Raise IndexError for oversized SQLite blob indices (#9048)

Use index-sized conversion, preserve __index__ exceptions, and bound native type names to the UTF-8-safe diagnostic limit. Include in-memory blob read and write regressions without changing callback ownership.

Assisted-by: OpenAI Codex:model identifier unavailable

crates/stdlib/src/_sqlite3.rs

@@ -2839,15 +2839,31 @@ mod _sqlite3 {
             }
         }
 
-        fn wrapped_index(index: PyIntRef, length: c_int, vm: &VirtualMachine) -> PyResult<c_int> {
-            let mut index = index.try_to_primitive::<c_int>(vm)?;
+        fn wrapped_index(
+            index: PyIntRef,
+            object: &PyObject,
+            length: c_int,
+            vm: &VirtualMachine,
+        ) -> PyResult<c_int> {
+            let mut index = index.try_to_primitive::<isize>(vm).map_err(|_| {
+                let class = object.class();
+                let type_name = class.slot_name();
+                let mut end = type_name.len().min(200);
+                while !type_name.is_char_boundary(end) {
+                    end -= 1;
+                }
+                vm.new_index_error(format!(
+                    "cannot fit '{}' into an index-sized integer",
+                    &type_name[..end]
+                ))
+            })?;
             if index < 0 {
-                index += length;
+                index += length as isize;
             }
-            if index < 0 || index >= length {
+            if index < 0 || index >= length as isize {
                 Err(vm.new_index_error("Blob index out of range"))
             } else {
-                Ok(index)
+                Ok(index as c_int)
             }
         }
 
@@ -2874,7 +2890,7 @@ mod _sqlite3 {
             let inner = self.inner(vm)?;
             if let Some(index) = needle.try_index_opt(vm) {
                 let blob_len = inner.blob.bytes();
-                let index = Self::wrapped_index(index?, blob_len, vm)?;
+                let index = Self::wrapped_index(index?, needle, blob_len, vm)?;
                 let mut byte: u8 = 0;
                 let ret = inner.blob.read_single(&mut byte, index);
                 self.check(ret, vm).map(|_| vm.ctx.new_int(byte).into())
@@ -2937,7 +2953,7 @@ mod _sqlite3 {
                     )));
                 };
                 let blob_len = inner.blob.bytes();
-                let index = Self::wrapped_index(index?, blob_len, vm)?;
+                let index = Self::wrapped_index(index?, needle, blob_len, vm)?;
                 // Mirror CPython ass_subscript_index: use PyLong_AsLong, treat any
                 // overflow (e.g. 2**65) as -1, then validate the [0, 255] range.
                 let val = int_val.as_bigint().to_i64().unwrap_or(-1);

extra_tests/snippets/stdlib_sqlite.py

@@ -306,3 +306,59 @@ for operation in (
     "replace_callback",
 ):
     check_nested_aggregate_destructor(operation)
+
+
+class BlobIndex:
+    def __init__(self, value):
+        self.value = value
+
+    def __index__(self):
+        return self.value
+
+
+class BlobInt(int):
+    pass
+
+
+class BrokenBlobIndex:
+    def __index__(self):
+        raise OverflowError("index conversion failed")
+
+
+cx.execute("CREATE TABLE blobindices(b BLOB)")
+cx.execute("INSERT INTO blobindices(b) VALUES (?)", (b"abc",))
+with cx.blobopen("blobindices", "b", 1) as blob:
+    assert blob[BlobIndex(-1)] == ord("c")
+    blob[BlobIndex(0)] = ord("A")
+    assert blob[0] == ord("A")
+
+    test = unittest.TestCase()
+    for index in (sys.maxsize, -sys.maxsize - 1):
+        with test.assertRaisesRegex(IndexError, "^Blob index out of range$"):
+            blob[index]
+        with test.assertRaisesRegex(IndexError, "^Blob index out of range$"):
+            blob[index] = 0
+
+    for value in (sys.maxsize + 1, -sys.maxsize - 2):
+        for index in (value, BlobInt(value), BlobIndex(value)):
+            message = (
+                f"^cannot fit '{type(index).__name__}' into an index-sized integer$"
+            )
+            with test.assertRaisesRegex(IndexError, message):
+                blob[index]
+            with test.assertRaisesRegex(IndexError, message):
+                blob[index] = 0
+
+    for name, bounded_name in (("X" * 250, "X" * 200), ("€" * 67, "€" * 66)):
+        long_index = type(name, (), {"__index__": lambda self: sys.maxsize + 1})()
+        message = f"^cannot fit '{bounded_name}' into an index-sized integer$"
+        with test.assertRaisesRegex(IndexError, message):
+            blob[long_index]
+        with test.assertRaisesRegex(IndexError, message):
+            blob[long_index] = 0
+
+    with test.assertRaisesRegex(OverflowError, "^index conversion failed$"):
+        blob[BrokenBlobIndex()]
+    with test.assertRaisesRegex(OverflowError, "^index conversion failed$"):
+        blob[BrokenBlobIndex()] = 0
+    assert blob[:] == b"Abc"