fix: building in zkvm guest

crates/codec/Cargo.toml

@@ -19,11 +19,14 @@ bitvec.workspace = true
 derive_more = { version = "2.0", default-features = false }
 eyre = { workspace = true, optional = true }
 thiserror = { version = "2.0", default-features = false }
-zstd = "=0.13.3"
+zstd = { version = "=0.13.3", optional = true }
+ruzstd = "0.8"
 
 [dev-dependencies]
 eyre.workspace = true
 serde_json = "1.0"
 
 [features]
+default = ["zstd"]
 test-utils = ["dep:eyre", "scroll-l1/test-utils"]
+zstd = ["dep:zstd"]

crates/codec/src/decoding/v2/zstd.rs

@@ -2,14 +2,18 @@
 
 use std::io::Read;
 
-use zstd::Decoder;
+#[cfg(feature = "zstd")]
+use ruzstd as _;
 
 /// The ZSTD magic number for zstd compressed data header.
 const ZSTD_MAGIC_NUMBER: [u8; 4] = [0x28, 0xb5, 0x2f, 0xfd];
 
 /// Uncompress the provided data.
+#[cfg(feature = "zstd")]
 pub fn decompress_blob_data(data: &[u8]) -> Vec<u8> {
+    use zstd::Decoder;
     let mut header_data = ZSTD_MAGIC_NUMBER.to_vec();
+
     header_data.extend_from_slice(data);
 
     // init decoder and owned output data.
@@ -31,3 +35,20 @@ pub fn decompress_blob_data(data: &[u8]) -> Vec<u8> {
 
     output
 }
+
+/// Uncompress the provided data.
+#[cfg(not(feature = "zstd"))]
+pub fn decompress_blob_data(data: &[u8]) -> Vec<u8> {
+    use ruzstd::decoding::StreamingDecoder;
+
+    let mut header_data = ZSTD_MAGIC_NUMBER.to_vec();
+    header_data.extend_from_slice(data);
+
+    // init decoder and owned output data.
+    let mut decoder = StreamingDecoder::new(header_data.as_slice()).unwrap();
+    // heuristic: use data length as the allocated output capacity.
+    let mut output = Vec::with_capacity(header_data.len());
+    decoder.read_to_end(&mut output).unwrap();
+
+    output
+}