--- /dev/null
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * array_size - routine for safely deriving the size of a visible array.
+ *
+ * This provides a simple ARRAY_SIZE() macro, which (given a good compiler)
+ * will also break compile if you try to use it on a pointer.
+ *
+ * This can ensure your code is robust to changes, without needing a gratuitous
+ * macro or constant.
+ *
+ * Example:
+ * #include <ccan/array_size/array_size.h>
+ * #include <stdlib.h>
+ *
+ * // We currently use 32 random values.
+ * static unsigned int vals[32];
+ *
+ * void init_values(void)
+ * {
+ * unsigned int i;
+ * for (i = 0; i < ARRAY_SIZE(vals); i++)
+ * vals[i] = random();
+ * }
+ *
+ * Licence: LGPL (2 or any later version)
+ */
+int main(int argc, char *argv[])
+{
+ if (argc != 2)
+ return 1;
+
+ if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/build_assert\n");
+ return 0;
+ }
+
+ return 1;
+}
--- /dev/null
+#ifndef CCAN_ARRAY_SIZE_H
+#define CCAN_ARRAY_SIZE_H
+#include "config.h"
+#include <ccan/build_assert/build_assert.h>
+
+/**
+ * ARRAY_SIZE - get the number of elements in a visible array
+ * @arr: the array whose size you want.
+ *
+ * This does not work on pointers, or arrays declared as [], or
+ * function parameters. With correct compiler support, such usage
+ * will cause a build error (see build_assert).
+ */
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + _array_size_chk(arr))
+
+#if HAVE_BUILTIN_TYPES_COMPATIBLE_P && HAVE_TYPEOF
+/* Two gcc extensions.
+ * &a[0] degrades to a pointer: a different type from an array */
+#define _array_size_chk(arr) \
+ EXPR_BUILD_ASSERT(!__builtin_types_compatible_p(typeof(arr), \
+ typeof(&(arr)[0])))
+#else
+#define _array_size_chk(arr) 0
+#endif
+#endif /* CCAN_ALIGNOF_H */
--- /dev/null
+#include <ccan/array_size/array_size.h>
+#include <stdlib.h>
+
+struct foo {
+ unsigned int a, b;
+};
+
+int check_parameter(const struct foo array[4]);
+int check_parameter(const struct foo array[4])
+{
+#ifdef FAIL
+ return (ARRAY_SIZE(array) == 4);
+#else
+ return sizeof(array) == 4 * sizeof(struct foo);
+#endif
+}
+
+int main(int argc, char *argv[])
+{
+ return check_parameter(NULL);
+}
--- /dev/null
+#include "array_size/array_size.h"
+
+int main(int argc, char *argv[8])
+{
+ char array[100];
+#ifdef FAIL
+ return ARRAY_SIZE(argv) + ARRAY_SIZE(array);
+#if !HAVE_TYPEOF || !HAVE_BUILTIN_TYPES_COMPATIBLE_P
+#error "Unfortunately we don't fail if _array_size_chk is a noop."
+#endif
+#else
+ return ARRAY_SIZE(array);
+#endif
+}
--- /dev/null
+#include "array_size/array_size.h"
+#include "tap/tap.h"
+
+static char array1[1];
+static int array2[2];
+static unsigned long array3[3][5];
+struct foo {
+ unsigned int a, b;
+ char string[100];
+};
+static struct foo array4[4];
+
+/* Make sure they can be used in initializers. */
+static int array1_size = ARRAY_SIZE(array1);
+static int array2_size = ARRAY_SIZE(array2);
+static int array3_size = ARRAY_SIZE(array3);
+static int array4_size = ARRAY_SIZE(array4);
+
+int main(int argc, char *argv[])
+{
+ plan_tests(8);
+ ok1(array1_size == 1);
+ ok1(array2_size == 2);
+ ok1(array3_size == 3);
+ ok1(array4_size == 4);
+
+ ok1(ARRAY_SIZE(array1) == 1);
+ ok1(ARRAY_SIZE(array2) == 2);
+ ok1(ARRAY_SIZE(array3) == 3);
+ ok1(ARRAY_SIZE(array4) == 4);
+
+ return exit_status();
+}