From 13ceb583b892ecbe1094e473c058a6ff18ad0efb Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Tue, 21 Apr 2020 13:47:04 +0200
Subject: [PATCH] defining GNUNET_array_concatenate() for #6190

---
 src/include/gnunet_common.h       | 50 ++++++++++++++++++++++++++-----
 src/util/test_common_allocation.c | 26 ++++++++++++++--
 2 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/src/include/gnunet_common.h b/src/include/gnunet_common.h
index fcc510ec9..033a68894 100644
--- a/src/include/gnunet_common.h
+++ b/src/include/gnunet_common.h
@@ -1392,22 +1392,58 @@ GNUNET_is_zero_ (const void *a,
 
 /**
  * @ingroup memory
- * Append an element to a list (growing the list by one).
+ * Append an element to an array (growing the array by one).
  *
- * @param arr base-pointer of the vector, may be NULL if size is 0;
+ * @param arr base-pointer of the vector, may be NULL if @a len is 0;
  *        will be updated to reflect the new address. The TYPE of
  *        arr is important since size is the number of elements and
  *        not the size in bytes
- * @param size the number of elements in the existing vector (number
+ * @param len the number of elements in the existing vector (number
  *        of elements to copy over), will be updated with the new
- *        array size
+ *        array length
  * @param element the element that will be appended to the array
  */
-#define GNUNET_array_append(arr, size, element) \
+#define GNUNET_array_append(arr, len, element) \
+  do                                            \
+  {                                             \
+    GNUNET_assert ((len) + 1 > (len)); \
+    GNUNET_array_grow (arr, len, len + 1);    \
+    (arr) [len - 1] = element;                  \
+  } while (0)
+
+
+/**
+ * @ingroup memory
+ * Append @a arr2 to @a arr1 (growing @a arr1
+ * as needed).  The @a arr2 array is left unchanged. Naturally
+ * this function performs a shallow copy. Both arrays must have
+ * the same type for their elements.
+ *
+ * @param arr1 base-pointer of the vector, may be NULL if @a len is 0;
+ *        will be updated to reflect the new address. The TYPE of
+ *        arr is important since size is the number of elements and
+ *        not the size in bytes
+ * @param len1 the number of elements in the existing vector (number
+ *        of elements to copy over), will be updated with the new
+ *        array size
+ * @param arr2 base-pointer a second array to concatenate, may be NULL if @a len2 is 0;
+ *        will be updated to reflect the new address. The TYPE of
+ *        arr is important since size is the number of elements and
+ *        not the size in bytes
+ * @param len the number of elements in the existing vector (number
+ *        of elements to copy over), will be updated with the new
+ *        array size
+
+ */
+#define GNUNET_array_concatenate(arr1, len1, arr2, len2)   \
   do                                            \
   {                                             \
-    GNUNET_array_grow (arr, size, size + 1);    \
-    (arr) [size - 1] = element;                  \
+    const typeof (*arr2) * _a1 = (arr1);  \
+    const typeof (*arr1) * _a2 = (arr2);  \
+    GNUNET_assert ((len1) + (len2) >= (len1));                    \
+    GNUNET_assert (SIZE_MAX / sizeof (*_a1) >= ((len1) + (len2))); \
+    GNUNET_array_grow (arr1, len1, (len1) + (len2));            \
+    memcpy (&(arr1) [(len1) - (len2)], _a2, (len2) * sizeof (*arr1));    \
   } while (0)
 
 /**
diff --git a/src/util/test_common_allocation.c b/src/util/test_common_allocation.c
index e2fc29e82..a24af7124 100644
--- a/src/util/test_common_allocation.c
+++ b/src/util/test_common_allocation.c
@@ -27,7 +27,7 @@
 
 
 static int
-check ()
+check (void)
 {
 #define MAX_TESTVAL 1024
   char *ptrs[MAX_TESTVAL];
@@ -134,6 +134,28 @@ check ()
 }
 
 
+static int
+check2 (void)
+{
+  char *a1 = NULL;
+  unsigned int a1_len = 0;
+  const char *a2 = "test";
+
+  GNUNET_array_append (a1,
+                       a1_len,
+                       'x');
+  GNUNET_array_concatenate (a1,
+                            a1_len,
+                            a2,
+                            4);
+  GNUNET_assert (0 == strncmp ("xtest",
+                               a1,
+                               5));
+  GNUNET_assert (5 == a1_len);
+  return 0;
+}
+
+
 int
 main (int argc, char *argv[])
 {
@@ -142,7 +164,7 @@ main (int argc, char *argv[])
   GNUNET_log_setup ("test-common-allocation",
                     "WARNING",
                     NULL);
-  ret = check ();
+  ret = check () | check2 ();
   if (ret != 0)
     fprintf (stderr,
              "ERROR %d.\n",
-- 
2.25.1