1 files changed, 54 insertions, 0 deletions
diff --git a/src/shared/bpf-compat.h b/src/shared/bpf-compat.h
new file mode 100644
index 0000000..04ade82
--- /dev/null
+++ b/src/shared/bpf-compat.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+/* libbpf has been moving quickly.
+ * They added new symbols in the 0.x versions and shortly after removed
+ * deprecated symbols in 1.0.
+ * We only need bpf_map_create and libbpf_probe_bpf_prog_type so we work
+ * around the incompatibility here by:
+ *  - declaring both symbols, and looking for either depending on the libbpf
+ *    so version we found
+ *  - having helpers that automatically use the appropriate version behind the
+ *    new API for easy cleanup later
+ *
+ * The advantage of doing this instead of only looking for the symbols declared at
+ * compile time is that we can then load either the old or the new symbols at runtime
+ * regardless of the version we were compiled with */
+
+
+/* declare the struct for libbpf <= 0.6.0 -- it causes no harm on newer versions */
+struct bpf_map_create_opts;
+
+/* new symbols available from 0.7.0.
+ * We need the symbols here:
+ *  - after bpf_map_create_opts struct has been defined for older libbpf
+ *  - before the compat static inline helpers that use them.
+ * When removing this file move these back to bpf-dlopen.h */
+extern int (*sym_bpf_map_create)(enum bpf_map_type,  const char *, __u32, __u32, __u32, const struct bpf_map_create_opts *);
+extern bool (*sym_libbpf_probe_bpf_prog_type)(enum bpf_prog_type, const void *);
+
+/* compat symbols removed in libbpf 1.0 */
+extern int (*sym_bpf_create_map)(enum bpf_map_type, int key_size, int value_size, int max_entries, __u32 map_flags);
+extern bool (*sym_bpf_probe_prog_type)(enum bpf_prog_type, __u32);
+
+/* helpers to use the available variant behind new API */
+static inline int compat_bpf_map_create(enum bpf_map_type map_type,
+                const char *map_name,
+                __u32 key_size,
+                __u32 value_size,
+                __u32 max_entries,
+                const struct bpf_map_create_opts *opts) {
+        if (sym_bpf_map_create)
+                return sym_bpf_map_create(map_type, map_name, key_size,
+                                          value_size, max_entries, opts);
+
+        return sym_bpf_create_map(map_type, key_size, value_size, max_entries,
+                                  0 /* opts->map_flags, but opts is always NULL for us so skip build dependency on the type */);
+}
+
+static inline int compat_libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts) {
+        if (sym_libbpf_probe_bpf_prog_type)
+                return sym_libbpf_probe_bpf_prog_type(prog_type, opts);
+
+        return sym_bpf_probe_prog_type(prog_type, 0);
+}