added async read

src/info.rs

@@ -0,0 +1,13 @@
+//! Prints the information found in graph in different ways
+use super::*;
+
+use data::HierarchicalINodeGraph;
+use config::Config;
+
+/// Print the most basic info
+pub fn print_basic_max_info(cfg: &Config, graph: &HierarchicalINodeGraph)
+{
+    cfg_println!(Quiet; cfg, "Max size file: {:?}", graph.path_max_size_for(data::FsKind::File));
+    cfg_println!(Quiet; cfg, "Max size dir: {:?}", graph.path_max_size_for(data::FsKind::Directory));
+    cfg_println!(Quiet; cfg, "Max size all: {:?}", graph.path_max_size());
+}

src/main.rs

@@ -37,6 +37,7 @@ mod config;
 mod state;
 mod arg;
 mod work;
+mod info;
 #[cfg(feature="inspect")] mod serial;
 #[cfg(feature="defer-drop")] mod defer_drop;
 
@@ -151,9 +152,7 @@ async fn normal(cfg: config::Config) -> eyre::Result<()>
 	}
     };
 
-    cfg_println!(Quiet; cfg, "Max size file: {:?}", graph.path_max_size_for(data::FsKind::File));
-    cfg_println!(Quiet; cfg, "Max size dir: {:?}", graph.path_max_size_for(data::FsKind::Directory));
-    cfg_println!(Quiet; cfg, "Max size all: {:?}", graph.path_max_size());
+    info::print_basic_max_info(&cfg, &graph);
 
     #[cfg(feature="inspect")] 
     match writer.await {

src/serial.rs

@@ -2,6 +2,7 @@
 use super::*;
 use tokio::prelude::*;
 use std::ops::{Deref, DerefMut};
+use serde::de::DeserializeOwned;
 
 use async_compression::tokio_02::write::{
     BzEncoder,
@@ -12,6 +13,9 @@ type Compressor<T> = BzEncoder<T>;
 type Decompressor<T> = BzDecoder<T>;
 
 const DEFER_DROP_SIZE_FLOOR: usize = 1024 * 1024; // 1 MB
+const DESERIALISE_OBJECT_READ_LIMIT: usize = 1024 * 1024 * 1024 * 2; // 2GB
+
+const BUFFER_SIZE: usize = 4096;
 
 #[derive(Debug)]
 enum MaybeCompressor<'a, T>
@@ -89,6 +93,63 @@ where T: AsyncWrite + Unpin + Send + 'a
     }
 }
 
+async fn copy_with_limit<R,W>(mut from: R, mut to: W) -> io::Result<usize>
+where R: AsyncRead + Unpin,
+      W: AsyncWrite + Unpin
+{
+    let mut buffer = [0u8; BUFFER_SIZE];
+    
+    let mut read;
+    let mut done=0;
+    while {read = from.read(&mut buffer[..]).await?; read>0}
+    {
+	to.write_all(&buffer[..read]).await?;
+	done+=read;
+
+	if done > DESERIALISE_OBJECT_READ_LIMIT {
+	    return Err(io::Error::new(io::ErrorKind::ConnectionAborted, eyre!("Exceeded limit, aborting.")
+				      .with_section(|| DESERIALISE_OBJECT_READ_LIMIT.header("Object read size limit was"))
+				      .with_section(|| done.header("Currently read"))));
+	}
+    }
+    Ok(done)
+}
+
+/// Deserialise an object from this stream asynchronously
+///
+/// # Note
+/// If the stream is compressed, `compressed` must be set to true or an error will be produced.
+/// An autodetect feature may be added in the future
+pub async fn read_async<T: DeserializeOwned + Send + 'static, R>(mut from: R, compressed: bool) -> eyre::Result<T>
+where R: AsyncRead + Unpin + Send
+{
+    let sect_type_name = || std::any::type_name::<T>().header("Type trying to deserialise was");
+    let sect_stream_type_name = || std::any::type_name::<R>().header("Stream type was");
+
+    let vec = {
+	let mut vec = Vec::new();
+	let mut writer = MaybeCompressor::new(&mut vec, compressed.then(|| CompKind::Decompress));
+
+	copy_with_limit(&mut from, writer.deref_mut()).await
+	    .wrap_err(eyre!("Failed to copy stream into in-memory buffer"))
+	    .with_section(sect_type_name.clone())
+	    .with_section(sect_stream_type_name.clone())?;
+	
+	writer.flush().await.wrap_err(eyre!("Failed to flush decompression stream"))?;
+	writer.shutdown().await.wrap_err(eyre!("Failed to shutdown decompression stream"))?;
+	vec
+    };
+
+    tokio::task::spawn_blocking(move || {
+	(serde_cbor::from_slice(&vec[..])
+         .wrap_err(eyre!("Failed to deseralised decompressed data"))
+	 .with_section(sect_type_name.clone())
+	 .with_section(sect_stream_type_name.clone()),
+	 
+	 {drop!(vec vec);}).0
+    }).await.wrap_err(eyre!("Panic while deserialising decompressed data"))?
+}
+
 /// Serialise this object asynchronously
 ///
 /// # Note
@@ -211,7 +272,7 @@ mod prealloc {
     pub fn read_prealloc<T: serde::de::DeserializeOwned>(file: &File) -> eyre::Result<T>
     {
 	let map = unsafe { Mmap::map(file) }
-	.wrap_err(eyre!("Failed to map file for read + write"))
+	.wrap_err(eyre!("Failed to map file for read"))
 	    .with_section(|| file.as_raw_fd().header("fd was"))
 	    .with_suggestion(|| "Do we have the premissions for both reading and writing of this file and fd?")?;