1 files changed, 30 insertions, 0 deletions
diff --git a/third_party/rust/wasmparser/src/readers/component/start.rs b/third_party/rust/wasmparser/src/readers/component/start.rs
new file mode 100644
index 0000000000..dc01fa4340
--- /dev/null
+++ b/third_party/rust/wasmparser/src/readers/component/start.rs
@@ -0,0 +1,30 @@
+use crate::limits::{MAX_WASM_FUNCTION_RETURNS, MAX_WASM_START_ARGS};
+use crate::{BinaryReader, FromReader, Result};
+
+/// Represents the start function in a WebAssembly component.
+#[derive(Debug, Clone)]
+pub struct ComponentStartFunction {
+    /// The index to the start function.
+    pub func_index: u32,
+    /// The start function arguments.
+    ///
+    /// The arguments are specified by value index.
+    pub arguments: Box<[u32]>,
+    /// The number of expected results for the start function.
+    pub results: u32,
+}
+
+impl<'a> FromReader<'a> for ComponentStartFunction {
+    fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
+        let func_index = reader.read_var_u32()?;
+        let arguments = reader
+            .read_iter(MAX_WASM_START_ARGS, "start function arguments")?
+            .collect::<Result<_>>()?;
+        let results = reader.read_size(MAX_WASM_FUNCTION_RETURNS, "start function results")? as u32;
+        Ok(ComponentStartFunction {
+            func_index,
+            arguments,
+            results,
+        })
+    }
+}