fix(bin): semi-preserve file modes and make binaries executable (#259)

Fixes: #250

This makes sure that:

1. All files extracted are writable.
2. The mode that was set on the tarball files is preserved (while ensuring rw perms for owner)
3. Any files being used as package bins are executable

Cargo.toml

@@ -111,6 +111,7 @@ regex = "1.7.2"
 reqwest = "0.11.14"
 reqwest-middleware = "0.2.0"
 resvg = "0.29.0"
+rkyv = "0.7.41"
 serde = "1.0.152"
 serde_json = "1.0.93"
 serde-wasm-bindgen = "0.4.5"

crates/nassun/Cargo.toml

@@ -49,6 +49,7 @@ backon = { workspace = true }
 cacache = { workspace = true }
 flate2 = { workspace = true }
 io_tee = { workspace = true }
+rkyv = { workspace = true, features = ["validation"] }
 tar = { workspace = true }
 tempfile = { workspace = true }
 which = { workspace = true }

crates/nassun/src/error.rs

@@ -69,6 +69,11 @@ pub enum NassunError {
     #[diagnostic(code(nassun::cache::extract), url(docsrs))]
     ExtractCacheError(#[source] cacache::Error, Option<PathBuf>),
 
+    #[cfg(not(target_arch = "wasm32"))]
+    #[error("Missing file index for cache entry for {0}.")]
+    #[diagnostic(code(nassun::cache::missing_index), url(docsrs))]
+    CacheMissingIndexError(String),
+
     /// A generic IO error occurred. Refer tot he error message for more
     /// details.
     #[error(transparent)]
@@ -155,6 +160,11 @@ pub enum NassunError {
     #[diagnostic(code(nassun::dummy_no_name), url(docsrs))]
     DummyNoName,
 
+    /// An error occurred while serializing tarball metadata to cache.
+    #[error("Failed to serialize tarball metadata to cache: {0}")]
+    #[diagnostic(code(nassun::cache::serialize), url(docsrs))]
+    SerializeCacheError(String),
+
     /// A miscellaneous, usually internal error. This is used mainly to wrap
     /// either manual InternalErrors, or those using external errors that
     /// don't implement std::error::Error.

crates/nassun/src/package.rs

@@ -15,6 +15,8 @@ use crate::error::Result;
 use crate::fetch::PackageFetcher;
 use crate::resolver::PackageResolution;
 use crate::tarball::Tarball;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::tarball::TarballIndex;
 
 /// A resolved package. A concrete version has been determined from its
 /// PackageSpec by the version resolver.
@@ -254,20 +256,26 @@ impl Package {
         dir: &Path,
         cache: &Path,
         entry: cacache::Metadata,
-        prefer_copy: bool,
+        mut prefer_copy: bool,
         validate: bool,
     ) -> Result<()> {
         let dir = PathBuf::from(dir);
         let cache = PathBuf::from(cache);
+        let name = self.name().to_owned();
         async_std::task::spawn_blocking(move || {
             let mut created = std::collections::HashSet::new();
-            let map = entry
-                .metadata
-                .as_object()
-                .expect("how is this not an object?");
-            for (path, sri) in map {
-                let sri: Integrity = sri.as_str().expect("how is this not a string?").parse()?;
-                let path = dir.join(path);
+            let index = unsafe {
+                rkyv::util::archived_root::<TarballIndex>(
+                    entry
+                        .raw_metadata
+                        .as_ref()
+                        .ok_or_else(|| NassunError::CacheMissingIndexError(name))?,
+                )
+            };
+            prefer_copy = index.should_copy || prefer_copy;
+            for (path, (sri, mode)) in index.files.iter() {
+                let sri: Integrity = sri.parse()?;
+                let path = dir.join(&path[..]);
                 let parent = PathBuf::from(path.parent().expect("this will always have a parent"));
                 if !created.contains(&parent) {
                     std::fs::create_dir_all(path.parent().expect("this will always have a parent"))
@@ -281,7 +289,20 @@ impl Package {
                     created.insert(parent);
                 }
 
-                crate::tarball::extract_from_cache(&cache, &sri, &path, prefer_copy, validate)?;
+                crate::tarball::extract_from_cache(
+                    &cache,
+                    &sri,
+                    &path,
+                    prefer_copy,
+                    validate,
+                    *mode,
+                )?;
+            }
+            #[cfg(unix)]
+            for binpath in index.bin_paths.iter() {
+                {
+                    crate::tarball::set_bin_mode(&dir.join(&binpath[..]))?;
+                }
             }
             Ok::<_, NassunError>(())
         })