From d1474cdaa089282e53d4fae4443df54c3d51ff78 Mon Sep 17 00:00:00 2001
From: Maksim Kurnikov <maxim.kurnikov@gmail.com>
Date: Tue, 10 Nov 2020 13:57:35 +0300
Subject: [PATCH] add meta block: for block height

---
 executor/src/execution.rs          |  8 ++++-
 executor/src/meta.rs               |  2 ++
 executor/src/oracles.rs            | 11 +++++++
 executor/tests/test_executor.rs    | 53 ++++++++++++++++++++++++++++++
 resources/assets/stdlib/block.move | 15 +++++++++
 5 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 resources/assets/stdlib/block.move

diff --git a/executor/src/execution.rs b/executor/src/execution.rs
index bba39194..e3fb5f68 100644
--- a/executor/src/execution.rs
+++ b/executor/src/execution.rs
@@ -19,7 +19,7 @@ use crate::explain::{
     explain_type_error,
 };
 use crate::meta::ExecutionMeta;
-use crate::oracles::{oracle_coins_module, time_metadata, coin_balance_metadata};
+use crate::oracles::{oracle_coins_module, time_metadata, coin_balance_metadata, block_metadata};
 use move_vm_runtime::logging::NoContextLog;
 use crate::session::ConstsMap;
 
@@ -176,6 +176,7 @@ pub fn execute_script(
         current_time,
         aborts_with,
         status,
+        block,
         dry_run,
     } = meta;
     if !oracle_prices.is_empty() {
@@ -194,6 +195,11 @@ pub fn execute_script(
             lcs::to_bytes(&current_time).unwrap(),
         );
     }
+    let block_height = block.unwrap_or(100);
+    ds.resources.insert(
+        (std_addr, block_metadata()),
+        lcs::to_bytes(&block_height).unwrap(),
+    );
     for (price_tag, val) in oracle_prices {
         ds.resources
             .insert((std_addr, price_tag), lcs::to_bytes(&val).unwrap());
diff --git a/executor/src/meta.rs b/executor/src/meta.rs
index 7f416c7d..659e394c 100644
--- a/executor/src/meta.rs
+++ b/executor/src/meta.rs
@@ -33,6 +33,7 @@ pub struct ExecutionMeta {
     pub accounts_balance: Vec<(AccountAddress, String, u128)>,
     pub oracle_prices: Vec<(StructTag, u128)>,
     pub current_time: Option<u64>,
+    pub block: Option<u64>,
     pub aborts_with: Option<u64>,
     pub status: Option<u64>,
     pub dry_run: bool,
@@ -86,6 +87,7 @@ impl ExecutionMeta {
                     eprintln!("Unknown status code name: {:?}", val);
                 }
             }
+            "block" => self.block = Some(val.parse().unwrap()),
             "dry_run" => self.dry_run = val.parse().unwrap(),
             _ => eprintln!("Unimplemented meta key, {:?}", key),
         }
diff --git a/executor/src/oracles.rs b/executor/src/oracles.rs
index a6feabf6..c64156b2 100644
--- a/executor/src/oracles.rs
+++ b/executor/src/oracles.rs
@@ -11,6 +11,8 @@ const ACCOUNT_BALANCE_STRUCT: &str = "Balance";
 const XFI_MODULE: &str = "XFI";
 const XFI_RESOURCE: &str = "T";
 
+const BLOCK_RESOURCE: &str = "BlockMetadata";
+
 /// Currency price.
 #[derive(Debug, PartialEq, Eq)]
 pub struct Price {
@@ -52,6 +54,15 @@ pub fn oracle_metadata(first: &str, second: &str) -> StructTag {
     }
 }
 
+pub fn block_metadata() -> StructTag {
+    StructTag {
+        address: CORE_CODE_ADDRESS,
+        name: Identifier::new(BLOCK_RESOURCE).expect("Valid module name."),
+        module: Identifier::new("Block").expect("Valid module name."),
+        type_params: vec![],
+    }
+}
+
 pub fn time_metadata() -> StructTag {
     StructTag {
         address: CORE_CODE_ADDRESS,
diff --git a/executor/tests/test_executor.rs b/executor/tests/test_executor.rs
index bd0d006b..7e175c1d 100644
--- a/executor/tests/test_executor.rs
+++ b/executor/tests/test_executor.rs
@@ -1037,3 +1037,56 @@ script {
         "Expected error: Execution failed with an arithmetic error (i.e., integer overflow/underflow, div/mod by zero, or invalid shift) in script at code offset 2"
     );
 }
+
+#[test]
+fn test_set_block_height() {
+    let _pool = ConstPool::new();
+
+    let text = r"
+/// block: 1024
+script {
+    use 0x1::Block;
+
+    fun success() {
+        assert(Block::get_current_block_height() == 1024, 1);
+    }
+}    ";
+
+    execute_script(
+        MoveFile::with_content(script_path(), text),
+        vec![stdlib_mod("block.move")],
+        "libra",
+        "0x3",
+        vec![],
+    )
+    .unwrap()
+    .last()
+    .unwrap()
+    .effects();
+}
+
+#[test]
+fn test_block_height_default_100() {
+    let _pool = ConstPool::new();
+
+    let text = r"
+script {
+    use 0x1::Block;
+
+    fun success() {
+        assert(Block::get_current_block_height() == 100, 1);
+    }
+}    ";
+
+    execute_script(
+        MoveFile::with_content(script_path(), text),
+        vec![stdlib_mod("block.move")],
+        "libra",
+        "0x3",
+        vec![],
+    )
+    .unwrap()
+    .last()
+    .unwrap()
+    .effects();
+}
diff --git a/resources/assets/stdlib/block.move b/resources/assets/stdlib/block.move
new file mode 100644
index 00000000..b4e47f20
--- /dev/null
+++ b/resources/assets/stdlib/block.move
@@ -0,0 +1,15 @@
+address 0x1 {
+
+module Block {
+
+    resource struct BlockMetadata {
+        // height of the current block
+        height: u64,
+    }
+
+    // Get the current block height
+    public fun get_current_block_height(): u64 acquires BlockMetadata {
+        borrow_global<BlockMetadata>(0x1).height
+    }
+}
+}