Initial commit

I started this project on February 2021, but postponed further
development until now. The only modification introduced since then is
try_trait_v2 (try_trait no longer exists).

1 files changed, 112 insertions, 0 deletions

diff --git a/src/util.rs b/src/util.rs
new file mode 100644
index 0000000..dba954b
--- /dev/null
+++ b/src/util.rs
@@ -0,0 +1,112 @@
+use std::{
+    fmt,
+    os::unix::io::{IntoRawFd, RawFd},
+};
+
+use nix::{self, errno::Errno, unistd::close};
+use quick_error::quick_error;
+
+quick_error! {
+    #[derive(Debug)]
+    pub enum FuseError {
+        Io(err: std::io::Error) { from() }
+        ProtocolInit { display("fuse handshake failed (ancient kernel?)") }
+        Truncated { display("fuse request truncated") }
+        BadOpcode { display("unknown fuse operation") }
+        BadLength { display("bad length in fuse request") }
+        ShortWrite { display("fuse reply was trimmed on write()") }
+    }
+}
+
+pub type FuseResult<T> = Result<T, FuseError>;
+
+pub struct DumbFd(pub RawFd);
+
+pub struct OutputChain<'a> {
+    segments: &'a [&'a [u8]],
+    then: Option<&'a OutputChain<'a>>,
+}
+
+pub struct OutputChainIter<'a>(Option<&'a OutputChain<'a>>);
+
+impl IntoRawFd for DumbFd {
+    fn into_raw_fd(self) -> RawFd {
+        let fd = self.0;
+        std::mem::forget(self);
+        fd
+    }
+}
+
+impl Drop for DumbFd {
+    fn drop(&mut self) {
+        let _ = close(self.0);
+    }
+}
+
+impl<'a> OutputChain<'a> {
+    pub fn empty() -> Self {
+        OutputChain {
+            segments: &[],
+            then: None,
+        }
+    }
+
+    pub fn tail(segments: &'a [&'a [u8]]) -> Self {
+        OutputChain {
+            segments,
+            then: None,
+        }
+    }
+
+    pub fn preceded(&'a self, segments: &'a [&'a [u8]]) -> Self {
+        OutputChain {
+            segments,
+            then: Some(&self),
+        }
+    }
+
+    pub fn iter(&self) -> OutputChainIter {
+        OutputChainIter(Some(&self))
+    }
+}
+
+impl<'a> Iterator for OutputChainIter<'a> {
+    type Item = &'a [&'a [u8]];
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = self.0.and_then(|chain| chain.then);
+        std::mem::replace(&mut self.0, next).map(|chain| chain.segments)
+    }
+}
+
+pub fn from_nix_error(error: nix::Error) -> std::io::Error {
+    use nix::Error::*;
+    let from_raw = |code| std::io::Error::from_raw_os_error(code as i32);
+
+    match error {
+        Sys(errno) => errno.into(),
+        InvalidPath => from_raw(Errno::ENAMETOOLONG),
+        InvalidUtf8 => from_raw(Errno::EILSEQ),
+        UnsupportedOperation => from_raw(Errno::EOPNOTSUPP),
+    }
+}
+
+pub fn display_or<'a, T: fmt::Display + 'a>(
+    maybe: Option<T>,
+    default: &'a str,
+) -> impl fmt::Display + 'a {
+    struct Params<'a, T: fmt::Display>(Option<T>, &'a str);
+
+    impl<T: fmt::Display> fmt::Display for Params<'_, T> {
+        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+            let Params(maybe, placeholder) = &self;
+            if let Some(t) = maybe {
+                write!(fmt, "{}", t)
+            } else {
+                fmt.write_str(placeholder)
+            }
+        }
+    }
+
+    Params(maybe, default)
+}