Implement seal_code_hash and seal_own_code_hash (#1205)

* seal_code_hash() added

* +docs

* seal_own_code_hash() added

* ci errors fixes

* more ci fixes

* more ci fixes

* refactored on what to return

* Apply suggestions from code review

Co-authored-by: Michael Müller <mich@elmueller.net>

* fix: new funcs are in TypedEnvBackend trait

* errors section to code_hash doc + own_code_hash to return non-wrapped val

* bug caught and fixed: wrong return val for seal_own_code_hash

* Update crates/env/src/api.rs

Co-authored-by: Michael Müller <mich@elmueller.net>

* Apply suggestions from code review

Co-authored-by: Michael Müller <mich@elmueller.net>

* own_code_hash to return Result, as there could be decoding issues

* bugfix (e2e testing caught)

* ci fix

* Apply suggestions from code review

Co-authored-by: Michael Müller <mich@elmueller.net>

* Revert "Apply suggestions from code review"

This reverts commit 5591d95.

Co-authored-by: Michael Müller <mich@elmueller.net>

crates/env/src/api.rs

@@ -514,6 +514,35 @@ where
     })
 }
 
+/// Retrieves the code hash of the contract at the specified account id.
+///
+/// # Errors
+///
+/// - If no code hash was found for the specified account id.
+/// - If the returned value cannot be properly decoded.
+pub fn code_hash<E>(account: &E::AccountId) -> Result<E::Hash>
+where
+    E: Environment,
+{
+    <EnvInstance as OnInstance>::on_instance(|instance| {
+        TypedEnvBackend::code_hash::<E>(instance, account)
+    })
+}
+
+/// Retrieves the code hash of the currently executing contract.
+///
+/// # Errors
+///
+/// If the returned value cannot be properly decoded.
+pub fn own_code_hash<E>() -> Result<E::Hash>
+where
+    E: Environment,
+{
+    <EnvInstance as OnInstance>::on_instance(|instance| {
+        TypedEnvBackend::own_code_hash::<E>(instance)
+    })
+}
+
 /// Checks whether the caller of the current contract is the origin of the whole call stack.
 ///
 /// Prefer this over [`is_contract`] when checking whether your contract is being called by

crates/env/src/backend.rs

@@ -447,4 +447,22 @@ pub trait TypedEnvBackend: EnvBackend {
     fn caller_is_origin<E>(&mut self) -> bool
     where
         E: Environment;
+
+    /// Retrieves the code hash of the contract at the given `account` id.
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`code_hash`][`crate::code_hash`]
+    fn code_hash<E>(&mut self, account: &E::AccountId) -> Result<E::Hash>
+    where
+        E: Environment;
+
+    /// Retrieves the code hash of the currently executing contract.
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`own_code_hash`][`crate::own_code_hash`]
+    fn own_code_hash<E>(&mut self) -> Result<E::Hash>
+    where
+        E: Environment;
 }

crates/env/src/engine/off_chain/impls.rs

@@ -486,4 +486,18 @@ impl TypedEnvBackend for EnvInstance {
     {
         unimplemented!("off-chain environment does not support cross-contract calls")
     }
+
+    fn code_hash<E>(&mut self, _account: &E::AccountId) -> Result<E::Hash>
+    where
+        E: Environment,
+    {
+        unimplemented!("off-chain environment does not support `code_hash`")
+    }
+
+    fn own_code_hash<E>(&mut self) -> Result<E::Hash>
+    where
+        E: Environment,
+    {
+        unimplemented!("off-chain environment does not support `own_code_hash`")
+    }
 }

crates/env/src/engine/on_chain/ext.rs

@@ -347,6 +347,17 @@ mod sys {
             message_hash_ptr: Ptr32<[u8]>,
             output_ptr: Ptr32Mut<[u8]>,
         ) -> ReturnCode;
+
+        pub fn seal_code_hash(
+            account_id_ptr: Ptr32<[u8]>,
+            output_ptr: Ptr32Mut<[u8]>,
+            output_len_ptr: Ptr32Mut<u32>,
+        ) -> ReturnCode;
+
+        pub fn seal_own_code_hash(
+            output_ptr: Ptr32Mut<[u8]>,
+            output_len_ptr: Ptr32Mut<u32>,
+        );
     }
 }
 
@@ -676,3 +687,25 @@ pub fn caller_is_origin() -> bool {
     let ret_val = unsafe { sys::seal_caller_is_origin() };
     ret_val.into_bool()
 }
+
+pub fn code_hash(account_id: &[u8], output: &mut [u8]) -> Result {
+    let mut output_len = output.len() as u32;
+    let ret_val = unsafe {
+        sys::seal_code_hash(
+            Ptr32::from_slice(account_id),
+            Ptr32Mut::from_slice(output),
+            Ptr32Mut::from_ref(&mut output_len),
+        )
+    };
+    ret_val.into()
+}
+
+pub fn own_code_hash(output: &mut [u8]) {
+    let mut output_len = output.len() as u32;
+    unsafe {
+        sys::seal_own_code_hash(
+            Ptr32Mut::from_slice(output),
+            Ptr32Mut::from_ref(&mut output_len),
+        )
+    }
+}

crates/env/src/engine/on_chain/impls.rs

@@ -512,4 +512,28 @@ impl TypedEnvBackend for EnvInstance {
     {
         ext::caller_is_origin()
     }
+
+    fn code_hash<E>(&mut self, account_id: &E::AccountId) -> Result<E::Hash>
+    where
+        E: Environment,
+    {
+        let mut scope = self.scoped_buffer();
+        let output = scope.take(32);
+        scope.append_encoded(account_id);
+        let enc_account_id = scope.take_appended();
+
+        ext::code_hash(enc_account_id, output)?;
+        let hash = scale::Decode::decode(&mut &output[..])?;
+        Ok(hash)
+    }
+
+    fn own_code_hash<E>(&mut self) -> Result<E::Hash>
+    where
+        E: Environment,
+    {
+        let output = &mut self.scoped_buffer().take(32);
+        ext::own_code_hash(output);
+        let hash = scale::Decode::decode(&mut &output[..])?;
+        Ok(hash)
+    }
 }

crates/lang/src/env_access.rs

@@ -901,4 +901,68 @@ where
     pub fn caller_is_origin(self) -> bool {
         ink_env::caller_is_origin::<E>()
     }
+
+    /// Returns the code hash of the contract at the given `account` id.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use ink_lang as ink;
+    /// # #[ink::contract]
+    /// # pub mod my_contract {
+    /// #     #[ink(storage)]
+    /// #     pub struct MyContract { }
+    /// #
+    /// #     impl MyContract {
+    /// #         #[ink(constructor)]
+    /// #         pub fn new() -> Self {
+    /// #             Self {}
+    /// #         }
+    /// #
+    /// #[ink(message)]
+    /// pub fn code_hash(&mut self, account_id: AccountId) -> Option<Hash> {
+    ///     self.env().code_hash(&account_id).ok()
+    /// }
+    /// #    }
+    /// # }
+    /// ```
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`ink_env::code_hash`]
+    pub fn code_hash(self, account_id: &E::AccountId) -> Result<E::Hash> {
+        ink_env::code_hash::<E>(account_id)
+    }
+
+    /// Returns the code hash of the contract at the given `account` id.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use ink_lang as ink;
+    /// # #[ink::contract]
+    /// # pub mod my_contract {
+    /// #     #[ink(storage)]
+    /// #     pub struct MyContract { }
+    /// #
+    /// #     impl MyContract {
+    /// #         #[ink(constructor)]
+    /// #         pub fn new() -> Self {
+    /// #             Self {}
+    /// #         }
+    /// #
+    /// #[ink(message)]
+    /// pub fn own_code_hash(&mut self) -> Hash {
+    ///     self.env().own_code_hash().expect("contract should have a code hash")
+    /// }
+    /// #    }
+    /// # }
+    /// ```
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`ink_env::own_code_hash`]
+    pub fn own_code_hash(self) -> Result<E::Hash> {
+        ink_env::own_code_hash::<E>()
+    }
 }