1 files changed, 100 insertions, 0 deletions
diff --git a/vendor/zip/src/crc32.rs b/vendor/zip/src/crc32.rs
new file mode 100644
index 000000000..ebace898d
--- /dev/null
+++ b/vendor/zip/src/crc32.rs
@@ -0,0 +1,100 @@
+//! Helper module to compute a CRC32 checksum
+
+use std::io;
+use std::io::prelude::*;
+
+use crc32fast::Hasher;
+
+/// Reader that validates the CRC32 when it reaches the EOF.
+pub struct Crc32Reader<R> {
+    inner: R,
+    hasher: Hasher,
+    check: u32,
+    /// Signals if `inner` stores aes encrypted data.
+    /// AE-2 encrypted data doesn't use crc and sets the value to 0.
+    ae2_encrypted: bool,
+}
+
+impl<R> Crc32Reader<R> {
+    /// Get a new Crc32Reader which checks the inner reader against checksum.
+    /// The check is disabled if `ae2_encrypted == true`.
+    pub(crate) fn new(inner: R, checksum: u32, ae2_encrypted: bool) -> Crc32Reader<R> {
+        Crc32Reader {
+            inner,
+            hasher: Hasher::new(),
+            check: checksum,
+            ae2_encrypted,
+        }
+    }
+
+    fn check_matches(&self) -> bool {
+        self.check == self.hasher.clone().finalize()
+    }
+
+    pub fn into_inner(self) -> R {
+        self.inner
+    }
+}
+
+impl<R: Read> Read for Crc32Reader<R> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let invalid_check = !buf.is_empty() && !self.check_matches() && !self.ae2_encrypted;
+
+        let count = match self.inner.read(buf) {
+            Ok(0) if invalid_check => {
+                return Err(io::Error::new(io::ErrorKind::Other, "Invalid checksum"))
+            }
+            Ok(n) => n,
+            Err(e) => return Err(e),
+        };
+        self.hasher.update(&buf[0..count]);
+        Ok(count)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use std::io::Read;
+
+    #[test]
+    fn test_empty_reader() {
+        let data: &[u8] = b"";
+        let mut buf = [0; 1];
+
+        let mut reader = Crc32Reader::new(data, 0, false);
+        assert_eq!(reader.read(&mut buf).unwrap(), 0);
+
+        let mut reader = Crc32Reader::new(data, 1, false);
+        assert!(reader
+            .read(&mut buf)
+            .unwrap_err()
+            .to_string()
+            .contains("Invalid checksum"));
+    }
+
+    #[test]
+    fn test_byte_by_byte() {
+        let data: &[u8] = b"1234";
+        let mut buf = [0; 1];
+
+        let mut reader = Crc32Reader::new(data, 0x9be3e0a3, false);
+        assert_eq!(reader.read(&mut buf).unwrap(), 1);
+        assert_eq!(reader.read(&mut buf).unwrap(), 1);
+        assert_eq!(reader.read(&mut buf).unwrap(), 1);
+        assert_eq!(reader.read(&mut buf).unwrap(), 1);
+        assert_eq!(reader.read(&mut buf).unwrap(), 0);
+        // Can keep reading 0 bytes after the end
+        assert_eq!(reader.read(&mut buf).unwrap(), 0);
+    }
+
+    #[test]
+    fn test_zero_read() {
+        let data: &[u8] = b"1234";
+        let mut buf = [0; 5];
+
+        let mut reader = Crc32Reader::new(data, 0x9be3e0a3, false);
+        assert_eq!(reader.read(&mut buf[..0]).unwrap(), 0);
+        assert_eq!(reader.read(&mut buf).unwrap(), 4);
+    }
+}