%%% @copyright 2012-2020 Michael Santos <michael.santos@gmail.com>

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%%% this list of conditions and the following disclaimer.
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-module(perc_prctl).

-include("perc.hrl").
-include("perc_prctl.hrl").

-export([
    arch/0, arch/1,
    define/1,
    seccomp_data/1
]).

arch() ->
    case erlang:system_info(system_architecture) of
        "x86_64" ++ _ ->
            arch(x86_64);
        "i386" ++ _ ->
            arch(i386);
        _ ->
            {error, unsupported}
    end.

% linux/audit.h
arch(x86_64) -> 16#C000003E;
arch(i386) -> 16#40000003.

define(pr_get_seccomp) -> ?PR_GET_SECCOMP;
define(pr_set_seccomp) -> ?PR_SET_SECCOMP.

% struct seccomp_data {
%     int nr;
%     __u32 arch;
%     __u64 instruction_pointer;
%     __u64 args[6];
% };
seccomp_data(#seccomp_data{
    nr = NR,
    arch = Arch,
    instruction_pointer = Ptr,
    args = Args
}) ->
    <<?INT32(NR), ?UINT32(Arch), ?UINT64(Ptr), Args/binary>>;
seccomp_data(<<?INT32(NR), ?UINT32(Arch), ?UINT64(Ptr), Args/binary>>) ->
    #seccomp_data{
        nr = NR,
        arch = Arch,
        instruction_pointer = Ptr,
        args = Args
    }.