Initial commit.

xsd/src/bus.rs

@@ -0,0 +1,149 @@
+use std::error::Error;
+use std::ffi::{CString, FromVecWithNulError, NulError};
+use std::fs::metadata;
+use std::io::{Read, Write};
+use std::mem::size_of;
+use std::net::Shutdown;
+use std::os::unix::net::UnixStream;
+use std::str::Utf8Error;
+use std::string::FromUtf8Error;
+use crate::sys::{XSD_ERROR, XsdMessageHeader};
+
+const XEN_BUS_PATHS: &'static [&'static str] = &[
+    "/var/run/xenstored/socket"
+];
+
+fn find_bus_path() -> Option<String> {
+    for path in XEN_BUS_PATHS {
+        match metadata(path) {
+            Ok(_) => return Some(String::from(*path)),
+            Err(_) => continue
+        }
+    }
+    None
+}
+
+#[derive(Debug)]
+pub struct XsdBusError {
+    message: String
+}
+
+impl XsdBusError {
+    pub fn new(msg: &str) -> XsdBusError {
+        return XsdBusError {message: msg.to_string()};
+    }
+}
+
+impl std::fmt::Display for XsdBusError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f,"{}", self.message)
+    }
+}
+
+impl Error for XsdBusError {
+    fn description(&self) -> &str {
+        &self.message
+    }
+}
+
+impl From<std::io::Error> for XsdBusError {
+    fn from(value: std::io::Error) -> Self {
+        XsdBusError::new(value.to_string().as_str())
+    }
+}
+
+impl From<NulError> for XsdBusError {
+    fn from(_: NulError) -> Self {
+        XsdBusError::new("Unable to coerce data into a C string.")
+    }
+}
+
+impl From<FromVecWithNulError> for XsdBusError {
+    fn from(_: FromVecWithNulError) -> Self {
+        XsdBusError::new("Unable to coerce data into a C string.")
+    }
+}
+
+impl From<Utf8Error> for XsdBusError {
+    fn from(_: Utf8Error) -> Self {
+        XsdBusError::new("Unable to coerce data into a UTF8 string.")
+    }
+}
+
+impl From<FromUtf8Error> for XsdBusError {
+    fn from(_: FromUtf8Error) -> Self {
+        XsdBusError::new("Unable to coerce data into a UTF8 string.")
+    }
+}
+
+pub struct XsdSocket {
+    handle: UnixStream
+}
+
+#[derive(Debug)]
+pub struct XsdResponse {
+    pub header: XsdMessageHeader,
+    pub payload: Vec<u8>
+}
+
+impl XsdResponse {
+    pub fn parse_string_vec(&self) -> Result<Vec<String>, XsdBusError> {
+        let mut strings: Vec<String> = Vec::new();
+        let mut buffer: Vec<u8> = Vec::new();
+        for b in &self.payload {
+            if *b == 0 {
+                let string = String::from_utf8(buffer.clone())?;
+                strings.push(string);
+                buffer.clear();
+                continue;
+            }
+            buffer.push(b.clone());
+        }
+        Ok(strings)
+    }
+}
+
+impl XsdSocket {
+    pub fn dial() -> Result<XsdSocket, XsdBusError> {
+        let path = match find_bus_path() {
+            Some(path) => path,
+            None => return Err(XsdBusError::new("Failed to find valid bus path."))
+        };
+        let stream = UnixStream::connect(path)?;
+        Ok(XsdSocket { handle: stream })
+    }
+
+    pub fn send(&mut self, tx: u32, typ: u32, buf: &[u8]) -> Result<XsdResponse, XsdBusError> {
+        let header = XsdMessageHeader {
+            typ,
+            req: 0,
+            tx,
+            len: buf.len() as u32
+        };
+        self.handle.write_all(bytemuck::bytes_of(&header))?;
+        self.handle.write_all(buf)?;
+        let mut result_buf = vec![0u8; size_of::<XsdMessageHeader>()];
+        self.handle.read(result_buf.as_mut_slice())?;
+        let result_header = bytemuck::from_bytes::<XsdMessageHeader>(&result_buf);
+        let mut payload = vec![0u8; result_header.len as usize];
+        self.handle.read_exact(payload.as_mut_slice())?;
+        if result_header.typ == XSD_ERROR {
+            let error = CString::from_vec_with_nul(payload)?;
+            return Err(XsdBusError::new(error.to_str()?));
+        }
+        let response = XsdResponse { header: header.clone(), payload };
+        Ok(response)
+    }
+
+    pub fn send_single(&mut self, tx: u32, typ: u32, string: &str) -> Result<XsdResponse, XsdBusError> {
+        let path = CString::new(string)?;
+        let buf = path.as_bytes_with_nul();
+        Ok(self.send(tx, typ, buf)?)
+    }
+}
+
+impl Drop for XsdSocket {
+    fn drop(&mut self) {
+        self.handle.shutdown(Shutdown::Both).unwrap()
+    }
+}