fold in sysvar errors as previously

Author: rustopian

sysvar/src/lib.rs

@@ -183,7 +183,8 @@ macro_rules! impl_sysvar_get {
     };
     // Variant for sysvars with padding at the end. Loads bincode-serialized data
     // (size - padding bytes) and zeros the padding to avoid undefined behavior.
-    // Only supports sysvars where padding is at the end of the layout.
+    // Only supports sysvars where padding is at the end of the layout. Caller
+    // must supply the correct number of padding bytes.
     ($sysvar_id:expr, $padding:literal) => {
         fn get() -> Result<Self, $crate::__private::ProgramError> {
             let mut var = core::mem::MaybeUninit::<Self>::uninit();
@@ -193,12 +194,19 @@ macro_rules! impl_sysvar_get {
             // SAFETY: The allocation is valid for `size_of::<Self>()`. We load
             // `(size - padding)` bytes from the syscall, which matches bincode
             // serialization. The remaining `padding` bytes are then zeroed.
-            unsafe {
-                $crate::get_sysvar_unchecked(var_addr, sysvar_id_ptr, 0, length as u64)?;
-                var_addr.add(length).write_bytes(0, $padding);
-                // SAFETY: All bytes now initialized: syscall filled data
-                // bytes and we zeroed padding.
-                Ok(var.assume_init())
+            let result =
+                unsafe { $crate::get_sysvar_unchecked(var_addr, sysvar_id_ptr, 0, length as u64) };
+            match result {
+                Ok(()) => {
+                    // SAFETY: All bytes now initialized: syscall filled data
+                    // bytes and we zeroed padding.
+                    unsafe {
+                        var_addr.add(length).write_bytes(0, $padding);
+                        Ok(var.assume_init())
+                    }
+                }
+                // Unexpected errors are folded into `UnsupportedSysvar`.
+                Err(_) => Err($crate::__private::ProgramError::UnsupportedSysvar),
             }
         }
     };