Initial code.

src/lib/util/memlimit.c

Index: src/lib/util/memlimit.c
diff --git a/src/lib/util/memlimit.c b/src/lib/util/memlimit.c
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+/*-
+ * Copyright 2009 Colin Percival
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * This file was originally written by Colin Percival as part of the Tarsnap
+ * online backup system.
+ */
+#include "scrypt_platform.h"
+
+#include <sys/types.h>
+#include <sys/resource.h>
+
+#ifdef HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
+#ifdef HAVE_SYSCTL_HW_USERMEM
+#include <sys/sysctl.h>
+#endif
+#ifdef HAVE_SYS_SYSINFO_H
+#include <sys/sysinfo.h>
+#endif
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
+#include "memlimit.h"
+
+#ifdef HAVE_SYSCTL_HW_USERMEM
+static int
+memlimit_sysctl_hw_usermem(size_t * memlimit)
+{
+	int mib[2];
+	uint8_t usermembuf[8];
+	size_t usermemlen = 8;
+	uint64_t usermem;
+
+	/* Ask the kernel how much RAM we have. */
+	mib[0] = CTL_HW;
+	mib[1] = HW_USERMEM;
+	if (sysctl(mib, 2, usermembuf, &usermemlen, NULL, 0))
+		return (1);
+
+	/*
+	 * Parse as either a uint64_t or a uint32_t based on the length of
+	 * output the kernel reports having copied out.  It appears that all
+	 * systems providing a sysctl interface for reading integers copy
+	 * them out as system-endian values, so we don't need to worry about
+	 * parsing them.
+	 */
+	if (usermemlen == sizeof(uint64_t))
+		usermem = *(uint64_t *)usermembuf;
+	else if (usermemlen == sizeof(uint32_t))
+		usermem = *(uint32_t *)usermembuf;
+	else
+		return (1);
+
+	/* Return the sysctl value, but clamp to SIZE_MAX if necessary. */
+#if UINT64_MAX > SIZE_MAX
+	if (usermem > SIZE_MAX)
+		*memlimit = SIZE_MAX;
+	else
+		*memlimit = usermem;
+#else
+	*memlimit = usermem;
+#endif
+
+	/* Success! */
+	return (0);
+}
+#endif
+
+/* If we don't HAVE_STRUCT_SYSINFO, we can't use sysinfo. */
+#ifndef HAVE_STRUCT_SYSINFO
+#undef HAVE_SYSINFO
+#endif
+
+/* If we don't HAVE_STRUCT_SYSINFO_TOTALRAM, we can't use sysinfo. */
+#ifndef HAVE_STRUCT_SYSINFO_TOTALRAM
+#undef HAVE_SYSINFO
+#endif
+
+#ifdef HAVE_SYSINFO
+static int
+memlimit_sysinfo(size_t * memlimit)
+{
+	struct sysinfo info;
+	uint64_t totalmem;
+
+	/* Get information from the kernel. */
+	if (sysinfo(&info))
+		return (1);
+	totalmem = info.totalram;
+
+	/* If we're on a modern kernel, adjust based on mem_unit. */
+#ifdef HAVE_STRUCT_SYSINFO_MEM_UNIT
+	totalmem = totalmem * info.mem_unit;
+#endif
+
+	/* Return the value, but clamp to SIZE_MAX if necessary. */
+#if UINT64_MAX > SIZE_MAX
+	if (totalmem > SIZE_MAX)
+		*memlimit = SIZE_MAX;
+	else
+		*memlimit = totalmem;
+#else
+	*memlimit = totalmem;
+#endif
+
+	/* Success! */
+	return (0);
+}
+#endif /* HAVE_SYSINFO */
+
+static int
+memlimit_rlimit(size_t * memlimit)
+{
+	struct rlimit rl;
+	uint64_t memrlimit;
+
+	/* Find the least of... */
+	memrlimit = (uint64_t)(-1);
+
+	/* ... RLIMIT_AS... */
+#ifdef RLIMIT_AS
+	if (getrlimit(RLIMIT_AS, &rl))
+		return (1);
+	if ((rl.rlim_cur != RLIM_INFINITY) &&
+	    ((uint64_t)rl.rlim_cur < memrlimit))
+		memrlimit = rl.rlim_cur;
+#endif
+
+	/* ... RLIMIT_DATA... */
+	if (getrlimit(RLIMIT_DATA, &rl))
+		return (1);
+	if ((rl.rlim_cur != RLIM_INFINITY) &&
+	    ((uint64_t)rl.rlim_cur < memrlimit))
+		memrlimit = rl.rlim_cur;
+
+	/* ... and RLIMIT_RSS. */
+#ifdef RLIMIT_RSS
+	if (getrlimit(RLIMIT_RSS, &rl))
+		return (1);
+	if ((rl.rlim_cur != RLIM_INFINITY) &&
+	    ((uint64_t)rl.rlim_cur < memrlimit))
+		memrlimit = rl.rlim_cur;
+#endif
+
+	/* Return the value, but clamp to SIZE_MAX if necessary. */
+#if UINT64_MAX > SIZE_MAX
+	if (memrlimit > SIZE_MAX)
+		*memlimit = SIZE_MAX;
+	else
+		*memlimit = memrlimit;
+#else
+	*memlimit = memrlimit;
+#endif
+
+	/* Success! */
+	return (0);
+}
+
+#ifdef _SC_PHYS_PAGES
+
+/* Some systems define _SC_PAGESIZE instead of _SC_PAGE_SIZE. */
+#ifndef _SC_PAGE_SIZE
+#define _SC_PAGE_SIZE _SC_PAGESIZE
+#endif
+
+static int
+memlimit_sysconf(size_t * memlimit)
+{
+	long pagesize;
+	long physpages;
+	uint64_t totalmem;
+
+	/* Set errno to 0 in order to distinguish "no limit" from "error". */
+	errno = 0;
+
+	/* Read the two limits. */
+	if (((pagesize = sysconf(_SC_PAGE_SIZE)) == -1) ||
+	    ((physpages = sysconf(_SC_PHYS_PAGES)) == -1)) {
+		/* Did an error occur? */
+		if (errno != 0)
+			return (1);
+
+		/* If not, there is no limit. */
+		totalmem = (uint64_t)(-1);
+	} else {
+		/* Compute the limit. */
+		totalmem = (uint64_t)(pagesize) * (uint64_t)(physpages);
+	}
+
+	/* Return the value, but clamp to SIZE_MAX if necessary. */
+#if UINT64_MAX > SIZE_MAX
+	if (totalmem > SIZE_MAX)
+		*memlimit = SIZE_MAX;
+	else
+		*memlimit = totalmem;
+#else
+	*memlimit = totalmem;
+#endif
+
+	/* Success! */
+	return (0);
+}
+#endif
+
+int
+memtouse(size_t maxmem, double maxmemfrac, size_t * memlimit)
+{
+	size_t sysctl_memlimit, sysinfo_memlimit, rlimit_memlimit;
+	size_t sysconf_memlimit;
+	size_t memlimit_min;
+	size_t memavail;
+
+	/* Get memory limits. */
+#ifdef HAVE_SYSCTL_HW_USERMEM
+	if (memlimit_sysctl_hw_usermem(&sysctl_memlimit))
+		return (1);
+#else
+	sysctl_memlimit = (size_t)(-1);
+#endif
+#ifdef HAVE_SYSINFO
+	if (memlimit_sysinfo(&sysinfo_memlimit))
+		return (1);
+#else
+	sysinfo_memlimit = (size_t)(-1);
+#endif
+	if (memlimit_rlimit(&rlimit_memlimit))
+		return (1);
+#ifdef _SC_PHYS_PAGES
+	if (memlimit_sysconf(&sysconf_memlimit))
+		return (1);
+#else
+	sysconf_memlimit = (size_t)(-1);
+#endif
+
+#ifdef DEBUG
+	fprintf(stderr, "Memory limits are %zu %zu %zu %zu\n",
+	    sysctl_memlimit, sysinfo_memlimit, rlimit_memlimit,
+	    sysconf_memlimit);
+#endif
+
+	/* Find the smallest of them. */
+	memlimit_min = (size_t)(-1);
+	if (memlimit_min > sysctl_memlimit)
+		memlimit_min = sysctl_memlimit;
+	if (memlimit_min > sysinfo_memlimit)
+		memlimit_min = sysinfo_memlimit;
+	if (memlimit_min > rlimit_memlimit)
+		memlimit_min = rlimit_memlimit;
+	if (memlimit_min > sysconf_memlimit)
+		memlimit_min = sysconf_memlimit;
+
+	/* Only use the specified fraction of the available memory. */
+	if ((maxmemfrac > 0.5) || (maxmemfrac == 0.0))
+		maxmemfrac = 0.5;
+	memavail = maxmemfrac * memlimit_min;
+
+	/* Don't use more than the specified maximum. */
+	if ((maxmem > 0) && (memavail > maxmem))
+		memavail = maxmem;
+
+	/* But always allow at least 1 MiB. */
+	if (memavail < 1048576)
+		memavail = 1048576;
+
+#ifdef DEBUG
+	fprintf(stderr, "Allowing up to %zu memory to be used\n", memavail);
+#endif
+
+	/* Return limit via the provided pointer. */
+	*memlimit = memavail;
+	return (0);
+}