Add 'corebinutils/nproc/' from commit 'b02e14aacf37412ca3632719075c9c42967e23b6'

git-subtree-dir: corebinutils/nproc
git-subtree-mainline: 5086370dd0d4e581d1f5e4b8a085cd421eb23235
git-subtree-split: b02e14aacf37412ca3632719075c9c42967e23b6

1 files changed, 343 insertions, 0 deletions

diff --git a/corebinutils/nproc/nproc.c b/corebinutils/nproc/nproc.c
new file mode 100644
index 0000000000..c2e01e421e
--- /dev/null
+++ b/corebinutils/nproc/nproc.c
@@ -0,0 +1,343 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Mateusz Guzik
+ * Copyright (c) 2026 Project Tick
+ *
+ * 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 REGENTS 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 REGENTS 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.
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <sched.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+enum command_mode {
+	MODE_RUN,
+	MODE_HELP,
+	MODE_VERSION
+};
+
+struct options {
+	enum command_mode mode;
+	bool all;
+	uintmax_t ignore;
+};
+
+static const char *progname = "nproc";
+
+static void die(const char *fmt, ...) __attribute__((__noreturn__, format(printf, 1, 2)));
+static void die_errno(const char *what) __attribute__((__noreturn__));
+static void help(FILE *stream);
+static size_t available_processors(void);
+static size_t count_set_bits(const unsigned char *mask, size_t mask_size);
+static size_t initial_mask_size(void);
+static size_t online_processors(void);
+static void parse_args(int argc, char **argv, struct options *options);
+static uintmax_t parse_ignore_count(const char *text);
+static size_t subtract_ignore(size_t count, uintmax_t ignore);
+static void usage_error(const char *fmt, ...) __attribute__((__noreturn__, format(printf, 1, 2)));
+static void version(void);
+
+int
+main(int argc, char **argv)
+{
+	struct options options;
+	size_t count;
+
+	if (argv[0] != NULL && argv[0][0] != '\0') {
+		const char *slash;
+
+		slash = strrchr(argv[0], '/');
+		progname = (slash != NULL && slash[1] != '\0') ? slash + 1 : argv[0];
+	}
+
+	parse_args(argc, argv, &options);
+
+	switch (options.mode) {
+	case MODE_HELP:
+		help(stderr);
+		return (EXIT_SUCCESS);
+	case MODE_VERSION:
+		version();
+		return (EXIT_SUCCESS);
+	case MODE_RUN:
+		break;
+	}
+
+	count = options.all ? online_processors() : available_processors();
+	count = subtract_ignore(count, options.ignore);
+
+	if (printf("%zu\n", count) < 0)
+		die_errno("stdout");
+
+	return (EXIT_SUCCESS);
+}
+
+static void
+parse_args(int argc, char **argv, struct options *options)
+{
+	int i;
+
+	memset(options, 0, sizeof(*options));
+	options->mode = MODE_RUN;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg;
+
+		arg = argv[i];
+		if (strcmp(arg, "--") == 0) {
+			i++;
+			break;
+		}
+		if (strcmp(arg, "--all") == 0) {
+			options->all = true;
+			continue;
+		}
+		if (strcmp(arg, "--help") == 0) {
+			if (argc != 2)
+				usage_error("option --help must be used alone");
+			options->mode = MODE_HELP;
+			return;
+		}
+		if (strcmp(arg, "--version") == 0) {
+			if (argc != 2)
+				usage_error("option --version must be used alone");
+			options->mode = MODE_VERSION;
+			return;
+		}
+		if (strcmp(arg, "--ignore") == 0) {
+			if (i + 1 >= argc)
+				usage_error("option requires an argument: --ignore");
+			i++;
+			options->ignore = parse_ignore_count(argv[i]);
+			continue;
+		}
+		if (strncmp(arg, "--ignore=", 9) == 0) {
+			options->ignore = parse_ignore_count(arg + 9);
+			continue;
+		}
+		if (arg[0] == '-') {
+			usage_error("unknown option: %s", arg);
+		}
+		break;
+	}
+
+	if (i < argc)
+		usage_error("unexpected operand: %s", argv[i]);
+}
+
+static uintmax_t
+parse_ignore_count(const char *text)
+{
+	char *end;
+	uintmax_t value;
+	const unsigned char *p;
+
+	if (text[0] == '\0')
+		die("invalid ignore count: %s", text);
+
+	for (p = (const unsigned char *)text; *p != '\0'; p++) {
+		if (!isdigit(*p))
+			die("invalid ignore count: %s", text);
+	}
+
+	errno = 0;
+	value = strtoumax(text, &end, 10);
+	if (errno == ERANGE || *end != '\0')
+		die("invalid ignore count: %s", text);
+	return (value);
+}
+
+static size_t
+online_processors(void)
+{
+	long value;
+
+	errno = 0;
+	value = sysconf(_SC_NPROCESSORS_ONLN);
+	if (value < 1) {
+		if (errno != 0)
+			die_errno("sysconf(_SC_NPROCESSORS_ONLN)");
+		die("sysconf(_SC_NPROCESSORS_ONLN) returned %ld", value);
+	}
+
+	return ((size_t)value);
+}
+
+static size_t
+initial_mask_size(void)
+{
+	long configured;
+	size_t bits;
+	size_t bytes;
+
+	errno = 0;
+	configured = sysconf(_SC_NPROCESSORS_CONF);
+	if (configured < 1 || configured > LONG_MAX / 2) {
+		if (errno != 0)
+			return (128);
+		return (128);
+	}
+
+	bits = (size_t)configured;
+	if (bits < CHAR_BIT)
+		bits = CHAR_BIT;
+
+	bytes = bits / CHAR_BIT;
+	if ((bits % CHAR_BIT) != 0)
+		bytes++;
+	if (bytes < sizeof(unsigned long))
+		bytes = sizeof(unsigned long);
+	return (bytes);
+}
+
+static size_t
+available_processors(void)
+{
+	unsigned char *mask;
+	size_t count;
+	size_t mask_size;
+
+	mask_size = initial_mask_size();
+
+	for (;;) {
+		int saved_errno;
+
+		mask = calloc(1, mask_size);
+		if (mask == NULL)
+			die_errno("calloc");
+
+		if (sched_getaffinity(0, mask_size, (cpu_set_t *)(void *)mask) == 0) {
+			count = count_set_bits(mask, mask_size);
+			free(mask);
+			if (count == 0)
+				die("sched_getaffinity returned an empty CPU mask");
+			return (count);
+		}
+
+		saved_errno = errno;
+		free(mask);
+		if (saved_errno != EINVAL) {
+			errno = saved_errno;
+			die_errno("sched_getaffinity");
+		}
+		if (mask_size > SIZE_MAX / 2)
+			die("sched_getaffinity CPU mask is too large");
+		mask_size *= 2;
+	}
+}
+
+static size_t
+count_set_bits(const unsigned char *mask, size_t mask_size)
+{
+	size_t count;
+	size_t i;
+
+	count = 0;
+	for (i = 0; i < mask_size; i++) {
+		unsigned int bits;
+
+		bits = mask[i];
+		while (bits != 0) {
+			count++;
+			bits &= bits - 1;
+		}
+	}
+
+	return (count);
+}
+
+static size_t
+subtract_ignore(size_t count, uintmax_t ignore)
+{
+	if (ignore >= count)
+		return (1);
+	return (count - (size_t)ignore);
+}
+
+static void
+help(FILE *stream)
+{
+	if (fprintf(stream,
+	    "usage: %s [--all] [--ignore=count]\n"
+	    "       %s --help\n"
+	    "       %s --version\n",
+	    progname, progname, progname) < 0) {
+		if (stream == stdout)
+			die_errno("stdout");
+		die_errno("stderr");
+	}
+}
+
+static void
+version(void)
+{
+	if (printf("%s (neither_GNU nor_coreutils) 8.32\n", progname) < 0)
+		die_errno("stdout");
+}
+
+static void
+usage_error(const char *fmt, ...)
+{
+	va_list ap;
+
+	fprintf(stderr, "%s: ", progname);
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	fputc('\n', stderr);
+	help(stderr);
+	exit(EXIT_FAILURE);
+}
+
+static void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	fprintf(stderr, "%s: ", progname);
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	fputc('\n', stderr);
+	exit(EXIT_FAILURE);
+}
+
+static void
+die_errno(const char *what)
+{
+	fprintf(stderr, "%s: %s: %s\n", progname, what, strerror(errno));
+	exit(EXIT_FAILURE);
+}