From 3ceb44d78a57e53a9f855c7ebc6e849e384a22ff Mon Sep 17 00:00:00 2001
From: Itzik Grossman <itzik@scrtlabs.com>
Date: Tue, 28 Mar 2023 15:46:38 +0300
Subject: [PATCH 1/2] Add ability to query how much gas was used by the
 contract

---
 packages/std/src/imports.rs      | 11 +++++++++++
 packages/std/src/testing/mock.rs |  4 ++++
 packages/std/src/traits.rs       |  2 ++
 3 files changed, 17 insertions(+)

diff --git a/packages/std/src/imports.rs b/packages/std/src/imports.rs
index 9123b9ef6d..a98383b8de 100644
--- a/packages/std/src/imports.rs
+++ b/packages/std/src/imports.rs
@@ -81,6 +81,8 @@ extern "C" {
     fn secp256k1_sign(messages_ptr: u32, private_key_ptr: u32) -> u64;
 
     fn ed25519_sign(messages_ptr: u32, private_key_ptr: u32) -> u64;
+
+    fn check_gas() -> u64;
 }
 
 /// A stateless convenience wrapper around database imports provided by the VM.
@@ -407,6 +409,15 @@ impl Api for ExternalApi {
             error_code => Err(SigningError::unknown_err(error_code)),
         }
     }
+
+    fn check_gas(&self) -> StdResult<u64> {
+        let result = unsafe { check_gas() };
+        if result != 0 {
+            return Err(StdError::generic_err("check_gas error"));
+        }
+
+        Ok(result)
+    }
 }
 
 /// Takes a pointer to a Region and reads the data into a String.
diff --git a/packages/std/src/testing/mock.rs b/packages/std/src/testing/mock.rs
index 91f913c8fa..67e4b004b9 100644
--- a/packages/std/src/testing/mock.rs
+++ b/packages/std/src/testing/mock.rs
@@ -227,6 +227,10 @@ impl Api for MockApi {
     fn ed25519_sign(&self, message: &[u8], private_key: &[u8]) -> Result<Vec<u8>, SigningError> {
         Ok(cosmwasm_crypto::ed25519_sign(message, private_key)?)
     }
+
+    fn check_gas(&self) -> StdResult<u64> {
+        Ok(0)
+    }
 }
 
 /// Returns a default enviroment with height, time, chain_id, and contract address
diff --git a/packages/std/src/traits.rs b/packages/std/src/traits.rs
index 158315f9e1..def7615d96 100644
--- a/packages/std/src/traits.rs
+++ b/packages/std/src/traits.rs
@@ -212,6 +212,8 @@ pub trait Api {
     /// - message: Arbitrary message.
     /// - private key: Raw ED25519 private key (32 bytes)
     fn ed25519_sign(&self, message: &[u8], private_key: &[u8]) -> Result<Vec<u8>, SigningError>;
+
+    fn check_gas(&self) -> StdResult<u64>;
 }
 
 /// A short-hand alias for the two-level query result (1. accessing the contract, 2. executing query in the contract)

From 97122ddc6e1b2a57e2b966f6b0663df95ed5d82b Mon Sep 17 00:00:00 2001
From: Itzik Grossman <itzik@scrtlabs.com>
Date: Wed, 29 Mar 2023 22:01:12 +0300
Subject: [PATCH 2/2] Merge master/gas evaporate

---
 packages/std/src/imports.rs | 2 +-
 packages/std/src/traits.rs  | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/std/src/imports.rs b/packages/std/src/imports.rs
index ab97c5dd31..661393397e 100644
--- a/packages/std/src/imports.rs
+++ b/packages/std/src/imports.rs
@@ -414,7 +414,7 @@ impl Api for ExternalApi {
 
     fn check_gas(&self) -> StdResult<u64> {
         let result = unsafe { check_gas() };
-        if result != 0 {
+        if result == 0 {
             return Err(StdError::generic_err("check_gas error"));
         }
 
diff --git a/packages/std/src/traits.rs b/packages/std/src/traits.rs
index 1b2f90d2cb..e97accfd17 100644
--- a/packages/std/src/traits.rs
+++ b/packages/std/src/traits.rs
@@ -213,6 +213,9 @@ pub trait Api {
     /// - private key: Raw ED25519 private key (32 bytes)
     fn ed25519_sign(&self, message: &[u8], private_key: &[u8]) -> Result<Vec<u8>, SigningError>;
 
+    /// Check Gas.
+    ///
+    /// This function will return the amount of gas currently used by the contract.
     fn check_gas(&self) -> StdResult<u64>;
 
     /// Gas evaporation.