// SPDX-License-Identifier: GPL-2.0-only
/*
 * Minimal BPF assembler
 *
 * Instead of libpcap high-level filter expressions, it can be quite
 * useful to define filters in low-level BPF assembler (that is kept
 * close to Steven McCanne and Van Jacobson's original BPF paper).
 * In particular for BPF JIT implementors, JIT security auditors, or
 * just for defining BPF expressions that contain extensions which are
 * not supported by compilers.
 *
 * How to get into it:
 *
 * 1) read Documentation/networking/filter.rst
 * 2) Run `bpf_asm [-c] <filter-prog file>` to translate into binary
 *    blob that is loadable with xt_bpf, cls_bpf et al. Note: -c will
 *    pretty print a C-like construct.
 *
 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
 */

#include <stdbool.h>
#include <stdio.h>
#include <string.h>

extern void bpf_asm_compile(FILE *fp, bool cstyle);

int main(int argc, char **argv)
{
        FILE *fp = stdin;
        bool cstyle = false;
        int i;

        for (i = 1; i < argc; i++) {
                if (!strncmp("-c", argv[i], 2)) {
                        cstyle = true;
                        continue;
                }

                fp = fopen(argv[i], "r");
                if (!fp) {
                        fp = stdin;
                        continue;
                }

                break;
        }

        bpf_asm_compile(fp, cstyle);

        return 0;
}