ns_plugin_expandpath() auto-extension unit-tests

Update existing ns_plugin_expandpath() unit test to cover the logic
appending the plugin extension if missing.

Because ns_plugin_expandpath() now relies on isc_file_exists() API, a
mocked version has been added in tests/ns/plugin_test.c and relies on the
linker --wrap mechanism.

tests/ns/meson.build

@@ -14,6 +14,12 @@ foreach unit : [
     'plugin',
     'query',
 ]
+    linkargs = ''
+    if unit == 'plugin'
+        linkargs = [
+            '-Wl,--wrap=isc_file_exists',
+        ]
+    endif
     test_bin = executable(
         unit,
         files(f'@unit@_test.c', 'netmgr_wrap.c'),
@@ -31,6 +37,7 @@ foreach unit : [
             cmocka_dep,
             nghttp2_dep,
         ],
+        link_args: linkargs,
     )
 
     test(

tests/ns/plugin_test.c

@@ -34,7 +34,16 @@
 
 #include <dns/lib.h>
 
-#include <ns/hooks.h>
+#include "../ns/hooks.c"
+
+bool
+__wrap_isc_file_exists(const char *pathname);
+
+bool
+__wrap_isc_file_exists(const char *pathname) {
+	UNUSED(pathname);
+	return mock();
+}
 
 #include <tests/ns.h>
 
@@ -43,8 +52,8 @@
  */
 typedef struct {
 	const ns_test_id_t id; /* libns test identifier */
-	const char *input;     /* source string - plugin name or path
+	const char *input;     /* source string - plugin name or path */
-				* */
+	bool exists;	       /* return of mocked isc_file_exists() */
 	size_t output_size;    /* size of target char array to
 				* allocate */
 	isc_result_t result;   /* expected return value */
@@ -65,6 +74,10 @@ run_full_path_test(const ns_plugin_expandpath_test_params_t *test,
 	REQUIRE(test->input != NULL);
 	REQUIRE(test->result != ISC_R_SUCCESS || test->output != NULL);
 
+	if (test->result == ISC_R_SUCCESS) {
+		will_return(__wrap_isc_file_exists, test->exists);
+	}
+
 	/*
 	 * Prepare a target buffer of given size.  Store it in 'state' so that
 	 * it can get cleaned up by _teardown() if the test fails.
@@ -108,6 +121,7 @@ ISC_RUN_TEST_IMPL(ns_plugin_expandpath) {
 		{
 			NS_TEST_ID("correct use with an absolute path"),
 			.input = "/usr/lib/named/foo.so",
+			.exists = true,
 			.output_size = PATH_MAX,
 			.result = ISC_R_SUCCESS,
 			.output = "/usr/lib/named/foo.so",
@@ -115,6 +129,7 @@ ISC_RUN_TEST_IMPL(ns_plugin_expandpath) {
 		{
 			NS_TEST_ID("correct use with a relative path"),
 			.input = "../../foo.so",
+			.exists = true,
 			.output_size = PATH_MAX,
 			.result = ISC_R_SUCCESS,
 			.output = "../../foo.so",
@@ -122,31 +137,72 @@ ISC_RUN_TEST_IMPL(ns_plugin_expandpath) {
 		{
 			NS_TEST_ID("correct use with a filename"),
 			.input = "foo.so",
+			.exists = true,
 			.output_size = PATH_MAX,
 			.result = ISC_R_SUCCESS,
 			.output = NAMED_PLUGINDIR "/foo.so",
 		},
+		{
+			NS_TEST_ID("correct use with an absolute path and no "
+				   "extension"),
+			.input = "/usr/lib/named/foo",
+			.exists = false,
+			.output_size = PATH_MAX,
+			.result = ISC_R_SUCCESS,
+			.output = "/usr/lib/named/foo.so",
+		},
+		{
+			NS_TEST_ID("correct use with a relative path and no "
+				   "extension"),
+			.input = "../../foo",
+			.exists = false,
+			.output_size = PATH_MAX,
+			.result = ISC_R_SUCCESS,
+			.output = "../../foo.so",
+		},
+		{
+			NS_TEST_ID("correct use with a filename and no "
+				   "extension"),
+			.input = "foo",
+			.exists = false,
+			.output_size = PATH_MAX,
+			.result = ISC_R_SUCCESS,
+			.output = NAMED_PLUGINDIR "/foo.so",
+		},
+		{
+			NS_TEST_ID("correct use with a filename and no "
+				   "extension but a name with dots"),
+			.input = "foo.bar",
+			.exists = false,
+			.output_size = PATH_MAX,
+			.result = ISC_R_SUCCESS,
+			.output = NAMED_PLUGINDIR "/foo.bar.so",
+		},
 		{
 			NS_TEST_ID("no space at all in target buffer"),
 			.input = "/usr/lib/named/foo.so",
+			.exists = true,
 			.output_size = 0,
 			.result = ISC_R_NOSPACE,
 		},
 		{
 			NS_TEST_ID("target buffer too small to fit input"),
 			.input = "/usr/lib/named/foo.so",
+			.exists = true,
 			.output_size = 1,
 			.result = ISC_R_NOSPACE,
 		},
 		{
 			NS_TEST_ID("target buffer too small to fit NULL byte"),
 			.input = "/foo.so",
+			.exists = true,
 			.output_size = 7,
 			.result = ISC_R_NOSPACE,
 		},
 		{
 			NS_TEST_ID("target buffer too small to fit full path"),
 			.input = "foo.so",
+			.exists = true,
 			.output_size = 7,
 			.result = ISC_R_NOSPACE,
 		},