BpfMap: introduce resetMap(type, entries, flags)

to replace less safe uses of BpfMap.reset(create(type, keysize, valuesize, entries, flags))

Meant to be used in tests only.

Bug: 235286176
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I869f1f935bcf5d00702c42bc46d6094ea552addc
(cherry picked from commit d2dec08c73b2bc1dd2a3969ccb504a59e9cb223f)
Merged-In: I869f1f935bcf5d00702c42bc46d6094ea552addc

1 files changed, 17 insertions, 0 deletions

diff --git a/common/native/bpf_headers/include/bpf/BpfMap.h b/common/native/bpf_headers/include/bpf/BpfMap.h
index bdffc0f0..d07d6104 100644
--- a/common/native/bpf_headers/include/bpf/BpfMap.h
+++ b/common/native/bpf_headers/include/bpf/BpfMap.h
@@ -102,6 +102,23 @@ class BpfMap {
     // Function that tries to get map from a pinned path.
     base::Result<void> init(const char* path);
 
+#ifdef TEST_BPF_MAP
+    // due to Android SELinux limitations which prevent map creation by anyone besides the bpfloader
+    // this should only ever be used by test code, it is equivalent to:
+    //   .reset(createMap(type, keysize, valuesize, max_entries, map_flags)
+    // TODO: derive map_flags from BpfMap vs BpfMapRO
+    base::Result<void> resetMap(bpf_map_type map_type, uint32_t max_entries, uint32_t map_flags = 0) {
+        int map_fd = createMap(map_type, sizeof(Key), sizeof(Value), max_entries, map_flags);
+        if (map_fd < 0) {
+             auto err = ErrnoErrorf("Unable to create map.");
+             mMapFd.reset();
+             return err;
+        };
+        mMapFd.reset(map_fd);
+        return {};
+    }
+#endif
+
     // Iterate through the map and handle each key retrieved based on the filter
     // without modification of map content.
     base::Result<void> iterate(