feat: use the build script to download the cairo crate from the stark…

…ware release page

crates/starknet_sierra_compile/build.rs

@@ -0,0 +1,75 @@
+use std::path::Path;
+use std::process::Command;
+use std::{env, fs};
+
+fn main() {
+    println!("cargo:rerun-if-changed=../../Cargo.lock");
+    println!("cargo:rerun-if-changed=build.rs");
+
+    download_cairo();
+}
+
+/// Downloads the Cairo crate from StarkWares release page and extracts its contents into the
+/// `target` directory. This crate includes the `starknet-sierra-compile` binary, which is used to
+/// compile Sierra to Casm. In this crate (`starknet_sierra_compile`), the binary is executed as a
+/// subprocess whenever Sierra compilation is required.
+fn download_cairo() {
+    let out_dir = env::var("OUT_DIR").expect("Failed to get the OUT_DIR environment variable");
+    // Navigate from this crate's build folder to reach the `target/BUILD_FLAVOR` directory.
+    let target_dir = Path::new(&out_dir)
+        .ancestors()
+        .nth(3)
+        .expect("Failed to navigate up three levels from OUT_DIR");
+    let cairo_folder_dir = target_dir.join("cairo");
+
+    if cairo_folder_dir.exists() {
+        println!(
+            "The cairo crate already exists in the target directory: {:?}",
+            cairo_folder_dir.display()
+        );
+        return;
+    }
+
+    let url = "https://github.com/starkware-libs/cairo/releases/download/v2.7.0-rc.1/release-x86_64-unknown-linux-musl.tar.gz";
+    let download_path = target_dir.join("release-x86_64-unknown-linux-musl.tar.gz");
+
+    // TODO(Arni): Consider using use reqwest::blocking::get; instead of wget. Then consider using
+    // the tar crate to extract the tar.gz file.
+    let wget_command_execution_status = Command::new("wget")
+        .arg("-O")
+        .arg(&download_path)
+        .arg(url)
+        .current_dir(target_dir)
+        .status()
+        .expect("Failed to execute wget command");
+
+    if !wget_command_execution_status.success() {
+        panic!("Failed to download the cairo tar");
+    }
+
+    println!("Successfully downloaded the cairo tar");
+
+    let tar_command_execution_status = Command::new("tar")
+        .arg("-xvf")
+        .arg(&download_path)
+        .current_dir(target_dir)
+        .status()
+        .expect("Failed to execute tar command");
+
+    // Clean up the downloaded file.
+    fs::remove_file(&download_path).expect("Failed to remove the downloaded file");
+
+    println!("Successfully removed the downloaded tar.gz file");
+
+    // Assert the unzip command was succesful.
+    if !tar_command_execution_status.success() {
+        panic!("Failed to extract the cairo crate from zip");
+    }
+
+    assert!(cairo_folder_dir.exists(), "cairo folder was not created as expected.");
+
+    println!(
+        "Successfully extracted the cairo crate into the target directory: {:?}",
+        cairo_folder_dir.display()
+    );
+}