vde-2/poll2select.c

   1 /*
   2  * poll2select - convert poll() calls to select() calls
   3  * Copyright 2005 Ludovico Gardenghi
   4  * Licensed under the GPLv2
   5  */
   6
   7 #include <config.h>
   8 #include <sys/select.h>
   9 #include <sys/time.h>
  10 #include <sys/types.h>
  11 #include <unistd.h>
  12 #include <errno.h>
  13 #include <syslog.h>
  14
  15 #include <consmgmt.h>
  16 #include <vde.h>
  17
  18 #include "poll2select.h"
  19
  20 #ifndef MAX
  21 #define MAX(x,y) ((x)>(y)?(x):(y))
  22 #endif
  23
  24 static int prepare_select(struct pollfd *ufds, nfds_t nfds, int timeout,
  25                 struct timeval **pstimeout, int *maxfdp1, fd_set *rfds, fd_set *wfds, fd_set *efds)
  26 {
  27         register int i;
  28         struct pollfd *currfd;
  29         struct timeval *stimeout = *pstimeout;
  30
  31         /*
  32          * Conversion of information about file descriptors
  33          */
  34
  35         *maxfdp1 = 0;
  36
  37         if ((nfds > 0) && (ufds == NULL))
  38         {
  39                 errno = EFAULT;
  40                 return 0;
  41         }
  42
  43         for (i = 0; i < nfds; i++)
  44         {
  45                 currfd = &ufds[i];
  46
  47                 if (currfd->fd < 0)
  48                 {
  49                         errno = EBADF;
  50                         return 0;
  51                 }
  52
  53                 if (currfd->events & POLLIN)
  54                         FD_SET(currfd->fd, rfds);
  55                 if (currfd->events & POLLOUT)
  56                         FD_SET(currfd->fd, wfds);
  57                 if (currfd->events & POLLPRI)
  58                         FD_SET(currfd->fd, efds);
  59
  60                 *maxfdp1 = MAX(*maxfdp1, currfd->fd);
  61         }
  62
  63         (*maxfdp1)++;
  64
  65         /*
  66          * Conversion of information about timeout
  67          */
  68
  69         if (timeout == 0)
  70         {
  71                 if (stimeout == NULL)
  72                 {
  73                         errno = EINVAL;
  74                         return 0;
  75                 }
  76                 stimeout->tv_sec = 0;
  77                 stimeout->tv_usec = 0;
  78         }
  79         else if (timeout > 0)
  80         {
  81                 if (stimeout == NULL)
  82                 {
  83                         errno = EINVAL;
  84                         return 0;
  85                 }
  86                 stimeout->tv_sec = timeout / 1000;
  87                 stimeout->tv_usec = (timeout % 1000) * 1000;
  88         }
  89         else // if (timeout < 0)
  90                 *pstimeout = NULL;
  91
  92         return 1;
  93 }
  94
  95 static int convert_results(struct pollfd *ufds, int nfds,
  96                 fd_set *rfds, fd_set *wfds, fd_set *efds)
  97 {
  98         register int i;
  99         struct pollfd *currfd;
 100         int retval = 0;
 101
 102         for (i = 0; i < nfds; i++)
 103         {
 104                 currfd = &ufds[i];
 105
 106                 currfd->revents = 0;
 107
 108                 if (FD_ISSET(currfd->fd, rfds))
 109                         currfd->revents |= POLLIN;
 110                 if (FD_ISSET(currfd->fd, wfds))
 111                         currfd->revents |= POLLOUT;
 112                 if (FD_ISSET(currfd->fd, efds))
 113                         currfd->revents |= POLLPRI;
 114
 115                 if (currfd->revents != 0)
 116                         retval++;
 117         }
 118
 119         return retval;
 120 }
 121
 122 int poll2select(struct pollfd *ufds, nfds_t nfds, int timeout)
 123 {
 124         fd_set rfds, wfds, efds;
 125         struct timeval stimeout;
 126         struct timeval *pstimeout = &stimeout;
 127         int maxfdp1;
 128         int pretval, sretval, tretval;
 129
 130         FD_ZERO(&rfds);
 131         FD_ZERO(&wfds);
 132         FD_ZERO(&efds);
 133
 134         tretval = prepare_select(ufds, nfds, timeout, &pstimeout, &maxfdp1, &rfds, &wfds, &efds);
 135         if (!tretval)
 136                 return -1;
 137
 138         sretval = select(maxfdp1, &rfds, &wfds, &efds, pstimeout);
 139         if (sretval <= 0)
 140                 return sretval;
 141
 142         pretval = convert_results(ufds, nfds, &rfds, &wfds, &efds);
 143
 144         return pretval;
 145 }
 146