nsprpub/pr/src/md/unix/uxwrap.c

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 *------------------------------------------------------------------------
 * File: uxwrap.c
 *
 *     Our wrapped versions of the Unix select() and poll() system calls.
 *
 *------------------------------------------------------------------------
 */

#include "primpl.h"

#if defined(_PR_PTHREADS) || defined(_PR_GLOBAL_THREADS_ONLY) || defined(QNX)
/* Do not wrap select() and poll(). */
#else /* defined(_PR_PTHREADS) || defined(_PR_GLOBAL_THREADS_ONLY) */
/* The include files for select() */
#  include <string.h>
#  include <sys/types.h>
#  include <sys/time.h>

#  define ZAP_SET(_to, _width)                                               \
    PR_BEGIN_MACRO                                                           \
    memset(                                                                  \
        _to, 0,                                                              \
        ((_width + 8 * sizeof(int) - 1) / (8 * sizeof(int))) * sizeof(int)); \
    PR_END_MACRO

/* see comments in ns/cmd/xfe/mozilla.c (look for "PR_XGetXtHackFD") */
static int _pr_xt_hack_fd = -1;

int PR_XGetXtHackFD(void) {
  int fds[2];

  if (_pr_xt_hack_fd == -1) {
    if (!pipe(fds)) {
      _pr_xt_hack_fd = fds[0];
    }
  }
  return _pr_xt_hack_fd;
}

static int (*_pr_xt_hack_okayToReleaseXLock)(void) = 0;

void PR_SetXtHackOkayToReleaseXLockFn(int (*fn)(void)) {
  _pr_xt_hack_okayToReleaseXLock = fn;
}

/*
 *-----------------------------------------------------------------------
 *  select() --
 *
 *    Wrap up the select system call so that we can deschedule
 *    a thread that tries to wait for i/o.
 *
 *-----------------------------------------------------------------------
 */

#  if defined(AIX_RENAME_SELECT)
int wrap_select(unsigned long width, void* rl, void* wl, void* el,
                struct timeval* tv)
#  elif defined(_PR_SELECT_CONST_TIMEVAL)
int select(int width, fd_set* rd, fd_set* wr, fd_set* ex,
           const struct timeval* tv)
#  else
int select(int width, fd_set* rd, fd_set* wr, fd_set* ex, struct timeval* tv)
#  endif
{
  int osfd;
  _PRUnixPollDesc *unixpds, *unixpd, *eunixpd;
  PRInt32 pdcnt;
  PRIntervalTime timeout;
  int retVal;
#  if defined(AIX_RENAME_SELECT)
  fd_set* rd = (fd_set*)rl;
  fd_set* wr = (fd_set*)wl;
  fd_set* ex = (fd_set*)el;
#  endif

#  if 0
    /*
     * Easy special case: zero timeout.  Simply call the native
     * select() with no fear of blocking.
     */
    if (tv != NULL && tv->tv_sec == 0 && tv->tv_usec == 0) {
#    if defined(AIX_RENAME_SELECT)
        return _MD_SELECT(width, rl, wl, el, tv);
#    else
        return _MD_SELECT(width, rd, wr, ex, tv);
#    endif
    }
#  endif

  if (!_pr_initialized) {
    _PR_ImplicitInitialization();
  }

#  ifndef _PR_LOCAL_THREADS_ONLY
  if (_PR_IS_NATIVE_THREAD(_PR_MD_CURRENT_THREAD())) {
    return _MD_SELECT(width, rd, wr, ex, tv);
  }
#  endif

  if (width < 0 || width > FD_SETSIZE) {
    errno = EINVAL;
    return -1;
  }

  /* Compute timeout */
  if (tv) {
    /*
     * These acceptable ranges for t_sec and t_usec are taken
     * from the select() man pages.
     */
    if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || tv->tv_usec < 0 ||
        tv->tv_usec >= 1000000) {
      errno = EINVAL;
      return -1;
    }

    /* Convert microseconds to ticks */
    timeout = PR_MicrosecondsToInterval(1000000 * tv->tv_sec + tv->tv_usec);
  } else {
    /* tv being a NULL pointer means blocking indefinitely */
    timeout = PR_INTERVAL_NO_TIMEOUT;
  }

  /* Check for no descriptors case (just doing a timeout) */
  if ((!rd && !wr && !ex) || !width) {
    PR_Sleep(timeout);
    return 0;
  }

  /*
   * Set up for PR_Poll().  The PRPollDesc array is allocated
   * dynamically.  If this turns out to have high performance
   * penalty, one can change to use a large PRPollDesc array
   * on the stack, and allocate dynamically only when it turns
   * out to be not large enough.
   *
   * I allocate an array of size 'width', which is the maximum
   * number of fds we may need to poll.
   */
  unixpds = (_PRUnixPollDesc*)PR_CALLOC(width * sizeof(_PRUnixPollDesc));
  if (!unixpds) {
    errno = ENOMEM;
    return -1;
  }

  pdcnt = 0;
  unixpd = unixpds;
  for (osfd = 0; osfd < width; osfd++) {
    int in_flags = 0;
    if (rd && FD_ISSET(osfd, rd)) {
      in_flags |= _PR_UNIX_POLL_READ;
    }
    if (wr && FD_ISSET(osfd, wr)) {
      in_flags |= _PR_UNIX_POLL_WRITE;
    }
    if (ex && FD_ISSET(osfd, ex)) {
      in_flags |= _PR_UNIX_POLL_EXCEPT;
    }
    if (in_flags) {
      unixpd->osfd = osfd;
      unixpd->in_flags = in_flags;
      unixpd->out_flags = 0;
      unixpd++;
      pdcnt++;
    }
  }

  /*
   * see comments in mozilla/cmd/xfe/mozilla.c (look for
   * "PR_XGetXtHackFD")
   */
  {
    int needToLockXAgain;

    needToLockXAgain = 0;
    if (rd && (_pr_xt_hack_fd != -1) && FD_ISSET(_pr_xt_hack_fd, rd) &&
        _PR_XIsLocked() &&
        (!_pr_xt_hack_okayToReleaseXLock || _pr_xt_hack_okayToReleaseXLock())) {
      _PR_XUnlock();
      needToLockXAgain = 1;
    }

    /* This is the potentially blocking step */
    retVal = _PR_WaitForMultipleFDs(unixpds, pdcnt, timeout);

    if (needToLockXAgain) {
      _PR_XLock();
    }
  }

  if (retVal > 0) {
    /* Compute select results */
    if (rd) {
      ZAP_SET(rd, width);
    }
    if (wr) {
      ZAP_SET(wr, width);
    }
    if (ex) {
      ZAP_SET(ex, width);
    }

    /*
     * The return value can be either the number of ready file
     * descriptors or the number of set bits in the three fd_set's.
     */
    retVal = 0; /* we're going to recompute */
    eunixpd = unixpds + pdcnt;
    for (unixpd = unixpds; unixpd < eunixpd; unixpd++) {
      if (unixpd->out_flags) {
        int nbits = 0; /* The number of set bits on for this fd */

        if (unixpd->out_flags & _PR_UNIX_POLL_NVAL) {
          errno = EBADF;
          PR_LOG(_pr_io_lm, PR_LOG_ERROR,
                 ("select returns EBADF for %d", unixpd->osfd));
          retVal = -1;
          break;
        }
        /*
         * If a socket has a pending error, it is considered
         * both readable and writable.  (See W. Richard Stevens,
         * Unix Network Programming, Vol. 1, 2nd Ed., Section 6.3,
         * pp. 153-154.)  We also consider a socket readable if
         * it has a hangup condition.
         */
        if (rd && (unixpd->in_flags & _PR_UNIX_POLL_READ) &&
            (unixpd->out_flags &
             (_PR_UNIX_POLL_READ | _PR_UNIX_POLL_ERR | _PR_UNIX_POLL_HUP))) {
          FD_SET(unixpd->osfd, rd);
          nbits++;
        }
        if (wr && (unixpd->in_flags & _PR_UNIX_POLL_WRITE) &&
            (unixpd->out_flags & (_PR_UNIX_POLL_WRITE | _PR_UNIX_POLL_ERR))) {
          FD_SET(unixpd->osfd, wr);
          nbits++;
        }
        if (ex && (unixpd->in_flags & _PR_UNIX_POLL_WRITE) &&
            (unixpd->out_flags & PR_POLL_EXCEPT)) {
          FD_SET(unixpd->osfd, ex);
          nbits++;
        }
        PR_ASSERT(nbits > 0);
#  if defined(HPUX) || defined(SOLARIS) || defined(AIX)
        retVal += nbits;
#  endif
      }
    }
  }

  PR_ASSERT(tv || retVal != 0);
  PR_LOG(_pr_io_lm, PR_LOG_MIN, ("select returns %d", retVal));
  PR_DELETE(unixpds);

  return retVal;
}

/*
 * Redefine poll, when supported on platforms, for local threads
 */

/*
 * I am commenting out the poll() wrapper for Linux for now
 * because it is difficult to define _MD_POLL that works on all
 * Linux varieties.  People reported that glibc 2.0.7 on Debian
 * 2.0 Linux machines doesn't have the __syscall_poll symbol
 * defined.  (WTC 30 Nov. 1998)
 */
#  if defined(_PR_POLL_AVAILABLE) && !defined(LINUX)

/*
 *-----------------------------------------------------------------------
 * poll() --
 *
 * RETURN VALUES:
 *     -1:  fails, errno indicates the error.
 *      0:  timed out, the revents bitmasks are not set.
 *      positive value: the number of file descriptors for which poll()
 *          has set the revents bitmask.
 *
 *-----------------------------------------------------------------------
 */

#    include <poll.h>

#    if defined(AIX_RENAME_SELECT)
int wrap_poll(void* listptr, unsigned long nfds, long timeout)
#    elif (defined(AIX) && !defined(AIX_RENAME_SELECT))
int poll(void* listptr, unsigned long nfds, long timeout)
#    elif defined(HPUX)
int poll(struct pollfd filedes[], unsigned int nfds, int timeout)
#    elif defined(NETBSD)
int poll(struct pollfd* filedes, nfds_t nfds, int timeout)
#    elif defined(OPENBSD)
int poll(struct pollfd filedes[], nfds_t nfds, int timeout)
#    elif defined(FREEBSD)
int poll(struct pollfd* filedes, unsigned nfds, int timeout)
#    else
int poll(struct pollfd* filedes, unsigned long nfds, int timeout)
#    endif
{
#    ifdef AIX
  struct pollfd* filedes = (struct pollfd*)listptr;
#    endif
  struct pollfd *pfd, *epfd;
  _PRUnixPollDesc *unixpds, *unixpd, *eunixpd;
  PRIntervalTime ticks;
  PRInt32 pdcnt;
  int ready;

  /*
   * Easy special case: zero timeout.  Simply call the native
   * poll() with no fear of blocking.
   */
  if (timeout == 0) {
#    if defined(AIX)
    return _MD_POLL(listptr, nfds, timeout);
#    else
    return _MD_POLL(filedes, nfds, timeout);
#    endif
  }

  if (!_pr_initialized) {
    _PR_ImplicitInitialization();
  }

#    ifndef _PR_LOCAL_THREADS_ONLY
  if (_PR_IS_NATIVE_THREAD(_PR_MD_CURRENT_THREAD())) {
    return _MD_POLL(filedes, nfds, timeout);
  }
#    endif

  /* We do not support the pollmsg structures on AIX */
#    ifdef AIX
  PR_ASSERT((nfds & 0xff00) == 0);
#    endif

  if (timeout < 0 && timeout != -1) {
    errno = EINVAL;
    return -1;
  }

  /* Convert timeout from miliseconds to ticks */
  if (timeout == -1) {
    ticks = PR_INTERVAL_NO_TIMEOUT;
  } else {
    ticks = PR_MillisecondsToInterval(timeout);
  }

  /* Check for no descriptor case (just do a timeout) */
  if (nfds == 0) {
    PR_Sleep(ticks);
    return 0;
  }

  unixpds = (_PRUnixPollDesc*)PR_MALLOC(nfds * sizeof(_PRUnixPollDesc));
  if (NULL == unixpds) {
    errno = EAGAIN;
    return -1;
  }

  pdcnt = 0;
  epfd = filedes + nfds;
  unixpd = unixpds;
  for (pfd = filedes; pfd < epfd; pfd++) {
    /*
     * poll() ignores negative fd's.
     */
    if (pfd->fd >= 0) {
      unixpd->osfd = pfd->fd;
#    ifdef _PR_USE_POLL
      unixpd->in_flags = pfd->events;
#    else
      /*
       * Map the poll events to one of the three that can be
       * represented by the select fd_sets:
       *     POLLIN, POLLRDNORM  ===> readable
       *     POLLOUT, POLLWRNORM ===> writable
       *     POLLPRI, POLLRDBAND ===> exception
       *     POLLNORM, POLLWRBAND (and POLLMSG on some platforms)
       *     are ignored.
       *
       * The output events POLLERR and POLLHUP are never turned on.
       * POLLNVAL may be turned on.
       */
      unixpd->in_flags = 0;
      if (pfd->events & (POLLIN
#      ifdef POLLRDNORM
                         | POLLRDNORM
#      endif
                         )) {
        unixpd->in_flags |= _PR_UNIX_POLL_READ;
      }
      if (pfd->events & (POLLOUT
#      ifdef POLLWRNORM
                         | POLLWRNORM
#      endif
                         )) {
        unixpd->in_flags |= _PR_UNIX_POLL_WRITE;
      }
      if (pfd->events & (POLLPRI
#      ifdef POLLRDBAND
                         | POLLRDBAND
#      endif
                         )) {
        unixpd->in_flags |= PR_POLL_EXCEPT;
      }
#    endif /* _PR_USE_POLL */
      unixpd->out_flags = 0;
      unixpd++;
      pdcnt++;
    }
  }

  ready = _PR_WaitForMultipleFDs(unixpds, pdcnt, ticks);
  if (-1 == ready) {
    if (PR_GetError() == PR_PENDING_INTERRUPT_ERROR) {
      errno = EINTR; /* XXX we aren't interrupted by a signal, but... */
    } else {
      errno = PR_GetOSError();
    }
  }
  if (ready <= 0) {
    goto done;
  }

  /*
   * Copy the out_flags from the _PRUnixPollDesc structures to the
   * user's pollfd structures and free the allocated memory
   */
  unixpd = unixpds;
  for (pfd = filedes; pfd < epfd; pfd++) {
    pfd->revents = 0;
    if (pfd->fd >= 0) {
#    ifdef _PR_USE_POLL
      pfd->revents = unixpd->out_flags;
#    else
      if (0 != unixpd->out_flags) {
        if (unixpd->out_flags & _PR_UNIX_POLL_READ) {
          if (pfd->events & POLLIN) {
            pfd->revents |= POLLIN;
          }
#      ifdef POLLRDNORM
          if (pfd->events & POLLRDNORM) {
            pfd->revents |= POLLRDNORM;
          }
#      endif
        }
        if (unixpd->out_flags & _PR_UNIX_POLL_WRITE) {
          if (pfd->events & POLLOUT) {
            pfd->revents |= POLLOUT;
          }
#      ifdef POLLWRNORM
          if (pfd->events & POLLWRNORM) {
            pfd->revents |= POLLWRNORM;
          }
#      endif
        }
        if (unixpd->out_flags & _PR_UNIX_POLL_EXCEPT) {
          if (pfd->events & POLLPRI) {
            pfd->revents |= POLLPRI;
          }
#      ifdef POLLRDBAND
          if (pfd->events & POLLRDBAND) {
            pfd->revents |= POLLRDBAND;
          }
#      endif
        }
        if (unixpd->out_flags & _PR_UNIX_POLL_ERR) {
          pfd->revents |= POLLERR;
        }
        if (unixpd->out_flags & _PR_UNIX_POLL_NVAL) {
          pfd->revents |= POLLNVAL;
        }
        if (unixpd->out_flags & _PR_UNIX_POLL_HUP) {
          pfd->revents |= POLLHUP;
        }
      }
#    endif /* _PR_USE_POLL */
      unixpd++;
    }
  }

done:
  PR_DELETE(unixpds);
  return ready;
}

#  endif /* !defined(LINUX) */

#endif /* defined(_PR_PTHREADS) || defined(_PR_GLOBAL_THREADS_ONLY) */

/* uxwrap.c */