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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-06-26 16:18:37 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-06-26 16:18:37 +0000
commitb6b00dd55e035bfbe311a527b567962ffa77ee43 (patch)
treecafc4d13785448e5a78bd40a51697ee07f07ac12 /lib/must_be.h
parentAdding debian version 1:4.13+dfsg1-5. (diff)
downloadshadow-b6b00dd55e035bfbe311a527b567962ffa77ee43.tar.xz
shadow-b6b00dd55e035bfbe311a527b567962ffa77ee43.zip
Merging upstream version 1:4.15.2.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+/*
+ * SPDX-FileCopyrightText: 2019-2023, Alejandro Colomar <alx@kernel.org>
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+
+#ifndef SHADOW_INCLUDE_LIBMISC_MUST_BE_H_
+#define SHADOW_INCLUDE_LIBMISC_MUST_BE_H_
+
+
+#include <config.h>
+
+#include <assert.h>
+
+
+/*
+ * SYNOPSIS
+ * int must_be(bool e);
+ *
+ * ARGUMENTS
+ * e Expression to be asserted.
+ *
+ * DESCRIPTION
+ * This macro fails compilation if 'e' is false. If 'e' is true,
+ * it returns (int) 0, so it doesn't affect the expression in which
+ * it is contained.
+ *
+ * This macro is similar to static_assert(3). While
+ * static_assert(3) can only be used where a statement is allowed,
+ * this must_be() macro can be used wherever an expression is
+ * allowed.
+ *
+ * RETURN VALUE
+ * 0
+ *
+ * ERRORS
+ * If 'e' is false, the compilation will fail, as when using
+ * static_assert(3).
+ *
+ * EXAMPLES
+ * #define must_be_array(a) must_be(is_array(a))
+ *
+ * #define NITEMS(a) (sizeof(a) / sizeof(*(a)) + must_be_array(a))
+ *
+ * int foo[42];
+ * int bar[NITEMS(foo)];
+ */
+
+
+#define must_be(e) \
+( \
+ 0 * (int) sizeof( \
+ struct { \
+ static_assert(e, ""); \
+ int ISO_C_forbids_a_struct_with_no_members_; \
+ } \
+ ) \
+)
+
+
+/*
+ * SYNOPSIS
+ * int must_be_array(a);
+ *
+ * ARGUMENTS
+ * a Array.
+ *
+ * DESCRIPTION
+ * This macro fails compilation if 'a' is not an array. It is
+ * useful in macros that accept an array as a parameter, where this
+ * macro can validate the macro argument. It prevent passing a
+ * pointer to such macros, which would otherwise produce silent
+ * bugs.
+ *
+ * RETURN VALUE
+ * 0
+ *
+ * ERRORS
+ * If 'a' is not an array, the compilation will fail.
+ *
+ * EXAMPLES
+ * int a[10];
+ * int *p;
+ *
+ * must_be_array(a); // Ok
+ * must_be_array(p); // Compile-time error
+ *
+ * SEE ALSO
+ * must_be()
+ */
+
+
+#define is_same_type(a, b) __builtin_types_compatible_p(a, b)
+#define is_same_typeof(a, b) is_same_type(typeof(a), typeof(b))
+#define is_array(a) (!is_same_typeof((a), &(a)[0]))
+#define must_be_array(a) must_be(is_array(a))
+
+
+#endif // include guard