rust/src/libstd/ptr.rs
2013-07-18 02:18:56 +02:00

700 lines
19 KiB
Rust

// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Unsafe pointer utility functions
use cast;
use clone::Clone;
use option::{Option, Some, None};
use sys;
use unstable::intrinsics;
use util::swap;
#[cfg(not(test))] use ops::{Add,Sub};
#[cfg(not(test))] use num::Int;
#[cfg(not(test))] use cmp::{Eq, Ord};
use uint;
/// Calculate the offset from a pointer
#[inline]
pub fn offset<T>(ptr: *T, count: uint) -> *T {
(ptr as uint + count * sys::size_of::<T>()) as *T
}
/// Calculate the offset from a const pointer
#[inline]
pub fn const_offset<T>(ptr: *const T, count: uint) -> *const T {
(ptr as uint + count * sys::size_of::<T>()) as *T
}
/// Calculate the offset from a mut pointer
#[inline]
pub fn mut_offset<T>(ptr: *mut T, count: uint) -> *mut T {
(ptr as uint + count * sys::size_of::<T>()) as *mut T
}
/// Return the offset of the first null pointer in `buf`.
#[inline]
pub unsafe fn buf_len<T>(buf: **T) -> uint {
position(buf, |i| *i == null())
}
impl<T> Clone for *T {
fn clone(&self) -> *T {
*self
}
}
/// Return the first offset `i` such that `f(buf[i]) == true`.
#[inline]
pub unsafe fn position<T>(buf: *T, f: &fn(&T) -> bool) -> uint {
let mut i = 0;
loop {
if f(&(*offset(buf, i))) { return i; }
else { i += 1; }
}
}
/// Create an unsafe null pointer
#[inline]
pub fn null<T>() -> *T { 0 as *T }
/// Create an unsafe mutable null pointer
#[inline]
pub fn mut_null<T>() -> *mut T { 0 as *mut T }
/// Returns true if the pointer is equal to the null pointer.
#[inline]
pub fn is_null<T>(ptr: *const T) -> bool { ptr == null() }
/// Returns true if the pointer is not equal to the null pointer.
#[inline]
pub fn is_not_null<T>(ptr: *const T) -> bool { !is_null(ptr) }
/**
* Copies data from one location to another.
*
* Copies `count` elements (not bytes) from `src` to `dst`. The source
* and destination may overlap.
*/
#[inline]
#[cfg(target_word_size = "32")]
pub unsafe fn copy_memory<T>(dst: *mut T, src: *const T, count: uint) {
use unstable::intrinsics::memmove32;
memmove32(dst, src as *T, count as u32);
}
/**
* Copies data from one location to another.
*
* Copies `count` elements (not bytes) from `src` to `dst`. The source
* and destination may overlap.
*/
#[inline]
#[cfg(target_word_size = "64")]
pub unsafe fn copy_memory<T>(dst: *mut T, src: *const T, count: uint) {
use unstable::intrinsics::memmove64;
memmove64(dst, src as *T, count as u64);
}
/**
* Copies data from one location to another.
*
* Copies `count` elements (not bytes) from `src` to `dst`. The source
* and destination may *not* overlap.
*/
#[inline]
#[cfg(target_word_size = "32")]
pub unsafe fn copy_nonoverlapping_memory<T>(dst: *mut T, src: *const T, count: uint) {
use unstable::intrinsics::memcpy32;
memcpy32(dst, src as *T, count as u32);
}
/**
* Copies data from one location to another.
*
* Copies `count` elements (not bytes) from `src` to `dst`. The source
* and destination may *not* overlap.
*/
#[inline]
#[cfg(target_word_size = "64")]
pub unsafe fn copy_nonoverlapping_memory<T>(dst: *mut T, src: *const T, count: uint) {
use unstable::intrinsics::memcpy64;
memcpy64(dst, src as *T, count as u64);
}
/**
* Invokes memset on the specified pointer, setting `count * size_of::<T>()`
* bytes of memory starting at `dst` to `c`.
*/
#[inline]
#[cfg(target_word_size = "32")]
pub unsafe fn set_memory<T>(dst: *mut T, c: u8, count: uint) {
use unstable::intrinsics::memset32;
memset32(dst, c, count as u32);
}
/**
* Invokes memset on the specified pointer, setting `count * size_of::<T>()`
* bytes of memory starting at `dst` to `c`.
*/
#[inline]
#[cfg(target_word_size = "64")]
pub unsafe fn set_memory<T>(dst: *mut T, c: u8, count: uint) {
use unstable::intrinsics::memset64;
memset64(dst, c, count as u64);
}
/**
* Zeroes out `count * size_of::<T>` bytes of memory at `dst`
*/
#[inline]
#[cfg(not(stage0))]
pub unsafe fn zero_memory<T>(dst: *mut T, count: uint) {
set_memory(dst, 0, count);
}
/**
* Zeroes out `count * size_of::<T>` bytes of memory at `dst`
*/
#[inline]
#[cfg(stage0)]
pub unsafe fn zero_memory<T>(dst: *mut T, count: uint) {
let mut count = count * sys::size_of::<T>();
let mut dst = dst as *mut u8;
while count > 0 {
*dst = 0;
dst = mut_offset(dst, 1);
count -= 1;
}
}
/**
* Swap the values at two mutable locations of the same type, without
* deinitialising or copying either one.
*/
#[inline]
pub unsafe fn swap_ptr<T>(x: *mut T, y: *mut T) {
// Give ourselves some scratch space to work with
let mut tmp: T = intrinsics::uninit();
let t: *mut T = &mut tmp;
// Perform the swap
copy_nonoverlapping_memory(t, x, 1);
copy_memory(x, y, 1); // `x` and `y` may overlap
copy_nonoverlapping_memory(y, t, 1);
// y and t now point to the same thing, but we need to completely forget `tmp`
// because it's no longer relevant.
cast::forget(tmp);
}
/**
* Replace the value at a mutable location with a new one, returning the old
* value, without deinitialising or copying either one.
*/
#[inline]
pub unsafe fn replace_ptr<T>(dest: *mut T, mut src: T) -> T {
swap(cast::transmute(dest), &mut src); // cannot overlap
src
}
/**
* Reads the value from `*src` and returns it. Does not copy `*src`.
*/
#[inline(always)]
pub unsafe fn read_ptr<T>(src: *mut T) -> T {
let mut tmp: T = intrinsics::uninit();
copy_nonoverlapping_memory(&mut tmp, src, 1);
tmp
}
/**
* Reads the value from `*src` and nulls it out.
* This currently prevents destructors from executing.
*/
#[inline(always)]
pub unsafe fn read_and_zero_ptr<T>(dest: *mut T) -> T {
// Copy the data out from `dest`:
let tmp = read_ptr(dest);
// Now zero out `dest`:
zero_memory(dest, 1);
tmp
}
/// Transform a region pointer - &T - to an unsafe pointer - *T.
#[inline]
pub fn to_unsafe_ptr<T>(thing: &T) -> *T {
thing as *T
}
/// Transform a const region pointer - &const T - to a const unsafe pointer - *const T.
#[inline]
pub fn to_const_unsafe_ptr<T>(thing: &const T) -> *const T {
thing as *const T
}
/// Transform a mutable region pointer - &mut T - to a mutable unsafe pointer - *mut T.
#[inline]
pub fn to_mut_unsafe_ptr<T>(thing: &mut T) -> *mut T {
thing as *mut T
}
/**
Given a **T (pointer to an array of pointers),
iterate through each *T, up to the provided `len`,
passing to the provided callback function
SAFETY NOTE: Pointer-arithmetic. Dragons be here.
*/
pub unsafe fn array_each_with_len<T>(arr: **T, len: uint, cb: &fn(*T)) {
debug!("array_each_with_len: before iterate");
if (arr as uint == 0) {
fail!("ptr::array_each_with_len failure: arr input is null pointer");
}
//let start_ptr = *arr;
uint::iterate(0, len, |e| {
let n = offset(arr, e);
cb(*n);
true
});
debug!("array_each_with_len: after iterate");
}
/**
Given a null-pointer-terminated **T (pointer to
an array of pointers), iterate through each *T,
passing to the provided callback function
SAFETY NOTE: This will only work with a null-terminated
pointer array. Barely less-dodgey Pointer Arithmetic.
Dragons be here.
*/
pub unsafe fn array_each<T>(arr: **T, cb: &fn(*T)) {
if (arr as uint == 0) {
fail!("ptr::array_each_with_len failure: arr input is null pointer");
}
let len = buf_len(arr);
debug!("array_each inferred len: %u",
len);
array_each_with_len(arr, len, cb);
}
#[allow(missing_doc)]
pub trait RawPtr<T> {
fn is_null(&self) -> bool;
fn is_not_null(&self) -> bool;
unsafe fn to_option(&self) -> Option<&T>;
fn offset(&self, count: uint) -> Self;
}
/// Extension methods for immutable pointers
impl<T> RawPtr<T> for *T {
/// Returns true if the pointer is equal to the null pointer.
#[inline]
fn is_null(&self) -> bool { is_null(*self) }
/// Returns true if the pointer is not equal to the null pointer.
#[inline]
fn is_not_null(&self) -> bool { is_not_null(*self) }
///
/// Returns `None` if the pointer is null, or else returns the value wrapped
/// in `Some`.
///
/// # Safety Notes
///
/// While this method is useful for null-safety, it is important to note
/// that this is still an unsafe operation because the returned value could
/// be pointing to invalid memory.
///
#[inline]
unsafe fn to_option(&self) -> Option<&T> {
if self.is_null() { None } else {
Some(cast::transmute(*self))
}
}
/// Calculates the offset from a pointer.
#[inline]
fn offset(&self, count: uint) -> *T { offset(*self, count) }
}
/// Extension methods for mutable pointers
impl<T> RawPtr<T> for *mut T {
/// Returns true if the pointer is equal to the null pointer.
#[inline]
fn is_null(&self) -> bool { is_null(*self) }
/// Returns true if the pointer is not equal to the null pointer.
#[inline]
fn is_not_null(&self) -> bool { is_not_null(*self) }
///
/// Returns `None` if the pointer is null, or else returns the value wrapped
/// in `Some`.
///
/// # Safety Notes
///
/// While this method is useful for null-safety, it is important to note
/// that this is still an unsafe operation because the returned value could
/// be pointing to invalid memory.
///
#[inline]
unsafe fn to_option(&self) -> Option<&T> {
if self.is_null() { None } else {
Some(cast::transmute(*self))
}
}
/// Calculates the offset from a mutable pointer.
#[inline]
fn offset(&self, count: uint) -> *mut T { mut_offset(*self, count) }
}
// Equality for pointers
#[cfg(not(test))]
impl<T> Eq for *const T {
#[inline]
fn eq(&self, other: &*const T) -> bool {
(*self as uint) == (*other as uint)
}
#[inline]
fn ne(&self, other: &*const T) -> bool { !self.eq(other) }
}
// Comparison for pointers
#[cfg(not(test))]
impl<T> Ord for *const T {
#[inline]
fn lt(&self, other: &*const T) -> bool {
(*self as uint) < (*other as uint)
}
#[inline]
fn le(&self, other: &*const T) -> bool {
(*self as uint) <= (*other as uint)
}
#[inline]
fn ge(&self, other: &*const T) -> bool {
(*self as uint) >= (*other as uint)
}
#[inline]
fn gt(&self, other: &*const T) -> bool {
(*self as uint) > (*other as uint)
}
}
#[cfg(not(test))]
impl<T, I: Int> Add<I, *T> for *T {
/// Add an integer value to a pointer to get an offset pointer.
/// Is calculated according to the size of the type pointed to.
#[inline]
pub fn add(&self, rhs: &I) -> *T {
self.offset(rhs.to_int() as uint)
}
}
#[cfg(not(test))]
impl<T, I: Int> Sub<I, *T> for *T {
/// Subtract an integer value from a pointer to get an offset pointer.
/// Is calculated according to the size of the type pointed to.
#[inline]
pub fn sub(&self, rhs: &I) -> *T {
self.offset(-rhs.to_int() as uint)
}
}
#[cfg(not(test))]
impl<T, I: Int> Add<I, *mut T> for *mut T {
/// Add an integer value to a pointer to get an offset pointer.
/// Is calculated according to the size of the type pointed to.
#[inline]
pub fn add(&self, rhs: &I) -> *mut T {
self.offset(rhs.to_int() as uint)
}
}
#[cfg(not(test))]
impl<T, I: Int> Sub<I, *mut T> for *mut T {
/// Subtract an integer value from a pointer to get an offset pointer.
/// Is calculated according to the size of the type pointed to.
#[inline]
pub fn sub(&self, rhs: &I) -> *mut T {
self.offset(-rhs.to_int() as uint)
}
}
#[cfg(test)]
pub mod ptr_tests {
use super::*;
use prelude::*;
use cast;
use libc;
use str;
use vec;
#[test]
fn test() {
unsafe {
struct Pair {
fst: int,
snd: int
};
let mut p = Pair {fst: 10, snd: 20};
let pptr: *mut Pair = &mut p;
let iptr: *mut int = cast::transmute(pptr);
assert_eq!(*iptr, 10);
*iptr = 30;
assert_eq!(*iptr, 30);
assert_eq!(p.fst, 30);
*pptr = Pair {fst: 50, snd: 60};
assert_eq!(*iptr, 50);
assert_eq!(p.fst, 50);
assert_eq!(p.snd, 60);
let v0 = ~[32000u16, 32001u16, 32002u16];
let mut v1 = ~[0u16, 0u16, 0u16];
copy_memory(mut_offset(vec::raw::to_mut_ptr(v1), 1u),
offset(vec::raw::to_ptr(v0), 1u), 1u);
assert!((v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16));
copy_memory(vec::raw::to_mut_ptr(v1),
offset(vec::raw::to_ptr(v0), 2u), 1u);
assert!((v1[0] == 32002u16 && v1[1] == 32001u16 &&
v1[2] == 0u16));
copy_memory(mut_offset(vec::raw::to_mut_ptr(v1), 2u),
vec::raw::to_ptr(v0), 1u);
assert!((v1[0] == 32002u16 && v1[1] == 32001u16 &&
v1[2] == 32000u16));
}
}
#[test]
fn test_position() {
use str::as_c_str;
use libc::c_char;
let s = ~"hello";
unsafe {
assert!(2u == as_c_str(s, |p| position(p,
|c| *c == 'l' as c_char)));
assert!(4u == as_c_str(s, |p| position(p,
|c| *c == 'o' as c_char)));
assert!(5u == as_c_str(s, |p| position(p,
|c| *c == 0 as c_char)));
}
}
#[test]
fn test_buf_len() {
let s0 = ~"hello";
let s1 = ~"there";
let s2 = ~"thing";
do str::as_c_str(s0) |p0| {
do str::as_c_str(s1) |p1| {
do str::as_c_str(s2) |p2| {
let v = ~[p0, p1, p2, null()];
do v.as_imm_buf |vp, len| {
assert_eq!(unsafe { buf_len(vp) }, 3u);
assert_eq!(len, 4u);
}
}
}
}
}
#[test]
fn test_is_null() {
let p: *int = null();
assert!(p.is_null());
assert!(!p.is_not_null());
let q = offset(p, 1u);
assert!(!q.is_null());
assert!(q.is_not_null());
let mp: *mut int = mut_null();
assert!(mp.is_null());
assert!(!mp.is_not_null());
let mq = mp.offset(1u);
assert!(!mq.is_null());
assert!(mq.is_not_null());
}
#[test]
fn test_to_option() {
unsafe {
let p: *int = null();
assert_eq!(p.to_option(), None);
let q: *int = &2;
assert_eq!(q.to_option().unwrap(), &2);
let p: *mut int = mut_null();
assert_eq!(p.to_option(), None);
let q: *mut int = &mut 2;
assert_eq!(q.to_option().unwrap(), &2);
}
}
#[test]
fn test_ptr_addition() {
use vec::raw::*;
unsafe {
let xs = ~[5, ..16];
let mut ptr = to_ptr(xs);
let end = ptr + 16;
while ptr < end {
assert_eq!(*ptr, 5);
ptr = ptr + 1u;
}
let mut xs_mut = xs.clone();
let mut m_ptr = to_mut_ptr(xs_mut);
let m_end = m_ptr + 16i16;
while m_ptr < m_end {
*m_ptr += 5;
m_ptr = m_ptr + 1u8;
}
assert_eq!(xs_mut, ~[10, ..16]);
}
}
#[test]
fn test_ptr_subtraction() {
use vec::raw::*;
unsafe {
let xs = ~[0,1,2,3,4,5,6,7,8,9];
let mut idx = 9i8;
let ptr = to_ptr(xs);
while idx >= 0i8 {
assert_eq!(*(ptr + idx), idx as int);
idx = idx - 1i8;
}
let mut xs_mut = xs.clone();
let m_start = to_mut_ptr(xs_mut);
let mut m_ptr = m_start + 9u32;
while m_ptr >= m_start {
*m_ptr += *m_ptr;
m_ptr = m_ptr - 1i8;
}
assert_eq!(xs_mut, ~[0,2,4,6,8,10,12,14,16,18]);
}
}
#[test]
fn test_ptr_array_each_with_len() {
unsafe {
let one = ~"oneOne";
let two = ~"twoTwo";
let three = ~"threeThree";
let arr: ~[*i8] = ~[
::cast::transmute(&one[0]),
::cast::transmute(&two[0]),
::cast::transmute(&three[0]),
];
let expected_arr = [
one, two, three
];
let arr_ptr = &arr[0];
let mut ctr = 0;
let mut iteration_count = 0;
array_each_with_len(arr_ptr, arr.len(),
|e| {
let actual = str::raw::from_c_str(e);
let expected = expected_arr[ctr].clone();
debug!(
"test_ptr_array_each e: %s, a: %s",
expected, actual);
assert_eq!(actual, expected);
ctr += 1;
iteration_count += 1;
});
assert_eq!(iteration_count, 3u);
}
}
#[test]
fn test_ptr_array_each() {
unsafe {
let one = ~"oneOne";
let two = ~"twoTwo";
let three = ~"threeThree";
let arr: ~[*i8] = ~[
::cast::transmute(&one[0]),
::cast::transmute(&two[0]),
::cast::transmute(&three[0]),
// fake a null terminator
0 as *i8
];
let expected_arr = [
one, two, three
];
let arr_ptr = &arr[0];
let mut ctr = 0;
let mut iteration_count = 0;
array_each(arr_ptr, |e| {
let actual = str::raw::from_c_str(e);
let expected = expected_arr[ctr].clone();
debug!(
"test_ptr_array_each e: %s, a: %s",
expected, actual);
assert_eq!(actual, expected);
ctr += 1;
iteration_count += 1;
});
assert_eq!(iteration_count, 3);
}
}
#[test]
#[should_fail]
#[ignore(cfg(windows))]
fn test_ptr_array_each_with_len_null_ptr() {
unsafe {
array_each_with_len(0 as **libc::c_char, 1, |e| {
str::raw::from_c_str(e);
});
}
}
#[test]
#[should_fail]
#[ignore(cfg(windows))]
fn test_ptr_array_each_null_ptr() {
unsafe {
array_each(0 as **libc::c_char, |e| {
str::raw::from_c_str(e);
});
}
}
#[test]
fn test_set_memory() {
let mut xs = [0u8, ..20];
let ptr = vec::raw::to_mut_ptr(xs);
unsafe { set_memory(ptr, 5u8, xs.len()); }
assert_eq!(xs, [5u8, ..20]);
}
}