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erlang
2161-init-Introduce-S-flag.patch
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File 2161-init-Introduce-S-flag.patch of Package erlang
From d4e90c4d00ee517ee2803b6253639600d7c5a2a7 Mon Sep 17 00:00:00 2001 From: Johannes Christ <jc@jchri.st> Date: Tue, 4 Jul 2023 11:20:43 +0200 Subject: [PATCH] init: Introduce -S flag The flag works similarly to `-s` and `-run`, except that: - Additional command line arguments starting with a hyphen will be passed to the invoked script as well, whilst with `-s` and `-run` these arguments will be passed to the runtime system. - Command-line arguments will be passed directly to the function, without having to call `init:get_plain_arguments`. - Scripts that make use of this option only need to define a function of arity one, as passing no arguments will result in a call like `func([])` as opposed to `func()`, which would be the behaviour of the existing options. The documentation for the existing `-s` and `-run` options was updated to mention that they will not forward arguments starting with a hyphen to the specified function, to prevent surprises when using `argparse` or other option parser libraries. --- erts/doc/src/erl_cmd.xml | 11 ++++++ erts/doc/src/init.xml | 32 +++++++++++++++++ erts/preloaded/src/init.erl | 68 +++++++++++++++++++++++++------------ 3 files changed, 89 insertions(+), 22 deletions(-) diff --git a/erts/doc/src/erl_cmd.xml b/erts/doc/src/erl_cmd.xml index 8a2337c5cd..5bd565b80c 100644 --- a/erts/doc/src/erl_cmd.xml +++ b/erts/doc/src/erl_cmd.xml @@ -627,6 +627,17 @@ $ <input>erl \ slave node on a remote host; see <seeerl marker="stdlib:slave"><c>slave(3)</c></seeerl>.</p> </item> + <tag><c><![CDATA[-S Mod [Func [Arg1, Arg2, ...]]]]></c> (init + flag)</tag> + <item> + <p>Makes <c><![CDATA[init]]></c> call the specified function. + <c><![CDATA[Func]]></c> defaults to <c><![CDATA[start]]></c>. + The function is assumed to be of arity 1, taking the list + <c><![CDATA[[Arg1,Arg2,...]]]></c> as argument, or an empty list + if no arguments are passed. All further arguments occurring after + this option are passed to the specified function as strings. + See <seeerl marker="init"> <c>init(3)</c></seeerl>.</p> + </item> <tag><c><![CDATA[-run Mod [Func [Arg1, Arg2, ...]]]]></c> (init flag)</tag> <item> diff --git a/erts/doc/src/init.xml b/erts/doc/src/init.xml index 2d6b22a826..0c358ba8c7 100644 --- a/erts/doc/src/init.xml +++ b/erts/doc/src/init.xml @@ -310,6 +310,28 @@ BF</pre> <seemfa marker="#get_plain_arguments/0"> <c>get_plain_arguments/0</c></seemfa>.</p> </item> + <tag><c>-S Mod [Func [Arg1, Arg2, ...]]</c></tag> + <item> + <p>Evaluates the specified function call during system + initialization. <c>Func</c> defaults to <c>start</c>. If no + arguments are provided, the function is assumed to be of arity + 0. Otherwise it is assumed to be of arity 1, taking the list + <c>[Arg1,Arg2,...]</c> as argument. All arguments are passed + as strings. If an exception is raised, Erlang stops with an + error message.</p> + <p>Example:</p> + <pre> + % <input>erl -S httpd serve --port 8080 /var/www/html</input></pre> + <p>This starts the Erlang runtime system and evaluates + the function <c>httpd:serve(["--port", "8080", "/var/www/html"])</c>. + All arguments up to the end of the command line will be passed + to the called function.</p> + <p>The function is executed sequentially in an initialization + process, which then terminates normally and passes control to + the user. This means that a <c>-S</c> call that does not + return blocks further processing; to avoid this, use + some variant of <c>spawn</c> in such cases.</p> + </item> <tag><c>-run Mod [Func [Arg1, Arg2, ...]]</c></tag> <item> <p>Evaluates the specified function call during system @@ -333,6 +355,10 @@ foo:bar(["baz", "1", "2"]).</code> the user. This means that a <c>-run</c> call that does not return blocks further processing; to avoid this, use some variant of <c>spawn</c> in such cases.</p> + <note><p>This flag will not forward arguments beginning with + a hyphen (-) to the specified function, as these will be + interpreted as flags to the runtime. If the function uses + flags in this form, it is advised to use <c>-S</c> instead.</p></note> </item> <tag><c>-s Mod [Func [Arg1, Arg2, ...]]</c></tag> <item> @@ -359,6 +385,12 @@ foo:bar([baz, '1', '2']).</code> some variant of <c>spawn</c> in such cases.</p> <p>Because of the limited length of atoms, it is recommended to use <c>-run</c> instead.</p> + <note><p>This flag will not forward arguments beginning with + a hyphen (-) to the specified function, as these will be + interpreted as flags to the runtime. If the function uses + flags in this form, it is advised to use <c>-S</c> instead, + with the additional caveat that arguments are passed as strings + instead of atoms.</p></note> </item> </taglist> </section> diff --git a/erts/preloaded/src/init.erl b/erts/preloaded/src/init.erl index 1f7ef28085..1b9af02591 100644 --- a/erts/preloaded/src/init.erl +++ b/erts/preloaded/src/init.erl @@ -39,6 +39,7 @@ %% -pz Path+ : Add my own paths last. %% -run : Start own processes. %% -s : Start own processes. +%% -S : Start own processes and terminate further option processing. %% %% Experimental flags: %% -profile_boot : Use an 'eprof light' to profile boot sequence @@ -256,25 +257,40 @@ boot(BootArgs) -> register(init, self()), process_flag(trap_exit, true), - {Start0,Flags,Args} = parse_boot_args(BootArgs), + {Start,Flags,Args} = parse_boot_args(BootArgs), %% We don't get to profile parsing of BootArgs case b2a(get_flag(profile_boot, Flags, false)) of false -> ok; true -> debug_profile_start() end, - Start = map(fun prepare_run_args/1, Start0), boot(Start, Flags, Args). -prepare_run_args({eval, [Expr]}) -> - {eval,Expr}; -prepare_run_args({_, L=[]}) -> - bs2as(L); -prepare_run_args({_, L=[_]}) -> - bs2as(L); -prepare_run_args({s, [M,F|Args]}) -> - [b2a(M), b2a(F) | bs2as(Args)]; -prepare_run_args({run, [M,F|Args]}) -> - [b2a(M), b2a(F) | bs2ss(Args)]. +fold_eval_args([Expr]) -> Expr; +fold_eval_args(Exprs) -> Exprs. + +%% Ensure that when no arguments were explicitly passed on the command line, +%% an empty arguments list will be passed to the function to be applied. +interpolate_empty_mfa_args({M, F, []}) -> {M, F, [[]]}; +interpolate_empty_mfa_args({_M, _F, [_Args]} = MFA) -> MFA. + +-spec run_args_to_mfa([binary()]) -> {atom(), atom(), [] | [nonempty_list(binary())]} | no_return(). +run_args_to_mfa([]) -> + erlang:display_string( + "Error! The -S option must be followed by at least a module to start, such as " + "`-S Module` or `-S Module Function` to start with a function.\r\n\r\n" + ), + erlang:error(undef); +run_args_to_mfa([M]) -> {b2a(M), start, []}; +run_args_to_mfa([M, F]) -> {b2a(M), b2a(F), []}; +run_args_to_mfa([M, F | A]) -> {b2a(M), b2a(F), [A]}. + +%% Convert -run / -s / -S arguments to startup instructions, such that +%% no instructions are emitted if no arguments follow the flag, otherwise, +%% an `{apply, M, F, A}' instruction is. +run_args_to_start_instructions([], _Converter) -> []; +run_args_to_start_instructions(Args, Converter) -> + {M, F, A} = run_args_to_mfa(Args), + [{apply, M, F, map(Converter, A)}]. b2a(Bin) when is_binary(Bin) -> list_to_atom(b2s(Bin)); @@ -1201,15 +1217,10 @@ start_it({eval,Bin}) -> erlang:display_string(binary_to_list(iolist_to_binary(Message))), erlang:raise(E,R,ST) end; -start_it([M|FA]) -> +start_it({apply,M,F,Args}) -> case code:ensure_loaded(M) of {module, M} -> - case FA of - [] -> M:start(); - [F] -> M:F(); - [F|Args] -> M:F(Args) % Args is a list - end; - + apply(M, F, Args); {error, Reason} -> Message = [explain_ensure_loaded_error(M, Reason), <<"\r\n\r\n">>], erlang:display_string(binary_to_list(iolist_to_binary(Message))), @@ -1288,6 +1299,7 @@ timer(T) -> %% -------------------------------------------------------- %% Parse the command line arguments and extract things to start, flags %% and other arguments. We keep the relative of the groups. +%% Returns a triplet in the form `{Start, Flags, Args}': %% -------------------------------------------------------- parse_boot_args(Args) -> @@ -1299,13 +1311,23 @@ parse_boot_args([B|Bs], Ss, Fs, As) -> {reverse(Ss),reverse(Fs),lists:reverse(As, Bs)}; % BIF start_arg -> {S,Rest} = get_args(Bs, []), - parse_boot_args(Rest, [{s, S}|Ss], Fs, As); + Instructions = run_args_to_start_instructions(S, fun bs2as/1), + parse_boot_args(Rest, Instructions ++ Ss, Fs, As); start_arg2 -> {S,Rest} = get_args(Bs, []), - parse_boot_args(Rest, [{run, S}|Ss], Fs, As); + Instructions = run_args_to_start_instructions(S, fun bs2ss/1), + parse_boot_args(Rest, Instructions ++ Ss, Fs, As); + ending_start_arg -> + {S,Rest} = get_args(Bs, []), + %% Forward any additional arguments to the function we are calling, + %% such that no init:get_plain_arguments is needed by it later. + MFA = run_args_to_mfa(S ++ Rest), + {M, F, A} = interpolate_empty_mfa_args(MFA), + StartersWithThis = [{apply, M, F, map(fun bs2ss/1, A)} | Ss], + {reverse(StartersWithThis),reverse(Fs),[]}; eval_arg -> {Expr,Rest} = get_args(Bs, []), - parse_boot_args(Rest, [{eval, Expr}|Ss], Fs, As); + parse_boot_args(Rest, [{eval, fold_eval_args(Expr)} | Ss], Fs, As); {flag,A} -> {F,Rest} = get_args(Bs, []), Fl = {A,F}, @@ -1321,6 +1343,7 @@ parse_boot_args([], Start, Flags, Args) -> check(<<"-extra">>) -> start_extra_arg; check(<<"-s">>) -> start_arg; check(<<"-run">>) -> start_arg2; +check(<<"-S">>) -> ending_start_arg; check(<<"-eval">>) -> eval_arg; check(<<"--">>) -> end_args; check(<<"-",Flag/binary>>) -> {flag,b2a(Flag)}; @@ -1333,6 +1356,7 @@ get_args([B|Bs], As) -> start_arg2 -> {reverse(As), [B|Bs]}; eval_arg -> {reverse(As), [B|Bs]}; end_args -> {reverse(As), Bs}; + ending_start_arg -> {reverse(As), [B|Bs]}; {flag,_} -> {reverse(As), [B|Bs]}; arg -> get_args(Bs, [B|As]) -- 2.35.3
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