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Author SHA1 Message Date
Niels Lohmann 32349b379b Make contains(json_pointer) return false instead of throwing on unrepresentable array-index tokens
contains(const json_pointer&) is documented to never throw, but a purely
numeric reference token that is syntactically a valid array index yet
numerically too large to be represented (exceeding size_type's max, or
exceeding ULLONG_MAX and causing strtoull() to set errno to ERANGE) made
it fall through to array_index(), which throws out_of_range.410/404.

Pre-check the token's magnitude the same way array_index() does, but
return false instead of throwing, mirroring how the surrounding code
already rejects other malformed tokens (leading zero, non-digit
characters, "-") without throwing. operator[]/at() are untouched and
keep throwing for these inputs.

Fixes #5395

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-05 21:57:41 +02:00
6 changed files with 98 additions and 354 deletions
+14
View File
@@ -748,6 +748,20 @@ class json_pointer
}
}
// the reference token consists only of digits at this point (cf. checks
// above); however, its numeric value might not be representable, in which
// case array_index() would throw out_of_range.404/410 -- contains() must
// not throw (see #5395), so such a reference token is treated as "not found"
errno = 0; // strtoull() does not reset errno on success
char* p_end = nullptr; // NOLINT(misc-const-correctness)
const unsigned long long magnitude = std::strtoull(reference_token.c_str(), &p_end, 10); // NOLINT(runtime/int)
if (JSON_HEDLEY_UNLIKELY(errno == ERANGE // the value exceeds ULLONG_MAX
|| magnitude >= static_cast<unsigned long long>((std::numeric_limits<typename BasicJsonType::size_type>::max)()))) // NOLINT(runtime/int)
{
// the array index cannot be represented as size_type
return false;
}
const auto idx = array_index<BasicJsonType>(reference_token);
if (idx >= ptr->size())
{
+17 -124
View File
@@ -3573,7 +3573,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
{
using std::swap;
swap(*(m_data.m_value.array), other);
set_parents();
}
else
{
@@ -3590,7 +3589,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
{
using std::swap;
swap(*(m_data.m_value.object), other);
set_parents();
}
else
{
@@ -5159,139 +5157,34 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
case value_t::object:
{
// first pass: record, for every source key, whether it is
// common to both objects (in source's iteration order) or
// was deleted (i.e., in source but not in target) -- this is
// a by-product of the target.find() call already needed to
// tell the two cases apart, so it adds no extra lookups. The
// "remove" ops themselves are emitted later, interleaved
// with the recursive per-key diffs in the fast path below,
// to match source's original iteration order (as the
// original, pre-reordering-aware implementation did) instead
// of grouping all removes before all recursive diffs.
std::vector<typename object_t::key_type> common_keys_source_order;
// first pass: traverse this object's elements
for (auto it = source.cbegin(); it != source.cend(); ++it)
{
// escape the key name to be used in a JSON patch
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
if (target.find(it.key()) != target.end())
{
common_keys_source_order.push_back(it.key());
// recursive call to compare object values at key it
auto temp_diff = diff(it.value(), target[it.key()], path_key);
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
}
else
{
// found a key that is not in o -> remove it
result.push_back(object(
{
{"op", "remove"}, {"path", path_key}
}));
}
}
// second pass: find keys that were added (i.e., in target but
// not in source), and record the keys common to both, in
// target's iteration order -- again a by-product of the
// source.find() call already needed to detect added keys. At
// the same time, determine whether every added key comes
// after every common key in target's order (a precondition
// for the fast path below, which only ever appends new keys
// at the very end): for an object_t whose iteration order is
// a pure function of the key set (e.g. the default std::map,
// which always iterates in sorted key order), the order
// check further below is always true and this whole
// mechanism is effectively a no-op; it only matters for a
// reorderable object_t such as the one backing `ordered_json`.
// patch ops for keys that were added (i.e., in target but not
// in source); built here so the fast path below can reuse
// them without a second source.find() per target key. Only
// used by the fast path -- the slow (reordering) path
// rebuilds "add" ops for every key itself.
std::vector<typename object_t::key_type> common_keys_target_order;
basic_json added_ops(value_t::array);
bool new_keys_form_suffix = true;
bool seen_new_key = false;
// second pass: traverse other object's elements
for (auto it = target.cbegin(); it != target.cend(); ++it)
{
if (source.find(it.key()) == source.end())
{
seen_new_key = true;
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
added_ops.push_back(
{
{"op", "add"}, {"path", path_key},
{"value", it.value()}
});
}
else
{
common_keys_target_order.push_back(it.key());
if (seen_new_key)
{
new_keys_form_suffix = false;
}
}
}
if (common_keys_source_order == common_keys_target_order && new_keys_form_suffix)
{
// fast path: order of common keys already matches (or the
// object_t's iteration order does not depend on
// insertion history), so a plain per-key recursive diff
// is correct and minimal, as before. common_keys_source_order
// is, by construction, the subsequence of source's keys
// that are common to both objects, in source's iteration
// order -- so it can be walked in lockstep with `source`
// using a cheap key comparison instead of another lookup.
// Deleted keys (those source keys not in common_keys_source_order)
// are interleaved here too, in source's original order, to
// match the historical (pre-reordering-aware) output order.
auto common_it = common_keys_source_order.cbegin();
for (auto it = source.cbegin(); it != source.cend(); ++it)
{
if (common_it != common_keys_source_order.cend() && it.key() == *common_it)
{
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
auto temp_diff = diff(it.value(), target[it.key()], path_key);
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
++common_it;
}
else
{
// found a key that is not in target -> remove it
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
result.push_back(object(
{
{"op", "remove"}, {"path", path_key}
}));
}
}
// append the "add" ops for brand-new keys collected above
// during the pass over target -- no second source.find()
// per target key needed
result.insert(result.end(), added_ops.begin(), added_ops.end());
}
else
{
// slow path: the common keys are in a different relative
// order in source and target (only possible for a
// reorderable object_t like ordered_map). Building a
// minimal reordering patch is a nontrivial (LCS-like)
// problem; instead, remove every source key -- both
// deleted keys (which must be removed regardless) and
// common keys (removed so they can be re-added in
// target's order) -- and re-add every key that should
// remain, with its final target value, in target's
// order. basic_json::patch()'s "add" operation on an
// object uses operator[], which appends at the end for a
// vector-backed insertion-ordered map when the key does
// not already exist -- so removing a key and then adding
// it moves it to the end, fixing its position.
for (auto it = source.cbegin(); it != source.cend(); ++it)
{
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
result.push_back(object(
{
{"op", "remove"}, {"path", path_key}
}));
}
// add every key that is either common (just removed
// above) or brand new, in target's iteration order, so
// that the final order after applying the patch matches
// target exactly
for (auto it = target.cbegin(); it != target.cend(); ++it)
{
// found a key that is not in this -> add it
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
result.push_back(
{
+31 -124
View File
@@ -16394,6 +16394,20 @@ class json_pointer
}
}
// the reference token consists only of digits at this point (cf. checks
// above); however, its numeric value might not be representable, in which
// case array_index() would throw out_of_range.404/410 -- contains() must
// not throw (see #5395), so such a reference token is treated as "not found"
errno = 0; // strtoull() does not reset errno on success
char* p_end = nullptr; // NOLINT(misc-const-correctness)
const unsigned long long magnitude = std::strtoull(reference_token.c_str(), &p_end, 10); // NOLINT(runtime/int)
if (JSON_HEDLEY_UNLIKELY(errno == ERANGE // the value exceeds ULLONG_MAX
|| magnitude >= static_cast<unsigned long long>((std::numeric_limits<typename BasicJsonType::size_type>::max)()))) // NOLINT(runtime/int)
{
// the array index cannot be represented as size_type
return false;
}
const auto idx = array_index<BasicJsonType>(reference_token);
if (idx >= ptr->size())
{
@@ -25001,7 +25015,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
{
using std::swap;
swap(*(m_data.m_value.array), other);
set_parents();
}
else
{
@@ -25018,7 +25031,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
{
using std::swap;
swap(*(m_data.m_value.object), other);
set_parents();
}
else
{
@@ -26587,139 +26599,34 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
case value_t::object:
{
// first pass: record, for every source key, whether it is
// common to both objects (in source's iteration order) or
// was deleted (i.e., in source but not in target) -- this is
// a by-product of the target.find() call already needed to
// tell the two cases apart, so it adds no extra lookups. The
// "remove" ops themselves are emitted later, interleaved
// with the recursive per-key diffs in the fast path below,
// to match source's original iteration order (as the
// original, pre-reordering-aware implementation did) instead
// of grouping all removes before all recursive diffs.
std::vector<typename object_t::key_type> common_keys_source_order;
// first pass: traverse this object's elements
for (auto it = source.cbegin(); it != source.cend(); ++it)
{
// escape the key name to be used in a JSON patch
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
if (target.find(it.key()) != target.end())
{
common_keys_source_order.push_back(it.key());
// recursive call to compare object values at key it
auto temp_diff = diff(it.value(), target[it.key()], path_key);
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
}
else
{
// found a key that is not in o -> remove it
result.push_back(object(
{
{"op", "remove"}, {"path", path_key}
}));
}
}
// second pass: find keys that were added (i.e., in target but
// not in source), and record the keys common to both, in
// target's iteration order -- again a by-product of the
// source.find() call already needed to detect added keys. At
// the same time, determine whether every added key comes
// after every common key in target's order (a precondition
// for the fast path below, which only ever appends new keys
// at the very end): for an object_t whose iteration order is
// a pure function of the key set (e.g. the default std::map,
// which always iterates in sorted key order), the order
// check further below is always true and this whole
// mechanism is effectively a no-op; it only matters for a
// reorderable object_t such as the one backing `ordered_json`.
// patch ops for keys that were added (i.e., in target but not
// in source); built here so the fast path below can reuse
// them without a second source.find() per target key. Only
// used by the fast path -- the slow (reordering) path
// rebuilds "add" ops for every key itself.
std::vector<typename object_t::key_type> common_keys_target_order;
basic_json added_ops(value_t::array);
bool new_keys_form_suffix = true;
bool seen_new_key = false;
// second pass: traverse other object's elements
for (auto it = target.cbegin(); it != target.cend(); ++it)
{
if (source.find(it.key()) == source.end())
{
seen_new_key = true;
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
added_ops.push_back(
{
{"op", "add"}, {"path", path_key},
{"value", it.value()}
});
}
else
{
common_keys_target_order.push_back(it.key());
if (seen_new_key)
{
new_keys_form_suffix = false;
}
}
}
if (common_keys_source_order == common_keys_target_order && new_keys_form_suffix)
{
// fast path: order of common keys already matches (or the
// object_t's iteration order does not depend on
// insertion history), so a plain per-key recursive diff
// is correct and minimal, as before. common_keys_source_order
// is, by construction, the subsequence of source's keys
// that are common to both objects, in source's iteration
// order -- so it can be walked in lockstep with `source`
// using a cheap key comparison instead of another lookup.
// Deleted keys (those source keys not in common_keys_source_order)
// are interleaved here too, in source's original order, to
// match the historical (pre-reordering-aware) output order.
auto common_it = common_keys_source_order.cbegin();
for (auto it = source.cbegin(); it != source.cend(); ++it)
{
if (common_it != common_keys_source_order.cend() && it.key() == *common_it)
{
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
auto temp_diff = diff(it.value(), target[it.key()], path_key);
result.insert(result.end(), temp_diff.begin(), temp_diff.end());
++common_it;
}
else
{
// found a key that is not in target -> remove it
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
result.push_back(object(
{
{"op", "remove"}, {"path", path_key}
}));
}
}
// append the "add" ops for brand-new keys collected above
// during the pass over target -- no second source.find()
// per target key needed
result.insert(result.end(), added_ops.begin(), added_ops.end());
}
else
{
// slow path: the common keys are in a different relative
// order in source and target (only possible for a
// reorderable object_t like ordered_map). Building a
// minimal reordering patch is a nontrivial (LCS-like)
// problem; instead, remove every source key -- both
// deleted keys (which must be removed regardless) and
// common keys (removed so they can be re-added in
// target's order) -- and re-add every key that should
// remain, with its final target value, in target's
// order. basic_json::patch()'s "add" operation on an
// object uses operator[], which appends at the end for a
// vector-backed insertion-ordered map when the key does
// not already exist -- so removing a key and then adding
// it moves it to the end, fixing its position.
for (auto it = source.cbegin(); it != source.cend(); ++it)
{
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
result.push_back(object(
{
{"op", "remove"}, {"path", path_key}
}));
}
// add every key that is either common (just removed
// above) or brand new, in target's iteration order, so
// that the final order after applying the patch matches
// target exactly
for (auto it = target.cbegin(); it != target.cend(); ++it)
{
// found a key that is not in this -> add it
const auto path_key = detail::concat<string_t>(path, '/', detail::escape(it.key()));
result.push_back(
{
-31
View File
@@ -273,36 +273,5 @@ TEST_CASE("Regression tests for extended diagnostics")
CHECK(j1["numbers"]["two"] == 2);
CHECK(j1["string"] == "t");
}
SECTION("Regression test - swap(array_t&)/swap(object_t&) must update JSON_DIAGNOSTICS parent pointers")
{
// swap(array_t&)
{
json j = json::array();
json::array_t arr = {json::array({1})};
j.swap(arr);
// parent pointers of the moved-in elements must point into j, not
// into the now-defunct free-standing array_t
CHECK_THROWS_WITH_AS(j[0][0].get<std::string>(), "[json.exception.type_error.302] (/0/0) type must be string, but is number", json::type_error);
// must not trigger assert_invariant() in a debug/assert-enabled build
json const k = j;
CHECK(k == j);
}
// swap(object_t&)
{
json o = json::object();
json::object_t obj = {{"a", json::array({1})}};
o.swap(obj);
CHECK_THROWS_WITH_AS(o["a"][0].get<std::string>(), "[json.exception.type_error.302] (/a/0) type must be string, but is number", json::type_error);
// must not trigger assert_invariant() in a debug/assert-enabled build
json const p = o;
CHECK(p == o);
}
}
}
+42
View File
@@ -319,6 +319,44 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_WITH_AS(j[jp] = 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j_const[jp] == 1, throw_msg.c_str(), json::out_of_range&);
// #5395: contains() must not throw for a reference token that is a
// syntactically valid array index but numerically exceeds ULLONG_MAX
// (causing strtoull() to set errno to ERANGE) -- it should just report
// that the pointer does not resolve to an element
CHECK(!j.contains(jp));
CHECK(!j_const.contains(jp));
}
{
// #5395: same as above, but using the exact reproduction from the issue
json::json_pointer const jp("/99999999999999999999");
std::string const throw_msg = "[json.exception.out_of_range.404] unresolved reference token '99999999999999999999'";
CHECK_THROWS_WITH_AS(j[jp] = 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j_const[jp] == 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j.at(jp) = 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j_const.at(jp) == 1, throw_msg.c_str(), json::out_of_range&);
CHECK(!j.contains(jp));
CHECK(!j_const.contains(jp));
}
{
// #5395: a reference token that is numerically representable in
// unsigned long long but exceeds size_type's max (e.g. ULLONG_MAX
// itself on typical 64-bit platforms, where size_type's max equals
// ULLONG_MAX) must not make contains() throw either
json::json_pointer const jp("/18446744073709551615");
std::string const throw_msg = "[json.exception.out_of_range.410] array index 18446744073709551615 exceeds size_type";
CHECK_THROWS_WITH_AS(j[jp] = 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j_const[jp] == 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j.at(jp) = 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j_const.at(jp) == 1, throw_msg.c_str(), json::out_of_range&);
CHECK(!j.contains(jp));
CHECK(!j_const.contains(jp));
}
// on some machines, the check below is not constant
@@ -334,6 +372,10 @@ TEST_CASE("JSON pointers")
CHECK_THROWS_WITH_AS(j[jp] = 1, throw_msg.c_str(), json::out_of_range&);
CHECK_THROWS_WITH_AS(j_const[jp] == 1, throw_msg.c_str(), json::out_of_range&);
// #5395: contains() must not throw for a reference token exceeding size_type's max
CHECK(!j.contains(jp));
CHECK(!j_const.contains(jp));
}
DOCTEST_MSVC_SUPPRESS_WARNING_POP
-81
View File
@@ -81,84 +81,3 @@ TEST_CASE("regression test for issue #3732 - iteration_proxy_value<iter_impl<ord
};
static_cast<void>(fn);
}
TEST_CASE("regression test - diff() must account for ordered_json member order")
{
SECTION("pure reorder, no value changes")
{
ordered_json a = {{"a", 1}, {"b", 2}};
ordered_json b = {{"b", 2}, {"a", 1}};
CHECK(a != b); // order-sensitive equality
CHECK(a.patch(ordered_json::diff(a, b)) == b);
}
SECTION("new key must land at the front")
{
ordered_json c = {{"b", 2}};
ordered_json e = {{"a", 1}, {"b", 2}};
CHECK(c.patch(ordered_json::diff(c, e)) == e);
}
SECTION("reorder plus a value change on one of the reordered keys")
{
ordered_json a = {{"a", 1}, {"b", 2}};
ordered_json b = {{"b", 20}, {"a", 1}};
CHECK(a != b);
CHECK(a.patch(ordered_json::diff(a, b)) == b);
}
SECTION("reorder plus a deleted key")
{
ordered_json a = {{"a", 1}, {"b", 2}, {"c", 3}};
ordered_json b = {{"b", 2}, {"a", 1}};
CHECK(a != b);
CHECK(a.patch(ordered_json::diff(a, b)) == b);
}
SECTION("reorder plus a nested value that itself needs a recursive diff")
{
ordered_json a = {{"a", {{"x", 1}, {"y", 2}}}, {"b", 2}};
ordered_json b = {{"b", 2}, {"a", {{"x", 1}, {"y", 99}}}};
CHECK(a != b);
CHECK(a.patch(ordered_json::diff(a, b)) == b);
}
SECTION("three or more keys shuffled into a different order")
{
ordered_json a = {{"a", 1}, {"b", 2}, {"c", 3}, {"d", 4}};
ordered_json b = {{"d", 4}, {"b", 2}, {"a", 1}, {"c", 3}};
CHECK(a != b);
CHECK(a.patch(ordered_json::diff(a, b)) == b);
}
SECTION("matching order still produces a minimal patch (fast path unaffected)")
{
ordered_json a = {{"a", 1}, {"b", 2}, {"c", 3}};
ordered_json b = {{"a", 1}, {"b", 20}, {"c", 3}};
auto p = ordered_json::diff(a, b);
// only the changed value should be touched, not a wholesale remove+add
CHECK(p.size() == 1);
CHECK(p[0]["op"] == "replace");
CHECK(p[0]["path"] == "/b");
CHECK(a.patch(p) == b);
}
SECTION("plain json (std::map-backed) is unaffected by same-key-different-insertion-order")
{
json a;
a["b"] = 2;
a["a"] = 1;
json b;
b["a"] = 1;
b["b"] = 2;
// std::map iteration is always sorted by key, so a == b regardless of
// insertion order, and diff() must still produce the same minimal
// (empty) result as before this fix
CHECK(a == b);
auto p = json::diff(a, b);
CHECK(p.empty());
CHECK(a.patch(p) == b);
}
}