Download compressed gz image from remote source

Accept url arguments for remote image download and copy.
Implements async support for use of reqwest. Bmap file is searched as in
local option in the current file with same name and the extension ".bmap"

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") => {
@@ -86,12 +92,30 @@ 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")
     }
 
-    let bmap = find_bmap(&c.image).ok_or_else(|| anyhow!("Couldn't find bmap file"))?;
+    let bmap = match input_type {
+        InputType::Local => {
+            find_bmap(&c.image).ok_or_else(|| anyhow!("Couldn't find bmap file"))?
+        },
+        InputType::Remote(_) => find_bmap(Path::new(&c.image.file_name().unwrap())).ok_or_else(|| anyhow!("Couldn't find bmap file"))?,
+    };
     println!("Found bmap file: {}", bmap.display());
 
     let mut b = File::open(&bmap).context("Failed to open bmap file")?;
@@ -109,18 +133,22 @@ 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,
     }
 }