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authorSteve Vinoski <[email protected]>2011-02-22 18:07:57 -0500
committerSverker Eriksson <[email protected]>2011-03-24 16:45:50 +0100
commitb02f03c979cda37e43828cd6e1787649f1d8ca8c (patch)
tree6ebe11e92b89c6a78830db053a14f0f1a5edb63a /erts/emulator/test
parentd9932cbb82954532fb39ffaa05cde74a6ec8869c (diff)
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add support for checking if an ERL_NIF_TERM is an exception
Add the enif_is_exception function to allow callers to determine whether an ERL_NIF_TERM represents an exception. (Currently the only supported exception is badarg since only enif_make_badarg exists, but this will likely be expanded in future releases.) This allows NIF code to call other NIF functions that return ERL_NIF_TERM and properly check to see if the returned terms are exceptions. Without the enif_is_exception function, developers have to create their own means of checking whether a function creates an exception, such as returning boolean success/failure indicators or some other special value indicating that an exception is in effect. The declaration of enif_is_exception in erl_nif_api_funcs.h respects the order of declarations required to keep compatibility on Windows. Add a new test to verify the operation of enif_is_exception. Modify the erl_nif man page to add a description of enif_is_exception and also to clarify the requirements of calling the enif_make_badarg function. If code calls enif_make_badarg, the env passed in gets set with exception information and so the return value of the calling function MUST be the badarg term returned from enif_make_badarg. Also clarify that the result of enif_make_badarg may be passed only to enif_is_exception and not to any other NIF API functions.
Diffstat (limited to 'erts/emulator/test')
-rw-r--r--erts/emulator/test/nif_SUITE.erl10
-rw-r--r--erts/emulator/test/nif_SUITE_data/nif_SUITE.c18
2 files changed, 27 insertions, 1 deletions
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index b79c30d8d9..91d695d979 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -1121,7 +1121,14 @@ is_checks(Config) when is_list(Config) ->
?line ensure_lib_loaded(Config, 1),
?line ok = check_is(hejsan, <<19,98>>, make_ref(), ok, fun() -> ok end,
self(), hd(erlang:ports()), [], [1,9,9,8],
- {hejsan, "hejsan", [$h,"ejs",<<"an">>]}).
+ {hejsan, "hejsan", [$h,"ejs",<<"an">>]}),
+ try
+ ?line error = check_is_exception(),
+ ?line throw(expected_badarg)
+ catch
+ error:badarg ->
+ ?line ok
+ end.
get_length(doc) -> ["Test all enif_get_length functions"];
get_length(Config) when is_list(Config) ->
@@ -1245,6 +1252,7 @@ release_resource(_) -> ?nif_stub.
last_resource_dtor_call() -> ?nif_stub.
make_new_resource(_,_) -> ?nif_stub.
check_is(_,_,_,_,_,_,_,_,_,_) -> ?nif_stub.
+check_is_exception() -> ?nif_stub.
length_test(_,_,_,_,_) -> ?nif_stub.
make_atoms() -> ?nif_stub.
make_strings() -> ?nif_stub.
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 8489124966..dc047394b5 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -802,6 +802,23 @@ static ERL_NIF_TERM check_is(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]
}
/*
+ * no arguments
+ *
+ * This function is separate from check_is because it calls enif_make_badarg
+ * and so it must return the badarg exception as its return value. Thus, the
+ * badarg exception indicates success. Failure is indicated by returning an
+ * error atom.
+ */
+static ERL_NIF_TERM check_is_exception(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+ ERL_NIF_TERM error_atom = enif_make_atom(env, "error");
+ ERL_NIF_TERM badarg = enif_make_badarg(env);
+ if (enif_is_exception(env, error_atom)) return error_atom;
+ if (!enif_is_exception(env, badarg)) return error_atom;
+ return badarg;
+}
+
+/*
* argv[0] atom with length of 6
* argv[1] list with length of 6
* argv[2] empty list
@@ -1383,6 +1400,7 @@ static ErlNifFunc nif_funcs[] =
{"last_resource_dtor_call", 0, last_resource_dtor_call},
{"make_new_resource", 2, make_new_resource},
{"check_is", 10, check_is},
+ {"check_is_exception", 0, check_is_exception},
{"length_test", 5, length_test},
{"make_atoms", 0, make_atoms},
{"make_strings", 0, make_strings},