systemd/SOURCES/0269-macro-introduce-FOREACH_ARRAY-macro.patch

From b9f50b820804113811bcf291f586793de434fcdc Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Sun, 5 Mar 2023 14:56:15 +0900
Subject: [PATCH] macro: introduce FOREACH_ARRAY() macro

The pattern that runs all array element is quite common.
But, sometimes, the number of element may be in a signed integer, or the
array may be NULL.

(cherry picked from commit 5716c27e1f52d2aba9dd02916c01d6271d9d0b16)

Related: #2182632
---
 src/basic/macro.h     |  7 ++++++
 src/test/test-macro.c | 50 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/src/basic/macro.h b/src/basic/macro.h
index 237117db12..b977730e54 100644
--- a/src/basic/macro.h
+++ b/src/basic/macro.h
@@ -329,6 +329,13 @@ static inline int __coverity_check_and_return__(int condition) {
 #endif
 #endif
 
+#define _FOREACH_ARRAY(i, array, num, m, s)                             \
+        for (typeof(num) m = (num); m > 0; m = 0)                       \
+                for (typeof(array[0]) *s = (array), *i = s; s && i < s + m; i++)
+
+#define FOREACH_ARRAY(i, array, num)                                    \
+        _FOREACH_ARRAY(i, array, num, UNIQ_T(m, UNIQ), UNIQ_T(s, UNIQ))
+
 #define DEFINE_TRIVIAL_DESTRUCTOR(name, type, func)             \
         static inline void name(type *p) {                      \
                 func(p);                                        \
diff --git a/src/test/test-macro.c b/src/test/test-macro.c
index 049ea2c14e..6a5f4bbeb7 100644
--- a/src/test/test-macro.c
+++ b/src/test/test-macro.c
@@ -521,4 +521,54 @@ TEST(ISPOWEROF2) {
         assert_se(!ISPOWEROF2(u));
 }
 
+TEST(FOREACH_ARRAY) {
+        int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+        int b[10] = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
+        int x, n;
+
+        x = n = 0;
+        FOREACH_ARRAY(i, a, 10) {
+                x += *i;
+                n++;
+        }
+        assert_se(x == 45);
+        assert_se(n == 10);
+
+        x = n = 0;
+        FOREACH_ARRAY(i, a, 10)
+                FOREACH_ARRAY(j, b, 10) {
+                        x += (*i) * (*j);
+                        n++;
+                }
+        assert_se(x == 45 * 45);
+        assert_se(n == 10 * 10);
+
+        x = n = 0;
+        FOREACH_ARRAY(i, a, 5)
+                FOREACH_ARRAY(j, b, 5) {
+                        x += (*i) * (*j);
+                        n++;
+                }
+        assert_se(x == 10 * 35);
+        assert_se(n == 5 * 5);
+
+        x = n = 0;
+        FOREACH_ARRAY(i, a, 0)
+                FOREACH_ARRAY(j, b, 0) {
+                        x += (*i) * (*j);
+                        n++;
+                }
+        assert_se(x == 0);
+        assert_se(n == 0);
+
+        x = n = 0;
+        FOREACH_ARRAY(i, a, -1)
+                FOREACH_ARRAY(j, b, -1) {
+                        x += (*i) * (*j);
+                        n++;
+                }
+        assert_se(x == 0);
+        assert_se(n == 0);
+}
+
 DEFINE_TEST_MAIN(LOG_INFO);