Use Decoder Enum for NSIS over Boxed dyn Read

russellbanks · Feb 7, 2025 · fb0c4ff · fb0c4ff
1 parent c5fb679
commit fb0c4ff
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Showing 3 changed files with 38 additions and 11 deletions.
diff --git a/src/installers/nsis/header/decoder.rs b/src/installers/nsis/header/decoder.rs
@@ -0,0 +1,22 @@
+use bzip2::read::BzDecoder;
+use flate2::read::DeflateDecoder;
+use liblzma::read::XzDecoder;
+use std::io::Read;
+
+pub enum Decoder<R: Read> {
+    Lzma(XzDecoder<R>),
+    BZip2(BzDecoder<R>),
+    Zlib(DeflateDecoder<R>),
+    None(R),
+}
+
+impl<R: Read> Read for Decoder<R> {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        match self {
+            Decoder::Lzma(reader) => reader.read(buf),
+            Decoder::BZip2(reader) => reader.read(buf),
+            Decoder::Zlib(reader) => reader.read(buf),
+            Decoder::None(reader) => reader.read(buf),
+        }
+    }
+}
diff --git a/src/installers/nsis/header/mod.rs b/src/installers/nsis/header/mod.rs
@@ -1,9 +1,11 @@
 pub mod block;
 pub mod compression;
+pub mod decoder;
 pub mod flags;
 
 use crate::installers::nsis::first_header::FirstHeader;
 use crate::installers::nsis::header::compression::Compression;
+use crate::installers::nsis::header::decoder::Decoder;
 use crate::installers::utils::read_lzma_stream_header;
 use byteorder::{ByteOrder, ReadBytesExt, LE};
 use bzip2::read::BzDecoder;
@@ -56,7 +58,7 @@ pub struct Decompressed<'data> {
     pub is_solid: bool,
     pub non_solid_start_offset: u32,
     pub compression: Compression,
-    pub decoder: Box<dyn Read + 'data>,
+    pub decoder: Decoder<&'data [u8]>,
 }
 
 fn is_lzma(data: &[u8]) -> Option<Compression> {
@@ -120,14 +122,14 @@ impl Header {
             &data[NON_SOLID_EXTRA_BYTES as usize..]
         };
 
-        let mut decoder: Box<dyn Read> = match compression {
+        let mut decoder = match compression {
             Compression::Lzma(_) => {
                 let stream = read_lzma_stream_header(&mut data)?;
-                Box::new(XzDecoder::new_stream(data, stream))
+                Decoder::Lzma(XzDecoder::new_stream(data, stream))
             }
-            Compression::BZip2 => Box::new(BzDecoder::new(data)),
-            Compression::Zlib => Box::new(DeflateDecoder::new(data)),
-            Compression::None => Box::new(data),
+            Compression::BZip2 => Decoder::BZip2(BzDecoder::new(data)),
+            Compression::Zlib => Decoder::Zlib(DeflateDecoder::new(data)),
+            Compression::None => Decoder::None(data),
         };
 
         if is_solid && decoder.read_u32::<LE>()? != first_header.length_of_header.get() {

diff --git a/src/installers/nsis/mod.rs b/src/installers/nsis/mod.rs
@@ -12,6 +12,7 @@ use crate::installers::nsis::entry::Entry;
 use crate::installers::nsis::first_header::FirstHeader;
 use crate::installers::nsis::header::block::BlockHeaders;
 use crate::installers::nsis::header::compression::Compression;
+use crate::installers::nsis::header::decoder::Decoder;
 use crate::installers::nsis::header::flags::CommonHeaderFlags;
 use crate::installers::nsis::header::{Decompressed, Header};
 use crate::installers::utils::{read_lzma_stream_header, RELATIVE_PROGRAM_FILES_64};
@@ -157,20 +158,22 @@ impl Nsis {
                         position
                     })
                     .and_then(|position| {
-                        let mut decoder: Box<dyn Read> = if is_solid {
+                        let mut decoder = if is_solid {
                             solid_decoder
                         } else {
                             match compression {
                                 Compression::Lzma(filter_flag) => {
                                     let mut data = &data[position + usize::from(filter_flag)..];
                                     let stream = read_lzma_stream_header(&mut data).ok()?;
-                                    Box::new(XzDecoder::new_stream(data, stream))
+                                    Decoder::Lzma(XzDecoder::new_stream(data, stream))
+                                }
+                                Compression::BZip2 => {
+                                    Decoder::BZip2(BzDecoder::new(&data[position..]))
                                 }
-                                Compression::BZip2 => Box::new(BzDecoder::new(&data[position..])),
                                 Compression::Zlib => {
-                                    Box::new(DeflateDecoder::new(&data[position..]))
+                                    Decoder::Zlib(DeflateDecoder::new(&data[position..]))
                                 }
-                                Compression::None => Box::new(&data[position..]),
+                                Compression::None => Decoder::None(&data[position..]),
                             }
                         };
                         let mut void = io::sink();