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jviotti merged 3 commits into from
Apr 30, 2026
Merged

Stricter $id/id framing checks across dialects #2365

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931179d
Stricter `$id` framing checks in 2019-09 and 2020-12
jviotti Apr 30, 2026
95e3c7b
Test the id #
jviotti Apr 30, 2026
1cfe72f
Empty id
jviotti Apr 30, 2026
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13 changes: 11 additions & 2 deletions src/core/jsonschema/frame.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,9 @@ auto find_anchors(const sourcemeta::core::JSON &schema,
if (id_value) {
assert(id_value->is_string());
const std::string_view id_view{id_value->to_string()};
if (id_view.starts_with('#')) {
// A bare "#" carries no anchor name, so we treat it as no anchor at
// all.
if (id_view.starts_with('#') && id_view.size() > 1) {
// The original string is "#fragment", skip the '#'
result.emplace_back(id_view.substr(1), AnchorType::Static);
}
Expand All @@ -181,7 +183,9 @@ auto find_anchors(const sourcemeta::core::JSON &schema,
if (id_value) {
assert(id_value->is_string());
const std::string_view id_view{id_value->to_string()};
if (id_view.starts_with('#')) {
// A bare "#" carries no anchor name, so we treat it as no anchor at
// all.
if (id_view.starts_with('#') && id_view.size() > 1) {
// The original string is "#fragment", skip the '#'
result.emplace_back(id_view.substr(1), AnchorType::Static);
}
Expand Down Expand Up @@ -661,6 +665,11 @@ auto SchemaFrame::analyse(const JSON &root, const SchemaWalker &walker,

const auto maybe_fragment{maybe_relative.fragment()};

// Both 2019-09 and 2020-12 state:
//
// "$id" MUST NOT contain a non-empty fragment, and SHOULD NOT
// contain an empty fragment.
//
// See
// https://json-schema.org/draft/2019-09/draft-handrews-json-schema-02#rfc.section.8.2.2
// See
Expand Down
15 changes: 14 additions & 1 deletion src/core/jsonschema/jsonschema.cc
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Expand Up @@ -156,7 +156,7 @@ auto sourcemeta::core::identify(const JSON &schema,
}

const auto &identifier{schema.at(keyword)};
if (!identifier.is_string() || identifier.empty()) {
if (!identifier.is_string()) {
std::ostringstream value;
sourcemeta::core::stringify(identifier, value);
throw sourcemeta::core::SchemaKeywordError(
Expand All @@ -180,6 +180,19 @@ auto sourcemeta::core::identify(const JSON &schema,
return default_id;
}

// An empty string identifier and an identifier consisting solely of the
// empty-fragment marker "#" are both valid URI-references that resolve to
// the parent base, carrying no information. We treat them as if no
// identifier was declared at all (i.e. no new schema resource is
// introduced).
// See
// https://json-schema.org/draft/2019-09/draft-handrews-json-schema-02#rfc.section.8.2.2
// See
// https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-01#section-8.2.1-5
if (identifier.to_string().empty() || identifier.to_string() == "#") {
return default_id;
}

return identifier.to_string();
}

Expand Down
247 changes: 247 additions & 0 deletions test/jsonschema/jsonschema_frame_2019_09_test.cc
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Expand Up @@ -3263,3 +3263,250 @@ TEST(JSONSchema_frame_2019_09, anchor_with_valid_colon) {
EXPECT_FRAME_LOCATION_REACHABLE(
frame, Static, "https://www.sourcemeta.com/schema#foo:bar", frame.root());
}

TEST(JSONSchema_frame_2019_09, top_level_id_absolute_with_non_empty_fragment) {
const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
"$id": "https://www.sourcemeta.com/schema#foo",
"$schema": "https://json-schema.org/draft/2019-09/schema"
})JSON");

sourcemeta::core::SchemaFrame frame{
sourcemeta::core::SchemaFrame::Mode::References};

try {
frame.analyse(document, sourcemeta::core::schema_walker,
sourcemeta::core::schema_resolver);
FAIL();
} catch (const sourcemeta::core::SchemaFrameError &error) {
EXPECT_EQ(error.identifier(), "https://www.sourcemeta.com/schema#foo");
} catch (...) {
FAIL();
}
}

TEST(JSONSchema_frame_2019_09, nested_id_absolute_with_non_empty_fragment) {
const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
"$id": "https://www.sourcemeta.com/schema",
"$schema": "https://json-schema.org/draft/2019-09/schema",
"$defs": {
"foo": {
"$id": "https://www.sourcemeta.com/nested#foo"
}
}
})JSON");

sourcemeta::core::SchemaFrame frame{
sourcemeta::core::SchemaFrame::Mode::References};

try {
frame.analyse(document, sourcemeta::core::schema_walker,
sourcemeta::core::schema_resolver);
FAIL();
} catch (const sourcemeta::core::SchemaFrameError &error) {
EXPECT_EQ(error.identifier(), "https://www.sourcemeta.com/nested#foo");
} catch (...) {
FAIL();
}
}

TEST(JSONSchema_frame_2019_09, top_level_id_empty_fragment_only) {
const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
"$id": "#",
"$schema": "https://json-schema.org/draft/2019-09/schema"
})JSON");

sourcemeta::core::SchemaFrame frame{
sourcemeta::core::SchemaFrame::Mode::References};
frame.analyse(document, sourcemeta::core::schema_walker,
sourcemeta::core::schema_resolver);

EXPECT_TRUE(frame.root().empty());

EXPECT_EQ(frame.locations().size(), 3);

EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
frame, "", "", "https://json-schema.org/draft/2019-09/schema",
JSON_Schema_2019_09, std::nullopt, false, false);
EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
frame, "#/$id", "/$id", "https://json-schema.org/draft/2019-09/schema",
JSON_Schema_2019_09, "", false, false);
EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
frame, "#/$schema", "/$schema",
"https://json-schema.org/draft/2019-09/schema", JSON_Schema_2019_09, "",
false, false);

// References

EXPECT_EQ(frame.references().size(), 1);

EXPECT_STATIC_REFERENCE(
frame, "/$schema", "https://json-schema.org/draft/2019-09/schema",
"https://json-schema.org/draft/2019-09/schema", std::nullopt,
"https://json-schema.org/draft/2019-09/schema");

// Reachability

EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "", frame.root());
}

TEST(JSONSchema_frame_2019_09, nested_id_empty_fragment_only) {
const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
"$id": "https://www.sourcemeta.com/schema",
"$schema": "https://json-schema.org/draft/2019-09/schema",
"$defs": {
"foo": {
"$id": "#"
}
}
})JSON");

sourcemeta::core::SchemaFrame frame{
sourcemeta::core::SchemaFrame::Mode::References};
frame.analyse(document, sourcemeta::core::schema_walker,
sourcemeta::core::schema_resolver);

EXPECT_EQ(frame.root(), "https://www.sourcemeta.com/schema");

EXPECT_EQ(frame.locations().size(), 6);

EXPECT_FRAME_STATIC_2019_09_RESOURCE(
frame, "https://www.sourcemeta.com/schema",
"https://www.sourcemeta.com/schema", "",
"https://www.sourcemeta.com/schema", "", std::nullopt, false, false);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$id",
"https://www.sourcemeta.com/schema", "/$id",
"https://www.sourcemeta.com/schema", "/$id", "", false, false);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$schema",
"https://www.sourcemeta.com/schema", "/$schema",
"https://www.sourcemeta.com/schema", "/$schema", "", false, false);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$defs",
"https://www.sourcemeta.com/schema", "/$defs",
"https://www.sourcemeta.com/schema", "/$defs", "", false, false);
EXPECT_FRAME_STATIC_2019_09_SUBSCHEMA(
frame, "https://www.sourcemeta.com/schema#/$defs/foo",
"https://www.sourcemeta.com/schema", "/$defs/foo",
"https://www.sourcemeta.com/schema", "/$defs/foo", "", false, true);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$defs/foo/$id",
"https://www.sourcemeta.com/schema", "/$defs/foo/$id",
"https://www.sourcemeta.com/schema", "/$defs/foo/$id", "/$defs/foo",
false, true);

// References

EXPECT_EQ(frame.references().size(), 1);

EXPECT_STATIC_REFERENCE(
frame, "/$schema", "https://json-schema.org/draft/2019-09/schema",
"https://json-schema.org/draft/2019-09/schema", std::nullopt,
"https://json-schema.org/draft/2019-09/schema");

// Reachability

EXPECT_FRAME_LOCATION_REACHABLE(
frame, Static, "https://www.sourcemeta.com/schema", frame.root());
}

TEST(JSONSchema_frame_2019_09, top_level_id_empty_string) {
const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
"$id": "",
"$schema": "https://json-schema.org/draft/2019-09/schema"
})JSON");

sourcemeta::core::SchemaFrame frame{
sourcemeta::core::SchemaFrame::Mode::References};
frame.analyse(document, sourcemeta::core::schema_walker,
sourcemeta::core::schema_resolver);

EXPECT_TRUE(frame.root().empty());

EXPECT_EQ(frame.locations().size(), 3);

EXPECT_ANONYMOUS_FRAME_STATIC_SUBSCHEMA(
frame, "", "", "https://json-schema.org/draft/2019-09/schema",
JSON_Schema_2019_09, std::nullopt, false, false);
EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
frame, "#/$id", "/$id", "https://json-schema.org/draft/2019-09/schema",
JSON_Schema_2019_09, "", false, false);
EXPECT_ANONYMOUS_FRAME_STATIC_POINTER(
frame, "#/$schema", "/$schema",
"https://json-schema.org/draft/2019-09/schema", JSON_Schema_2019_09, "",
false, false);

// References

EXPECT_EQ(frame.references().size(), 1);

EXPECT_STATIC_REFERENCE(
frame, "/$schema", "https://json-schema.org/draft/2019-09/schema",
"https://json-schema.org/draft/2019-09/schema", std::nullopt,
"https://json-schema.org/draft/2019-09/schema");

// Reachability

EXPECT_FRAME_LOCATION_REACHABLE(frame, Static, "", frame.root());
}

TEST(JSONSchema_frame_2019_09, nested_id_empty_string) {
const sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
"$id": "https://www.sourcemeta.com/schema",
"$schema": "https://json-schema.org/draft/2019-09/schema",
"$defs": {
"foo": {
"$id": ""
}
}
})JSON");

sourcemeta::core::SchemaFrame frame{
sourcemeta::core::SchemaFrame::Mode::References};
frame.analyse(document, sourcemeta::core::schema_walker,
sourcemeta::core::schema_resolver);

EXPECT_EQ(frame.root(), "https://www.sourcemeta.com/schema");

EXPECT_EQ(frame.locations().size(), 6);

EXPECT_FRAME_STATIC_2019_09_RESOURCE(
frame, "https://www.sourcemeta.com/schema",
"https://www.sourcemeta.com/schema", "",
"https://www.sourcemeta.com/schema", "", std::nullopt, false, false);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$id",
"https://www.sourcemeta.com/schema", "/$id",
"https://www.sourcemeta.com/schema", "/$id", "", false, false);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$schema",
"https://www.sourcemeta.com/schema", "/$schema",
"https://www.sourcemeta.com/schema", "/$schema", "", false, false);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$defs",
"https://www.sourcemeta.com/schema", "/$defs",
"https://www.sourcemeta.com/schema", "/$defs", "", false, false);
EXPECT_FRAME_STATIC_2019_09_SUBSCHEMA(
frame, "https://www.sourcemeta.com/schema#/$defs/foo",
"https://www.sourcemeta.com/schema", "/$defs/foo",
"https://www.sourcemeta.com/schema", "/$defs/foo", "", false, true);
EXPECT_FRAME_STATIC_2019_09_POINTER(
frame, "https://www.sourcemeta.com/schema#/$defs/foo/$id",
"https://www.sourcemeta.com/schema", "/$defs/foo/$id",
"https://www.sourcemeta.com/schema", "/$defs/foo/$id", "/$defs/foo",
false, true);

// References

EXPECT_EQ(frame.references().size(), 1);

EXPECT_STATIC_REFERENCE(
frame, "/$schema", "https://json-schema.org/draft/2019-09/schema",
"https://json-schema.org/draft/2019-09/schema", std::nullopt,
"https://json-schema.org/draft/2019-09/schema");

// Reachability

EXPECT_FRAME_LOCATION_REACHABLE(
frame, Static, "https://www.sourcemeta.com/schema", frame.root());
}
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