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Author SHA1 Message Date
Niels Lohmann a33e015e39 Add test coverage for documented lenient BSON input handling
Issue #5333 documented three intentionally-lenient behaviors of the BSON
reader (any non-zero byte accepted as a boolean `true`, BSON array element
keys not validated against the required decimal sequence, and the payload
of binary subtype 0x02 "old binary" returned as-is including its inner
length prefix), but none of them was pinned by a test, so a future change
could silently regress the documented behavior.

Also add coverage for the out_of_range.412 length-overflow check
(shared by binary, string, and (sub-)document BSON length fields) for
the string and document cases; only the binary case was previously
tested.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-05 20:52:05 +02:00
7 changed files with 114 additions and 251 deletions
-8
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@@ -34,10 +34,6 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
("add", "remove", "move")
- Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
location is a proper prefix of its "path" location.
- Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
unsuccessful.
@@ -79,7 +75,3 @@ is thrown. In any case, the original value is not changed: the patch is applied
- Added in version 2.0.0.
- Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
target location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.
@@ -30,10 +30,6 @@ No guarantees, value may be corrupted by an unsuccessful patch operation.
("add", "remove", "move")
- Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
location has a parent that is neither an object nor an array.
- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
location is a proper prefix of its "path" location.
- Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
unsuccessful.
@@ -76,7 +72,3 @@ function throws an exception.
- Added in version 3.11.0.
- Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
target location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
location has a non-object/non-array parent in version 3.13.0.
- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.
-28
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@@ -933,34 +933,6 @@ BSON stores the length of documents, arrays, strings, and binary values in a sig
[`to_bson`](../api/basic_json/to_bson.md) produced documents with negative length prefixes that
[`from_bson`](../api/basic_json/from_bson.md) rejected.
### json.exception.out_of_range.413
A JSON Patch `remove` operation cannot be applied because the target location's parent is neither an object nor an array. Per [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902), a `remove` target must reference a member of an existing object or an element of an existing array; a primitive value (string, number, boolean, etc.) or `null` has no members or elements to remove.
!!! failure "Example message"
```
cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array
```
!!! note
This exception was added in version 3.13.0. Before that, this situation was silently ignored (the `remove` operation had no effect).
### json.exception.out_of_range.414
A JSON Patch `move` operation's `"from"` location is a proper prefix of its `"path"` location. Per [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902) (section 4.4), a location cannot be moved into one of its own children.
!!! failure "Example message"
```
cannot move value: 'from' path '/0' is a proper prefix of 'path' '/0/0'
```
!!! note
This exception was added in version 3.13.0. Before that, this situation could succeed with a corrupted result: for an array target, removing the "from" element before the "add" step shifted subsequent indices, so "path" silently re-resolved to a different element than intended.
## Further exceptions
This exception is thrown in case of errors that cannot be classified with the
-19
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@@ -4939,12 +4939,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
// note erase performs range check
parent.erase(json_pointer::template array_index<basic_json_t>(last_path));
}
else
{
// the parent of a "remove" target must be an object or array
// (see #5396)
JSON_THROW(out_of_range::create(413, detail::concat("cannot remove value: the JSON Patch 'remove' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
}
};
// type check: top level value must be an array
@@ -5022,19 +5016,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
const auto from_path = get_value("move", "from", true).template get<string_t>();
json_pointer from_ptr(from_path);
// RFC 6902 (section 4.4) forbids "from" from being a
// proper prefix of "path": a location cannot be moved
// into one of its own children. Compare the pointers'
// reference tokens (already unescaped by json_pointer's
// parser) rather than the raw pointer strings, since a
// token may itself contain an escaped '/' or '~' that
// would defeat a naive string-prefix comparison.
if (JSON_HEDLEY_UNLIKELY(from_ptr.reference_tokens.size() < ptr.reference_tokens.size()
&& std::equal(from_ptr.reference_tokens.begin(), from_ptr.reference_tokens.end(), ptr.reference_tokens.begin())))
{
JSON_THROW(out_of_range::create(414, detail::concat("cannot move value: 'from' path '", from_path, "' is a proper prefix of 'path' '", path, "'"), &result));
}
// the "from" location must exist - use at()
basic_json const v = result.at(from_ptr);
-19
View File
@@ -26367,12 +26367,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
// note erase performs range check
parent.erase(json_pointer::template array_index<basic_json_t>(last_path));
}
else
{
// the parent of a "remove" target must be an object or array
// (see #5396)
JSON_THROW(out_of_range::create(413, detail::concat("cannot remove value: the JSON Patch 'remove' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
}
};
// type check: top level value must be an array
@@ -26450,19 +26444,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
const auto from_path = get_value("move", "from", true).template get<string_t>();
json_pointer from_ptr(from_path);
// RFC 6902 (section 4.4) forbids "from" from being a
// proper prefix of "path": a location cannot be moved
// into one of its own children. Compare the pointers'
// reference tokens (already unescaped by json_pointer's
// parser) rather than the raw pointer strings, since a
// token may itself contain an escaped '/' or '~' that
// would defeat a naive string-prefix comparison.
if (JSON_HEDLEY_UNLIKELY(from_ptr.reference_tokens.size() < ptr.reference_tokens.size()
&& std::equal(from_ptr.reference_tokens.begin(), from_ptr.reference_tokens.end(), ptr.reference_tokens.begin())))
{
JSON_THROW(out_of_range::create(414, detail::concat("cannot move value: 'from' path '", from_path, "' is a proper prefix of 'path' '", path, "'"), &result));
}
// the "from" location must exist - use at()
basic_json const v = result.at(from_ptr);
+114 -3
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@@ -38,6 +38,26 @@ class huge_binary_t : public std::vector<std::uint8_t>
using huge_binary_json = nlohmann::basic_json <
std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t,
double, std::allocator, nlohmann::adl_serializer, huge_binary_t, void >;
// a string type that reports a size beyond INT32_MAX without allocating that
// much memory, so BSON length overflow can be tested for strings and
// (embedded) documents as well, following the same idea as huge_binary_t
class huge_string_t : public std::string
{
public:
using std::string::string;
huge_string_t(const std::string& s) : std::string(s) {} // NOLINT(google-explicit-constructor,hicpp-explicit-conversions)
size_type size() const noexcept // NOLINT(readability-convert-member-functions-to-static)
{
// one byte more than the BSON length field can represent
return static_cast<size_type>((std::numeric_limits<std::int32_t>::max)()) + 1;
}
};
using huge_string_json = nlohmann::basic_json <
std::map, std::vector, huge_string_t, bool, std::int64_t, std::uint64_t,
double, std::allocator, nlohmann::adl_serializer, std::vector<std::uint8_t>, void >;
} // namespace
TEST_CASE("BSON")
@@ -105,10 +125,36 @@ TEST_CASE("BSON")
SECTION("lengths exceeding INT32_MAX cannot be serialized to BSON")
{
huge_binary_json j;
j["b"] = huge_binary_json::binary(huge_binary_t{});
// out_of_range.412 is thrown from a single shared helper
// (to_bson_length) that guards the BSON length fields of binary
// values, strings, and (embedded) documents alike
SECTION("binary")
{
huge_binary_json j;
j["b"] = huge_binary_json::binary(huge_binary_t{});
CHECK_THROWS_WITH_AS(huge_binary_json::to_bson(j), "[json.exception.out_of_range.412] BSON length 2147483661 exceeds maximum of 2147483647", huge_binary_json::out_of_range&);
CHECK_THROWS_WITH_AS(huge_binary_json::to_bson(j), "[json.exception.out_of_range.412] BSON length 2147483661 exceeds maximum of 2147483647", huge_binary_json::out_of_range&);
}
SECTION("string")
{
huge_string_json j;
j["s"] = huge_string_json::string_t("value");
CHECK_THROWS_WITH_AS(huge_string_json::to_bson(j), "[json.exception.out_of_range.412] BSON length 4294967308 exceeds maximum of 2147483647", huge_string_json::out_of_range&);
}
SECTION("document")
{
// an oversized string nested one level deep makes the
// *embedded* document's own length exceed INT32_MAX as well
huge_string_json nested;
nested["s"] = huge_string_json::string_t("value");
huge_string_json j;
j["nested"] = nested;
CHECK_THROWS_WITH_AS(huge_string_json::to_bson(j), "[json.exception.out_of_range.412] BSON length 6442450963 exceeds maximum of 2147483647", huge_string_json::out_of_range&);
}
}
SECTION("string length must be at least 1")
@@ -193,6 +239,23 @@ TEST_CASE("BSON")
CHECK(json::from_bson(result, true, false) == j);
}
SECTION("non-empty object with bool from a non-0/1 byte (lenient parsing)")
{
// documented lenient behavior (see gh-5333): any non-zero byte
// is accepted as `true`, not just 0x01
std::vector<std::uint8_t> const input =
{
0x0D, 0x00, 0x00, 0x00, // size (little endian)
0x08, // entry: boolean
'e', 'n', 't', 'r', 'y', '\x00',
0x02, // value = 0x02 (neither 0x00 nor 0x01)
0x00 // end marker
};
const json expected = { { "entry", true } };
CHECK(json::from_bson(input) == expected);
}
SECTION("non-empty object with double")
{
json const j =
@@ -499,6 +562,29 @@ TEST_CASE("BSON")
CHECK(json::from_bson(result, true, false) == j);
}
SECTION("array elements with non-conforming keys (lenient parsing)")
{
// documented lenient behavior (see gh-5333): BSON array element
// keys are not checked against the required decimal sequence
// "0", "1", "2", ... - elements are taken in encoded order
std::vector<std::uint8_t> const input =
{
0x26, 0x00, 0x00, 0x00, // size (little endian)
0x04, 'e', 'n', 't', 'r', 'y', '\x00', // entry: embedded array
0x1A, 0x00, 0x00, 0x00, // size (little endian)
0x10, '5', 0x00, 0x0A, 0x00, 0x00, 0x00, // key "5" (bogus) -> 10
0x10, 'x', 0x00, 0x14, 0x00, 0x00, 0x00, // key "x" (non-numeric) -> 20
0x10, '1', 0x00, 0x1E, 0x00, 0x00, 0x00, // key "1" (out of order) -> 30
0x00, // end marker (embedded array)
0x00 // end marker
};
const json expected = { { "entry", json::array({10, 20, 30}) } };
CHECK(json::from_bson(input) == expected);
}
SECTION("non-empty object with binary member")
{
const size_t N = 10;
@@ -594,6 +680,31 @@ TEST_CASE("BSON")
CHECK(json::from_bson(result, true, false) == j);
}
SECTION("binary member with subtype 0x02 (old binary) keeps its inner length prefix (lenient parsing)")
{
// documented lenient behavior (see gh-5333): the payload for
// binary subtype 0x02 ("old binary") is returned as-is,
// including its own inner 4-byte length prefix; it is not
// stripped or reinterpreted
std::vector<std::uint8_t> const input =
{
0x17, 0x00, 0x00, 0x00, // size (little endian)
0x05, 'e', 'n', 't', 'r', 'y', '\x00', // entry: binary
0x06, 0x00, 0x00, 0x00, // size of binary (little endian)
0x02, // "old binary" subtype
0x02, 0x00, 0x00, 0x00, // inner length prefix (part of the old-binary payload)
0x68, 0x69, // payload ('h', 'i')
0x00 // end marker
};
// the inner length prefix is part of the (unmodified) payload
const std::vector<std::uint8_t> expected_payload = {0x02, 0x00, 0x00, 0x00, 0x68, 0x69};
const json expected = { { "entry", json::binary(expected_payload, 0x02) } };
CHECK(json::from_bson(input) == expected);
}
SECTION("Some more complex document")
{
json const j =
-166
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@@ -1389,172 +1389,6 @@ TEST_CASE("JSON patch - add to a primitive parent (regression #4292)")
}
}
TEST_CASE("JSON patch - remove with primitive or null parent (regression #5396)")
{
// Regression test for https://github.com/nlohmann/json/issues/5396
//
// RFC 6902 (§4.2) requires the target location of a "remove" operation
// to exist. When the target's parent resolves to a primitive value or
// null, the operation must fail. Previously operation_remove silently
// did nothing in this case (neither the "is_object" nor the "is_array"
// branch matched, and there was no final "else"), so the patch appeared
// to succeed without changing the document. It now throws
// out_of_range.413.
SECTION("parent is a primitive (number)")
{
json const doc = {{"a", 1}};
json const patch = {{{"op", "remove"}, {"path", "/a/b"}}};
#if JSON_DIAGNOSTICS
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] (/a) cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array", json::out_of_range&);
#else
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array", json::out_of_range&);
#endif
}
SECTION("parent is a primitive (string)")
{
json const doc = {{"foo", {{"bar", "a string"}}}};
json const patch = {{{"op", "remove"}, {"path", "/foo/bar/baz"}}};
#if JSON_DIAGNOSTICS
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] (/foo/bar) cannot remove value: the JSON Patch 'remove' target's parent is of type string, but must be an object or array", json::out_of_range&);
#else
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] cannot remove value: the JSON Patch 'remove' target's parent is of type string, but must be an object or array", json::out_of_range&);
#endif
}
SECTION("top-level document is null")
{
json const doc = nullptr;
json const patch = {{{"op", "remove"}, {"path", "/a"}}};
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] cannot remove value: the JSON Patch 'remove' target's parent is of type null, but must be an object or array", json::out_of_range&);
}
SECTION("legitimate removes still work")
{
// object member
json const doc1 = {{"a", 1}, {"b", 2}};
json const patch1 = {{{"op", "remove"}, {"path", "/a"}}};
CHECK(doc1.patch(patch1) == json({{"b", 2}}));
// array element
json const doc2 = R"([1, 2, 3])"_json;
json const patch2 = {{{"op", "remove"}, {"path", "/1"}}};
CHECK(doc2.patch(patch2) == R"([1, 3])"_json);
}
}
TEST_CASE("JSON patch - move where 'from' is a proper prefix of 'path' (regression #5397)")
{
// Regression test for https://github.com/nlohmann/json/issues/5397
//
// RFC 6902 (§4.4) forbids "from" from being a proper prefix of "path"
// for a "move" operation: "a location cannot be moved into one of its
// children." "move" is implemented as remove-then-add; for an object
// target this happened to throw anyway as a side effect of the "add"
// step re-resolving through the now-removed parent, but for an array
// target the removal shifted subsequent indices, so "path" silently
// re-resolved to a different element and the operation "succeeded"
// with a corrupted result. It now throws out_of_range.414 for both
// object and array targets.
SECTION("array target (from the issue)")
{
json const doc = R"([[1,2],[3]])"_json;
json const patch = {{{"op", "move"}, {"from", "/0"}, {"path", "/0/0"}}};
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/0' is a proper prefix of 'path' '/0/0'", json::out_of_range&);
}
SECTION("object target")
{
json const doc = R"({"a": {"b": 1}})"_json;
json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", "/a/b"}}};
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/a' is a proper prefix of 'path' '/a/b'", json::out_of_range&);
}
SECTION("from == path is not a proper prefix and must not be rejected")
{
// "from" equal to "path" is a no-op move; it is not a *proper*
// prefix relationship, so this new check must not reject it.
json const doc = R"({"a": 1, "b": 2})"_json;
json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", "/a"}}};
CHECK(doc.patch(patch) == doc);
}
SECTION("raw string prefix that is not a pointer-token prefix must be allowed")
{
// "/ab" is a string-prefix of "/abc/x" as raw text, but "ab" and
// "abc" are different reference tokens, so this is NOT a
// pointer-token prefix relationship and the move must succeed.
// This is the key case proving the check compares tokens, not
// raw pointer text (a naive std::string prefix/rfind check on
// the undecoded pointer would wrongly reject this).
json const doc = R"({"ab": 1, "abc": {"x": 2}})"_json;
json const patch = {{{"op", "move"}, {"from", "/ab"}, {"path", "/abc/x"}}};
json const result = R"({"abc": {"x": 1}})"_json;
CHECK(doc.patch(patch) == result);
}
SECTION("escaped reference tokens are compared unescaped")
{
// "from" is the single token "a/b" (escaped as "a~1b"); "path"
// addresses member "x" of that same value, so "from" is a
// proper (token-level) prefix of "path" and must be rejected.
json const doc = R"({"a/b": {"x": 1}})"_json;
json const patch = {{{"op", "move"}, {"from", "/a~1b"}, {"path", "/a~1b/x"}}};
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/a~1b' is a proper prefix of 'path' '/a~1b/x'", json::out_of_range&);
}
SECTION("ordinary valid moves still work")
{
// unrelated top-level members
json const doc1 = R"({"a": 1, "b": 2})"_json;
json const patch1 = {{{"op", "move"}, {"from", "/a"}, {"path", "/c"}}};
CHECK(doc1.patch(patch1) == R"({"b": 2, "c": 1})"_json);
// sibling paths that share a textual prefix but are unrelated
json const doc2 = R"({"a": {"x": 1}, "b": {"y": 2}})"_json;
json const patch2 = {{{"op", "move"}, {"from", "/a/x"}, {"path", "/b/z"}}};
CHECK(doc2.patch(patch2) == R"({"a": {}, "b": {"y": 2, "z": 1}})"_json);
// "path" is a proper prefix of "from" (the reverse relationship,
// which RFC 6902 does not forbid)
json const doc3 = R"({"a": {"b": 1}})"_json;
json const patch3 = {{{"op", "move"}, {"from", "/a/b"}, {"path", "/a"}}};
CHECK(doc3.patch(patch3) == R"({"a": 1})"_json);
}
SECTION("root 'from' is a proper prefix of every non-root 'path'")
{
// the whole document is a proper prefix of any location inside it
json const doc = R"({"a": 1})"_json;
json const patch = {{{"op", "move"}, {"from", ""}, {"path", "/a"}}};
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '' is a proper prefix of 'path' '/a'", json::out_of_range&);
}
SECTION("root 'path' is never a proper prefix violation for a non-root 'from'")
{
// the reverse of the above: moving a non-root location to the root
// is the "path is a prefix of from" relationship, which RFC 6902
// permits (already covered generally above; this pins the root
// case specifically, since root is the one path with no reference
// tokens at all)
json const doc = R"({"a": {"b": 1}})"_json;
json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", ""}}};
CHECK(doc.patch(patch) == R"({"b": 1})"_json);
}
SECTION("the array-append token '-' is an ordinary child token")
{
// "-" (append-to-array) addresses a location *inside* the array,
// so "from" pointing at the array is still a proper prefix of
// "path" ending in "-" and must be rejected like any other child.
json const doc = R"({"a": [1, 2]})"_json;
json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", "/a/-"}}};
CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/a' is a proper prefix of 'path' '/a/-'", json::out_of_range&);
}
}
TEST_CASE("JSON patch - diff emits array removals in descending index order")
{
SECTION("array shrunk to empty")