feat: introduce a build script checking licenses

Signed-off-by: ljedrz <ljedrz@gmail.com>

.rustfmt.toml

@@ -9,7 +9,6 @@ use_try_shorthand = true
 
 # Nightly configurations
 # imports_layout = "HorizontalVertical"
-# license_template_path = ".resources/license_header"
 # imports_granularity = "Crate"
 # overflow_delimited_expr = true
 # reorder_impl_items = true

Cargo.toml

@@ -129,6 +129,9 @@ version = "0.11.2"
 [dev-dependencies.test_dir]
 version = "0.2.0"
 
+[build-dependencies.walkdir]
+version = "2"
+
 [features]
 default = [ ]
 ci_skip = [ "leo-compiler/ci_skip" ]

build.rs

@@ -0,0 +1,75 @@
+// Copyright (C) 2019-2021 Aleo Systems Inc.
+// This file is part of the Leo library.
+
+// The Leo library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// The Leo library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with the Leo library. If not, see <https://www.gnu.org/licenses/>.
+
+use std::{fs::File, io::Read, path::Path};
+
+use walkdir::WalkDir;
+
+// The following license text that should be present at the beginning of every source file.
+const EXPECTED_LICENSE_TEXT: &[u8] = include_bytes!(".resources/license_header");
+
+// The following directories will be excluded from the license scan.
+const DIRS_TO_SKIP: [&str; 8] = [
+    ".cargo",
+    ".circleci",
+    ".git",
+    ".github",
+    ".resources",
+    "docs",
+    "examples",
+    "target",
+];
+
+fn check_file_licenses<P: AsRef<Path>>(path: P) {
+    let path = path.as_ref();
+
+    let mut iter = WalkDir::new(path).into_iter();
+    while let Some(entry) = iter.next() {
+        let entry = entry.unwrap();
+        let entry_type = entry.file_type();
+
+        // Skip the specified directories.
+        if entry_type.is_dir() && DIRS_TO_SKIP.contains(&entry.file_name().to_str().unwrap_or("")) {
+            iter.skip_current_dir();
+
+            continue;
+        }
+
+        // Check all files with the ".rs" extension.
+        if entry_type.is_file() && entry.file_name().to_str().unwrap_or("").ends_with(".rs") {
+            let file = File::open(entry.path()).unwrap();
+            let mut contents = Vec::with_capacity(EXPECTED_LICENSE_TEXT.len());
+            file.take(EXPECTED_LICENSE_TEXT.len() as u64)
+                .read_to_end(&mut contents)
+                .unwrap();
+
+            assert!(
+                contents == EXPECTED_LICENSE_TEXT,
+                "The license in \"{}\" is either missing or it doesn't match the expected string!",
+                entry.path().display()
+            );
+        }
+    }
+
+    // Re-run upon any changes to the workspace.
+    println!("cargo:rerun-if-changed=.");
+}
+
+// The build script; it currently only checks the licenses.
+fn main() {
+    // Check licenses in the current folder.
+    check_file_licenses(".");
+}