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67 lines
1.8 KiB
C
67 lines
1.8 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file physmem.h
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/// \brief Get the amount of physical memory
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//
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// This code has been put into the public domain.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef PHYSMEM_H
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#define PHYSMEM_H
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#if defined(HAVE_PHYSMEM_SYSCTL) || defined(HAVE_NCPU_SYSCTL)
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# ifdef HAVE_SYS_PARAM_H
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# include <sys/param.h>
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# endif
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# ifdef HAVE_SYS_SYSCTL_H
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# include <sys/sysctl.h>
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# endif
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#endif
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/// \brief Get the amount of physical memory in bytes
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///
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/// \return Amount of physical memory in bytes. On error, zero is
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/// returned.
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static inline uint64_t
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physmem(void)
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{
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uint64_t ret = 0;
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#if defined(HAVE_PHYSMEM_SYSCONF)
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const long pagesize = sysconf(_SC_PAGESIZE);
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const long pages = sysconf(_SC_PHYS_PAGES);
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if (pagesize != -1 || pages != -1)
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// According to docs, pagesize * pages can overflow.
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// Simple case is 32-bit box with 4 GiB or more RAM,
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// which may report exactly 4 GiB of RAM, and "long"
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// being 32-bit will overflow. Casting to uint64_t
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// hopefully avoids overflows in the near future.
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ret = (uint64_t)(pagesize) * (uint64_t)(pages);
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#elif defined(HAVE_PHYSMEM_SYSCTL)
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int name[2] = { CTL_HW, HW_PHYSMEM };
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unsigned long mem;
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size_t mem_ptr_size = sizeof(mem);
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if (!sysctl(name, 2, &mem, &mem_ptr_size, NULL, NULL)) {
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// Some systems use unsigned int as the "return value".
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// This makes a difference on 64-bit boxes.
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if (mem_ptr_size != sizeof(mem)) {
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if (mem_ptr_size == sizeof(unsigned int))
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ret = *(unsigned int *)(&mem);
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} else {
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ret = mem;
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}
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}
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#endif
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return ret;
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}
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#endif
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