Download compressed gz image from remote source

Accept url arguments for remote image download and copy.
Implements async support for use of reqwest.

Signed-off-by: Rafael Garcia Ruiz <rafael.garcia@collabora.com>

bmap-rs/Cargo.toml

@@ -12,3 +12,6 @@ anyhow = "1"
 structopt = "0.3"
 nix = "0.25"
 flate2 = "1"
+tokio = { version = "1.21.2", features = ["full"] }
+reqwest = { version = "0.11.12"}
+bytes = "1.2.1"

bmap-rs/src/main.rs

@@ -1,7 +1,9 @@
 use anyhow::{anyhow, bail, Context, Result};
 use bmap::{Bmap, Discarder, SeekForward};
+use bytes::Buf;
 use flate2::read::GzDecoder;
 use nix::unistd::ftruncate;
+use reqwest::Url;
 use std::ffi::OsStr;
 use std::fs::File;
 use std::io::Read;
@@ -14,7 +16,11 @@ struct Copy {
     image: PathBuf,
     dest: PathBuf,
 }
-
+#[derive(PartialEq)]
+enum InputType {
+    Local,
+    Remote(Url),
+}
 #[derive(StructOpt, Debug)]
 enum Command {
     Copy(Copy),
@@ -75,7 +81,7 @@ impl SeekForward for Decoder {
     }
 }
 
-fn setup_input(path: &Path) -> Result<Decoder> {
+fn setup_local_input(path: &Path) -> Result<Decoder> {
     let f = File::open(path)?;
     match path.extension().and_then(OsStr::to_str) {
         Some("gz") => {
@@ -86,8 +92,21 @@ fn setup_input(path: &Path) -> Result<Decoder> {
     }
 }
 
-fn copy(c: Copy) -> Result<()> {
-    if !c.image.exists() {
+async fn setup_remote_input(url: &Url) -> Result<Decoder> {
+    if url.to_file_path().unwrap().extension().unwrap() != "gz" {
+        bail!("Image file format not implemented")
+    }
+    let data = reqwest::get(url.clone()).await?.bytes().await?;
+    let reader = GzDecoder::new(data.reader());
+    Ok(Decoder::new(Discarder::new(reader)))
+}
+
+async fn copy(c: Copy) -> Result<()> {
+    let input_type = match Url::parse(c.image.to_str().unwrap()) {
+        Ok(url) => InputType::Remote(url),
+        Err(_) => InputType::Local,
+    };
+    if !c.image.exists() && input_type == InputType::Local {
         bail!("Image file doesn't exist")
     }
 
@@ -109,18 +128,22 @@ fn copy(c: Copy) -> Result<()> {
             .context("Failed to truncate file")?;
     }
 
-    let mut input = setup_input(&c.image)?;
+    let mut input = match input_type {
+        InputType::Local => setup_local_input(&c.image)?,
+        InputType::Remote(url) => setup_remote_input(&url).await?,
+    };
     bmap::copy(&mut input, &mut output, &bmap)?;
     println!("Done: Syncing...");
     output.sync_all().expect("Sync failure");
 
     Ok(())
 }
 
-fn main() -> Result<()> {
+#[tokio::main]
+async fn main() -> Result<()> {
     let opts = Opts::from_args();
 
     match opts.command {
-        Command::Copy(c) => copy(c),
+        Command::Copy(c) => copy(c).await,
     }
 }