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// Copyright (c) 2016-2017, The Tor Project, Inc. */
// See LICENSE for licensing information */
use libc::{c_char, c_void};
use std::{ptr, slice, mem};
#[cfg(not(test))]
extern "C" {
fn tor_malloc_(size: usize) -> *mut c_void;
}
// Defined only for tests, used for testing purposes, so that we don't need
// to link to tor C files. Uses the system allocator
#[cfg(test)]
unsafe extern "C" fn tor_malloc_(size: usize) -> *mut c_void {
use libc::malloc;
malloc(size)
}
/// Allocate memory using tor_malloc_ and copy an existing string into the
/// allocated buffer, returning a pointer that can later be called in C.
///
/// # Inputs
///
/// * `src`, a reference to a String.
///
/// # Returns
///
/// A `*mut c_char` that should be freed by tor_free in C
///
pub fn allocate_and_copy_string(src: &String) -> *mut c_char {
let bytes: &[u8] = src.as_bytes();
let size = mem::size_of_val::<[u8]>(bytes);
let size_one_byte = mem::size_of::<u8>();
// handle integer overflow when adding one to the calculated length
let size_with_null_byte = match size.checked_add(size_one_byte) {
Some(n) => n,
None => return ptr::null_mut(),
};
let dest = unsafe { tor_malloc_(size_with_null_byte) as *mut u8 };
if dest.is_null() {
return ptr::null_mut();
}
unsafe { ptr::copy_nonoverlapping(bytes.as_ptr(), dest, size) };
// set the last byte as null, using the ability to index into a slice
// rather than doing pointer arithmatic
let slice = unsafe { slice::from_raw_parts_mut(dest, size_with_null_byte) };
slice[size] = 0; // add a null terminator
dest as *mut c_char
}
#[cfg(test)]
mod test {
#[test]
fn test_allocate_and_copy_string_with_empty() {
use std::ffi::CStr;
use libc::{free, c_void};
use tor_allocate::allocate_and_copy_string;
let empty = String::new();
let allocated_empty = allocate_and_copy_string(&empty);
let allocated_empty_rust =
unsafe { CStr::from_ptr(allocated_empty).to_str().unwrap() };
assert_eq!("", allocated_empty_rust);
unsafe { free(allocated_empty as *mut c_void) };
}
#[test]
fn test_allocate_and_copy_string_with_not_empty_string() {
use std::ffi::CStr;
use libc::{free, c_void};
use tor_allocate::allocate_and_copy_string;
let empty = String::from("foo bar biz");
let allocated_empty = allocate_and_copy_string(&empty);
let allocated_empty_rust =
unsafe { CStr::from_ptr(allocated_empty).to_str().unwrap() };
assert_eq!("foo bar biz", allocated_empty_rust);
unsafe { free(allocated_empty as *mut c_void) };
}
}
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