Function string_from_bytes

bindings/rust/src/lib.rs:258–296

General internal routine to copy bytes from a C array into a Rust String

(bytes: *const ::std::os::raw::c_char, max_length: usize)

// General internal routine to copy bytes from a C array into a Rust String
fn string_from_bytes(bytes: *const ::std::os::raw::c_char, max_length: usize) -> Result<String> {
    let mut newbytes = vec![0u8; max_length];

    // Get length of the string in old-fashioned style
    let mut length: usize = 0;
    let mut count = 0;
    let mut tmpbytes = bytes;
    while count < max_length || length == 0 {
        if unsafe { *tmpbytes } == 0 && length == 0 {
            length = count;
            break;
        }
        count += 1;
        tmpbytes = unsafe { tmpbytes.offset(1) }
    }

    // Cope with an empty string
    if length == 0 {
        return Ok(String::new());
    }

    unsafe {
        // We need to fully copy it, not shallow copy it.
        // Messy casting on both parts of the copy here to get it to work on both signed
        // and unsigned char machines
        copy_nonoverlapping(bytes as *mut i8, newbytes.as_mut_ptr() as *mut i8, length);
    }

    let cs = match CString::new(&newbytes[0..length]) {
        Ok(c1) => c1,
        Err(_) => return Err(CsError::CsErrRustString),
    };

    // This is just to convert the error type
    match cs.into_string() {
        Ok(s) => Ok(s),
        Err(_) => Err(CsError::CsErrRustString),
    }
}