Detect the number of available CPU cores by using either sched_getaffinity(), GetProcessAffinityMask() or sysconf(), depending on the target platform.

libslunkcrypt/src/thread.c

@@ -3,6 +3,12 @@
 /* This work has been released under the CC0 1.0 Universal license!           */
 /******************************************************************************/
 
+#ifdef _WIN32
+#  define _CRT_SECURE_NO_WARNINGS 1
+#else
+#  define _GNU_SOURCE 1
+#endif
+
 /* Internal */
 #include "thread.h"
 #include "compiler.h"
@@ -16,10 +22,17 @@
 #  define PTW32_STATIC_LIB 1
 #endif
 #include <pthread.h>
+#include <sched.h>
 
-/* System info */
+/* Platform */
-#ifdef __unix__
+#if defined(__linux__) || defined(PTW32_VERSION) || defined(__CYGWIN__)
-#  include <sys/sysinfo.h>
+#  define HAVE_SCHED_GETAFFINITY 1
+#elif defined(_WIN32)
+#  define WIN32_LEAN_AND_MEAN 1
+#  define HAVE_GETPROCESSAFFINITYMASK 1
+#  include <Windows.h>
+#else
+#  include <unistd.h> /* fall back to sysconf() function */
 #endif
 
 /* States */
@@ -120,6 +133,35 @@ while(0)
 } \
 while(0)
 
+// ==========================================================================
+// System info
+// ==========================================================================
+
+static size_t detect_available_cpu_count(void)
+{
+	long num_processors = 0L;
+#if defined(HAVE_SCHED_GETAFFINITY)
+	cpu_set_t cpu_mask;
+	CPU_ZERO(&cpu_mask);
+	if (sched_getaffinity(0, sizeof(cpu_set_t), &cpu_mask) == 0)
+	{
+		num_processors = CPU_COUNT(&cpu_mask);
+	}
+#elif defined(HAVE_GETPROCESSAFFINITYMASK)
+	DWORD_PTR proc_mask, sys_mask;
+	if (GetProcessAffinityMask(GetCurrentProcess(), &proc_mask, &sys_mask))
+	{
+		for (; proc_mask != 0U; proc_mask &= proc_mask - 1U)
+		{
+			++num_processors;
+		}
+	}
+#else
+	num_processors = sysconf(_SC_NPROCESSORS_ONLN);
+#endif
+	return (num_processors > 0) ? ((size_t)num_processors) : 1U;
+}
+
 // ==========================================================================
 // Thread main
 // ==========================================================================
@@ -157,28 +199,6 @@ static void *worker_thread_main(void *const arg)
 	}
 }
 
-// ==========================================================================
-// System info
-// ==========================================================================
-
-#if defined(__unix__)
-#  define NUM_PROCESSORS_FUNC get_nprocs
-#elif defined(PTW32_VERSION)
-#  define NUM_PROCESSORS_FUNC pthread_num_processors_np
-#endif
-
-static size_t detect_cpu_count(void)
-{
-#ifdef NUM_PROCESSORS_FUNC
-	const int cpu_count = NUM_PROCESSORS_FUNC();
-	if (cpu_count > 0)
-	{
-		return (size_t) cpu_count;
-	}
-#endif
-	return 1U;
-}
-
 // ==========================================================================
 // Thread pool API
 // ==========================================================================
@@ -188,7 +208,7 @@ thrdpl_t *slunkcrypt_thrdpl_create(const size_t count, const thrdpl_worker_t wor
 	size_t i;
 	thrdpl_t *thrdpl = NULL;
 
-	const size_t cpu_count = BOUND(1U, (count > 0U) ? count : detect_cpu_count(), MAX_THREADS);
+	const size_t cpu_count = BOUND(1U, (count > 0U) ? count : detect_available_cpu_count(), MAX_THREADS);
 	if (cpu_count < 2U)
 	{
 		return NULL;