Add `ToCString` trait.

Allows easy conversion of any `T: AsOsStr` to a `CString`, whose
`as_ptr()` method is quite convenient for FFI calls.

Note that `std::path::Path` implements `AsOsStr`, which means we can
easily take paths and get a pointer to `*const libc::c_char`.

2 files changed, 13 insertions, 1 deletions

diff --git a/src/lib.rs b/src/lib.rs
index f7358b7..379be2f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,4 @@
-#![feature(core, libc)]
+#![feature(core, libc, std_misc)]
 extern crate libc;
 
 #[macro_use]
diff --git a/src/utils.rs b/src/utils.rs
index ad8bcac..7e17ab9 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -3,6 +3,8 @@ use std::{
     str,
 };
 
+use std::os::unix::ffi::OsStrExt;
+
 use libc;
 
 pub trait NotmuchEnum {
@@ -12,6 +14,16 @@ pub trait NotmuchEnum {
     fn to_notmuch_t(self) -> Self::NotmuchT;
 }
 
+pub trait ToCString {
+    fn to_cstring(&self) -> Result<ffi::CString, ffi::NulError>;
+}
+
+impl<T: ffi::AsOsStr> ToCString for T {
+    fn to_cstring(&self) -> Result<ffi::CString, ffi::NulError> {
+        self.as_os_str().to_cstring()
+    }
+}
+
 pub trait ToStr {
     fn to_str(&self) -> Result<&str, str::Utf8Error>;
 }