lib: Add macro ARRAY_DEL_ELEMENT()

Every time I have to remove an element from within an array I have to
scratch my head about the memmove arguments. Make this easier to use.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

2 files changed, 48 insertions, 0 deletions

diff --git a/lib/replace/replace.h b/lib/replace/replace.h
index 177be37edbe..59f0b60f8a0 100644
--- a/lib/replace/replace.h
+++ b/lib/replace/replace.h
@@ -850,6 +850,12 @@ typedef unsigned long long ptrdiff_t ;
 #define ARRAY_SIZE(a) (sizeof(a)/sizeof(a[0]))
 
 /**
+ * Remove an array element by moving the rest one down
+ */
+#define ARRAY_DEL_ELEMENT(a,i,n) \
+if((i)<((n)-1)){memmove(&((a)[(i)]),&((a)[(i)+1]),(sizeof(*(a))*((n)-(i)-1)));}
+
+/**
  * Pointer difference macro
  */
 #define PTR_DIFF(p1,p2) ((ptrdiff_t)(((const char *)(p1)) - (const char *)(p2)))
diff --git a/lib/replace/tests/testsuite.c b/lib/replace/tests/testsuite.c
index 7f9801e9f98..2ece95332d2 100644
--- a/lib/replace/tests/testsuite.c
+++ b/lib/replace/tests/testsuite.c
@@ -1095,6 +1095,47 @@ static bool test_closefrom(void)
 	return true;
 }
 
+static bool test_array_del_element(void)
+{
+	int a[] = { 1,2,3,4,5 };
+
+	printf("test: array_del_element\n");
+
+	ARRAY_DEL_ELEMENT(a, 4, ARRAY_SIZE(a));
+
+	if ((a[0] != 1) ||
+	    (a[1] != 2) ||
+	    (a[2] != 3) ||
+	    (a[3] != 4) ||
+	    (a[4] != 5)) {
+		return false;
+	}
+
+	ARRAY_DEL_ELEMENT(a, 0, ARRAY_SIZE(a));
+
+	if ((a[0] != 2) ||
+	    (a[1] != 3) ||
+	    (a[2] != 4) ||
+	    (a[3] != 5) ||
+	    (a[4] != 5)) {
+		return false;
+	}
+
+	ARRAY_DEL_ELEMENT(a, 2, ARRAY_SIZE(a));
+
+	if ((a[0] != 2) ||
+	    (a[1] != 3) ||
+	    (a[2] != 5) ||
+	    (a[3] != 5) ||
+	    (a[4] != 5)) {
+		return false;
+	}
+
+	printf("success: array_del_element\n");
+
+	return true;
+}
+
 bool torture_local_replace(struct torture_context *ctx)
 {
 	bool ret = true;
@@ -1145,6 +1186,7 @@ bool torture_local_replace(struct torture_context *ctx)
 	ret &= test_utimes();
 	ret &= test_memmem();
 	ret &= test_closefrom();
+	ret &= test_array_del_element();
 
 	return ret;
 }