+ * @param  expression  The expression that failed, `NULL` if `assert_perror` failed
+ * @param  errnum      The code of the fatal error, 0 if `assert` failed
+ * @param  file        The filename of the source cose whence the assertion was made
+ * @param  line        The line in the source code whence the assertion was made
+ * @param  func        The function in the source code whence the assertion was made
+ */
+void __attribute__((noreturn, nonnull(3, 4, 5)))
+__assert_fail(const char* expression, int errnum, const char* file, int line, const char* func);
+
+
+
+#endif
+