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};
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 either. They may overlap.
108 pub unsafe fn swap<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 either.
128 pub unsafe fn replace<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.
137 pub unsafe fn read<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<T>(dest: *mut T) -> T {
149 // Copy the data out from `dest`:
150 let tmp = read(&*dest);
152 // Now zero out `dest`:
153 zero_memory(dest, 1);
159 Given a **T (pointer to an array of pointers),
160 iterate through each *T, up to the provided `len`,
161 passing to the provided callback function
163 SAFETY NOTE: Pointer-arithmetic. Dragons be here.
165 pub unsafe fn array_each_with_len<T>(arr: **T, len: uint, cb: |*T|) {
167 fail!("ptr::array_each_with_len failure: arr input is null pointer");
169 //let start_ptr = *arr;
170 for e in range(0, len) {
171 let n = arr.offset(e as int);
177 Given a null-pointer-terminated **T (pointer to
178 an array of pointers), iterate through each *T,
179 passing to the provided callback function
181 SAFETY NOTE: This will only work with a null-terminated
182 pointer array. Barely less-dodgy Pointer Arithmetic.
185 pub unsafe fn array_each<T>(arr: **T, cb: |*T|) {
187 fail!("ptr::array_each_with_len failure: arr input is null pointer");
189 let len = buf_len(arr);
190 array_each_with_len(arr, len, cb);
193 /// Extension methods for raw pointers.
194 pub trait RawPtr<T> {
195 /// Returns the null pointer.
197 /// Returns true if the pointer is equal to the null pointer.
198 fn is_null(&self) -> bool;
199 /// Returns true if the pointer is not equal to the null pointer.
200 fn is_not_null(&self) -> bool { !self.is_null() }
201 /// Returns the value of this pointer (ie, the address it points to)
202 fn to_uint(&self) -> uint;
203 /// Returns `None` if the pointer is null, or else returns the value wrapped
208 /// While this method is useful for null-safety, it is important to note
209 /// that this is still an unsafe operation because the returned value could
210 /// be pointing to invalid memory.
211 unsafe fn to_option(&self) -> Option<&T>;
212 /// Calculates the offset from a pointer. The offset *must* be in-bounds of
213 /// the object, or one-byte-past-the-end. `count` is in units of T; e.g. a
214 /// `count` of 3 represents a pointer offset of `3 * sizeof::<T>()` bytes.
215 unsafe fn offset(self, count: int) -> Self;
218 impl<T> RawPtr<T> for *T {
220 fn null() -> *T { null() }
223 fn is_null(&self) -> bool { *self == RawPtr::null() }
226 fn to_uint(&self) -> uint { *self as uint }
229 unsafe fn offset(self, count: int) -> *T { intrinsics::offset(self, count) }
232 unsafe fn to_option(&self) -> Option<&T> {
236 Some(cast::transmute(*self))
241 impl<T> RawPtr<T> for *mut T {
243 fn null() -> *mut T { mut_null() }
246 fn is_null(&self) -> bool { *self == RawPtr::null() }
249 fn to_uint(&self) -> uint { *self as uint }
252 unsafe fn offset(self, count: int) -> *mut T { intrinsics::offset(self as *T, count) as *mut T }
255 unsafe fn to_option(&self) -> Option<&T> {
259 Some(cast::transmute(*self))
264 // Equality for pointers
268 fn eq(&self, other: &*T) -> bool {
272 fn ne(&self, other: &*T) -> bool { !self.eq(other) }
276 impl<T> Eq for *mut T {
278 fn eq(&self, other: &*mut T) -> bool {
282 fn ne(&self, other: &*mut T) -> bool { !self.eq(other) }
285 // Equivalence for pointers
287 impl<T> Equiv<*mut T> for *T {
288 fn equiv(&self, other: &*mut T) -> bool {
289 self.to_uint() == other.to_uint()
294 impl<T> Equiv<*T> for *mut T {
295 fn equiv(&self, other: &*T) -> bool {
296 self.to_uint() == other.to_uint()
300 // Equality for extern "C" fn pointers
302 mod externfnpointers {
306 impl<_R> Eq for extern "C" fn() -> _R {
308 fn eq(&self, other: &extern "C" fn() -> _R) -> bool {
309 let self_: *() = unsafe { cast::transmute(*self) };
310 let other_: *() = unsafe { cast::transmute(*other) };
314 fn ne(&self, other: &extern "C" fn() -> _R) -> bool {
318 macro_rules! fnptreq(
320 impl<_R,$($p),*> Eq for extern "C" fn($($p),*) -> _R {
322 fn eq(&self, other: &extern "C" fn($($p),*) -> _R) -> bool {
323 let self_: *() = unsafe { cast::transmute(*self) };
324 let other_: *() = unsafe { cast::transmute(*other) };
328 fn ne(&self, other: &extern "C" fn($($p),*) -> _R) -> bool {
341 // Comparison for pointers
345 fn lt(&self, other: &*T) -> bool {
349 fn le(&self, other: &*T) -> bool {
353 fn ge(&self, other: &*T) -> bool {
357 fn gt(&self, other: &*T) -> bool {
363 impl<T> Ord for *mut T {
365 fn lt(&self, other: &*mut T) -> bool {
369 fn le(&self, other: &*mut T) -> bool {
373 fn ge(&self, other: &*mut T) -> bool {
377 fn gt(&self, other: &*mut T) -> bool {
391 use slice::{ImmutableVector, MutableVector};
400 let mut p = Pair {fst: 10, snd: 20};
401 let pptr: *mut Pair = &mut p;
402 let iptr: *mut int = cast::transmute(pptr);
403 assert_eq!(*iptr, 10);
405 assert_eq!(*iptr, 30);
406 assert_eq!(p.fst, 30);
408 *pptr = Pair {fst: 50, snd: 60};
409 assert_eq!(*iptr, 50);
410 assert_eq!(p.fst, 50);
411 assert_eq!(p.snd, 60);
413 let v0 = ~[32000u16, 32001u16, 32002u16];
414 let mut v1 = ~[0u16, 0u16, 0u16];
416 copy_memory(v1.as_mut_ptr().offset(1),
417 v0.as_ptr().offset(1), 1);
418 assert!((v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16));
419 copy_memory(v1.as_mut_ptr(),
420 v0.as_ptr().offset(2), 1);
421 assert!((v1[0] == 32002u16 && v1[1] == 32001u16 &&
423 copy_memory(v1.as_mut_ptr().offset(2),
425 assert!((v1[0] == 32002u16 && v1[1] == 32001u16 &&
434 "hello".with_c_str(|p| {
436 assert!(2u == position(p, |c| *c == 'l' as c_char));
437 assert!(4u == position(p, |c| *c == 'o' as c_char));
438 assert!(5u == position(p, |c| *c == 0 as c_char));
445 "hello".with_c_str(|p0| {
446 "there".with_c_str(|p1| {
447 "thing".with_c_str(|p2| {
448 let v = ~[p0, p1, p2, null()];
450 assert_eq!(buf_len(v.as_ptr()), 3u);
459 let p: *int = null();
460 assert!(p.is_null());
461 assert!(!p.is_not_null());
463 let q = unsafe { p.offset(1) };
464 assert!(!q.is_null());
465 assert!(q.is_not_null());
467 let mp: *mut int = mut_null();
468 assert!(mp.is_null());
469 assert!(!mp.is_not_null());
471 let mq = unsafe { mp.offset(1) };
472 assert!(!mq.is_null());
473 assert!(mq.is_not_null());
477 fn test_to_option() {
479 let p: *int = null();
480 assert_eq!(p.to_option(), None);
483 assert_eq!(q.to_option().unwrap(), &2);
485 let p: *mut int = mut_null();
486 assert_eq!(p.to_option(), None);
488 let q: *mut int = &mut 2;
489 assert_eq!(q.to_option().unwrap(), &2);
494 fn test_ptr_addition() {
497 let mut ptr = xs.as_ptr();
498 let end = ptr.offset(16);
505 let mut xs_mut = xs.clone();
506 let mut m_ptr = xs_mut.as_mut_ptr();
507 let m_end = m_ptr.offset(16);
509 while m_ptr < m_end {
511 m_ptr = m_ptr.offset(1);
514 assert_eq!(xs_mut, ~[10, ..16]);
519 fn test_ptr_subtraction() {
521 let xs = ~[0,1,2,3,4,5,6,7,8,9];
523 let ptr = xs.as_ptr();
526 assert_eq!(*(ptr.offset(idx as int)), idx as int);
530 let mut xs_mut = xs.clone();
531 let m_start = xs_mut.as_mut_ptr();
532 let mut m_ptr = m_start.offset(9);
534 while m_ptr >= m_start {
536 m_ptr = m_ptr.offset(-1);
539 assert_eq!(xs_mut, ~[0,2,4,6,8,10,12,14,16,18]);
544 fn test_ptr_array_each_with_len() {
546 let one = "oneOne".to_c_str();
547 let two = "twoTwo".to_c_str();
548 let three = "threeThree".to_c_str();
550 one.with_ref(|buf| buf),
551 two.with_ref(|buf| buf),
552 three.with_ref(|buf| buf),
559 let mut iteration_count = 0;
560 array_each_with_len(arr.as_ptr(), arr.len(), |e| {
561 let actual = str::raw::from_c_str(e);
562 let expected = expected_arr[ctr].with_ref(|buf| {
563 str::raw::from_c_str(buf)
566 "test_ptr_array_each_with_len e: {}, a: {}",
568 assert_eq!(actual, expected);
570 iteration_count += 1;
572 assert_eq!(iteration_count, 3u);
577 fn test_ptr_array_each() {
579 let one = "oneOne".to_c_str();
580 let two = "twoTwo".to_c_str();
581 let three = "threeThree".to_c_str();
583 one.with_ref(|buf| buf),
584 two.with_ref(|buf| buf),
585 three.with_ref(|buf| buf),
586 // fake a null terminator
593 let arr_ptr = arr.as_ptr();
595 let mut iteration_count = 0;
596 array_each(arr_ptr, |e| {
597 let actual = str::raw::from_c_str(e);
598 let expected = expected_arr[ctr].with_ref(|buf| {
599 str::raw::from_c_str(buf)
602 "test_ptr_array_each e: {}, a: {}",
604 assert_eq!(actual, expected);
606 iteration_count += 1;
608 assert_eq!(iteration_count, 3);
614 fn test_ptr_array_each_with_len_null_ptr() {
616 array_each_with_len(0 as **libc::c_char, 1, |e| {
617 str::raw::from_c_str(e);
623 fn test_ptr_array_each_null_ptr() {
625 array_each(0 as **libc::c_char, |e| {
626 str::raw::from_c_str(e);
632 fn test_set_memory() {
633 let mut xs = [0u8, ..20];
634 let ptr = xs.as_mut_ptr();
635 unsafe { set_memory(ptr, 5u8, xs.len()); }
636 assert!(xs == [5u8, ..20]);