Refactor - derive `CloneZeroed` (#28771)

* Adds proc_macro_derive(CloneZeroed).

* Switches over all use sites of clone_zeroed() and copy_field().

* Removes clone_zeroed() and copy_field().

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

sdk/macro/src/lib.rs

@@ -405,3 +405,38 @@ pub fn wasm_bindgen_stub(_attr: TokenStream, item: TokenStream) -> TokenStream {
     }
     .into()
 }
+
+// Sets padding in structures to zero explicitly.
+// Otherwise padding could be inconsistent across the network and lead to divergence / consensus failures.
+#[proc_macro_derive(CloneZeroed)]
+pub fn derive_clone_zeroed(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    match parse_macro_input!(input as syn::Item) {
+        syn::Item::Struct(item_struct) => {
+            let clone_statements = match item_struct.fields {
+                syn::Fields::Named(ref fields) => fields.named.iter().map(|f| {
+                    let name = &f.ident;
+                    quote! {
+                        std::ptr::addr_of_mut!((*ptr).#name).write(self.#name);
+                    }
+                }),
+                _ => unimplemented!(),
+            };
+            let name = &item_struct.ident;
+            quote! {
+                impl Clone for #name {
+                    fn clone(&self) -> Self {
+                        let mut value = std::mem::MaybeUninit::<Self>::uninit();
+                        unsafe {
+                            std::ptr::write_bytes(&mut value, 0, 1);
+                            let ptr = value.as_mut_ptr();
+                            #(#clone_statements)*
+                            value.assume_init()
+                        }
+                    }
+                }
+            }
+        }
+        _ => unimplemented!(),
+    }
+    .into()
+}

sdk/program/src/clock.rs

@@ -20,10 +20,7 @@
 //!
 //! [oracle]: https://docs.solana.com/implemented-proposals/validator-timestamp-oracle
 
-use {
-    crate::{clone_zeroed, copy_field},
-    std::mem::MaybeUninit,
-};
+use solana_sdk_macro::CloneZeroed;
 
 /// The default tick rate that the cluster attempts to achieve (160 per second).
 ///
@@ -147,7 +144,7 @@ pub type UnixTimestamp = i64;
 ///
 /// All members of `Clock` start from 0 upon network boot.
 #[repr(C)]
-#[derive(Serialize, Deserialize, Debug, Default, PartialEq, Eq)]
+#[derive(Serialize, Deserialize, Debug, CloneZeroed, Default, PartialEq, Eq)]
 pub struct Clock {
     /// The current `Slot`.
     pub slot: Slot,
@@ -170,21 +167,6 @@ pub struct Clock {
     pub unix_timestamp: UnixTimestamp,
 }
 
-impl Clone for Clock {
-    fn clone(&self) -> Self {
-        clone_zeroed(|cloned: &mut MaybeUninit<Self>| {
-            let ptr = cloned.as_mut_ptr();
-            unsafe {
-                copy_field!(ptr, self, slot);
-                copy_field!(ptr, self, epoch_start_timestamp);
-                copy_field!(ptr, self, epoch);
-                copy_field!(ptr, self, leader_schedule_epoch);
-                copy_field!(ptr, self, unix_timestamp);
-            }
-        })
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

sdk/program/src/epoch_schedule.rs

@@ -12,10 +12,7 @@
 //! epochs increasing in slots until they last for [`DEFAULT_SLOTS_PER_EPOCH`].
 
 pub use crate::clock::{Epoch, Slot, DEFAULT_SLOTS_PER_EPOCH};
-use {
-    crate::{clone_zeroed, copy_field},
-    std::mem::MaybeUninit,
-};
+use solana_sdk_macro::CloneZeroed;
 
 /// The default number of slots before an epoch starts to calculate the leader schedule.
 pub const DEFAULT_LEADER_SCHEDULE_SLOT_OFFSET: u64 = DEFAULT_SLOTS_PER_EPOCH;
@@ -32,7 +29,7 @@ pub const MAX_LEADER_SCHEDULE_EPOCH_OFFSET: u64 = 3;
 pub const MINIMUM_SLOTS_PER_EPOCH: u64 = 32;
 
 #[repr(C)]
-#[derive(Debug, Copy, PartialEq, Eq, Deserialize, Serialize, AbiExample)]
+#[derive(Debug, CloneZeroed, Copy, PartialEq, Eq, Deserialize, Serialize, AbiExample)]
 #[serde(rename_all = "camelCase")]
 pub struct EpochSchedule {
     /// The maximum number of slots in each epoch.
@@ -66,21 +63,6 @@ impl Default for EpochSchedule {
     }
 }
 
-impl Clone for EpochSchedule {
-    fn clone(&self) -> Self {
-        clone_zeroed(|cloned: &mut MaybeUninit<Self>| {
-            let ptr = cloned.as_mut_ptr();
-            unsafe {
-                copy_field!(ptr, self, slots_per_epoch);
-                copy_field!(ptr, self, leader_schedule_slot_offset);
-                copy_field!(ptr, self, warmup);
-                copy_field!(ptr, self, first_normal_epoch);
-                copy_field!(ptr, self, first_normal_slot);
-            }
-        })
-    }
-}
-
 impl EpochSchedule {
     pub fn new(slots_per_epoch: u64) -> Self {
         Self::custom(slots_per_epoch, slots_per_epoch, true)

sdk/program/src/lib.rs

@@ -742,25 +742,6 @@ macro_rules! unchecked_div_by_const {
     }};
 }
 
-use std::{mem::MaybeUninit, ptr::write_bytes};
-
-#[macro_export]
-macro_rules! copy_field {
-    ($ptr:expr, $self:ident, $field:ident) => {
-        std::ptr::addr_of_mut!((*$ptr).$field).write($self.$field)
-    };
-}
-
-pub fn clone_zeroed<T, F>(clone: F) -> T
-where
-    F: Fn(&mut MaybeUninit<T>),
-{
-    let mut value = MaybeUninit::<T>::uninit();
-    unsafe { write_bytes(&mut value, 0, 1) }
-    clone(&mut value);
-    unsafe { value.assume_init() }
-}
-
 // This module is purposefully listed after all other exports: because of an
 // interaction within rustdoc between the reexports inside this module of
 // `solana_program`'s top-level modules, and `solana_sdk`'s glob re-export of

sdk/program/src/rent.rs

@@ -4,14 +4,11 @@
 
 #![allow(clippy::integer_arithmetic)]
 
-use {
-    crate::{clock::DEFAULT_SLOTS_PER_EPOCH, clone_zeroed, copy_field},
-    std::mem::MaybeUninit,
-};
+use {crate::clock::DEFAULT_SLOTS_PER_EPOCH, solana_sdk_macro::CloneZeroed};
 
 /// Configuration of network rent.
 #[repr(C)]
-#[derive(Serialize, Deserialize, PartialEq, Copy, Debug, AbiExample)]
+#[derive(Serialize, Deserialize, PartialEq, CloneZeroed, Copy, Debug, AbiExample)]
 pub struct Rent {
     /// Rental rate in lamports/byte-year.
     pub lamports_per_byte_year: u64,
@@ -62,19 +59,6 @@ impl Default for Rent {
     }
 }
 
-impl Clone for Rent {
-    fn clone(&self) -> Self {
-        clone_zeroed(|cloned: &mut MaybeUninit<Self>| {
-            let ptr = cloned.as_mut_ptr();
-            unsafe {
-                copy_field!(ptr, self, lamports_per_byte_year);
-                copy_field!(ptr, self, exemption_threshold);
-                copy_field!(ptr, self, burn_percent);
-            }
-        })
-    }
-}
-
 impl Rent {
     /// Calculate how much rent to burn from the collected rent.
     ///

sdk/program/src/sysvar/fees.rs

@@ -22,10 +22,9 @@
 
 use {
     crate::{
-        clone_zeroed, copy_field, fee_calculator::FeeCalculator, impl_sysvar_get,
-        program_error::ProgramError, sysvar::Sysvar,
+        fee_calculator::FeeCalculator, impl_sysvar_get, program_error::ProgramError, sysvar::Sysvar,
     },
-    std::mem::MaybeUninit,
+    solana_sdk_macro::CloneZeroed,
 };
 
 crate::declare_deprecated_sysvar_id!("SysvarFees111111111111111111111111111111111", Fees);
@@ -36,22 +35,11 @@ crate::declare_deprecated_sysvar_id!("SysvarFees11111111111111111111111111111111
     note = "Please do not use, will no longer be available in the future"
 )]
 #[repr(C)]
-#[derive(Serialize, Deserialize, Debug, Default, PartialEq, Eq)]
+#[derive(Serialize, Deserialize, Debug, CloneZeroed, Default, PartialEq, Eq)]
 pub struct Fees {
     pub fee_calculator: FeeCalculator,
 }
 
-impl Clone for Fees {
-    fn clone(&self) -> Self {
-        clone_zeroed(|cloned: &mut MaybeUninit<Self>| {
-            let ptr = cloned.as_mut_ptr();
-            unsafe {
-                copy_field!(ptr, self, fee_calculator);
-            }
-        })
-    }
-}
-
 impl Fees {
     pub fn new(fee_calculator: &FeeCalculator) -> Self {
         #[allow(deprecated)]

sdk/src/lib.rs

@@ -13,11 +13,11 @@ pub use signer::signers;
 pub use solana_program::program_stubs;
 pub use solana_program::{
     account_info, address_lookup_table_account, blake3, borsh, bpf_loader, bpf_loader_deprecated,
-    bpf_loader_upgradeable, clock, clone_zeroed, config, copy_field, custom_heap_default,
-    custom_panic_default, debug_account_data, declare_deprecated_sysvar_id, declare_sysvar_id,
-    decode_error, ed25519_program, epoch_schedule, fee_calculator, impl_sysvar_get, incinerator,
-    instruction, keccak, lamports, loader_instruction, loader_upgradeable_instruction, message,
-    msg, native_token, nonce, program, program_error, program_memory, program_option, program_pack,
+    bpf_loader_upgradeable, clock, config, custom_heap_default, custom_panic_default,
+    debug_account_data, declare_deprecated_sysvar_id, declare_sysvar_id, decode_error,
+    ed25519_program, epoch_schedule, fee_calculator, impl_sysvar_get, incinerator, instruction,
+    keccak, lamports, loader_instruction, loader_upgradeable_instruction, message, msg,
+    native_token, nonce, program, program_error, program_memory, program_option, program_pack,
     rent, sanitize, sdk_ids, secp256k1_program, secp256k1_recover, serialize_utils, short_vec,
     slot_hashes, slot_history, stake, stake_history, syscalls, system_instruction, system_program,
     sysvar, unchecked_div_by_const, vote, wasm_bindgen,