1 files changed, 125 insertions, 0 deletions

diff --git a/src/zip/file/read.rs b/src/zip/file/read.rs
new file mode 100644
index 0000000..56f42da
--- /dev/null
+++ b/src/zip/file/read.rs
@@ -0,0 +1,125 @@
+use crate::driver::FileDriver;
+use crate::zip::{CompressionMethod, ZipError, ZipFileInfo, ZipResult};
+use bzip2::read::BzDecoder;
+use flate2::read::DeflateDecoder;
+use std::io::{
+    Error as IoError, ErrorKind as IoErrorKind, Read, Result as IoResult, Seek, SeekFrom,
+};
+use xz2::read::XzDecoder;
+
+enum IoProxy<Io: Read> {
+    Store(Io),
+    Deflate(DeflateDecoder<Io>),
+    BZip2(BzDecoder<Io>),
+    XZ(XzDecoder<Io>),
+}
+
+pub struct ZipFileReader<'d, Io: Read> {
+    io: IoProxy<&'d mut Io>,
+    info: &'d ZipFileInfo,
+
+    bounds: (u64, u64),
+    cursor: u64,
+}
+
+impl<'d, Io: Read> FileDriver for ZipFileReader<'d, Io> {
+    type Io = Io;
+    type FileInfo = ZipFileInfo;
+
+    fn info(&self) -> &Self::FileInfo {
+        self.info
+    }
+}
+
+impl<'d, Io: Read + Seek> ZipFileReader<'d, Io> {
+    pub fn new(io: &'d mut Io, info: &'d ZipFileInfo) -> ZipResult<Self> {
+        io.seek(SeekFrom::Start(info.header_pointer))?;
+        let buf = {
+            let mut buf = [0; 30];
+            io.read(&mut buf)?;
+            buf
+        };
+        if u32::from_le_bytes(buf[..4].try_into().unwrap()) != 0x04034b50 {
+            return Err(ZipError::InvalidFileHeaderSignature.into());
+        }
+        let data_pointer = info.header_pointer
+            + 30
+            + u16::from_le_bytes(buf[26..28].try_into().unwrap()) as u64
+            + u16::from_le_bytes(buf[28..30].try_into().unwrap()) as u64;
+        io.seek(SeekFrom::Start(data_pointer))?;
+
+        Ok(Self {
+            io: match info.compression_method {
+                CompressionMethod::Store => IoProxy::Store(io),
+                CompressionMethod::Deflate => IoProxy::Deflate(DeflateDecoder::new(io)),
+                CompressionMethod::BZip2 => IoProxy::BZip2(BzDecoder::new(io)),
+                CompressionMethod::LZMA => IoProxy::XZ(XzDecoder::new(io)),
+                CompressionMethod::XZ => IoProxy::XZ(XzDecoder::new(io)),
+            },
+            info,
+
+            bounds: (data_pointer, data_pointer + info.compressed_size),
+            cursor: data_pointer,
+        })
+    }
+
+    pub fn seekable(&self) -> bool {
+        match self.io {
+            IoProxy::Store(..) => true,
+            _ => false,
+        }
+    }
+}
+
+impl<'d, Io: Read> Read for ZipFileReader<'d, Io> {
+    fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
+        let upper = buf.len().min((self.bounds.1 - self.cursor) as usize);
+        let bytes = match &mut self.io {
+            IoProxy::Store(io) => io.read(&mut buf[..upper]),
+            IoProxy::Deflate(io) => io.read(&mut buf[..upper]),
+            IoProxy::BZip2(io) => io.read(&mut buf[..upper]),
+            IoProxy::XZ(io) => io.read(&mut buf[..upper]),
+        }?;
+        self.cursor += upper as u64;
+        Ok(bytes)
+    }
+}
+
+impl<'d, Io: Read + Seek> Seek for ZipFileReader<'d, Io> {
+    fn seek(&mut self, pos: SeekFrom) -> IoResult<u64> {
+        match &mut self.io {
+            IoProxy::Store(io) => {
+                self.cursor = match pos {
+                    SeekFrom::Start(offset) => self.bounds.0 + offset,
+                    SeekFrom::End(offset) => {
+                        let cursor = self.bounds.1.saturating_add_signed(offset);
+                        if cursor < self.bounds.0 {
+                            return Err(IoError::new(
+                                IoErrorKind::InvalidInput,
+                                ZipError::NegativeFileOffset,
+                            ));
+                        }
+                        cursor
+                    }
+                    SeekFrom::Current(offset) => {
+                        let cursor = self.cursor.saturating_add_signed(offset);
+                        if cursor < self.bounds.0 {
+                            return Err(IoError::new(
+                                IoErrorKind::InvalidInput,
+                                ZipError::NegativeFileOffset,
+                            ));
+                        }
+                        cursor
+                    }
+                }
+                .min(self.bounds.1);
+
+                Ok(io.seek(SeekFrom::Start(self.cursor))? - self.bounds.0)
+            }
+            _ => Err(IoError::new(
+                IoErrorKind::Unsupported,
+                ZipError::CompressionDataIsUnseekable,
+            )),
+        }
+    }
+}