impls for null-terminated FFI string types

Fixes #800.

serde/src/de/impls.rs

@@ -25,6 +25,8 @@ use std::net;
 #[cfg(feature = "std")]
 use std::path;
 use core::str;
+#[cfg(feature = "std")]
+use std::ffi::{CStr, CString};
 
 #[cfg(feature = "std")]
 use std::rc::Rc;
@@ -295,6 +297,33 @@ impl Deserialize for String {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#[cfg(feature = "std")]
+impl Deserialize for Box<CStr> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where D: Deserializer
+    {
+        use std::mem;
+        let s = try!(CString::deserialize(deserializer));
+        let slice = s.into_bytes_with_nul().into_boxed_slice();
+        Ok(unsafe { mem::transmute::<Box<[u8]>, Box<CStr>>(slice) })
+    }
+}
+
+
+#[cfg(feature = "std")]
+impl Deserialize for CString {
+    fn deserialize<D>(deserializer: D) -> Result<CString, D::Error>
+        where D: Deserializer
+    {
+        let mut v: Vec<u8> = try!(Deserialize::deserialize(deserializer));
+        v.pop(); // cut trailing NULL, because CString::new adds it
+        CString::new(v)
+            .map_err(|e| Error::custom(format!("unexpected NULL at byte {}", e.nul_position())))
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 struct OptionVisitor<T> {
     marker: PhantomData<T>,
 }

serde/src/ser/impls.rs

@@ -22,6 +22,8 @@ use core::ops;
 #[cfg(feature = "std")]
 use std::path;
 #[cfg(feature = "std")]
+use std::ffi::{CString, CStr};
+#[cfg(feature = "std")]
 use std::rc::Rc;
 #[cfg(all(feature = "alloc", not(feature = "std")))]
 use alloc::rc::Rc;
@@ -98,6 +100,28 @@ impl Serialize for String {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#[cfg(feature = "std")]
+impl Serialize for CStr {
+    #[inline]
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where S: Serializer
+    {
+        (self.to_bytes_with_nul()).serialize(serializer)
+    }
+}
+
+#[cfg(feature = "std")]
+impl Serialize for CString {
+    #[inline]
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where S: Serializer
+    {
+        (self.to_bytes_with_nul()).serialize(serializer)
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 impl<T> Serialize for Option<T>
     where T: Serialize
 {