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/* Copyright (C) 2025 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "precompiled.h"
#include "lib/sysdep/vm.h"
#include "lib/debug.h"
#include "lib/posix/posix_mman.h"
#include "lib/status.h"
#include <cerrno>
#include <cstddef>
#include <cstdint>
// "anonymous" effectively means mapping /dev/zero, but is more efficient.
// MAP_ANONYMOUS is not in SUSv3, but is a very common extension.
// unfortunately, MacOS X only defines MAP_ANON, which Solaris says is
// deprecated. workaround there: define MAP_ANONYMOUS in terms of MAP_ANON.
#ifndef MAP_ANONYMOUS
# define MAP_ANONYMOUS MAP_ANON
#endif
static const int mmap_flags = MAP_PRIVATE|MAP_ANONYMOUS;
namespace vm {
void* ReserveAddressSpace(size_t size, size_t /*commitSize*/, PageType /*pageType*/, int /*prot*/)
{
errno = 0;
void* p = mmap(0, size, PROT_NONE, mmap_flags|MAP_NORESERVE, -1, 0);
if(p == MAP_FAILED)
return 0;
return p;
}
void ReleaseAddressSpace(void* p, size_t size)
{
ENSURE(size != 0);
errno = 0;
if(munmap(p, size) != 0)
DEBUG_WARN_ERR(StatusFromErrno());
}
bool Commit(uintptr_t address, size_t size, PageType, int prot)
{
if(prot == PROT_NONE) // would be understood as a request to decommit
{
DEBUG_WARN_ERR(ERR::INVALID_PARAM);
return false;
}
errno = 0;
if(mmap((void*)address, size, prot, mmap_flags|MAP_FIXED, -1, 0) == MAP_FAILED)
return false;
if(prot != (PROT_READ|PROT_WRITE))
(void)Protect(address, size, prot);
return true;
}
bool Decommit(uintptr_t address, size_t size)
{
errno = 0;
if(mmap((void*)address, size, PROT_NONE, mmap_flags|MAP_NORESERVE|MAP_FIXED, -1, 0) == MAP_FAILED)
return false;
return true;
}
bool Protect(uintptr_t address, size_t size, int prot)
{
errno = 0;
if(mprotect((void*)address, size, prot) != 0)
{
DEBUG_WARN_ERR(ERR::FAIL);
return false;
}
return true;
}
void* Allocate(size_t size, PageType pageType, int prot)
{
void* p = ReserveAddressSpace(size);
if(!p)
return 0;
if(!Commit(uintptr_t(p), size, pageType, prot))
{
ReleaseAddressSpace(p, size);
return 0;
}
return p;
}
void Free(void* p, size_t size)
{
// (only the Windows implementation distinguishes between Free and ReleaseAddressSpace)
vm::ReleaseAddressSpace(p, size);
}
void BeginOnDemandCommits()
{
// not yet implemented, but possible with a signal handler
}
void EndOnDemandCommits()
{
// not yet implemented, but possible with a signal handler
}
void DumpStatistics()
{
// we haven't collected any statistics
}
} // namespace vm
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