%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2017-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(group_history).
-export([load/0, add/1]).
%% Make a minimal size that should encompass set of lines and then make
%% a file rotation for N files of this size.
-define(DEFAULT_HISTORY_FILE, "erlang-shell-log").
-define(MAX_HISTORY_FILES, 10).
-define(DEFAULT_SIZE, 1024*512). % 512 kb total default
-define(DEFAULT_STATUS, disabled).
-define(MIN_HISTORY_SIZE, (50*1024)). % 50 kb, in bytes
-define(DEFAULT_DROP, []).
-define(DISK_LOG_FORMAT, internal). % since we want repairs
-define(LOG_NAME, '$#group_history').
-define(VSN, {0,1,0}).
%%%%%%%%%%%%%%
%%% PUBLIC %%%
%%%%%%%%%%%%%%
%% @doc Loads the shell history from memory. This function should only be
%% called from group:server/3 to inject itself in the previous commands
%% stack.
-spec load() -> [string()].
load() ->
wait_for_kernel_safe_sup(),
case history_status() of
enabled ->
case open_log() of
{ok, ?LOG_NAME} ->
read_full_log(?LOG_NAME);
{repaired, ?LOG_NAME, {recovered, Good}, {badbytes, Bad}} ->
report_repairs(?LOG_NAME, Good, Bad),
read_full_log(?LOG_NAME);
{error, {need_repair, _FileName}} ->
repair_log(?LOG_NAME);
{error, {arg_mismatch, repair, true, false}} ->
repair_log(?LOG_NAME);
{error, {name_already_open, _}} ->
show_rename_warning(),
read_full_log(?LOG_NAME);
{error, {size_mismatch, Current, New}} ->
show_size_warning(Current, New),
resize_log(?LOG_NAME, Current, New),
load();
{error, {invalid_header, {vsn, Version}}} ->
upgrade_version(?LOG_NAME, Version),
load();
{error, Reason} ->
handle_open_error(Reason),
disable_history(),
[]
end;
_ ->
[]
end.
%% @doc adds a log line to the erlang history log, if configured to do so.
-spec add(iodata()) -> ok.
add(Line) -> add(Line, history_status()).
add(Line, enabled) ->
case lists:member(Line, to_drop()) of
false ->
case disk_log:log(?LOG_NAME, Line) of
ok ->
ok;
{error, no_such_log} ->
_ = open_log(), % a wild attempt we hope works!
disk_log:log(?LOG_NAME, Line);
{error, _Other} ->
% just ignore, we're too late
ok
end;
true ->
ok
end;
add(_Line, disabled) ->
ok.
%%%%%%%%%%%%%%%
%%% PRIVATE %%%
%%%%%%%%%%%%%%%
%% Because loading the shell happens really damn early, processes we depend on
%% might not be there yet. Luckily, the load function is called from the shell
%% after a new process has been spawned, so we can block in here
wait_for_kernel_safe_sup() ->
case whereis(kernel_safe_sup) of
undefined ->
timer:sleep(50),
wait_for_kernel_safe_sup();
_ ->
ok
end.
%% Repair the log out of band
repair_log(Name) ->
Opts = lists:keydelete(size, 1, log_options()),
case disk_log:open(Opts) of
{repaired, ?LOG_NAME, {recovered, Good}, {badbytes, Bad}} ->
report_repairs(?LOG_NAME, Good, Bad);
_ ->
ok
end,
_ = disk_log:close(Name),
load().
%% Return whether the shell history is enabled or not
-spec history_status() -> enabled | disabled.
history_status() ->
case is_user() orelse application:get_env(kernel, shell_history) of
true -> disabled; % don't run for user proc
{ok, enabled} -> enabled;
undefined -> ?DEFAULT_STATUS;
_ -> disabled
end.
%% Return whether the user process is running this
-spec is_user() -> boolean().
is_user() ->
case process_info(self(), registered_name) of
{registered_name, user} -> true;
_ -> false
end.
%% Open a disk_log file while ensuring the required path is there.
open_log() ->
Opts = log_options(),
_ = ensure_path(Opts),
disk_log:open(Opts).
%% Return logger options
log_options() ->
Path = find_path(),
File = filename:join([Path, ?DEFAULT_HISTORY_FILE]),
Size = find_wrap_values(),
[{name, ?LOG_NAME},
{file, File},
{repair, true},
{format, internal},
{type, wrap},
{size, Size},
{distributed, []},
{notify, false},
{head, {vsn, ?VSN}},
{quiet, true},
{mode, read_write}].
-spec ensure_path([{file, string()} | {atom(), _}, ...]) -> ok | {error, term()}.
ensure_path(Opts) ->
{file, Path} = lists:keyfind(file, 1, Opts),
filelib:ensure_dir(Path).
%% @private read the logs from an already open file. Treat closed files
%% as wrong and returns an empty list to avoid crash loops in the shell.
-spec read_full_log(term()) -> [string()].
read_full_log(Name) ->
case disk_log:chunk(Name, start) of
{error, no_such_log} ->
show_unexpected_close_warning(),
[];
eof ->
[];
{Cont, Logs} ->
lists:reverse(maybe_drop_header(Logs) ++ read_full_log(Name, Cont))
end.
read_full_log(Name, Cont) ->
case disk_log:chunk(Name, Cont) of
{error, no_such_log} ->
show_unexpected_close_warning(),
[];
eof ->
[];
{NextCont, Logs} ->
maybe_drop_header(Logs) ++ read_full_log(Name, NextCont)
end.
maybe_drop_header([{vsn, _} | Rest]) -> Rest;
maybe_drop_header(Logs) -> Logs.
-spec handle_open_error(_) -> ok.
handle_open_error({arg_mismatch, OptName, CurrentVal, NewVal}) ->
show('$#erlang-history-arg-mismatch',
"Log file argument ~p changed value from ~p to ~p "
"and cannot be automatically updated. Please clear the "
"history files and try again.~n",
[OptName, CurrentVal, NewVal]);
handle_open_error({not_a_log_file, FileName}) ->
show_invalid_file_warning(FileName);
handle_open_error({invalid_index_file, FileName}) ->
show_invalid_file_warning(FileName);
handle_open_error({invalid_header, Term}) ->
show('$#erlang-history-invalid-header',
"Shell history expects to be able to use the log files "
"which currently have unknown headers (~p) and may belong to "
"another mechanism. History logging will be "
"disabled.~n",
[Term]);
handle_open_error({file_error, FileName, Reason}) ->
show('$#erlang-history-file-error',
"Error handling File ~ts. Reason: ~p~n"
"History logging will be disabled.~n",
[FileName, Reason]);
handle_open_error(Err) ->
show_unexpected_warning({disk_log, open, 1}, Err).
find_wrap_values() ->
ConfSize = case application:get_env(kernel, shell_history_file_bytes) of
undefined -> ?DEFAULT_SIZE;
{ok, S} -> S
end,
SizePerFile = max(?MIN_HISTORY_SIZE, ConfSize div ?MAX_HISTORY_FILES),
FileCount = if SizePerFile > ?MIN_HISTORY_SIZE ->
?MAX_HISTORY_FILES
; SizePerFile =< ?MIN_HISTORY_SIZE ->
max(1, ConfSize div SizePerFile)
end,
{SizePerFile, FileCount}.
report_repairs(_, _, 0) ->
%% just a regular close repair
ok;
report_repairs(_, Good, Bad) ->
show('$#erlang-history-report-repairs',
"The shell history log file was corrupted and was repaired. "
"~p bytes were recovered and ~p were lost.~n", [Good, Bad]).
resize_log(Name, _OldSize, NewSize) ->
show('$#erlang-history-resize-attempt',
"Attempting to resize the log history file to ~p...", [NewSize]),
Opts = lists:keydelete(size, 1, log_options()),
_ = case disk_log:open(Opts) of
{error, {need_repair, _}} ->
_ = repair_log(Name),
disk_log:open(Opts);
_ ->
ok
end,
case disk_log:change_size(Name, NewSize) of
ok ->
show('$#erlang-history-resize-result',
"ok~n", []);
{error, {new_size_too_small, _, _}} ->
show('$#erlang-history-resize-result',
"failed (new size is too small)~n", []),
disable_history();
{error, Reason} ->
show('$#erlang-history-resize-result',
"failed (~p)~n", [Reason]),
disable_history()
end.
upgrade_version(_Name, Unsupported) ->
%% We only know of one version and can't support a newer one
show('$#erlang-history-upgrade',
"The version for the shell logs found on disk (~p) is "
"not supported by the current version (~p)~n",
[Unsupported, ?VSN]),
disable_history().
disable_history() ->
show('$#erlang-history-disable', "Disabling shell history logging.~n", []),
application:set_env(kernel, shell_history, force_disabled).
find_path() ->
case application:get_env(kernel, shell_history_path) of
undefined -> filename:basedir(user_cache, "erlang-history");
{ok, Path} -> Path
end.
to_drop() ->
case application:get_env(kernel, shell_history_drop) of
undefined ->
application:set_env(kernel, shell_history_drop, ?DEFAULT_DROP),
?DEFAULT_DROP;
{ok, V} when is_list(V) -> [Ln++"\n" || Ln <- V];
{ok, _} -> ?DEFAULT_DROP
end.
%%%%%%%%%%%%%%%%%%%%%%%%
%%% Output functions %%%
%%%%%%%%%%%%%%%%%%%%%%%%
show_rename_warning() ->
show('$#erlang-history-rename-warn',
"A history file with a different path has already "
"been started for the shell of this node. The old "
"name will keep being used for this session.~n",
[]).
show_invalid_file_warning(FileName) ->
show('$#erlang-history-invalid-file',
"Shell history expects to be able to use the file ~ts "
"which currently exists and is not a file usable for "
"history logging purposes. History logging will be "
"disabled.~n", [FileName]).
show_unexpected_warning({M,F,A}, Term) ->
show('$#erlang-history-unexpected-return',
"unexpected return value from ~p:~p/~p: ~p~n"
"shell history will be disabled for this session.~n",
[M,F,A,Term]).
show_unexpected_close_warning() ->
show('$#erlang-history-unexpected-close',
"The shell log file has mysteriousy closed. Ignoring "
"currently unread history.~n", []).
show_size_warning(_Current, _New) ->
show('$#erlang-history-size',
"The configured log history file size is different from "
"the size of the log file on disk.~n", []).
show(Key, Format, Args) ->
case get(Key) of
undefined ->
io:format(standard_error, Format, Args),
put(Key, true),
ok;
true ->
ok
end.
