ffi_utils 0.17.0

// Copyright 2019 MaidSafe.net limited.
//
// This SAFE Network Software is licensed to you under the MIT license <LICENSE-MIT
// http://opensource.org/licenses/MIT> or the Modified BSD license <LICENSE-BSD
// https://opensource.org/licenses/BSD-3-Clause>, at your option. This file may not be copied,
// modified, or distributed except according to those terms. Please review the Licences for the
// specific language governing permissions and limitations relating to use of the SAFE Network
// Software.

//! Utilities for passing strings across FFI boundaries.

use crate::repr_c::ReprC;
use serde_derive::{Deserialize, Serialize};
use std::ffi::{CStr, IntoStringError, NulError};
use std::os::raw::c_char;
use std::str::Utf8Error;

impl ReprC for String {
    type C = *const c_char;
    type Error = StringError;

    unsafe fn clone_from_repr_c(c_repr: Self::C) -> Result<Self, Self::Error> {
        if c_repr.is_null() {
            // Return an error instead of an empty String, as a null pointer input is most likely a
            // logic error in the consuming code.
            return Err(StringError::Null(
                "String could not be constructed from C null pointer".to_owned(),
            ));
        }
        Ok(CStr::from_ptr(c_repr).to_str()?.to_owned())
    }
}

/// Error type for strings
#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
pub enum StringError {
    /// UTF8 error
    Utf8(String),
    /// Null error
    Null(String),
    /// IntoString error
    IntoString(String),
}

impl From<Utf8Error> for StringError {
    fn from(e: Utf8Error) -> Self {
        StringError::Utf8(e.to_string())
    }
}

impl From<NulError> for StringError {
    fn from(e: NulError) -> Self {
        StringError::Null(e.to_string())
    }
}

impl From<IntoStringError> for StringError {
    fn from(e: IntoStringError) -> Self {
        StringError::IntoString(e.to_string())
    }
}