nostd

src/stdext.rs

@@ -0,0 +1,68 @@
+use core::fmt::Write;
+use core::{ffi, fmt};
+
+pub struct LibCStdoutWriter;
+
+impl Write for LibCStdoutWriter {
+    fn write_str(&mut self, mut s: &str) -> fmt::Result {
+        loop {
+            let r = unsafe { libc::write(libc::STDOUT_FILENO, s.as_ptr().cast(), s.len()) };
+            if r < 0 {
+                return Err(fmt::Error);
+            }
+            if r == 0 {
+                return Ok(());
+            }
+            s = &s[(r as usize)..];
+        }
+    }
+}
+
+pub fn print(args: fmt::Arguments<'_>) -> fmt::Result {
+    write!(LibCStdoutWriter, "{}", args)
+}
+
+macro_rules! print {
+    ($($tt:tt)*) => {{
+       $crate::stdext::print(format_args!($($tt)*)).unwrap();
+    }};
+}
+
+macro_rules! trace {
+    ($($tt:tt)*) => {
+        print!("UWUWIND TRACE | uwuwind/{}:{}: {}\n", file!(), line!(), format_args!($($tt)*))
+    };
+}
+
+pub(crate) use trace;
+
+pub(crate) fn abort() -> ! {
+    // SAFETY: We abort.
+    unsafe { libc::abort() };
+}
+
+fn errno() -> i32 {
+    // SAFETY: Surely errno_location would be valid, right?
+    unsafe { *libc::__errno_location() }
+}
+
+pub(crate) fn with_last_os_error_str<R>(f: impl FnOnce(&str) -> R) -> R {
+    let mut buf: [u8; 512] = [0; 512];
+
+    extern "C" {
+        // the libc crate only has the definition for the POSIX version, but a GNU system has the GNU version.
+        fn strerror_r(errnum: i32, buf: *mut ffi::c_char, buflen: usize) -> i32;
+    }
+
+    // SAFETY: Our buffer length is passed correctly
+    let error = unsafe { libc::strerror_r(errno(), buf.as_mut_ptr().cast(), buf.len()) };
+    // SAFETY: strerror_r writes the string to buf, even if it didnt write anything, we did zero init it.
+    let cstr = if error != 0 {
+        ffi::CStr::from_bytes_with_nul(b"<strerror_r returned an error>\n").unwrap()
+    } else {
+        unsafe { ffi::CStr::from_ptr(buf.as_ptr().cast()) }
+    };
+    f(cstr
+        .to_str()
+        .unwrap_or("<error message contained invalid utf8>"))
+}