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I having crypto_server problems:
=CRASH REPORT==== 23-Jul-2019::10:20:17 ===
crasher:
pid: <0.49.0>
registered_name: crypto_server
exception exit: {einval,
[{erlang,open_port,
[{spawn,
"crypto_drv elibcrypto
c:/myapp/lib/crypto-1.5.3/priv/lib/win32/elibcrypto"},
[]]},
{crypto_server,open_ports,2},
{gen_server,init_it,6},
{proc_lib,init_p_do_apply,3}]}
in function gen_server:init_it/6
initial call: crypto_server:init/1
ancestors: [crypto_sup,<0.47.0>]
messages: []
links: [<0.48.0>]
dictionary: []
trap_exit: true
status: running
heap_size: 610
stack_size: 23
reductions: 425
neighbours:
and the application doesn't start:
Kernel pid terminated (application_controller)
({application_start_failure,crypto,{shutdown,{crypto_app,start,[normal,[]]}}})
einval is a is a linux error that means invalid argument. Erlang returns quite a few of those types of errors back to the user. If you need a handy lookup table, you check look here.
I'm guessing the version of OpenSSL you have installed is incompatible with the old version of erlang. You could always start a trace on the init and see what's happening in during all of the message passing. You'll have to add the trace to your start up code before starting up the crypto lib. Here's a basic primer on tracing.
You must start the tracer program:
dbg:tracer().
Then you need to identify which process(es) you'd like to trace. The simple version is to watch all processes. (c is short for [call], which means trace all function calls.)
dbg:p(all, c).
Finally, say what function calls you're interested in tracing by Module; Module and Function; or Module, Function, and Arity. You can use '_' in place of any of them.
dbg:tpl(Module, cx).
dbg:tpl(Module, Function, cx).
dbg:tpl(Module, Function, Arity, cx).
You can turn tracing off with a similar function that disables tracing for all functions; by Module; by Module and Function; or by Module, Function, and Arity. Again, you can use '_' in place of any of them.
dbg:ctpl().
dbg:ctpl(Module).
dbg:ctpl(Module, Function).
dbg:ctpl(Module, Function, Arity).
A simple, working example that you can copy/paste into a fresh repl:
dbg:tracer().
dbg:p(all, c).
dbg:tpl(file, open, cx).
file:open("idontexist", []).
dbg:ctpl(file).
file:open("idontexist", []).
That should produce something like:
1> dbg:tracer().
{ok,<0.299.0>}
2> dbg:p(all, c).
{ok,[{matched,engine#ryan,215}]}
3> dbg:tpl(file, open, cx).
{ok,[{matched,node#sam,1},{saved,cx}]}
4> file:open("idontexist", []).
(<0.50.0>) call file:open("idontexist",[]) ({erl_eval,do_apply,6})
(<0.50.0>) returned from file:open/2 -> {error,enoent}
{error,enoent}
5> dbg:ctpl(file).
{ok,[{matched,node#sam,95}]}
6> file:open("idontexist", []).
{error,enoent}
7>
Alright, what am I doing wrong here. I'm trying the simple example of embedded YAWs from http://yaws.hyber.org/embed.yaws but with an appmod. I've added the my_app.erl file and compiled it. It works if not in embedded YAWs so I think it is specific to embedded.
-module(ybed).
-compile(export_all).
start() ->
{ok, spawn(?MODULE, run, [])}.
run() ->
Id = "embedded",
GconfList = [{ebin_dir, ["/Users/someuser/yawsembedded/ebin"]}],
Docroot = "/Users/someuser/yawstest",
SconfList = [{port, 8888},
{listen, {0,0,0,0}},
{docroot, Docroot},
{appmods, [{"/", my_app}]}
],
{ok, SCList, GC, ChildSpecs} =
yaws_api:embedded_start_conf(Docroot, SconfList, GconfList),
[supervisor:start_child(ybed_sup, Ch) || Ch <- ChildSpecs],
yaws_api:setconf(GC, SCList),
{ok, self()}.
Getting this Error:
ERROR erlang code threw an uncaught exception:
File: appmod:0
Class: error
Exception: undef
Req: {http_request,'GET',{abs_path,"/demo"},{1,1}}
Stack: [{my_app,out,
[{arg,#Port<0.2721>,
{{127,0,0,1},63720},
{headers,"keep-alive",
"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
"0.0.0.0:8888",undefined,undefined,undefined,undefined,
undefined,undefined,undefined,
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:40.0) Gecko/20100101 Firefox/40.0",
undefined,[],undefined,undefined,undefined,undefined,
undefined,undefined,undefined,undefined,
[{http_header,0,"Dnt",undefined,"1"},
{http_header,10,'Accept-Encoding',undefined,
"gzip, deflate"},
{http_header,11,'Accept-Language',undefined,"null"}]},
{http_request,'GET',{abs_path,"/demo"},{1,1}},
{http_request,'GET',{abs_path,"/demo"},{1,1}},
undefined,"/demo",undefined,undefined,
"/Users/someuser/yawstest","/",
"/Users/someuser/yawstest/demo",undefined,undefined,
<0.63.0>,[],"/","/",undefined}],
[]},
{yaws_server,deliver_dyn_part,8,
[{file,"yaws_server.erl"},{line,2818}]},
{yaws_server,aloop,4,[{file,"yaws_server.erl"},{line,1232}]},
{yaws_server,acceptor0,2,[{file,"yaws_server.erl"},{line,1068}]},
{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,239}]}]
The stack trace shows that your my_app:out/1 function is getting called, but you're getting an undef exception. This is occurring because the runtime can't find the my_app:out/1 function, which means either it can't find the module or the module exists but does not export an out/1 function. For example, I was able to duplicate the error using the example code by not providing a my_app module.
First, make sure your my_app.erl file exports an out/1 function. Here's a trivial one that just returns a 405 error for all requests:
-module(my_app).
-export([out/1]).
out(_Arg) ->
{status, 405}.
Compile your my_app.erl file and put the compiled my_app.beam file either in a load path already known to the Erlang runtime, or in a directory you add to the load path. In your code it appears you're trying the latter approach, since you're specifically adding an ebin_dir with this Yaws global configuration directive:
GconfList = [{ebin_dir, ["/Users/someuser/yawsembedded/ebin"]}],
You need to verify that the /Users/someuser/yawsembedded/ebin directory exists, and that the compiled my_app.beam file is located there.
I am trying out a cowboy example provided by this github repository:
https://github.com/ninenines/cowboy/tree/master/examples/web_server
I build the release successfully using erlang.mk and run the following command, which opens the Erlang shell in my linux terminal:
$ ./_rel/web_server_example/bin/web_server_example console
But when I then open http://localhost:8080 in my web-browser, I get the following error report:
=ERROR REPORT==== 26-Nov-2014::14:33:48 === Error in process <0.166.0> on node 'web_server_example#127.0.0.1' with exit value:
{function_clause,[{cowboy_req,ensure_response,[{ok,{http_req,#Port<0.454>,ranch_tcp,keepalive,<0.166.0>,<<3
bytes>>,'HTTP/1.1',{{127,0,0,1},57150},<<9 bytes>>,undefined,8080,<<1
byte>>,undefined,<<0 bytes>>,undefined,undefined,[{<<4 bytes>>,<<14
bytes>>},{<<10 bytes>>,<<10 bytes>>},{<<13 bytes>>,<<9 bytes>>},{<<6
bytes>>,<<74 bytes>>},{<<10 bytes>>,<<104 bytes>>},{<<15 bytes>>,<<19
bytes>>},{<<15 bytes>>,<<35 bytes>>}],[{<<10 bytes>>,[<<10
bytes>>]}],undefined,[],waiting,<<0 bytes>>,undefined...
=ERROR REPORT==== 26-Nov-2014::14:33:48 === Ranch listener http had connection process started with cowboy_protocol:start_link/4 at
<0.166.0> exit with reason:
{function_clause,[{cowboy_req,ensure_response,[{ok,{http_req,#Port<0.454>,ranch_tcp,keepalive,<0.166.0>,<<"GET">>,'HTTP/1.1',{{127,0,0,1},57150},<<"localhost">>,undefined,8080,<<"/">>,undefined,<<>>,undefined,undefined,[{<<"host">>,<<"localhost:8080">>},{<<"connection">>,<<"keep-alive">>},{<<"cache-control">>,<<"max-age=0">>},{<<"accept">>,<<"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8">>},{<<"user-agent">>,<<"Mozilla/5.0
(X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko)
Chrome/39.0.2171.65 Safari/537.36">>},{<<"accept-encoding">>,<<"gzip,
deflate,
sdch">>},{<<"accept-language">>,<<"sv-SE,sv;q=0.8,en-US;q=0.6,en;q=0.4">>}],[{<<"connection">>,[<<"keep-alive">>]}],undefined,[],waiting,<<>>,undefined,false,done,[],<<>>,undefined}},204],[{file,"src/cowboy_req.erl"},{line,1009}]},{cowboy_protocol,next_request,3,[{file,"src/cowboy_protocol.erl"},{line,454}]}]}
This is "src/cowboy_protocol.erl" around line 454:
-spec next_request(cowboy_req:req(), #state{}, any()) -> ok.
next_request(Req, State=#state{req_keepalive=Keepalive, timeout=Timeout},
HandlerRes) ->
cowboy_req:ensure_response(Req, 204),
%% If we are going to close the connection,
%% we do not want to attempt to skip the body.
case cowboy_req:get(connection, Req) of
close ->
terminate(State);
_ ->
%% Skip the body if it is reasonably sized. Close otherwise.
Buffer = case cowboy_req:body(Req) of
{ok, _, Req2} -> cowboy_req:get(buffer, Req2);
_ -> close
end,
%% Flush the resp_sent message before moving on.
if HandlerRes =:= ok, Buffer =/= close ->
receive {cowboy_req, resp_sent} -> ok after 0 -> ok end,
?MODULE:parse_request(Buffer,
State#state{req_keepalive=Keepalive + 1,
until=until(Timeout)}, 0);
true ->
terminate(State)
end
end.
And the webb_server_app.erl file:
%% Feel free to use, reuse and abuse the code in this file.
%% #private
-module(web_server_app).
-behaviour(application).
%% API.
-export([start/2]).
-export([stop/1]).
%% API.
start(_Type, _Args) ->
Dispatch = cowboy_router:compile([
{'_', [
{"/[...]", cowboy_static, {priv_dir, web_server, "", [
{mimetypes, cow_mimetypes, all},
{dir_handler, directory_handler}
]}}
]}
]),
{ok, _} = cowboy:start_http(http, 100, [{port, 8080}], [
{env, [{dispatch, Dispatch}]},
{middlewares, [cowboy_router, directory_lister, cowboy_handler]}
]),
web_server_sup:start_link().
stop(_State) ->
ok.
Does anyone have any suggestion as to what is exactly causing this problem, and how to solve it? Thanks.
EDIT:
I can confirm that the fault was in the Erlang OTP version R16B02 in my case. Changing to the latest Erlang release (17.3), as well as resolving missing file dependencies that arose during the configuration stage (with the solutions in the following link):
https://sites.google.com/site/comptekkia/erlang/how-to-install-erlang-on-ubuntu-10-10
Solved the problem(s). The web_server example runs without error now.
The error says function clause, so the arguments to cowboy_req:ensure_response/2 must be wrong. And indeed they are, because first argument is {ok, Request} instead of Request. You have to trace back, which function called next_request/3 with bad argument, because it clearly should be called without ok.
Probably somewhere at the end, you will find something like:
Req = some_function(...)
And you will need to change it to:
{ok, Req} = some_function(...)
Good luck and happy bug hunting :D
UPDATE: I just cloned the repo and it works fine for me. I got the directory listing, so it is not bug in cowboy, but somewhere in user code.
I'm trying to call a function (from an external module) in erlang. both beam files are located in the same directory.
-module(drop2).
-export([fall_velocity/1]).
fall_velocity(Distance) -> math:sqrt(2 * 9.8 * Distance).
Then I'm calling
-module(ask).
-export([term/0]).
term() ->
Input = io:read("Enter {x,distance} ? >>"),
Term = element(2,Input),
drop2:fall_velocity(Term).
it gives the following error.I tested individual modules for errors. it is compiling with out any errors or warning.
Eshell V5.10.2 (abort with ^G)
1> ask:term().
Enter {x,distance} ? >>{test,10}.
** exception error: an error occurred when evaluating an arithmetic expression
in function drop2:fall_velocity/1 (drop2.erl, line 3)
Not sure why it is throwing arithmetic expression error .
You could read the documentation to figure out that the result is {ok, Term}. You could try the io:read/1 function in the console, then you'd see following:
1> io:read("Enter > ").
Enter > {test, 42}.
{ok,{test,42}}
2>
That means that you need to deconstruct the result of io:read/1 differently, for example like this:
-module(ask).
-export([term/0]).
term() ->
{ok, {_, Distance}} = io:read("Enter {x, distance} > "),
drop2:fall_velocity(Distance).
I'm working on an erlang program and getting a strange runtime error. Any idea why? Thanks!
The errors are (after compiling the program successfully):
8> PID = spawn(planner,start,[]).
** exception error: no match of right hand side value <0.65.0>
9>
This is the program:
-module(planner).
-export([start/0]).
start() ->
loop([],[]).
loop(ContactsList,EventsList) ->
receive
{contact, Last, First, Number} ->
loop([{Last,First,Number}|ContactsList],EventsList);
{event, Date, Time, What} ->
loop([{Date,Time,What}|ContactsList],EventsList);
print_contacts ->
NewList=lists:sort(ContactsList),
lists:foreach(fun(Elem)->io:format("~p~n", [Elem]) end, NewList),
loop(ContactsList,EventsList);
print_events ->
NewList=lists:sort(EventsList),
lists:foreach(fun(Elem)->io:format("~p~n", [Elem]) end, NewList),
loop(ContactsList,EventsList);
exit ->
io:format("Exiting.~n");
_ ->
io:format("Dude, I don't even know what you're talking about.~n"),
loop(ContactsList,EventsList)
end.
The variable PID is probably set to something else but <0.65.0> from an earlier line you entered in the shell:
5> PID = spawn(...).
<0.42.0>
8> PID = spawn(...).
** exception error: no match of right hand side value <0.65.0>
This effectively makes the line which generates the error something like
8> <0.42.0> = <0.65.0>.
which will result in a "no match" error.
More obvious illustration of the issue:
1> X = 1.
1
2> X = 2.
** exception error: no match of right hand side value 2
As to solving your issue: You probably want to run f(PID) to have the shell forget just the PID variable, or even f() to have the shell forget ALL variables.