From b19e69d5a1d3c363f98f9994fbf3d5a2a6c0ceb8 Mon Sep 17 00:00:00 2001
From: Martin Nordholts <enselic@gmail.com>
Date: Mon, 6 Dec 2021 13:29:50 +0100
Subject: [PATCH] Limit line length to 100 MB to not exhaust system memory on
 `/dev/zero`

Closes #636
---
 CHANGELOG.md               |  1 +
 src/input.rs               | 16 ++++++++++++++--
 tests/integration_tests.rs | 12 ++++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7971bb4ed..deb4f8b0b7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@
 - Python syntax highlighting no longer suffers from abysmal performance in specific scenarios. See #1688 (@keith-hall)
 - First line not shown in diff context. See #1891 (@divagant-martian)
 - Do not ignore syntaxes that handle file names with a `*.conf` extension. See #1703 (@cbolgiano)
+- Limit line length to 100 MB to not exhaust system memory on `/dev/zero`. See #1972 (@Enselic)
 
 ## Performance
 
diff --git a/src/input.rs b/src/input.rs
index ffaca0ae0b..d8123ff0bd 100644
--- a/src/input.rs
+++ b/src/input.rs
@@ -251,7 +251,7 @@ pub(crate) struct InputReader<'a> {
 impl<'a> InputReader<'a> {
     fn new<R: BufRead + 'a>(mut reader: R) -> InputReader<'a> {
         let mut first_line = vec![];
-        reader.read_until(b'\n', &mut first_line).ok();
+        Self::read_line_safely(&mut reader, &mut first_line).ok();
 
         let content_type = if first_line.is_empty() {
             None
@@ -276,7 +276,7 @@ impl<'a> InputReader<'a> {
             return Ok(true);
         }
 
-        let res = self.inner.read_until(b'\n', buf).map(|size| size > 0)?;
+        let res = Self::read_line_safely(&mut self.inner, buf).map(|size| size > 0)?;
 
         if self.content_type == Some(ContentType::UTF_16LE) {
             let _ = self.inner.read_until(0x00, buf);
@@ -284,6 +284,18 @@ impl<'a> InputReader<'a> {
 
         Ok(res)
     }
+
+    fn read_line_safely<R: BufRead + 'a>(reader: &mut R, buf: &mut Vec<u8>) -> io::Result<usize> {
+        let limit = 100_000_000_usize;
+
+        match reader.take(limit as u64).read_until(b'\n', buf) {
+            Ok(n) if n == limit => Err(io::Error::new(
+                io::ErrorKind::Other,
+                "Lines longer than 100 MB are not supported",
+            )),
+            r => r,
+        }
+    }
 }
 
 #[test]
diff --git a/tests/integration_tests.rs b/tests/integration_tests.rs
index 17e9dc4e1f..86cb347d8c 100644
--- a/tests/integration_tests.rs
+++ b/tests/integration_tests.rs
@@ -344,6 +344,18 @@ fn no_args_doesnt_break() {
     assert!(exit_status.success());
 }
 
+#[cfg(unix)]
+#[test]
+fn dev_zero() {
+    bat()
+        .arg("/dev/zero")
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains(
+            "Lines longer than 100 MB are not supported",
+        ));
+}
+
 #[test]
 fn tabs_numbers() {
     bat()