Return a list of files written to disk in binstalk_downloader::download::Download::and_extract (#856)

to avoid collecting extracted files from disk again in resolution stage.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/binstalk-downloader/src/download/extracted_files.rs

@@ -0,0 +1,102 @@
+use std::{
+    collections::{hash_map::Entry as HashMapEntry, HashMap, HashSet},
+    ffi::OsStr,
+    path::Path,
+};
+
+#[derive(Debug)]
+#[cfg_attr(test, derive(Eq, PartialEq))]
+pub enum ExtractedFilesEntry {
+    Dir(Box<HashSet<Box<OsStr>>>),
+    File,
+}
+
+impl ExtractedFilesEntry {
+    fn new_dir(file_name: Option<&OsStr>) -> Self {
+        ExtractedFilesEntry::Dir(Box::new(
+            file_name
+                .map(|file_name| HashSet::from([file_name.into()]))
+                .unwrap_or_else(HashSet::default),
+        ))
+    }
+}
+
+#[derive(Debug)]
+pub struct ExtractedFiles(pub(super) HashMap<Box<Path>, ExtractedFilesEntry>);
+
+impl ExtractedFiles {
+    pub(super) fn new() -> Self {
+        Self(Default::default())
+    }
+
+    /// * `path` - must be canonical and must not be empty
+    ///
+    /// NOTE that if the entry for the `path` is previously set to a dir,
+    /// it would be replaced with a file.
+    pub(super) fn add_file(&mut self, path: &Path) {
+        self.0.insert(path.into(), ExtractedFilesEntry::File);
+        self.add_dir_if_has_parent(path);
+    }
+
+    fn add_dir_if_has_parent(&mut self, path: &Path) {
+        if let Some(parent) = path.parent() {
+            if !parent.as_os_str().is_empty() {
+                self.add_dir_inner(parent, path.file_name());
+                self.add_dir_if_has_parent(parent);
+            } else {
+                self.add_dir_inner(Path::new("."), path.file_name())
+            }
+        }
+    }
+
+    /// * `path` - must be canonical and must not be empty
+    ///
+    /// NOTE that if the entry for the `path` is previously set to a dir,
+    /// it would be replaced with an empty Dir entry.
+    pub(super) fn add_dir(&mut self, path: &Path) {
+        self.add_dir_inner(path, None);
+        self.add_dir_if_has_parent(path);
+    }
+
+    /// * `path` - must be canonical and must not be empty
+    ///
+    /// NOTE that if the entry for the `path` is previously set to a dir,
+    /// it would be replaced with a Dir entry containing `file_name` if it
+    /// is `Some(..)`, or an empty Dir entry.
+    fn add_dir_inner(&mut self, path: &Path, file_name: Option<&OsStr>) {
+        match self.0.entry(path.into()) {
+            HashMapEntry::Vacant(entry) => {
+                entry.insert(ExtractedFilesEntry::new_dir(file_name));
+            }
+            HashMapEntry::Occupied(entry) => match entry.into_mut() {
+                ExtractedFilesEntry::Dir(hash_set) => {
+                    if let Some(file_name) = file_name {
+                        hash_set.insert(file_name.into());
+                    }
+                }
+                entry => *entry = ExtractedFilesEntry::new_dir(file_name),
+            },
+        }
+    }
+
+    /// * `path` - must be canonical and must not be empty, but could be "."
+    ///            for top-level.
+    pub fn get_entry(&self, path: &Path) -> Option<&ExtractedFilesEntry> {
+        self.0.get(path)
+    }
+
+    /// * `path` - must be canonical and must not be empty, but could be "."
+    ///            for top-level.
+    pub fn get_dir(&self, path: &Path) -> Option<&HashSet<Box<OsStr>>> {
+        match self.get_entry(path)? {
+            ExtractedFilesEntry::Dir(file_names) => Some(file_names),
+            ExtractedFilesEntry::File => None,
+        }
+    }
+
+    /// * `path` - must be canonical and must not be empty, but could be "."
+    ///            for top-level.
+    pub fn has_file(&self, path: &Path) -> bool {
+        matches!(self.get_entry(path), Some(ExtractedFilesEntry::File))
+    }
+}