RustPython · youknowone · Jun 30, 2026 · Jun 24, 2026 · Jun 25, 2026 · Jun 26, 2026
diff --git a/.cspell.dict/cpython.txt b/.cspell.dict/cpython.txt
@@ -4,6 +4,7 @@ argdefs
 argtypes
 asdl
 asname
+ASNATIVEBYTES
 atopen
 atext
 attro

diff --git a/Cargo.lock b/Cargo.lock
diff --git a/crates/capi/Cargo.toml b/crates/capi/Cargo.toml
@@ -15,6 +15,7 @@ crate-type = ["cdylib", "rlib"]
 bitflags = { workspace = true }
 itertools = { workspace = true }
 libc = { workspace = true }
+malachite-bigint = { workspace = true }
 num-complex = { workspace = true }
 rustpython-vm = { workspace = true, features = ["threading", "compiler", "importlib", "host_env"] }
 rustpython-stdlib = {workspace = true, features = ["threading"] }

diff --git a/crates/capi/src/longobject.rs b/crates/capi/src/longobject.rs
@@ -1,9 +1,13 @@
 use crate::PyObject;
 use crate::object::define_py_check;
 use crate::pystate::with_vm;
-use core::ffi::{c_long, c_longlong, c_ulong, c_ulonglong};
-use rustpython_vm::PyResult;
-use rustpython_vm::builtins::PyInt;
+use bitflags::bitflags;
+use core::ffi::{CStr, c_char, c_double, c_int, c_long, c_longlong, c_ulong, c_ulonglong, c_void};
+use malachite_bigint::{BigInt, Sign};
+use rustpython_vm::builtins::{PyInt, try_bigint_to_f64, try_f64_to_bigint};
+use rustpython_vm::common::int::bytes_to_int;
+use rustpython_vm::protocol::handle_bytes_to_int_err;
+use rustpython_vm::{AsObject, PyResult, VirtualMachine};
 
 define_py_check!(fn PyLong_Check, types.int_type);
 define_py_check!(exact fn PyLong_CheckExact, types.int_type);
@@ -38,6 +42,150 @@ pub extern "C" fn PyLong_FromUnsignedLongLong(value: c_ulonglong) -> *mut PyObje
     with_vm(|vm| vm.ctx.new_int(value))
 }
 
+#[unsafe(no_mangle)]
+pub extern "C" fn PyLong_FromDouble(value: c_double) -> *mut PyObject {
+    with_vm(|vm| Ok(vm.ctx.new_bigint(&try_f64_to_bigint(value, vm)?)))
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PyLong_FromInt32(value: i32) -> *mut PyObject {
+    with_vm(|vm| vm.ctx.new_int(value))
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PyLong_FromInt64(value: i64) -> *mut PyObject {
+    with_vm(|vm| vm.ctx.new_int(value))
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PyLong_FromUInt32(value: u32) -> *mut PyObject {
+    with_vm(|vm| vm.ctx.new_int(value))
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PyLong_FromUInt64(value: u64) -> *mut PyObject {
+    with_vm(|vm| vm.ctx.new_int(value))
+}
+
+bitflags! {
+    #[derive(Clone, Copy)]
+    struct AsNativeBytesFlags: c_int {
+        const BIG_ENDIAN = 0;
+        const LITTLE_ENDIAN = 1;
+        const NATIVE_ENDIAN = 3;
+        const UNSIGNED_BUFFER = 4;
+        const REJECT_NEGATIVE = 8;
+        const ALLOW_INDEX = 16;
+    }
+}
+
+impl AsNativeBytesFlags {
+    #[inline]
+    fn is_little_endian(self) -> bool {
+        if self.contains(Self::NATIVE_ENDIAN) {
+            cfg!(target_endian = "little")
+        } else {
+            self.contains(Self::LITTLE_ENDIAN)
+        }
+    }
+
+    fn from_bits_or_default(vm: &VirtualMachine, raw_flags: c_int) -> PyResult<Self> {
+        const PY_ASNATIVEBYTES_DEFAULTS: c_int = -1;
+        if raw_flags == PY_ASNATIVEBYTES_DEFAULTS {
+            return Ok(Self::default());
+        };
+
+        let flags = Self::from_bits(raw_flags)
+            .ok_or_else(|| vm.new_value_error("Invalid NativeBytes flags"))?;
+        if flags.contains(Self::LITTLE_ENDIAN) & flags.contains(Self::NATIVE_ENDIAN) {
+            Err(vm.new_value_error("Cannot specify both LITTLE_ENDIAN and NATIVE_ENDIAN"))
+        } else {
+            Ok(flags)
+        }
+    }
+}
+
+impl Default for AsNativeBytesFlags {
+    fn default() -> Self {
+        Self::NATIVE_ENDIAN | Self::UNSIGNED_BUFFER
+    }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_FromNativeBytes(
+    buffer: *const c_void,
+    n_bytes: usize,
+    flags: c_int,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let flags = AsNativeBytesFlags::from_bits_or_default(vm, flags)?;
+        let little_endian = flags.is_little_endian();
+        let bytes = unsafe { core::slice::from_raw_parts(buffer.cast::<u8>(), n_bytes) };
+
+        let value = if flags.contains(AsNativeBytesFlags::UNSIGNED_BUFFER) {
+            if little_endian {
+                BigInt::from_bytes_le(Sign::Plus, bytes)
+            } else {
+                BigInt::from_bytes_be(Sign::Plus, bytes)
+            }
+        } else if little_endian {
+            BigInt::from_signed_bytes_le(bytes)
+        } else {
+            BigInt::from_signed_bytes_be(bytes)
+        };
+
+        Ok(vm.ctx.new_bigint(&value))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_FromUnsignedNativeBytes(
+    buffer: *const c_void,
+    n_bytes: usize,
+    flags: c_int,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let flags = AsNativeBytesFlags::from_bits_or_default(vm, flags)?;
+        let bytes = unsafe { core::slice::from_raw_parts(buffer.cast::<u8>(), n_bytes) };
+
+        let value = if flags.is_little_endian() {
+            BigInt::from_bytes_le(Sign::Plus, bytes)
+        } else {
+            BigInt::from_bytes_be(Sign::Plus, bytes)
+        };
+
+        Ok(vm.ctx.new_bigint(&value))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PyLong_FromVoidPtr(ptr: *mut c_void) -> *mut PyObject {
+    with_vm(|vm| vm.ctx.new_int(ptr as usize))
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_FromString(
+    str: *const c_char,
+    pend: *mut *mut c_char,
+    base: c_int,
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let bytes = unsafe { CStr::from_ptr(str) }.to_bytes();
+        let parsed = bytes_to_int(bytes, base as u32, vm.state.int_max_str_digits.load())
+            .map(|value| vm.ctx.new_bigint(&value));
+
+        if let Some(pend) = unsafe { pend.as_mut() } {
+            let end_offset = if parsed.is_ok() { bytes.len() } else { 0 };
+            unsafe { *pend = bytes.as_ptr().add(end_offset).cast_mut().cast() };
+        }
+
+        parsed.map_err(|err| {
+            let obj = vm.ctx.new_bytes(bytes.to_vec());
+            handle_bytes_to_int_err(err, obj.as_object(), vm)
+        })
+    })
+}
+
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn PyLong_AsLong(obj: *mut PyObject) -> c_long {
     with_vm::<PyResult<c_long>, _>(|vm| {
@@ -50,12 +198,173 @@ pub unsafe extern "C" fn PyLong_AsLong(obj: *mut PyObject) -> c_long {
     })
 }
 
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsDouble(obj: *mut PyObject) -> c_double {
+    with_vm::<PyResult<c_double>, _>(|vm| {
+        let int = unsafe { &*obj }.try_downcast_ref::<PyInt>(vm)?;
+        try_bigint_to_f64(int.as_bigint(), vm)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsInt(obj: *mut PyObject) -> c_int {
+    with_vm::<PyResult<c_int>, _>(|vm| {
+        unsafe { &*obj }
+            .to_owned()
+            .try_index(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to C int"))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsInt32(obj: *mut PyObject, out: *mut i32) -> c_int {
+    with_vm(|vm| {
+        let value: i32 = unsafe { &*obj }
+            .to_owned()
+            .try_index(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to int32_t"))?;
+        unsafe { *out = value };
+        Ok(())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsInt64(obj: *mut PyObject, out: *mut i64) -> c_int {
+    with_vm(|vm| {
+        let value: i64 = unsafe { &*obj }
+            .to_owned()
+            .try_index(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to int64_t"))?;
+        unsafe { *out = value };
+        Ok(())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsLongLong(obj: *mut PyObject) -> c_longlong {
+    with_vm::<PyResult<c_longlong>, _>(|vm| {
+        unsafe { &*obj }
+            .to_owned()
+            .try_index(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to C long long"))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsSize_t(obj: *mut PyObject) -> usize {
+    with_vm::<PyResult<usize>, _>(|vm| {
+        let value: usize = unsafe { &*obj }
+            .try_downcast_ref::<PyInt>(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to C size_t"))?;
+        Ok(value)
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsSsize_t(obj: *mut PyObject) -> isize {
+    with_vm::<PyResult<isize>, _>(|vm| {
+        unsafe { &*obj }
+            .try_downcast_ref::<PyInt>(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to C ssize_t"))
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsUInt32(obj: *mut PyObject, out: *mut u32) -> c_int {
+    with_vm(|vm| {
+        let value: u32 = unsafe { &*obj }
+            .to_owned()
+            .try_index(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to uint32_t"))?;
+        unsafe { *out = value };
+        Ok(())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsUInt64(obj: *mut PyObject, out: *mut u64) -> c_int {
+    with_vm(|vm| {
+        let value: u64 = unsafe { &*obj }
+            .to_owned()
+            .try_index(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| vm.new_overflow_error("Python int too large to convert to uint64_t"))?;
+        unsafe { *out = value };
+        Ok(())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsUnsignedLong(obj: *mut PyObject) -> c_ulong {
+    with_vm::<PyResult<c_ulong>, _>(|vm| {
+        unsafe { &*obj }
+            .try_downcast_ref::<PyInt>(vm)?
+            .as_bigint()
+            .try_into()
+            .map_err(|_| {
+                vm.new_overflow_error("Python int too large to convert to C unsigned long")
+            })
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsUnsignedLongMask(obj: *mut PyObject) -> c_ulong {
+    with_vm::<PyResult<c_ulong>, _>(|vm| {
+        let int = unsafe { &*obj }.to_owned().try_index(vm)?;
+        if const { c_ulong::BITS == 32 } {
+            Ok(c_ulong::from(int.as_u32_mask()))
+        } else {
+            Ok(int.as_u64_mask() as c_ulong)
+        }
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsUnsignedLongLongMask(obj: *mut PyObject) -> c_ulonglong {
+    with_vm::<PyResult<c_ulonglong>, _>(|vm| {
+        let int = unsafe { &*obj }.to_owned().try_index(vm)?;
+        Ok(int.as_u64_mask())
+    })
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyLong_AsVoidPtr(obj: *mut PyObject) -> *mut c_void {
+    with_vm(|vm| {
+        let value = unsafe { &*obj }.try_downcast_ref::<PyInt>(vm)?;
+
+        let unsigned: Result<usize, _> = value.as_bigint().try_into();
+        if let Ok(v) = unsigned {
+            return Ok(v as *mut c_void);
+        }
+        let signed: Result<isize, _> = value.as_bigint().try_into();
+        if let Ok(v) = signed {
+            return Ok((v as usize) as *mut c_void);
+        }
+
+        Err(vm.new_overflow_error("int too large to convert to pointer"))
+    })
+}
+
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn PyLong_AsUnsignedLongLong(obj: *mut PyObject) -> c_ulonglong {
     with_vm::<PyResult<c_ulonglong>, _>(|vm| {
         unsafe { &*obj }
-            .to_owned()
-            .try_downcast::<PyInt>(vm)?
+            .try_downcast_ref::<PyInt>(vm)?
             .as_bigint()
             .try_into()
             .map_err(|_| {
@@ -86,4 +395,13 @@ mod tests {
             assert_eq!(number.extract::<u64>().unwrap(), 123);
         })
     }
+
+    #[test]
+    fn py_int_u128() {
+        Python::attach(|py| {
+            let value = 1u128 << 100;
+            let number = PyInt::new(py, value);
+            assert_eq!(number.extract::<u128>().unwrap(), value);
+        })
+    }
 }
-Original file line number
+Diff line change
@@ Expand Up / @@ -4,6 +4,7 @@ argdefs @@
     argtypes
     asdl
     asname
+    ASNATIVEBYTES
     atopen
     atext
     attro
@@ Expand Down @@