Add abstraction model for BPF programs

This object takes a number of bpf_insn members and wraps them together with
the in-kernel reference id. Will be needed by the firewall code.

src/basic/bpf-program.h

@@ -0,0 +1,55 @@
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Daniel Mack
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+
+  [Except for the stuff copy/pasted from the kernel sources, see below]
+***/
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <sys/syscall.h>
+
+#include "list.h"
+#include "macro.h"
+
+typedef struct BPFProgram BPFProgram;
+
+struct BPFProgram {
+        int kernel_fd;
+        uint32_t prog_type;
+
+        size_t n_instructions;
+        size_t allocated;
+        struct bpf_insn *instructions;
+};
+
+int bpf_program_new(uint32_t prog_type, BPFProgram **ret);
+BPFProgram *bpf_program_unref(BPFProgram *p);
+
+int bpf_program_add_instructions(BPFProgram *p, const struct bpf_insn *insn, size_t count);
+int bpf_program_load_kernel(BPFProgram *p, char *log_buf, size_t log_size);
+
+int bpf_program_cgroup_attach(BPFProgram *p, int type, const char *path);
+int bpf_program_cgroup_detach(int type, const char *path);
+
+int bpf_map_new(enum bpf_map_type type, size_t key_size, size_t value_size, size_t max_entries, uint32_t flags);
+int bpf_map_update_element(int fd, const void *key, void *value);
+int bpf_map_lookup_element(int fd, const void *key, void *value);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(BPFProgram*, bpf_program_unref);