glfw/src/posix_poll.c

//========================================================================
// GLFW 3.4 POSIX - www.glfw.org
//------------------------------------------------------------------------
// Copyright (c) 2022 Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================
// It is fine to use C99 in this file because it will not be built with VS
//========================================================================

#define _GNU_SOURCE

#include "internal.h"

#include <signal.h>
#include <time.h>
#include <errno.h>

GLFWbool _glfwPollPOSIX(struct pollfd* fds, nfds_t count, double* timeout)
{
    for (;;)
    {
        if (timeout)
        {
            const uint64_t base = _glfwPlatformGetTimerValue();

#if defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__CYGWIN__)
            const time_t seconds = (time_t) *timeout;
            const long nanoseconds = (long) ((*timeout - seconds) * 1e9);
            const struct timespec ts = { seconds, nanoseconds };
            const int result = ppoll(fds, count, &ts, NULL);
#elif defined(__NetBSD__)
            const time_t seconds = (time_t) *timeout;
            const long nanoseconds = (long) ((*timeout - seconds) * 1e9);
            const struct timespec ts = { seconds, nanoseconds };
            const int result = pollts(fds, count, &ts, NULL);
#else
            const int milliseconds = (int) (*timeout * 1e3);
            const int result = poll(fds, count, milliseconds);
#endif
            const int error = errno; // clock_gettime may overwrite our error

            *timeout -= (_glfwPlatformGetTimerValue() - base) /
                (double) _glfwPlatformGetTimerFrequency();

            if (result > 0)
                return GLFW_TRUE;
            else if (result == -1 && error != EINTR && error != EAGAIN)
                return GLFW_FALSE;
            else if (*timeout <= 0.0)
                return GLFW_FALSE;
        }
        else
        {
            const int result = poll(fds, count, -1);
            if (result > 0)
                return GLFW_TRUE;
            else if (result == -1 && errno != EINTR && errno != EAGAIN)
                return GLFW_FALSE;
        }
    }
}