Use ruzstd to decompress in Wasm

Allow decompressing bytecodes when running in `wasm32-unknown-unknown`.

Author: jvff

Cargo.lock

@@ -108,6 +108,7 @@ quote = "1.0"
 rand = { version = "0.8.5", default-features = false }
 rand_chacha = { version = "0.3.1", default-features = false }
 rand_distr = { version = "0.4.3", default-features = false }
+ruzstd = "0.7.1"
 k8s-openapi = { version = "0.21.1", features = ["v1_28"] }
 pathdiff = "0.2.1"
 kube = "0.88.1"

Cargo.toml

@@ -56,6 +56,9 @@ tracing-subscriber = { workspace = true, features = ["json", "fmt", "ansi"] }
 wasm-bindgen-futures = { workspace = true, optional = true }
 web-time = { workspace = true, optional = true }
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+ruzstd.workspace = true
+
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 chrono.workspace = true
 rand = { workspace = true, features = ["getrandom", "std", "std_rng"] }

examples/Cargo.lock

@@ -843,8 +843,14 @@ impl fmt::Debug for Bytecode {
 #[derive(Error, Debug)]
 pub enum DecompressionError {
     /// Compressed bytecode is invalid, and could not be decompressed.
+    #[cfg(not(target_arch = "wasm32"))]
     #[error("Bytecode could not be decompressed")]
     InvalidCompressedBytecode(#[source] io::Error),
+
+    /// Compressed bytecode is invalid, and could not be decompressed.
+    #[cfg(target_arch = "wasm32")]
+    #[error("Bytecode could not be decompressed")]
+    InvalidCompressedBytecode(#[from] ruzstd::frame_decoder::FrameDecoderError),
 }
 
 /// A compressed WebAssembly module's bytecode.
@@ -884,7 +890,29 @@ impl TryFrom<&CompressedBytecode> for Bytecode {
     }
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(target_arch = "wasm32")]
+impl TryFrom<&CompressedBytecode> for Bytecode {
+    type Error = DecompressionError;
+
+    fn try_from(compressed_bytecode: &CompressedBytecode) -> Result<Self, Self::Error> {
+        use ruzstd::{io::Read, streaming_decoder::StreamingDecoder};
+
+        let compressed_bytes = &*compressed_bytecode.compressed_bytes;
+        let mut bytes = Vec::new();
+        let mut decoder = StreamingDecoder::new(compressed_bytes)?;
+
+        // Decode multiple frames, if present
+        // (https://github.com/KillingSpark/zstd-rs/issues/57)
+        while !decoder.get_ref().is_empty() {
+            decoder
+                .read_to_end(&mut bytes)
+                .expect("Reading from a slice in memory should not result in IO errors");
+        }
+
+        Ok(Bytecode { bytes })
+    }
+}
+
 impl TryFrom<CompressedBytecode> for Bytecode {
     type Error = DecompressionError;