crates/android_logger/patches/0002-Avoid-panic-on-buffers-with-embedded-nul-bytes.patch

From c8429943e1c53006652e8925d1d5e3728828c566 Mon Sep 17 00:00:00 2001
From: Marcin Radomski <dextero@google.com>
Date: Tue, 18 Mar 2025 13:31:21 +0000
Subject: [PATCH] Avoid panic on buffers with embedded nul bytes

Upstream PR: https://github.com/rust-mobile/android_logger-rs/pull/90

Some crates use log crate with a message padded with a number of
nullbytes [1]. This currently causes panics.

Replace the nullbytes with spaces when printing the log message to
prevent this crash.

[1] https://github.com/cloudflare/quiche/blob/d0efd2c5278b9dbe8d6544c3015f8c772f3513b4/quiche/src/tls/mod.rs#L1040
---
 src/platform_log_writer.rs | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/platform_log_writer.rs b/src/platform_log_writer.rs
index 85826ca..2a7b53a 100644
--- a/src/platform_log_writer.rs
+++ b/src/platform_log_writer.rs
@@ -113,7 +113,7 @@ impl PlatformLogWriter<'_> {
     /// Output buffer up until the \0 which will be placed at `len` position.
     ///
     /// # Safety
-    /// The first `len` bytes of `self.buffer` must be initialized.
+    /// The first `len` bytes of `self.buffer` must be initialized and not contain nullbytes.
     unsafe fn output_specified_len(&mut self, len: usize) {
         let mut last_byte = MaybeUninit::new(b'\0');
 
@@ -152,7 +152,13 @@ impl fmt::Write for PlatformLogWriter<'_> {
                 .zip(incoming_bytes)
                 .enumerate()
                 .fold(None, |acc, (i, (output, input))| {
-                    output.write(*input);
+                    if *input == b'\0' {
+                        // Replace nullbytes with whitespace, so we can put the message in a CStr
+                        // later to pass it through a const char*.
+                        output.write(b' ');
+                    } else {
+                        output.write(*input);
+                    }
                     if *input == b'\n' { Some(i) } else { acc }
                 });
 
@@ -297,6 +303,20 @@ pub mod tests {
         );
     }
 
+    #[test]
+    fn writer_substitutes_nullbytes_with_spaces() {
+        let test_string = "Test_string_with\0\0\0\0nullbytes\0";
+        let mut writer = get_tag_writer();
+        writer
+            .write_str(test_string)
+            .expect("Unable to write to PlatformLogWriter");
+
+        assert_eq!(
+            unsafe { slice_assume_init_ref(&writer.buffer[..test_string.len()]) },
+            test_string.replace("\0", " ").as_bytes()
+        );
+    }
+
     fn get_tag_writer() -> PlatformLogWriter<'static> {
         PlatformLogWriter::new(
             None,
-- 
2.49.0.rc1.451.g8f38331e32-goog