Ensure that all free methods tolerate NULL

NEWS

@@ -2,9 +2,10 @@ serd (0.30.5) unstable;
 
   * Fix various minor warnings and other code quality issues
   * Improve reader error handling
+  * Make all free functions tolerant of NULL
   * Parse prefixed names more strictly
 
- -- David Robillard <d@drobilla.net>  Sat, 15 Aug 2020 16:22:12 +0000
+ -- David Robillard <d@drobilla.net>  Sun, 16 Aug 2020 11:01:53 +0000
 
 serd (0.30.4) stable;
 

src/env.c

@@ -47,6 +47,10 @@ serd_env_new(const SerdNode* base_uri)
 void
 serd_env_free(SerdEnv* env)
 {
+	if (!env) {
+		return;
+	}
+
 	for (size_t i = 0; i < env->n_prefixes; ++i) {
 		serd_node_free(&env->prefixes[i].name);
 		serd_node_free(&env->prefixes[i].uri);

src/reader.c

@@ -218,6 +218,10 @@ serd_reader_set_error_sink(SerdReader*   reader,
 void
 serd_reader_free(SerdReader* reader)
 {
+	if (!reader) {
+		return;
+	}
+
 	pop_node(reader, reader->rdf_nil);
 	pop_node(reader, reader->rdf_rest);
 	pop_node(reader, reader->rdf_first);

src/writer.c

@@ -978,6 +978,10 @@ serd_writer_set_prefix(SerdWriter*     writer,
 void
 serd_writer_free(SerdWriter* writer)
 {
+	if (!writer) {
+		return;
+	}
+
 	serd_writer_finish(writer);
 	serd_stack_free(&writer->anon_stack);
 	free(writer->bprefix);

tests/free_null_test.c

@@ -0,0 +1,33 @@
+/*
+  Copyright 2020 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#undef NDEBUG
+
+#include "serd/serd.h"
+
+#include <stddef.h>
+
+int
+main(void)
+{
+	serd_free(NULL);
+	serd_node_free(NULL);
+	serd_env_free(NULL);
+	serd_reader_free(NULL);
+	serd_writer_free(NULL);
+
+	return 0;
+}

wscript

@@ -212,6 +212,7 @@ def build(bld):
         # Test programs
         for prog in [('serdi_static', 'src/serdi.c'),
                      ('env_test', 'tests/env_test.c'),
+                     ('free_null_test', 'tests/free_null_test.c'),
                      ('read_chunk_test', 'tests/read_chunk_test.c'),
                      ('serd_test', 'tests/serd_test.c')]:
             bld(features     = 'c cprogram',
@@ -535,6 +536,7 @@ def test(tst):
 
     with tst.group('Unit') as check:
         check(['./env_test'])
+        check(['./free_null_test'])
         check(['./read_chunk_test'])
         check(['./serd_test'])