vde-2/src/common/poll.c

   1 /*
   2  * poll2select - convert poll() calls to select() calls
   3  * Copyright 2005 Ludovico Gardenghi
   4  * Licensed under the GPLv2
   5  */
   6
   7 #include <sys/select.h>
   8 #include <sys/time.h>
   9 #include <sys/types.h>
  10 #include <unistd.h>
  11 #include <errno.h>
  12 #include <syslog.h>
  13
  14 #include <config.h>
  15 #include <vde.h>
  16 #include <vdecommon.h>
  17
  18 #ifndef MAX
  19 #define MAX(x,y) ((x)>(y)?(x):(y))
  20 #endif
  21
  22 static int prepare_select(struct pollfd *ufds, nfds_t nfds, int timeout,
  23                 struct timeval **pstimeout, int *maxfdp1, fd_set *rfds, fd_set *wfds, fd_set *efds)
  24 {
  25         int i;
  26         struct pollfd *currfd;
  27         struct timeval *stimeout = *pstimeout;
  28
  29         /*
  30          * Conversion of information about file descriptors
  31          */
  32
  33         *maxfdp1 = 0;
  34
  35         if ((nfds > 0) && (ufds == NULL))
  36         {
  37                 errno = EFAULT;
  38                 return 0;
  39         }
  40
  41         for (i = 0; i < nfds; i++)
  42         {
  43                 currfd = &ufds[i];
  44
  45                 if (currfd->fd < 0)
  46                 {
  47                         errno = EBADF;
  48                         return 0;
  49                 }
  50
  51                 if (currfd->events & POLLIN)
  52                         FD_SET(currfd->fd, rfds);
  53                 if (currfd->events & POLLOUT)
  54                         FD_SET(currfd->fd, wfds);
  55                 if (currfd->events & POLLPRI)
  56                         FD_SET(currfd->fd, efds);
  57
  58                 *maxfdp1 = MAX(*maxfdp1, currfd->fd);
  59         }
  60
  61         (*maxfdp1)++;
  62
  63         /*
  64          * Conversion of information about timeout
  65          */
  66
  67         if (timeout == 0)
  68         {
  69                 if (stimeout == NULL)
  70                 {
  71                         errno = EINVAL;
  72                         return 0;
  73                 }
  74                 stimeout->tv_sec = 0;
  75                 stimeout->tv_usec = 0;
  76         }
  77         else if (timeout > 0)
  78         {
  79                 if (stimeout == NULL)
  80                 {
  81                         errno = EINVAL;
  82                         return 0;
  83                 }
  84                 stimeout->tv_sec = timeout / 1000;
  85                 stimeout->tv_usec = (timeout % 1000) * 1000;
  86         }
  87         else // if (timeout < 0)
  88                 *pstimeout = NULL;
  89
  90         return 1;
  91 }
  92
  93 static int convert_results(struct pollfd *ufds, int nfds,
  94                 fd_set *rfds, fd_set *wfds, fd_set *efds)
  95 {
  96         int i;
  97         struct pollfd *currfd;
  98         int retval = 0;
  99
 100         for (i = 0; i < nfds; i++)
 101         {
 102                 currfd = &ufds[i];
 103
 104                 currfd->revents = 0;
 105
 106                 if (FD_ISSET(currfd->fd, rfds))
 107                         currfd->revents |= POLLIN;
 108                 if (FD_ISSET(currfd->fd, wfds))
 109                         currfd->revents |= POLLOUT;
 110                 if (FD_ISSET(currfd->fd, efds))
 111                         currfd->revents |= POLLPRI;
 112
 113                 if (currfd->revents != 0)
 114                         retval++;
 115         }
 116
 117         return retval;
 118 }
 119
 120 int vde_poll(struct pollfd *ufds, nfds_t nfds, int timeout)
 121 {
 122         fd_set rfds, wfds, efds;
 123         struct timeval stimeout;
 124         struct timeval *pstimeout = &stimeout;
 125         int maxfdp1;
 126         int pretval, sretval, tretval;
 127
 128         FD_ZERO(&rfds);
 129         FD_ZERO(&wfds);
 130         FD_ZERO(&efds);
 131
 132         tretval = prepare_select(ufds, nfds, timeout, &pstimeout, &maxfdp1, &rfds, &wfds, &efds);
 133         if (!tretval)
 134                 return -1;
 135
 136         sretval = select(maxfdp1, &rfds, &wfds, &efds, pstimeout);
 137         if (sretval <= 0)
 138                 return sretval;
 139
 140         pretval = convert_results(ufds, nfds, &rfds, &wfds, &efds);
 141
 142         return pretval;
 143 }
 144