add README.md to explain the purposes of the project better.

makefile is now more compiler-agnostic and consistent with how one
expects a makefile to be built.

.editorconfig

@@ -5,8 +5,8 @@ trim_trailing_whitespace = true
 
 [*.{c,h}]
 indent_style = tab
-indent_size = 4
+indent_size = tab
 
 [{makefile,Makefile}]
 indent_style = tab
-indent_size = 2
+indent_size = tab

README.md

@@ -0,0 +1,10 @@
+# cpusetcores
+This is a utility application for managing CPU cores / threads on Linux machines.
+It allows you to enable/disable threads (via reading/writing to `/sys/devices/system/cpu/cpuX/online`).
+
+The plan is to eventually through deamons or some kernel magic to manage the amount of cores automatically, in hopes of saving power.
+How well this'll work and how much power is gained from it is still researched and the project is not actively being worked on.
+So for now it just serves as something faster than a shell script.
+
+I assume the kernel likely already has things for this, or it is being worked on.
+I just haven't looked into it that much yet, since I haven't really started the project yet.

makefile

@@ -1,72 +1,32 @@
-# project name = the workspace directory name
+SHELL = bash -e -o pipefail -O globstar
-NAME := $(shell basename $(PWD))
 
-# compiler settings
+NAME = cpusetcores
-CC := clang
+VERSION = 0.0.2
-STD := c17
-LANG = c
-CFLAGS := -target x86_64-pc-linux-gnu -Wall -Wextra -Wpedantic -Wno-pointer-arith
-LDFLAGS := -lc
 DEBUG ?= 0
+CC ?= cc
 
-ifeq ($(DEBUG),1)
+CFLAGS = -c -std=gnu99 -Wall -Wextra -Wpedantic -MMD -MP
-CFLAGS += -DDEBUG -fsanitize=address,undefined -g -Og
+LFLAGS = -flto
-PROF := dbg
-else
-REL_FLAGS += -O2
-PROF := rel
-endif
 
-# dirs
+SRC := $(wildcard src/*.c) $(wildcard src/**/*.c)
-DIR_BIN := bin
+OBJ := $(SRC:%.c=obj/%.o)
-DIR_OBJ := obj
+BIN := bin/$(NAME)
-DIR_BUILD := $(DIR_BIN)/$(PROF)
-DIR := $(DIR_BIN)/$(PROF) $(DIR_OBJ)/$(PROF)
 
-# source files
+.PHONY:
-SRC := $(wildcard src/*.c) $(wildcard src/**/*.c) $(wildcard src/**/**/*.c) $(wildcard src/**/**/**/*.c) $(wildcard src/**/**/**/**/*.c)
+compile: $(BIN)
 
-# output locations
+$(BIN): $(OBJ)
-OBJ := $(patsubst src/%,$(DIR_OBJ)/$(PROF)/%,$(SRC:.c=.o))
+	$(info [CC/LD] $@)
-DEP := $(OBJ:.o=.d)
+	@mkdir -p $(@D)
-TARGET := $(DIR_BUILD)/$(NAME)
+	@$(CC) -o $@ $^ $(LDFLAGS)
 
-define wr_colour
+obj/%.o: %.c
-	@echo -e "\033[$(2)m$(1)\033[0m"
+	$(info [CC] $@)
-endef
+	@mkdir -p $(@D)
+	@$(CC) $(CFLAGS) -o $@ $<
 
-compile: compile_commands.json $(DIR) $(TARGET)
 clean:
-	rm -rf $(DIR_BIN) $(DIR_OBJ) compile_commands.json
+	rm -rv obj/ bin/
-
-# create the binary (linking step)
-$(TARGET): $(OBJ)
-	@$(call wr_colour,"CC: '$(CC)'",94)
-	@$(call wr_colour,"CFLAGS: '$(CFLAGS)'",94)
-	@$(call wr_colour,"LDFLAGS: '$(LDFLAGS)'",94)
-	@$(call wr_colour,"linking to: '$@'",92)
-	@$(CC) -o $(TARGET) $^ $(CFLAGS) $(LDFLAGS)
-	@$(call wr_colour,"current profile: '$(PROF)'",93)
-
-# create .o and .d files
-$(DIR_OBJ)/$(PROF)/%.o: src/%.c
-	@$(call wr_colour,"compiling $(notdir $@) from $(notdir $<)",92)
-	@mkdir -p $(dir $@)
-	@$(CC) -o $@ -MD -MP -c $< $(CFLAGS) -std=$(STD) -x $(LANG) -Wno-unused-command-line-argument
-
-# create directories
-$(DIR):
-	mkdir -p $@
-
-# update compile commands if the makefile has been updated (for linting)
-ifeq ($(DEBUG),1)
-compile_commands.json: makefile
-	$(MAKE) clean
-	@touch compile_commands.json
-	bear -- make compile
-else
-compile_commands.json:
-endif
 
 # include the dependencies
 -include $(DEP)

src/atrb.h

@@ -0,0 +1,59 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+
+#if defined(__GNUC__)
+#if __has_attribute(__pure__)
+#define PURE __attribute__((__pure__))
+#else
+#define PURE
+#endif
+
+#if __has_attribute(__const__)
+#define CONST __attribute__((__const__))
+#else
+#define CONST
+#endif
+
+#if __has_attribute(__noreturn__)
+#define NORET __attribute__((__noreturn__))
+#else
+#define NORET
+#endif
+
+#if __has_attribute(__malloc__)
+#define MALLOC __attribute__((__malloc__))
+#else
+#define MALLOC
+#endif
+
+#if __has_attribute(__used__)
+#define USED __attribute__((__used__))
+#else
+#define USED
+#endif
+
+#if __has_attribute(__unused__)
+#define UNUSED __attribute__((__unused__))
+#else
+#define UNUSED
+#endif
+
+#if __has_attribute(__deprecated__)
+#define DEPRECATED __attribute__((__deprecated__))
+#else
+#define DEPRECATED
+#endif
+
+#if __has_attribute(__format__)
+#define FORMAT(...) __attribute__((format(__VA_ARGS__)))
+#else
+#define FORMAT(...)
+#endif
+
+#if __has_attribute(__nonnull__)
+#define NONNULL(...) __attribute__((nonnull(__VA_ARGS__)))
+#else
+#define NONNULL(...)
+#endif
+#endif

src/cpu.c

@@ -1,39 +1,44 @@
 #include "cpu.h"
 
+#include <assert.h>
+#include <math.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <unistd.h>
 
-char const* const cpu_path = "/sys/devices/system/cpu/cpu%i/online";
+const char cpu_path[] = "/sys/devices/system/cpu/cpu%i/online";
 
-bool getcpu(uint32_t id) {
+int cpu_getenabled(uint id) {
-	// get the file path
+	const size_t pathlen = sizeof(cpu_path) + (uint)(log10(-1u) + 1);
-	char path[64];                    // contains the file path (max length is 64 due to the path and a bunch of extra wiggle room)
+	char path[pathlen];
-	snprintf(path, 64, cpu_path, id); // writes the path using the id
+	snprintf(path, pathlen, cpu_path, id);
 
-	// if the file doesn't exist; return true
 	if (access(path, R_OK) != 0)
-		return true;
+		return 1;
 
-	// read a character from the file, store in state
 	char state = '\0';
-	FILE* f = fopen(path, "r");
+	FILE *f = fopen(path, "r");
+	assert(f);
 	fread(&state, 1, 1, f);
 	fclose(f);
 
-	// return whether state is truthy
+	return state != '0';
-	return !!(state - 0x30);
 }
 
-void setcpu(uint32_t id, bool state) {
+int cpu_setenabled(uint id, int state) {
-	char path[64];
+	const size_t pathlen = sizeof(cpu_path) + (uint)(log10(-1u) + 1);
-	snprintf(path, 64, cpu_path, id);
+	char path[pathlen];
+	snprintf(path, pathlen, cpu_path, id);
 
-	char s = 0x30 + (char)state; // convert the state to a character
+	char s = 0x30 + (state & 1);
 
-	// write the state to the file (creates file if it doesn't exist)
+	if (access(path, W_OK) != 0)
-	FILE* f = fopen(path, "w");
+		return 1;
+
+	FILE *f = fopen(path, "w");
+	assert(f);
 	fwrite(&s, 1, 1, f);
 	fclose(f);
+	return 0;
 }

src/cpu.h

@@ -1,6 +1,10 @@
 #pragma once
-#include <stdbool.h>
+#include "util/intdef.h"
-#include <stdint.h>
 
-bool getcpu(uint32_t);       // gets the state of core (id)
+/* gets the current state of a CPU thread,
-void setcpu(uint32_t, bool); // sets the state of core (id)
+ * returns a boolean value (`1` for enabled, `0` for disabled) */
+int cpu_getenabled(uint id);
+
+/* sets the current state of a CPU thread.
+ * returns `0` upon success, `1` upon failure */
+int cpu_setenabled(uint id, int state);

src/error.c

@@ -1,18 +0,0 @@
-#include "error.h"
-
-#include <stdarg.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdnoreturn.h>
-
-noreturn void fatal(char const* fmt, ...) {
-	char buf[128];
-	va_list args;
-	va_start(args, fmt);
-	vsnprintf(buf, 128, fmt, args);
-	va_end(args);
-
-	fprintf(stderr, "\033[91mE: %s\033[0m\n", buf);
-	exit(1);
-}

src/error.h

@@ -1,7 +1,21 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
 #pragma once
-#include <stdarg.h>
-#include <stdint.h>
-#include <stdnoreturn.h>
 
-// prints an error message and aborts execution
+#if __INCLUDE_LEVEL__ > 0
-noreturn void fatal(char const*, ...);
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "util/macro.h"
+#endif
+
+#define debug(s, ...) printf("\033[95m" __FILE__ ":" MACRO_STR2(__LINE__) ": [DBG]: " s "\033[0m\n", ##__VA_ARGS__)
+#define info(s, ...)  printf(__FILE__ ":" MACRO_STR2(__LINE__) ": [INF]: " s "\n", ##__VA_ARGS__)
+#define warn(s, ...)  fprintf(stderr, "\033[93m" __FILE__ ":" MACRO_STR2(__LINE__) ": [WAR]: " s "\033[0m\n", ##__VA_ARGS__)
+#define error(s, ...) fprintf(stderr, "\033[91m" __FILE__ ":" MACRO_STR2(__LINE__) ": [ERR]: " s "\033[0m\n", ##__VA_ARGS__)
+
+#define fatal(s, ...)                                                                                                    \
+	do {                                                                                                             \
+		fprintf(stderr, "\033[101m" __FILE__ ":" MACRO_STR2(__LINE__) ": [FAT]: " s "\033[0m\n", ##__VA_ARGS__); \
+		exit(EXIT_FAILURE);                                                                                      \
+	} while (0)

src/main.c

@@ -1,3 +1,4 @@
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <sys/sysinfo.h>
@@ -7,28 +8,25 @@
 #include "error.h"
 #include "opts.h"
 
-static inline bool cpu_setter(uint32_t id, bool nstate, uint8_t opts) {
+/* sets CPU `id` to `nstate`, if it hasn't been set yet.
-	bool cstate = !nstate;
+ * If `opt` contains `OPT_SET_ALL`, this check is ignored.
-	if (!(opts & OPT_SET_ALL))
+ * Returns `0` upon success, `1` upon failure. */
-		cstate = getcpu(id);
+static int setcpu(uint id, int nstate, u8 opts) {
-
+	bool nsetall = !(opts & OPT_SET_ALL);                               // if SET_ALL has not been set
-	if (cstate != nstate) {
+	int cstate = nsetall && cpu_getenabled(id);                         // get state if nsetall=1
-		setcpu(id, nstate);
+	return (nsetall && cstate == nstate) || cpu_setenabled(id, nstate); // set if cstate matches nstate, unless nsetall=1
-		return true;
-	}
-	return false;
 }
 
-static inline void print_cpu_count(int32_t mcpus) {
+static inline void print_cpu_count(uint mcpus) {
 	printf("%i/%i cpus enabled.\n", get_nprocs(), mcpus); // get the number of available processors
 }
 
-int32_t main(int32_t argc, char** argv) {
+int main(int argc, char **argv) {
 	if (geteuid() != 0) fatal("must be executed as the root user!");
 
-	int32_t ncpus;                                 // the number of CPUs to activate
+	int mcpus, ncpus;                         // the number of CPUs to activate
-	uint8_t opts = getoptions(argc, argv, &ncpus); // the options to use
+	u8 opts = getoptions(argc, argv, &ncpus); // the options to use
-	int32_t mcpus = get_nprocs_conf();             // the max number of CPUs that are available
+	mcpus = get_nprocs_conf();                // the max number of CPUs that are available
 
 	if (opts & OPT_LIST_CORES && ncpus < 0) {
 		print_cpu_count(mcpus);
@@ -42,18 +40,18 @@ int32_t main(int32_t argc, char** argv) {
 	if (ncpus > mcpus) fatal("%i exeeds the maximum numbers of cpus available (%i)", ncpus, mcpus);
 	if (ncpus < 1) fatal("may not keep less than 1 cpu enabled, requested to enable %i", ncpus);
 
-	char const* const cpu_set_log = "set cpu %i to %hi\n";
+	const char *const cpu_set_log = "set cpu %i to %hi\n";
-	for (int32_t id = 1; id < mcpus; id++) { // start at CPU 1, as CPU 0 is not writeable
+	for (int id = 1; id < mcpus; id++) { // start at CPU 1, as CPU 0 is not writeable
 		// whilst the id is less then the amount of cpus to enable
 		if (id < ncpus) {
 			// enable the cpu & print if it was actually set (if -v was given)
-			if (cpu_setter(id, true, opts) && (opts & OPT_VERBOSE))
+			if (!setcpu(id, true, opts) && (opts & OPT_VERBOSE))
 				printf(cpu_set_log, id, 1);
 			continue;
 		}
 
 		// disable the cpu & print if it was actually set (if -v was given)
-		if (cpu_setter(id, false, opts) && (opts & OPT_VERBOSE)) {
+		if (!setcpu(id, false, opts) && (opts & OPT_VERBOSE)) {
 			printf(cpu_set_log, id, 0);
 			continue;
 		}

src/opts.c

@@ -1,45 +1,49 @@
 #include "opts.h"
 
+#include <errno.h>
 #include <getopt.h>
 #include <stdint.h>
 #include <stdlib.h>
 
 #include "error.h"
+#include "util/intdef.h"
 
-uint8_t getoptions(int32_t argc, char* const* argv, int32_t* ncpus) {
+u8 getoptions(int argc, char *const *argv, int *ncpus) {
+	*ncpus = -1;
 	uint8_t opts = 0;
 	char opt;
 
-	char const* const msg = "-%c has already been set";
+	while ((opt = getopt(argc, argv, "lavih")) != -1) {
-	while ((opt = getopt(argc, argv, "lavi")) != -1) {
 		switch (opt) {
-		case 'l':
+		case 'l': opts |= OPT_LIST_CORES; break;
-			if (opts & OPT_LIST_CORES) fatal(msg, 'l');
+		case 'a': opts |= OPT_SET_ALL; break;
-			opts |= OPT_LIST_CORES;
+		case 'v': opts |= OPT_VERBOSE | OPT_LIST_CORES; break;
-			break;
+		case 'i': opts |= OPT_INVERT; break;
-		case 'a':
-			if (opts & OPT_SET_ALL) fatal(msg, 'a');
-			opts |= OPT_SET_ALL;
-			break;
-		case 'v':
-			if (opts & OPT_VERBOSE) fatal(msg, 'v');
-			opts |= OPT_VERBOSE | OPT_LIST_CORES;
-			break;
-		case 'i':
-			if (opts & OPT_INVERT) fatal(msg, 'i');
-			opts |= OPT_INVERT;
-			break;
 		case '?':
-			fatal("usage: %s [number] [-l] [-a] [-v] [-i]", argv[0]);
+			printf("specify -h for help\n");
+			exit(EXIT_FAILURE);
+		case 'h':
+			printf(
+				"%s: a tool for turning on/off CPU threads\n"
+				"USAGE: %s [integer] [-l] [-a] [-v] [-i] [-h]\n"
+				"ARGUMENTS:\n"
+				"\t-l : List cores after executing the command. May be specified without integer.\n"
+				"\t-a : Writes to all cores, regardless of their state.\n"
+				"\t-v : Print the cores that are written. (implies -l)\n"
+				"\t-i : Instead of the given number.\n"
+				"\t-h : Shows this dialogue.\n",
+				argv[0], argv[0]);
+			exit(EXIT_SUCCESS);
 		}
 	}
 
 	if (optind < argc) {
-		char* num = argv[optind];
+		char *end;
-		*ncpus = atoi(num);
+		char *num = argv[optind];
-	} else if (opts & OPT_LIST_CORES) {
+		*ncpus = strtol(num, &end, 0);
-		*ncpus = -1;
+		if (errno || end == num || *end != '\0')
-	} else
+			fatal("failed to parse numeric value from string '%s'", num);
+	} else if (!(opts & OPT_LIST_CORES))
 		fatal("must execute with either a number or [-l]");
 
 	return opts;

src/opts.h

@@ -1,6 +1,8 @@
 #pragma once
 #include <stdint.h>
 
+#include "util/intdef.h"
+
 enum opt {
 	OPT_LIST_CORES = 1, // option that lists the total amount of cores that are set
 	OPT_SET_ALL = 2,    // option to set all cores, regardless of their assumed state
@@ -8,4 +10,7 @@ enum opt {
 	OPT_INVERT = 8,     // 'num' now represents the amount of cores to disable
 };
 
-uint8_t getoptions(int32_t, char* const*, int32_t*);
+/* acquires the options given by the user through arguments.
+ * returns the bitmap of these options.
+ * `ncpus` is set to `-1`, or the amount of CPUs that the user requested to enable.*/
+u8 getoptions(int argc, char *const *argv, int *ncpus);

src/util/intdef.h

@@ -0,0 +1,20 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+
+/* variable-width integer types */
+typedef unsigned int uint;         // ≥16 bit unsigned integer
+typedef unsigned long ulong;       // ≥32 bit unsigned integer
+typedef signed long long llong;    // ≥64 bit signed integer
+typedef unsigned long long ullong; // ≥64 bit unsigned integer
+
+/* fixed-width integer types */
+#include <stdint.h>
+typedef int8_t i8;
+typedef int16_t i16;
+typedef int32_t i32;
+typedef int64_t i64;
+typedef uint8_t u8;
+typedef uint16_t u16;
+typedef uint32_t u32;
+typedef uint64_t u64;

src/util/macro.h

@@ -0,0 +1,9 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+
+#define WIDTHOF(t)       (sizeof(t) * 8) // gets the bit width of a type
+#define MACRO_CAT(x, y)  x##y            // concatenate two macro variables together
+#define MACRO_CAT2(x, y) MACRO_CAT(x, y) // concatenate two macro variables together
+#define MACRO_STR(v)     #v              // for converting macro variable into a string
+#define MACRO_STR2(v)    MACRO_STR(v)    // for a recursive string generation