Return sysvars via syscalls (#16422)

sdk/program/src/program_stubs.rs

@@ -2,7 +2,10 @@
 
 #![cfg(not(target_arch = "bpf"))]
 
-use crate::{account_info::AccountInfo, entrypoint::ProgramResult, instruction::Instruction};
+use crate::{
+    account_info::AccountInfo, entrypoint::ProgramResult, instruction::Instruction,
+    program_error::UNSUPPORTED_SYSVAR,
+};
 use std::sync::{Arc, RwLock};
 
 lazy_static::lazy_static! {
@@ -31,6 +34,19 @@ pub trait SyscallStubs: Sync + Send {
         sol_log("SyscallStubs: sol_invoke_signed() not available");
         Ok(())
     }
+
+    fn sol_get_clock_sysvar(&self, _var_addr: *mut u8) -> u64 {
+        UNSUPPORTED_SYSVAR
+    }
+    fn sol_get_epoch_schedule_sysvar(&self, _var_addr: *mut u8) -> u64 {
+        UNSUPPORTED_SYSVAR
+    }
+    fn sol_get_fees_sysvar(&self, _var_addr: *mut u8) -> u64 {
+        UNSUPPORTED_SYSVAR
+    }
+    fn sol_get_rent_sysvar(&self, _var_addr: *mut u8) -> u64 {
+        UNSUPPORTED_SYSVAR
+    }
 }
 
 struct DefaultSyscallStubs {}
@@ -61,3 +77,22 @@ pub(crate) fn sol_invoke_signed(
         .unwrap()
         .sol_invoke_signed(instruction, account_infos, signers_seeds)
 }
+
+pub(crate) fn sol_get_clock_sysvar(var_addr: *mut u8) -> u64 {
+    SYSCALL_STUBS.read().unwrap().sol_get_clock_sysvar(var_addr)
+}
+
+pub(crate) fn sol_get_epoch_schedule_sysvar(var_addr: *mut u8) -> u64 {
+    SYSCALL_STUBS
+        .read()
+        .unwrap()
+        .sol_get_epoch_schedule_sysvar(var_addr)
+}
+
+pub(crate) fn sol_get_fees_sysvar(var_addr: *mut u8) -> u64 {
+    SYSCALL_STUBS.read().unwrap().sol_get_fees_sysvar(var_addr)
+}
+
+pub(crate) fn sol_get_rent_sysvar(var_addr: *mut u8) -> u64 {
+    SYSCALL_STUBS.read().unwrap().sol_get_rent_sysvar(var_addr)
+}