1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Unsafe pointer utility functions
17 use iter::{range, Iterator};
19 use option::{Option, Some, None};
20 use unstable::intrinsics;
22 #[cfg(not(test))] use cmp::{Eq, Ord};
24 /// Return the offset of the first null pointer in `buf`.
26 pub unsafe fn buf_len<T>(buf: **T) -> uint {
27 position(buf, |i| *i == null())
30 impl<T> Clone for *T {
32 fn clone(&self) -> *T {
37 impl<T> Clone for *mut T {
39 fn clone(&self) -> *mut T {
44 /// Return the first offset `i` such that `f(buf[i]) == true`.
46 pub unsafe fn position<T>(buf: *T, f: |&T| -> bool) -> uint {
49 if f(&(*buf.offset(i as int))) { return i; }
54 /// Create an unsafe null pointer
56 pub fn null<T>() -> *T { 0 as *T }
58 /// Create an unsafe mutable null pointer
60 pub fn mut_null<T>() -> *mut T { 0 as *mut T }
63 * Copies data from one location to another.
65 * Copies `count` elements (not bytes) from `src` to `dst`. The source
66 * and destination may overlap.
69 pub unsafe fn copy_memory<T>(dst: *mut T, src: *T, count: uint) {
70 intrinsics::copy_memory(dst, src, count)
74 * Copies data from one location to another.
76 * Copies `count` elements (not bytes) from `src` to `dst`. The source
77 * and destination may *not* overlap.
80 pub unsafe fn copy_nonoverlapping_memory<T>(dst: *mut T,
83 intrinsics::copy_nonoverlapping_memory(dst, src, count)
87 * Invokes memset on the specified pointer, setting `count * size_of::<T>()`
88 * bytes of memory starting at `dst` to `c`.
91 pub unsafe fn set_memory<T>(dst: *mut T, c: u8, count: uint) {
92 intrinsics::set_memory(dst, c, count)
96 * Zeroes out `count * size_of::<T>` bytes of memory at `dst`
99 pub unsafe fn zero_memory<T>(dst: *mut T, count: uint) {
100 set_memory(dst, 0, count);
104 * Swap the values at two mutable locations of the same type, without
105 * deinitialising or copying either one.
108 pub unsafe fn swap_ptr<T>(x: *mut T, y: *mut T) {
109 // Give ourselves some scratch space to work with
110 let mut tmp: T = mem::uninit();
111 let t: *mut T = &mut tmp;
114 copy_nonoverlapping_memory(t, &*x, 1);
115 copy_memory(x, &*y, 1); // `x` and `y` may overlap
116 copy_nonoverlapping_memory(y, &*t, 1);
118 // y and t now point to the same thing, but we need to completely forget `tmp`
119 // because it's no longer relevant.
124 * Replace the value at a mutable location with a new one, returning the old
125 * value, without deinitialising or copying either one.
128 pub unsafe fn replace_ptr<T>(dest: *mut T, mut src: T) -> T {
129 mem::swap(cast::transmute(dest), &mut src); // cannot overlap
134 * Reads the value from `*src` and returns it. Does not copy `*src`.
137 pub unsafe fn read_ptr<T>(src: *T) -> T {
138 let mut tmp: T = mem::uninit();
139 copy_nonoverlapping_memory(&mut tmp, src, 1);
144 * Reads the value from `*src` and nulls it out.
145 * This currently prevents destructors from executing.
148 pub unsafe fn read_and_zero_ptr<T>(dest: *mut T) -> T {
149 // Copy the data out from `dest`:
150 let tmp = read_ptr(&*dest);
152 // Now zero out `dest`:
153 zero_memory(dest, 1);
158 /// Transform a region pointer - &T - to an unsafe pointer - *T.
160 pub fn to_unsafe_ptr<T>(thing: &T) -> *T {
164 /// Transform a mutable region pointer - &mut T - to a mutable unsafe pointer - *mut T.
166 pub fn to_mut_unsafe_ptr<T>(thing: &mut T) -> *mut T {
171 Given a **T (pointer to an array of pointers),
172 iterate through each *T, up to the provided `len`,
173 passing to the provided callback function
175 SAFETY NOTE: Pointer-arithmetic. Dragons be here.
177 pub unsafe fn array_each_with_len<T>(arr: **T, len: uint, cb: |*T|) {
178 debug!("array_each_with_len: before iterate");
179 if arr as uint == 0 {
180 fail!("ptr::array_each_with_len failure: arr input is null pointer");
182 //let start_ptr = *arr;
183 for e in range(0, len) {
184 let n = arr.offset(e as int);
187 debug!("array_each_with_len: after iterate");
191 Given a null-pointer-terminated **T (pointer to
192 an array of pointers), iterate through each *T,
193 passing to the provided callback function
195 SAFETY NOTE: This will only work with a null-terminated
196 pointer array. Barely less-dodgy Pointer Arithmetic.
199 pub unsafe fn array_each<T>(arr: **T, cb: |*T|) {
200 if arr as uint == 0 {
201 fail!("ptr::array_each_with_len failure: arr input is null pointer");
203 let len = buf_len(arr);
204 debug!("array_each inferred len: {}", len);
205 array_each_with_len(arr, len, cb);
208 #[allow(missing_doc)]
209 pub trait RawPtr<T> {
211 fn is_null(&self) -> bool;
212 fn is_not_null(&self) -> bool;
213 fn to_uint(&self) -> uint;
214 unsafe fn to_option(&self) -> Option<&T>;
215 unsafe fn offset(self, count: int) -> Self;
218 /// Extension methods for immutable pointers
219 impl<T> RawPtr<T> for *T {
220 /// Returns the null pointer.
222 fn null() -> *T { null() }
224 /// Returns true if the pointer is equal to the null pointer.
226 fn is_null(&self) -> bool { *self == RawPtr::null() }
228 /// Returns true if the pointer is not equal to the null pointer.
230 fn is_not_null(&self) -> bool { *self != RawPtr::null() }
232 /// Returns the address of this pointer.
234 fn to_uint(&self) -> uint { *self as uint }
237 /// Returns `None` if the pointer is null, or else returns the value wrapped
242 /// While this method is useful for null-safety, it is important to note
243 /// that this is still an unsafe operation because the returned value could
244 /// be pointing to invalid memory.
247 unsafe fn to_option(&self) -> Option<&T> {
248 if self.is_null() { None } else {
249 Some(cast::transmute(*self))
253 /// Calculates the offset from a pointer. The offset *must* be in-bounds of
254 /// the object, or one-byte-past-the-end.
256 unsafe fn offset(self, count: int) -> *T { intrinsics::offset(self, count) }
259 /// Extension methods for mutable pointers
260 impl<T> RawPtr<T> for *mut T {
261 /// Returns the null pointer.
263 fn null() -> *mut T { mut_null() }
265 /// Returns true if the pointer is equal to the null pointer.
267 fn is_null(&self) -> bool { *self == RawPtr::null() }
269 /// Returns true if the pointer is not equal to the null pointer.
271 fn is_not_null(&self) -> bool { *self != RawPtr::null() }
273 /// Returns the address of this pointer.
275 fn to_uint(&self) -> uint { *self as uint }
278 /// Returns `None` if the pointer is null, or else returns the value wrapped
283 /// While this method is useful for null-safety, it is important to note
284 /// that this is still an unsafe operation because the returned value could
285 /// be pointing to invalid memory.
288 unsafe fn to_option(&self) -> Option<&T> {
289 if self.is_null() { None } else {
290 Some(cast::transmute(*self))
294 /// Calculates the offset from a pointer. The offset *must* be in-bounds of
295 /// the object, or one-byte-past-the-end. An arithmetic overflow is also
296 /// undefined behaviour.
298 /// This method should be preferred over `offset` when the guarantee can be
299 /// satisfied, to enable better optimization.
301 unsafe fn offset(self, count: int) -> *mut T { intrinsics::offset(self as *T, count) as *mut T }
304 // Equality for pointers
308 fn eq(&self, other: &*T) -> bool {
312 fn ne(&self, other: &*T) -> bool { !self.eq(other) }
316 impl<T> Eq for *mut T {
318 fn eq(&self, other: &*mut T) -> bool {
322 fn ne(&self, other: &*mut T) -> bool { !self.eq(other) }
325 // Equivalence for pointers
327 impl<T> Equiv<*mut T> for *T {
328 fn equiv(&self, other: &*mut T) -> bool {
329 self.to_uint() == other.to_uint()
334 impl<T> Equiv<*T> for *mut T {
335 fn equiv(&self, other: &*T) -> bool {
336 self.to_uint() == other.to_uint()
340 // Equality for extern "C" fn pointers
342 mod externfnpointers {
346 impl<_R> Eq for extern "C" fn() -> _R {
348 fn eq(&self, other: &extern "C" fn() -> _R) -> bool {
349 let self_: *() = unsafe { cast::transmute(*self) };
350 let other_: *() = unsafe { cast::transmute(*other) };
354 fn ne(&self, other: &extern "C" fn() -> _R) -> bool {
358 macro_rules! fnptreq(
360 impl<_R,$($p),*> Eq for extern "C" fn($($p),*) -> _R {
362 fn eq(&self, other: &extern "C" fn($($p),*) -> _R) -> bool {
363 let self_: *() = unsafe { cast::transmute(*self) };
364 let other_: *() = unsafe { cast::transmute(*other) };
368 fn ne(&self, other: &extern "C" fn($($p),*) -> _R) -> bool {
381 // Comparison for pointers
385 fn lt(&self, other: &*T) -> bool {
389 fn le(&self, other: &*T) -> bool {
393 fn ge(&self, other: &*T) -> bool {
397 fn gt(&self, other: &*T) -> bool {
403 impl<T> Ord for *mut T {
405 fn lt(&self, other: &*mut T) -> bool {
409 fn le(&self, other: &*mut T) -> bool {
413 fn ge(&self, other: &*mut T) -> bool {
417 fn gt(&self, other: &*mut T) -> bool {
431 use vec::{ImmutableVector, MutableVector};
440 let mut p = Pair {fst: 10, snd: 20};
441 let pptr: *mut Pair = &mut p;
442 let iptr: *mut int = cast::transmute(pptr);
443 assert_eq!(*iptr, 10);
445 assert_eq!(*iptr, 30);
446 assert_eq!(p.fst, 30);
448 *pptr = Pair {fst: 50, snd: 60};
449 assert_eq!(*iptr, 50);
450 assert_eq!(p.fst, 50);
451 assert_eq!(p.snd, 60);
453 let v0 = ~[32000u16, 32001u16, 32002u16];
454 let mut v1 = ~[0u16, 0u16, 0u16];
456 copy_memory(v1.as_mut_ptr().offset(1),
457 v0.as_ptr().offset(1), 1);
458 assert!((v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16));
459 copy_memory(v1.as_mut_ptr(),
460 v0.as_ptr().offset(2), 1);
461 assert!((v1[0] == 32002u16 && v1[1] == 32001u16 &&
463 copy_memory(v1.as_mut_ptr().offset(2),
465 assert!((v1[0] == 32002u16 && v1[1] == 32001u16 &&
474 "hello".with_c_str(|p| {
476 assert!(2u == position(p, |c| *c == 'l' as c_char));
477 assert!(4u == position(p, |c| *c == 'o' as c_char));
478 assert!(5u == position(p, |c| *c == 0 as c_char));
485 "hello".with_c_str(|p0| {
486 "there".with_c_str(|p1| {
487 "thing".with_c_str(|p2| {
488 let v = ~[p0, p1, p2, null()];
490 assert_eq!(buf_len(v.as_ptr()), 3u);
499 let p: *int = null();
500 assert!(p.is_null());
501 assert!(!p.is_not_null());
503 let q = unsafe { p.offset(1) };
504 assert!(!q.is_null());
505 assert!(q.is_not_null());
507 let mp: *mut int = mut_null();
508 assert!(mp.is_null());
509 assert!(!mp.is_not_null());
511 let mq = unsafe { mp.offset(1) };
512 assert!(!mq.is_null());
513 assert!(mq.is_not_null());
517 fn test_to_option() {
519 let p: *int = null();
520 assert_eq!(p.to_option(), None);
523 assert_eq!(q.to_option().unwrap(), &2);
525 let p: *mut int = mut_null();
526 assert_eq!(p.to_option(), None);
528 let q: *mut int = &mut 2;
529 assert_eq!(q.to_option().unwrap(), &2);
534 fn test_ptr_addition() {
537 let mut ptr = xs.as_ptr();
538 let end = ptr.offset(16);
545 let mut xs_mut = xs.clone();
546 let mut m_ptr = xs_mut.as_mut_ptr();
547 let m_end = m_ptr.offset(16);
549 while m_ptr < m_end {
551 m_ptr = m_ptr.offset(1);
554 assert_eq!(xs_mut, ~[10, ..16]);
559 fn test_ptr_subtraction() {
561 let xs = ~[0,1,2,3,4,5,6,7,8,9];
563 let ptr = xs.as_ptr();
566 assert_eq!(*(ptr.offset(idx as int)), idx as int);
570 let mut xs_mut = xs.clone();
571 let m_start = xs_mut.as_mut_ptr();
572 let mut m_ptr = m_start.offset(9);
574 while m_ptr >= m_start {
576 m_ptr = m_ptr.offset(-1);
579 assert_eq!(xs_mut, ~[0,2,4,6,8,10,12,14,16,18]);
584 fn test_ptr_array_each_with_len() {
586 let one = "oneOne".to_c_str();
587 let two = "twoTwo".to_c_str();
588 let three = "threeThree".to_c_str();
590 one.with_ref(|buf| buf),
591 two.with_ref(|buf| buf),
592 three.with_ref(|buf| buf),
599 let mut iteration_count = 0;
600 array_each_with_len(arr.as_ptr(), arr.len(), |e| {
601 let actual = str::raw::from_c_str(e);
602 let expected = expected_arr[ctr].with_ref(|buf| {
603 str::raw::from_c_str(buf)
606 "test_ptr_array_each_with_len e: {}, a: {}",
608 assert_eq!(actual, expected);
610 iteration_count += 1;
612 assert_eq!(iteration_count, 3u);
617 fn test_ptr_array_each() {
619 let one = "oneOne".to_c_str();
620 let two = "twoTwo".to_c_str();
621 let three = "threeThree".to_c_str();
623 one.with_ref(|buf| buf),
624 two.with_ref(|buf| buf),
625 three.with_ref(|buf| buf),
626 // fake a null terminator
633 let arr_ptr = arr.as_ptr();
635 let mut iteration_count = 0;
636 array_each(arr_ptr, |e| {
637 let actual = str::raw::from_c_str(e);
638 let expected = expected_arr[ctr].with_ref(|buf| {
639 str::raw::from_c_str(buf)
642 "test_ptr_array_each e: {}, a: {}",
644 assert_eq!(actual, expected);
646 iteration_count += 1;
648 assert_eq!(iteration_count, 3);
654 fn test_ptr_array_each_with_len_null_ptr() {
656 array_each_with_len(0 as **libc::c_char, 1, |e| {
657 str::raw::from_c_str(e);
663 fn test_ptr_array_each_null_ptr() {
665 array_each(0 as **libc::c_char, |e| {
666 str::raw::from_c_str(e);
672 fn test_set_memory() {
673 let mut xs = [0u8, ..20];
674 let ptr = xs.as_mut_ptr();
675 unsafe { set_memory(ptr, 5u8, xs.len()); }
676 assert_eq!(xs, [5u8, ..20]);