Add function to force an nvlist into the error state

Add an nvlist_set_error() function that can be used to force an
nvlist into the error state.  This is useful both for writing
tests and for writing APIs that use nvlists internally.

Differential Revision:		https://reviews.freebsd.org/D1878
Reviewed by:			pjd, jfv
MFC After:			1 month
Sponsored by:			Sandvine Inc.

5 files changed, 65 insertions, 1 deletions

diff --git a/lib/libnv/Makefile b/lib/libnv/Makefile
index c74c55c04f90..61b158fe57c4 100644
--- a/lib/libnv/Makefile
+++ b/lib/libnv/Makefile
@@ -22,6 +22,7 @@ MLINKS+=nv.3 libnv.3 \
 MLINKS+=nv.3 nvlist_create.3 \
 	nv.3 nvlist_destroy.3 \
 	nv.3 nvlist_error.3 \
+	nv.3 nvlist_set_error.3 \
 	nv.3 nvlist_empty.3 \
 	nv.3 nvlist_clone.3 \
 	nv.3 nvlist_dump.3 \
diff --git a/lib/libnv/nv.3 b/lib/libnv/nv.3
index 6ff63297ac81..be6e0fe03a76 100644
--- a/lib/libnv/nv.3
+++ b/lib/libnv/nv.3
@@ -35,6 +35,7 @@
 .Nm nvlist_create ,
 .Nm nvlist_destroy ,
 .Nm nvlist_error ,
+.Nm nvlist_set_error ,
 .Nm nvlist_empty ,
 .Nm nvlist_exists ,
 .Nm nvlist_free ,
@@ -63,6 +64,8 @@
 .Fn nvlist_destroy "nvlist_t *nvl"
 .Ft int
 .Fn nvlist_error "const nvlist_t *nvl"
+.Ft void
+.Fn nvlist_set_error "nvlist_t *nvl, int error"
 .Ft bool
 .Fn nvlist_empty "const nvlist_t *nvl"
 .\"
@@ -248,8 +251,17 @@ the
 error will be returned.
 .Pp
 The
+.Fn nvlist_set_error
+function sets an nvlist to be in the error state.
+Subsequent calls to
+.Fn nvlist_error
+will return the given error value.
+This function cannot be used to clear the error state from an nvlist.
+This function does nothing if the nvlist is already in the error state.
+.Pp
+The
 .Fn nvlist_empty
-functions returns
+function returns
 .Dv true
 if the given nvlist is empty and
 .Dv false
diff --git a/lib/libnv/nv.h b/lib/libnv/nv.h
index 738bc83ae7c5..bc80d688c8b8 100644
--- a/lib/libnv/nv.h
+++ b/lib/libnv/nv.h
@@ -69,6 +69,7 @@ nvlist_t	*nvlist_create(int flags);
 void		 nvlist_destroy(nvlist_t *nvl);
 int		 nvlist_error(const nvlist_t *nvl);
 bool		 nvlist_empty(const nvlist_t *nvl);
+void		 nvlist_set_error(nvlist_t *nvl, int error);
 
 nvlist_t *nvlist_clone(const nvlist_t *nvl);
 
diff --git a/lib/libnv/nvlist.c b/lib/libnv/nvlist.c
index 839f607fe2e9..90fcde3a5e28 100644
--- a/lib/libnv/nvlist.c
+++ b/lib/libnv/nvlist.c
@@ -137,6 +137,20 @@ nvlist_destroy(nvlist_t *nvl)
 	errno = serrno;
 }
 
+void
+nvlist_set_error(nvlist_t *nvl, int error)
+{
+
+	PJDLOG_ASSERT(error != 0);
+
+	/*
+	 * Check for error != 0 so that we don't do the wrong thing if somebody
+	 * tries to abuse this API when asserts are disabled.
+	 */
+	if (nvl != NULL && error != 0 && nvl->nvl_error == 0)
+		nvl->nvl_error = error;
+}
+
 int
 nvlist_error(const nvlist_t *nvl)
 {
diff --git a/lib/libnv/tests/nv_tests.cc b/lib/libnv/tests/nv_tests.cc
index dc86b2af09e7..e2a9924103ab 100644
--- a/lib/libnv/tests/nv_tests.cc
+++ b/lib/libnv/tests/nv_tests.cc
@@ -409,6 +409,22 @@ ATF_TEST_CASE_BODY(nvlist_clone__nested_nvlist)
 	nvlist_destroy(nvl);
 }
 
+ATF_TEST_CASE_WITHOUT_HEAD(nvlist_clone__error_nvlist);
+ATF_TEST_CASE_BODY(nvlist_clone__error_nvlist)
+{
+	nvlist_t *nvl, *clone;
+
+	nvl = nvlist_create(0);
+	ATF_REQUIRE(nvl != NULL);
+
+	nvlist_set_error(nvl, ENOMEM);
+
+	clone = nvlist_clone(nvl);
+	ATF_REQUIRE(clone == NULL);
+
+	nvlist_destroy(nvl);
+}
+
 ATF_TEST_CASE_WITHOUT_HEAD(nvlist_pack__empty_nvlist);
 ATF_TEST_CASE_BODY(nvlist_pack__empty_nvlist)
 {
@@ -550,6 +566,24 @@ ATF_TEST_CASE_BODY(nvlist_pack__multiple_values)
 	free(packed);
 }
 
+ATF_TEST_CASE_WITHOUT_HEAD(nvlist_pack__error_nvlist);
+ATF_TEST_CASE_BODY(nvlist_pack__error_nvlist)
+{
+	nvlist_t *nvl;
+	void *packed;
+	size_t size;
+
+	nvl = nvlist_create(0);
+	ATF_REQUIRE(nvl != NULL);
+
+	nvlist_set_error(nvl, ENOMEM);
+
+	packed = nvlist_pack(nvl, &size);
+	ATF_REQUIRE(packed == NULL);
+
+	nvlist_destroy(nvl);
+}
+
 ATF_TEST_CASE_WITHOUT_HEAD(nvlist_unpack__duplicate_key);
 ATF_TEST_CASE_BODY(nvlist_unpack__duplicate_key)
 {
@@ -1148,9 +1182,11 @@ ATF_INIT_TEST_CASES(tp)
 	ATF_ADD_TEST_CASE(tp, nvlist_clone__empty_nvlist);
 	ATF_ADD_TEST_CASE(tp, nvlist_clone__nonempty_nvlist);
 	ATF_ADD_TEST_CASE(tp, nvlist_clone__nested_nvlist);
+	ATF_ADD_TEST_CASE(tp, nvlist_clone__error_nvlist);
 
 	ATF_ADD_TEST_CASE(tp, nvlist_pack__empty_nvlist);
 	ATF_ADD_TEST_CASE(tp, nvlist_pack__multiple_values);
+	ATF_ADD_TEST_CASE(tp, nvlist_pack__error_nvlist);
 	ATF_ADD_TEST_CASE(tp, nvlist_unpack__duplicate_key);
 
 	ATF_ADD_TEST_CASE(tp, nvlist_move_string__single_insert);