1 files changed, 77 insertions, 0 deletions
diff --git a/src/common/physmem.h b/src/common/physmem.h
new file mode 100644
index 00000000..1d40b299
--- /dev/null
+++ b/src/common/physmem.h
@@ -0,0 +1,77 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       physmem.h
+/// \brief      Get the amount of physical memory
+//
+//  This code has been put into the public domain.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef PHYSMEM_H
+#define PHYSMEM_H
+
+#ifdef HAVE_CONFIG_H
+#	include <config.h>
+#endif
+
+#include <sys/types.h>
+#include <inttypes.h>
+
+#ifdef HAVE_LIMITS_H
+#	include <limits.h>
+#endif
+
+#if defined(HAVE_PHYSMEM_SYSCTL) || defined(HAVE_NCPU_SYSCTL)
+#	ifdef HAVE_SYS_PARAM_H
+#		include <sys/param.h>
+#	endif
+#	ifdef HAVE_SYS_SYSCTL_H
+#		include <sys/sysctl.h>
+#	endif
+#endif
+
+
+/// \brief      Get the amount of physical memory in bytes
+///
+/// \return     Amount of physical memory in bytes. On error, zero is
+///             returned.
+static inline uint64_t
+physmem(void)
+{
+	uint64_t ret = 0;
+
+#if defined(HAVE_PHYSMEM_SYSCONF)
+	const long pagesize = sysconf(_SC_PAGESIZE);
+	const long pages = sysconf(_SC_PHYS_PAGES);
+	if (pagesize != -1 || pages != -1)
+		// According to docs, pagesize * pages can overflow.
+		// Simple case is 32-bit box with 4 GiB or more RAM,
+		// which may report exactly 4 GiB of RAM, and "long"
+		// being 32-bit will overflow. Casting to uint64_t
+		// hopefully avoids overflows in the near future.
+		ret = (uint64_t)(pagesize) * (uint64_t)(pages);
+
+#elif defined(HAVE_PHYSMEM_SYSCTL)
+	int name[2] = { CTL_HW, HW_PHYSMEM };
+	unsigned long mem;
+	size_t mem_ptr_size = sizeof(mem);
+	if (!sysctl(name, 2, &mem, &mem_ptr_size, NULL, NULL)) {
+		// Some systems use unsigned int as the "return value".
+		// This makes a difference on 64-bit boxes.
+		if (mem_ptr_size != sizeof(mem)) {
+			if (mem_ptr_size == sizeof(unsigned int))
+				ret = *(unsigned int *)(&mem);
+		} else {
+			ret = mem;
+		}
+	}
+#endif
+
+	return ret;
+}
+
+#endif