select.c

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/*
  +----------------------------------------------------------------------+
  | Copyright (c) The PHP Group                                          |
  +----------------------------------------------------------------------+
  | This source file is subject to version 3.01 of the PHP license,      |
  | that is bundled with this package in the file LICENSE, and is        |
  | available through the world-wide-web at the following url:           |
  | https://www.php.net/license/3_01.txt                                 |
  | If you did not receive a copy of the PHP license and are unable to   |
  | obtain it through the world-wide-web, please send a note to          |
  | license@php.net so we can mail you a copy immediately.               |
  +----------------------------------------------------------------------+
  | Author: Wez Furlong <wez@thebrainroom.com>                           |
  +----------------------------------------------------------------------+
*/
 
#include "php.h"
#include "php_network.h"
 
/* Win32 select() will only work with sockets, so we roll our own implementation here.
 * - If you supply only sockets, this simply passes through to winsock select().
 * - If you supply file handles, there is no way to distinguish between
 *   ready for read/write or OOB, so any set in which the handle is found will
 *   be marked as ready.
 * - If you supply a mixture of handles and sockets, the system will interleave
 *   calls between select() and WaitForMultipleObjects(). The time slicing may
 *   cause this function call to take up to 100 ms longer than you specified.
 * - Calling this with NULL sets as a portable way to sleep with sub-second
 *   accuracy is not supported.
 * */
PHPAPI int php_select(php_socket_t max_fd, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *tv)
{
    ULONGLONG ms_total, limit;
    HANDLE handles[MAXIMUM_WAIT_OBJECTS];
    int handle_slot_to_fd[MAXIMUM_WAIT_OBJECTS];
    int n_handles = 0, i;
    fd_set sock_read, sock_write, sock_except;
    fd_set aread, awrite, aexcept;
    int sock_max_fd = -1;
    struct timeval tvslice;
    int retcode;
 
    /* As max_fd is unsigned, non socket might overflow. */
    if (max_fd > (php_socket_t)INT_MAX) {
        return -1;
    }
 
#define SAFE_FD_ISSET(fd, set)  (set != NULL && FD_ISSET(fd, set))
 
    /* calculate how long we need to wait in milliseconds */
    if (tv == NULL) {
        ms_total = INFINITE;
    } else {
        ms_total = tv->tv_sec * 1000;
        ms_total += tv->tv_usec / 1000;
    }
 
    FD_ZERO(&sock_read);
    FD_ZERO(&sock_write);
    FD_ZERO(&sock_except);
 
    /* build an array of handles for non-sockets */
    for (i = 0; (uint32_t)i < max_fd; i++) {
        if (SAFE_FD_ISSET(i, rfds) || SAFE_FD_ISSET(i, wfds) || SAFE_FD_ISSET(i, efds)) {
            handles[n_handles] = (HANDLE)(uintptr_t)_get_osfhandle(i);
            if (handles[n_handles] == INVALID_HANDLE_VALUE) {
                /* socket */
                if (SAFE_FD_ISSET(i, rfds)) {
                    FD_SET((uint32_t)i, &sock_read);
                }
                if (SAFE_FD_ISSET(i, wfds)) {
                    FD_SET((uint32_t)i, &sock_write);
                }
                if (SAFE_FD_ISSET(i, efds)) {
                    FD_SET((uint32_t)i, &sock_except);
                }
                if (i > sock_max_fd) {
                    sock_max_fd = i;
                }
            } else {
                handle_slot_to_fd[n_handles] = i;
                n_handles++;
            }
        }
    }
 
    if (n_handles == 0) {
        /* plain sockets only - let winsock handle the whole thing */
        return select(-1, rfds, wfds, efds, tv);
    }
 
    /* mixture of handles and sockets; lets multiplex between
     * winsock and waiting on the handles */
 
    FD_ZERO(&aread);
    FD_ZERO(&awrite);
    FD_ZERO(&aexcept);
 
    limit = GetTickCount64() + ms_total;
    do {
        retcode = 0;
 
        if (sock_max_fd >= 0) {
            /* overwrite the zero'd sets here; the select call
             * will clear those that are not active */
            aread = sock_read;
            awrite = sock_write;
            aexcept = sock_except;
 
            tvslice.tv_sec = 0;
            tvslice.tv_usec = 100000;
 
            retcode = select(-1, &aread, &awrite, &aexcept, &tvslice);
        }
        if (n_handles > 0) {
            /* check handles */
            DWORD wret;
 
            wret = WaitForMultipleObjects(n_handles, handles, FALSE, retcode > 0 ? 0 : 100);
 
            if (wret == WAIT_TIMEOUT) {
                /* set retcode to 0; this is the default.
                 * select() may have set it to something else,
                 * in which case we leave it alone, so this branch
                 * does nothing */
                ;
            } else if (wret == WAIT_FAILED) {
                if (retcode == 0) {
                    retcode = -1;
                }
            } else {
                if (retcode < 0) {
                    retcode = 0;
                }
                for (i = 0; i < n_handles; i++) {
                    if (WAIT_OBJECT_0 == WaitForSingleObject(handles[i], 0)) {
                        if (SAFE_FD_ISSET(handle_slot_to_fd[i], rfds)) {
                            FD_SET((uint32_t)handle_slot_to_fd[i], &aread);
                        }
                        if (SAFE_FD_ISSET(handle_slot_to_fd[i], wfds)) {
                            FD_SET((uint32_t)handle_slot_to_fd[i], &awrite);
                        }
                        if (SAFE_FD_ISSET(handle_slot_to_fd[i], efds)) {
                            FD_SET((uint32_t)handle_slot_to_fd[i], &aexcept);
                        }
                        retcode++;
                    }
                }
            }
        }
    } while (retcode == 0 && (ms_total == INFINITE || GetTickCount64() < limit));
 
    if (rfds) {
        *rfds = aread;
    }
    if (wfds) {
        *wfds = awrite;
    }
    if (efds) {
        *efds = aexcept;
    }
 
    return retcode;
}