From dedb17be4eb1a970594ae8acaa1c983f0513871c Mon Sep 17 00:00:00 2001
From: sgasho <SuganoShota1999@gmail.com>
Date: Sat, 14 Jun 2025 10:05:58 +0900
Subject: [PATCH 1/2] fix: accept an empty gzip as a valid input

---
 src/codec/gzip/decoder.rs | 28 +++++++++++++++++-----------
 src/codec/gzip/header.rs  |  7 +++++++
 src/util.rs               |  4 ++++
 tests/gzip.rs             | 28 ++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 11 deletions(-)

diff --git a/src/codec/gzip/decoder.rs b/src/codec/gzip/decoder.rs
index 4bb42606..3e2d0921 100644
--- a/src/codec/gzip/decoder.rs
+++ b/src/codec/gzip/decoder.rs
@@ -5,9 +5,9 @@ use crate::{
     },
     util::PartialBuffer,
 };
-use std::io::{Error, ErrorKind, Result};
-
 use flate2::Crc;
+use std::io::{Error, ErrorKind, Read, Result};
+use std::ops::Deref;
 
 #[derive(Debug)]
 enum State {
@@ -163,16 +163,22 @@ impl Decode for GzipDecoder {
 
     fn finish(
         &mut self,
-        _output: &mut PartialBuffer<impl AsRef<[u8]> + AsMut<[u8]>>,
+        output: &mut PartialBuffer<impl AsRef<[u8]> + AsMut<[u8]>>,
     ) -> Result<bool> {
-        // Because of the footer we have to have already flushed all the data out before we get here
-        if let State::Done = self.state {
-            Ok(true)
-        } else {
-            Err(Error::new(
-                ErrorKind::UnexpectedEof,
-                "unexpected end of file",
-            ))
+        match &mut self.state {
+            State::Done => return Ok(true),
+            State::Header(parser) => {
+                // In this case, the input was an empty gzip. Exit successfully with an empty gzip.
+                if parser.has_no_content() {
+                    return Ok(true);
+                }
+            }
+            _ => {}
         }
+
+        Err(Error::new(
+            ErrorKind::UnexpectedEof,
+            "unexpected end of file",
+        ))
     }
 }
diff --git a/src/codec/gzip/header.rs b/src/codec/gzip/header.rs
index ebe482af..28e108f0 100644
--- a/src/codec/gzip/header.rs
+++ b/src/codec/gzip/header.rs
@@ -161,4 +161,11 @@ impl Parser {
             };
         }
     }
+
+    pub(super) fn has_no_content(&self) -> bool {
+        match &self.state {
+            State::Fixed(data) => data.buffer().iter().all(|&b| b == 0),
+            _ => false,
+        }
+    }
 }
diff --git a/src/util.rs b/src/util.rs
index a00bce2d..c34611c7 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -20,6 +20,10 @@ impl<B: AsRef<[u8]>> PartialBuffer<B> {
         &self.buffer.as_ref()[self.index..]
     }
 
+    pub(crate) fn buffer(&self) -> &[u8] {
+        self.buffer.as_ref()
+    }
+
     pub(crate) fn advance(&mut self, amount: usize) {
         self.index += amount;
     }
diff --git a/tests/gzip.rs b/tests/gzip.rs
index d9cd4eff..fc51167b 100644
--- a/tests/gzip.rs
+++ b/tests/gzip.rs
@@ -6,6 +6,9 @@ test_cases!(gzip);
 #[allow(unused)]
 use utils::{algos::gzip::sync, InputStream};
 
+#[allow(unused)]
+use ntest::assert_true;
+
 #[cfg(feature = "futures-io")]
 use utils::algos::gzip::futures::bufread;
 
@@ -51,3 +54,28 @@ fn gzip_bufread_chunks_decompress_with_extra_header() {
 
     assert_eq!(output, &[1, 2, 3, 4, 5, 6][..]);
 }
+
+#[test]
+#[ntest::timeout(1000)]
+#[cfg(feature = "futures-io")]
+fn gzip_empty() {
+    let bytes = Vec::new();
+
+    let input = InputStream::from(bytes.chunks(2));
+    let output = bufread::decompress(bufread::from(&input));
+
+    assert_eq!(output, &[][..]);
+}
+
+#[test]
+#[ntest::timeout(1000)]
+#[cfg(feature = "futures-io")]
+fn invalid_gzip() {
+    let bytes = [0, 0, 0, 1, 0, 0];
+
+    let input = InputStream::from(bytes.chunks(2));
+
+    let result = std::panic::catch_unwind(|| bufread::decompress(bufread::from(&input)));
+
+    assert_true!(result.is_err());
+}

From ccdb74d0266f4a969334b16de8fa205b9edee010 Mon Sep 17 00:00:00 2001
From: sgasho <SuganoShota1999@gmail.com>
Date: Sun, 15 Jun 2025 00:18:17 +0900
Subject: [PATCH 2/2] refactor: simplify expressions

---
 src/codec/gzip/decoder.rs | 20 +++++++-------------
 src/codec/gzip/header.rs  |  5 +----
 2 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/src/codec/gzip/decoder.rs b/src/codec/gzip/decoder.rs
index 3e2d0921..ee5715b6 100644
--- a/src/codec/gzip/decoder.rs
+++ b/src/codec/gzip/decoder.rs
@@ -166,19 +166,13 @@ impl Decode for GzipDecoder {
         output: &mut PartialBuffer<impl AsRef<[u8]> + AsMut<[u8]>>,
     ) -> Result<bool> {
         match &mut self.state {
-            State::Done => return Ok(true),
-            State::Header(parser) => {
-                // In this case, the input was an empty gzip. Exit successfully with an empty gzip.
-                if parser.has_no_content() {
-                    return Ok(true);
-                }
-            }
-            _ => {}
+            State::Done => Ok(true),
+            // In this case, the input was an empty gzip. Exit successfully with an empty gzip.
+            State::Header(parser) if parser.has_no_content() => Ok(true),
+            _ => Err(Error::new(
+                ErrorKind::UnexpectedEof,
+                "unexpected end of file",
+            )),
         }
-
-        Err(Error::new(
-            ErrorKind::UnexpectedEof,
-            "unexpected end of file",
-        ))
     }
 }
diff --git a/src/codec/gzip/header.rs b/src/codec/gzip/header.rs
index 28e108f0..70b1399f 100644
--- a/src/codec/gzip/header.rs
+++ b/src/codec/gzip/header.rs
@@ -163,9 +163,6 @@ impl Parser {
     }
 
     pub(super) fn has_no_content(&self) -> bool {
-        match &self.state {
-            State::Fixed(data) => data.buffer().iter().all(|&b| b == 0),
-            _ => false,
-        }
+        matches!(&self.state, State::Fixed(data) if data.buffer().iter().all(|&b| b == 0))
     }
 }