From 49c14571d5538211094ea3dddf8654288265f4f1 Mon Sep 17 00:00:00 2001
From: Michael Vines <mvines@gmail.com>
Date: Mon, 11 Oct 2021 16:31:17 -0700
Subject: [PATCH] Add test to ensure instructions sysvar behaves as expected
 from within a CPI

---
 .../rust/instruction_introspection/src/lib.rs | 27 ++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/programs/bpf/rust/instruction_introspection/src/lib.rs b/programs/bpf/rust/instruction_introspection/src/lib.rs
index cf3a0685808c91..6e20f732564e07 100644
--- a/programs/bpf/rust/instruction_introspection/src/lib.rs
+++ b/programs/bpf/rust/instruction_introspection/src/lib.rs
@@ -2,14 +2,21 @@
 
 extern crate solana_program;
 use solana_program::{
-    account_info::next_account_info, account_info::AccountInfo, entrypoint,
-    entrypoint::ProgramResult, msg, program_error::ProgramError, pubkey::Pubkey,
+    account_info::next_account_info,
+    account_info::AccountInfo,
+    entrypoint,
+    entrypoint::ProgramResult,
+    instruction::{AccountMeta, Instruction},
+    msg,
+    program::invoke,
+    program_error::ProgramError,
+    pubkey::Pubkey,
     sysvar::instructions,
 };
 
 entrypoint!(process_instruction);
 fn process_instruction(
-    _program_id: &Pubkey,
+    program_id: &Pubkey,
     accounts: &[AccountInfo],
     instruction_data: &[u8],
 ) -> ProgramResult {
@@ -41,5 +48,19 @@ fn process_instruction(
 
     msg!(&format!("data[0]: {}", instruction.data[0]));
     msg!(&format!("index: {}", current_instruction));
+
+    if instruction_data.len() == 2 {
+        // CPI ourself with the same arguments to confirm the instructions sysvar reports the same
+        // results from within a CPI
+        invoke(
+            &Instruction::new_with_bytes(
+                *program_id,
+                &[instruction_data[0], instruction_data[1], 1],
+                vec![AccountMeta::new_readonly(instructions::id(), false)],
+            ),
+            &[instruction_accounts.clone()],
+        )?;
+    }
+
     Ok(())
 }