[php-src] Issue #10104: json_decode() fails on nested input of around 10000 characters.

Issue: https://github.com/php/php-src/issues/10104 Author: maksverver ### Description The following code: ```php <?php function test($i, $s) { try { json_decode($s, false, 999999999, JSON_THROW_ON_ERROR); echo "Test $i passed\n"; } catch (Exception $e) { echo "Test $i FAILED: $e\n"; } } // String like [[[[...1...]]]] fails at length 9999, nesting depth 4999. test(1, str_repeat('[', 4998) . '1' . str_repeat(']', 4998)); // pass test(2, str_repeat('[', 4999) . '1' . str_repeat(']', 4999)); // FAIL // String like [1,[1,[1,...1...]]] fails at length 10001, nesting depth 2499. test(3, str_repeat('[1,', 2499) . '1' . str_repeat(']', 2499)); // pass test(4, str_repeat('[1,', 2500) . '1' . str_repeat(']', 2500)); // FAIL // Flat string like [[1],[1],[1]...] passes even at much greater length. test(5, '[' . str_repeat('[1],', 9999) . '1]'); // pass ?> ``` Resulted in this output: ``` Test 1 passed Test 2 FAILED: JsonException: Syntax error in json_decode_bug.php:5 Stack trace: #0 json_decode_bug.php(5): json_decode() #1 json_decode_bug.php(14): test() #2 {main} Test 3 passed Test 4 FAILED: JsonException: Syntax error in json_decode_bug.php:5 Stack trace: #0 json_decode_bug.php(5): json_decode() #1 json_decode_bug.php(18): test() #2 {main} Test 5 passed ``` (I've removed the directory names from the stack trace for brevity.) But I expected this output instead: ``` Test 1 passed Test 2 passed Test 3 passed Test 4 passed Test 5 passed ``` Note that the exception message ("Syntax error') is different from what I get when I reduce the maximum depth argument from 999999999 to 999. Then I get JsonException: Maximum stack depth exceeded instead (which is expected). So it looks like the parser hits an undocumented limit when the input string reaches 10,000 characters, but only for the heavily-nested input. ### PHP Version PHP 8.1.13 ### Operating System Arch Linux (x86_64)