busybox/coreutils/nproc.c

/*
 * Copyright (C) 2017 Denys Vlasenko <vda.linux@googlemail.com>
 *
 * Licensed under GPLv2, see LICENSE in this source tree
 */
//config:config NPROC
//config:	bool "nproc (248 bytes)"
//config:	default y
//config:	help
//config:	Print number of CPUs

//applet:IF_NPROC(APPLET_NOFORK(nproc, nproc, BB_DIR_USR_BIN, BB_SUID_DROP, nproc))

//kbuild:lib-$(CONFIG_NPROC) += nproc.o

//usage:#define nproc_trivial_usage
//usage:	""IF_LONG_OPTS("--all --ignore=N")
//usage:#define nproc_full_usage "\n\n"
//usage:	"Print number of available CPUs"
//usage:	IF_LONG_OPTS(
//usage:     "\n"
//usage:     "\n	--all		Number of installed CPUs"
//usage:     "\n	--ignore=N	Exclude N CPUs"
//usage:	)

#include <sched.h>
#include "libbb.h"

int nproc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nproc_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
	unsigned long mask[1024];
	int count = 0;
#if ENABLE_LONG_OPTS
	int ignore = 0;
	int opts = getopt32long(argv, "\xfe:+",
			"ignore\0" Required_argument "\xfe"
			"all\0"    No_argument       "\xff"
			, &ignore
	);

	if (opts & (1 << 1)) {
		DIR *cpusd = opendir("/sys/devices/system/cpu");
		if (cpusd) {
			struct dirent *de;
			while (NULL != (de = readdir(cpusd))) {
				char *cpuid = strstr(de->d_name, "cpu");
				if (cpuid && isdigit(cpuid[strlen(cpuid) - 1]))
					count++;
			}
			closedir(cpusd);
		}
	} else
#endif
	if (sched_getaffinity(0, sizeof(mask), (void*)mask) == 0) {
		int i;
		for (i = 0; i < ARRAY_SIZE(mask); i++) {
			unsigned long m = mask[i];
			while (m) {
				if (m & 1)
					count++;
				m >>= 1;
			}
		}
	}

	IF_LONG_OPTS(count -= ignore;)
	if (count <= 0)
		count = 1;

	printf("%u\n", count);

	return 0;
}