René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"assertion failure at Modules/_sqlite/blob.c:146: `PyObject *read_multiple(pysqlite_Blob *, Py_ssize_t, Py_ssize_t): Assertion 'offset \u003c sqlite3_blob_bytes(self-\u003eblob)' failed`","articleBody":"# Crash report\n\n### What happened?\n\n```python\nimport sqlite3\n\n# 1. Setup an in-memory database with a BLOB column\ncon = sqlite3.connect(':memory:')\ncon.execute('create table test(b blob)')\n\n# 2. Insert a small amount of data.\n# The unicode character '\\u2603' (Snowman) is 3 bytes in UTF-8 (b'\\xe2\\x98\\x83').\n# The blob size will be 3.\ncon.execute('insert into test(b) values (?)', ('\\u2603',))\n\n# 3. Open the BLOB for incremental I/O\n# Table: 'test', Column: 'b', Row: 1\nblob = con.blobopen('test', 'b', 1)\n\n# 4. Trigger the crash\n# We request a slice starting at index 5 (which is beyond the blob size of 3)\n# and ending at index -5 (which wraps around to before the start).\n# This combination causes the internal 'offset' calculation in C to assert\n# failing that the offset (5) is not less than the blob bytes (3).\nblob[5:-5]\n```\n\n```\npython: ../Modules/_sqlite/blob.c:146: PyObject *read_multiple(pysqlite_Blob *, Py_ssize_t, Py_ssize_t): Assertion `offset \u003c sqlite3_blob_bytes(self-\u003eblob)' failed.\n```\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nLinux\n\n### Output from running 'python -VV' on the command line:\n\n_No response_\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-142824\n* gh-145297\n* gh-145298\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/YuanchengJiang","@type":"Person","name":"YuanchengJiang"},"datePublished":"2025-12-16T07:17:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/142787/cpython/issues/142787"}