1 /*
2  * Copyright (C) 2010 Apple Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #ifndef PageAllocation_h
27 #define PageAllocation_h
28 
29 #include <wtf/Assertions.h>
30 #include <wtf/OSAllocator.h>
31 #include <wtf/PageBlock.h>
32 #include <wtf/UnusedParam.h>
33 #include <wtf/VMTags.h>
34 #include <algorithm>
35 
36 #if OS(DARWIN)
37 #include <mach/mach_init.h>
38 #include <mach/vm_map.h>
39 #endif
40 
41 #if OS(WINDOWS)
42 #include <malloc.h>
43 #include <windows.h>
44 #endif
45 
46 #if HAVE(ERRNO_H)
47 #include <errno.h>
48 #endif
49 
50 #if HAVE(MMAP)
51 #include <sys/mman.h>
52 #include <unistd.h>
53 #endif
54 
55 namespace WTF {
56 
57 /*
58     PageAllocation
59 
60     The PageAllocation class provides a cross-platform memory allocation interface
61     with similar capabilities to posix mmap/munmap.  Memory is allocated by calling
62     PageAllocation::allocate, and deallocated by calling deallocate on the
63     PageAllocation object.  The PageAllocation holds the allocation's base pointer
64     and size.
65 
66     The allocate method is passed the size required (which must be a multiple of
67     the system page size, which can be accessed using PageAllocation::pageSize).
68     Callers may also optinally provide a flag indicating the usage (for use by
69     system memory usage tracking tools, where implemented), and boolean values
70     specifying the required protection (defaulting to writable, non-executable).
71 */
72 
73 class PageAllocation : private PageBlock {
74 public:
PageAllocation()75     PageAllocation()
76     {
77     }
78 
79     using PageBlock::size;
80     using PageBlock::base;
81 
82 #ifndef __clang__
83     using PageBlock::operator bool;
84 #else
85     // FIXME: This is a workaround for <rdar://problem/8876150>, wherein Clang incorrectly emits an access
86     // control warning when a client tries to use operator bool exposed above via "using PageBlock::operator bool".
87     operator bool() const { return PageBlock::operator bool(); }
88 #endif
89     bool operator<(const PageAllocation &b) { return base() < b.base(); }
90 
91     static PageAllocation allocate(size_t size,
92                                    OSAllocator::Usage usage = OSAllocator::UnknownUsage,
93                                    bool writable = true, bool executable = false,
94                                    bool includesGuardPages = false)
95     {
96         ASSERT(isPageAligned(size));
97         return PageAllocation(OSAllocator::reserveAndCommit(size, usage, writable, executable,
98                                                             includesGuardPages), size,
99                                                             includesGuardPages);
100     }
101 
deallocate()102     void deallocate()
103     {
104         // Clear base & size before calling release; if this is *inside* allocation
105         // then we won't be able to clear then after deallocating the memory.
106         PageAllocation tmp;
107         std::swap(tmp, *this);
108 
109         ASSERT(tmp);
110         ASSERT(!*this);
111 
112         OSAllocator::decommitAndRelease(tmp.realBase(), tmp.realSize());
113     }
114 
115 private:
116     PageAllocation(void* base, size_t size, bool includesGuardPages = false)
PageBlock(base,size,includesGuardPages)117         : PageBlock(base, size, includesGuardPages)
118     {
119     }
120 };
121 
122 } // namespace WTF
123 
124 using WTF::PageAllocation;
125 
126 #endif // PageAllocation_h
127