1 files changed, 105 insertions, 0 deletions
diff --git a/src/launcher/extract.rs b/src/launcher/extract.rs
new file mode 100644
index 0000000..c9e0dc9
--- /dev/null
+++ b/src/launcher/extract.rs
@@ -0,0 +1,105 @@
+use std::error::Error;
+use std::fmt::{Display, Formatter};
+use std::{fs, io};
+use std::fs::File;
+use std::io::{BufReader, Error as IOError};
+use std::path::{Component, Path, PathBuf};
+use log::debug;
+use zip::result::ZipError;
+use zip::ZipArchive;
+
+#[derive(Debug)]
+pub enum ZipExtractError {
+    IO { what: &'static str, error: IOError },
+    Zip { what: &'static str, error: ZipError },
+    InvalidEntry { why: &'static str, name: String }
+}
+
+impl From<(&'static str, IOError)> for ZipExtractError {
+    fn from((what, error): (&'static str, IOError)) -> Self {
+        ZipExtractError::IO { what, error }
+    }
+}
+
+impl From<(&'static str, ZipError)> for ZipExtractError {
+    fn from((what, error): (&'static str, ZipError)) -> Self {
+        ZipExtractError::Zip { what, error }
+    }
+}
+
+impl Display for ZipExtractError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ZipExtractError::IO { what, error } => write!(f, "i/o error ({what}): {error}"),
+            ZipExtractError::Zip { what, error } => write!(f, "zip error ({what}): {error}"),
+            ZipExtractError::InvalidEntry { why, name } => write!(f, "invalid entry in zip file ({why}): {name}")
+        }
+    }
+}
+
+impl Error for ZipExtractError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            ZipExtractError::IO { error, .. } => Some(error),
+            ZipExtractError::Zip { error, .. } => Some(error),
+            _ => None
+        }
+    }
+}
+
+pub fn extract_zip<F>(zip_path: impl AsRef<Path>, extract_root: impl AsRef<Path>, condition: F) -> Result<usize, ZipExtractError>
+where
+    F: Fn(&str) -> bool
+{
+    debug!("Extracting zip file {} into {}", zip_path.as_ref().display(), extract_root.as_ref().display());
+    
+    fs::create_dir_all(&extract_root).map_err(|e| ZipExtractError::from(("create extract root", e)))?;
+
+    let mut extracted = 0usize;
+
+    let file = File::open(zip_path).map_err(|e| ZipExtractError::from(("extract zip file (open)", e)))?;
+    let read = BufReader::new(file);
+
+    let mut archive = ZipArchive::new(read).map_err(|e| ZipExtractError::from(("read zip archive", e)))?;
+
+    for n in 0..archive.len() {
+        let mut entry = archive.by_index(n).map_err(|e| ZipExtractError::from(("access zip entry", e)))?;
+        let name = entry.name();
+
+        if !condition(name) {
+            continue;
+        }
+
+        let entry_path: &Path = Path::new(name);
+        let mut depth = 0usize;
+        for component in entry_path.components() {
+            depth = match component {
+                Component::Prefix(_) | Component::RootDir =>
+                    return Err(ZipExtractError::InvalidEntry {
+                        why: "root path component in entry",
+                        name: name.to_owned()
+                    }),
+                Component::ParentDir => depth.checked_sub(1)
+                    .map_or_else(|| Err(ZipExtractError::InvalidEntry {
+                        why: "entry path escapes extraction root",
+                        name: name.to_owned()
+                    }), |s| Ok(s))?,
+                Component::Normal(_) => depth + 1,
+                _ => depth
+            }
+        }
+
+        let entry_path: PathBuf = [extract_root.as_ref(), entry_path].iter().collect();
+
+        // hmm some redundant directory creations will be happening here on linux :(
+        if let Some(parent) = entry_path.parent() {
+            fs::create_dir_all(parent).map_err(|e| ZipExtractError::from(("create entry directory", e)))?;
+        }
+
+        let mut outfile = File::create(&entry_path).map_err(|e| ZipExtractError::from(("extract zip entry (open)", e)))?;
+        io::copy(&mut entry, &mut outfile).map_err(|e| ZipExtractError::from(("extract zip entry (write)", e)))?;
+        extracted += 1;
+    }
+
+    Ok(extracted)
+}