[RFC PATCH bpf-next v2 5/6] selftests/bpf: test BPF_MAP_DUMP command on a bpf hashmap

[Brian Vazquez]

This tests exercise the new command on a bpf hashmap and make sure it
works as expected.

Signed-off-by: Brian Vazquez <bria...@google.com>
---
 tools/testing/selftests/bpf/test_maps.c | 70 ++++++++++++++++++++++++-
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_maps.c 
b/tools/testing/selftests/bpf/test_maps.c
index a3fbc571280a9..3df72b46fd1d9 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -309,6 +309,73 @@ static void test_hashmap_walk(unsigned int task, void 
*data)
        close(fd);
 }
 
+static void test_hashmap_dump(void)
+{
+       int fd, i, max_entries = 3;
+       uint64_t keys[max_entries], values[max_entries];
+       uint64_t key, value, next_key;
+       bool next_key_valid = true;
+       void *buf, *elem, *prev_key;
+       u32 buf_len;
+       const int elem_size = sizeof(key) + sizeof(value);
+
+       fd = helper_fill_hashmap(max_entries);
+
+       // Get the elements in the hashmap, and store them in that order
+       assert(bpf_map_get_next_key(fd, NULL, &key) == 0);
+       i = 0;
+       keys[i] = key;
+       for (i = 1; next_key_valid; i++) {
+               next_key_valid = bpf_map_get_next_key(fd, &key, &next_key) == 0;
+               assert(bpf_map_lookup_elem(fd, &key, &values[i - 1]) == 0);
+               keys[i-1] = key;
+               key = next_key;
+       }
+
+       // Alloc memory for the whole table
+       buf = malloc(elem_size * max_entries);
+       assert(buf != NULL);
+
+       // Check that buf_len < elem_size returns EINVAL
+       buf_len = elem_size-1;
+       errno = 0;
+       assert(bpf_map_dump(fd, NULL, buf, &buf_len) == -1 && errno == EINVAL);
+
+       // Check that it returns the first two elements
+       errno = 0;
+       buf_len = elem_size * 2;
+       prev_key = NULL;
+       i = 0;
+       assert(bpf_map_dump(fd, prev_key, buf, &buf_len) == 0 &&
+              buf_len == 2*elem_size);
+       elem = buf;
+       assert((*(uint64_t *)elem) == keys[i] &&
+              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
+       elem = buf + elem_size;
+       i++;
+       assert((*(uint64_t *)elem) == keys[i] &&
+              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
+       i++;
+
+       /* Continue reading from map and verify buf_len only contains 1 element
+        * even though buf_len is 2 elem_size.
+        */
+       prev_key = elem;
+       assert(bpf_map_dump(fd, prev_key, buf, &buf_len) == 0 &&
+              buf_len == elem_size);
+       elem = buf;
+       assert((*(uint64_t *)elem) == keys[i] &&
+              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
+
+       // Check that there are no more entries after last_key
+       prev_key = &keys[i];
+       assert(bpf_map_dump(fd, prev_key, buf, &buf_len) == -1 &&
+              errno == ENOENT);
+
+       free(buf);
+       close(fd);
+}
+
 static void test_hashmap_zero_seed(void)
 {
        int i, first, second, old_flags;
@@ -1668,6 +1735,7 @@ static void run_all_tests(void)
        test_hashmap_percpu(0, NULL);
        test_hashmap_walk(0, NULL);
        test_hashmap_zero_seed();
+       test_hashmap_dump();
 
        test_arraymap(0, NULL);
        test_arraymap_percpu(0, NULL);
@@ -1705,11 +1773,9 @@ int main(void)
 
        map_flags = BPF_F_NO_PREALLOC;
        run_all_tests();
-
 #define CALL
 #include <map_tests/tests.h>
 #undef CALL
-
        printf("test_maps: OK, %d SKIPPED\n", skips);
        return 0;
 }
-- 
2.22.0.410.gd8fdbe21b5-goog