Retry downloads on network failure

Fixes #1280

build_system/prepare.rs

@@ -8,7 +8,7 @@
 use super::build_sysroot::{BUILD_SYSROOT, ORIG_BUILD_SYSROOT, SYSROOT_RUSTC_VERSION, SYSROOT_SRC};
 use super::path::{Dirs, RelPath};
 use super::rustc_info::{get_file_name, get_rustc_version};
-use super::utils::{copy_dir_recursively, spawn_and_wait, Compiler};
+use super::utils::{copy_dir_recursively, retry_spawn_and_wait, spawn_and_wait, Compiler};
 
 pub(crate) fn prepare(dirs: &Dirs) {
     if RelPath::DOWNLOAD.to_path(dirs).exists() {
@@ -140,8 +140,22 @@ fn clone_repo_shallow_github(dirs: &Dirs, download_dir: &Path, user: &str, repo:
 
     // Download zip archive
     let mut download_cmd = Command::new("curl");
-    download_cmd.arg("--location").arg("--output").arg(&archive_file).arg(archive_url);
-    spawn_and_wait(download_cmd);
+    download_cmd
+        .arg("--max-time")
+        .arg("600")
+        .arg("-y")
+        .arg("30")
+        .arg("-Y")
+        .arg("10")
+        .arg("--connect-timeout")
+        .arg("30")
+        .arg("--continue-at")
+        .arg("-")
+        .arg("--location")
+        .arg("--output")
+        .arg(&archive_file)
+        .arg(archive_url);
+    retry_spawn_and_wait(5, download_cmd);
 
     // Unpack tar archive
     let mut unpack_cmd = Command::new("tar");

build_system/utils.rs

@@ -188,6 +188,22 @@ pub(crate) fn spawn_and_wait(mut cmd: Command) {
     }
 }
 
+// Based on the retry function in rust's src/ci/shared.sh
+#[track_caller]
+pub(crate) fn retry_spawn_and_wait(tries: u64, mut cmd: Command) {
+    for i in 1..tries+1 {
+        if i != 1 {
+            println!("Command failed. Attempt {i}/{tries}:");
+        }
+        if cmd.spawn().unwrap().wait().unwrap().success() {
+            return;
+        }
+        std::thread::sleep(std::time::Duration::from_secs(i * 5));
+    }
+    println!("The command has failed after {tries} attempts.");
+    process::exit(1);
+}
+
 #[track_caller]
 pub(crate) fn spawn_and_wait_with_input(mut cmd: Command, input: String) -> String {
     let mut child = cmd