print error logs in stdio mode

Cargo.toml

@@ -44,7 +44,9 @@ path = "bzip2recover.rs"
 
 [dependencies]
 libc.workspace = true
-libbz2-rs-sys = { workspace = true, features = ["stdio", "std", "rust-allocator"] }
+# we need `std` here, because we test the log output of the binaries, and those only
+# get printed when std is enabled.
+libbz2-rs-sys = { workspace = true, features = ["stdio", "c-allocator"] }
 
 [dev-dependencies]
 tempfile = "3.13.0"

bzip2.rs

@@ -965,7 +965,6 @@ fn outOfMemory(config: &Config) -> ! {
 }
 
 fn configError() -> ! {
-    panic!();
     const MSG: &str = concat!(
         "bzip2: I'm not configured correctly for this platform!\n",
         "\tI require Int32, Int16 and Char to have sizes\n",

libbz2-rs-sys/src/lib.rs

@@ -83,17 +83,43 @@ pub(crate) use libbz2_rs_sys_version;
 
 // --- debug logs
 
+#[cfg(all(not(feature = "std"), feature = "stdio"))]
+pub(crate) struct StderrWritter;
+
+#[cfg(all(not(feature = "std"), feature = "stdio"))]
+impl core::fmt::Write for StderrWritter {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        use core::ffi::c_void;
+        use libc::write;
+
+        unsafe {
+            write(2, s.as_ptr() as *const c_void, s.len());
+        }
+        Ok(())
+    }
+}
+
 macro_rules! debug_log {
     ($($arg:tt)*) => {
         #[cfg(feature = "std")]
         std::eprint!($($arg)*);
+        #[cfg(all(not(feature = "std"), feature = "stdio"))]
+        {
+            use core::fmt::Write;
+            write!($crate::StderrWritter, $($arg)*);
+        }
     };
 }
 
 macro_rules! debug_logln {
     ($($arg:tt)*) => {
         #[cfg(feature = "std")]
         std::eprintln!($($arg)*);
+        #[cfg(all(not(feature = "std"), feature = "stdio"))]
+        {
+            use core::fmt::Write;
+            writeln!($crate::StderrWritter, $($arg)*);
+        }
     };
 }