check for a fine poll() before it is used to sleep subsecond

                                  Changelog

Daniel (27 June 2004)

- Based on Bob's bug report #979480, I wrote a configure check that checks if

  poll() can be used to wait on NULL as otherwise select() should be used to

  do it. The select() usage was also fixed according to his report.

  Mac OS X 10.3 says "poll() functionality for Mac OS X is implemented via an

  emulation layer on top of select(), not in the kernel directly. It is

  recommended that programs running under OS X 10.3 prefer select() over

  poll(). Configure scripts should look for the _POLL_EMUL_H_ define (instead

  of _POLL_H_ or _SYS_POLL_H_) and avoid implementations where poll is not

  implemented in the kernel."

  Yes, we can probably use select() on most platforms but today I prefered to

  leave the code unaltered.

Daniel (24 June 2004)

- The standard curl_version() string now only includes version info about

  involved libraries and not about particular features. Thus it will no longer

               )

fi

dnl poll() might be badly emulated, as in Mac OS X 10.3 (and other BSDs?) and

dnl to find out we make an extra check here!

if test "$ac_cv_func_poll" = "yes"; then

  AC_MSG_CHECKING([if poll works with NULL inputs])

  AC_RUN_IFELSE([

#ifdef HAVE_SYS_POLL_H

#include <sys/poll.h>

#endif

  int main(void)

  {

    /* make this return 0 == timeout since there's nothing to read from */

    return poll((void *)0, 0, 10 /*ms*/);

  }

],

  AC_MSG_RESULT(yes)

  AC_DEFINE(HAVE_POLL_FINE, 1, [If you have a fine poll]),

  AC_MSG_RESULT(no),

  AC_MSG_RESULT(cross-compiling assumes yes)

  AC_DEFINE(HAVE_POLL_FINE, 1, [If you have a fine poll])

  ) dnl end of AC_RUN_IFELSE

fi

AC_PATH_PROG( PERL, perl, , 

  $PATH:/usr/local/bin/perl:/usr/bin/:/usr/local/bin )

AC_SUBST(PERL)

/* Define if you have the `poll' function. */

#undef HAVE_POLL

/* Define if you have a good `poll' function that can wait on NULL. */

#undef HAVE_POLL_FINE

/* Define if you can write to argc[] strings */

#undef HAVE_WRITABLE_ARGV

static void go_sleep(long ms)

{

#ifdef HAVE_POLL

#ifdef HAVE_POLL_FINE

  /* portable subsecond "sleep" */

  poll((void *)0, 0, ms);

#else

  struct timeval timeout;

  timeout.tv_sec = ms/1000;

  ms -= ms/1000;

  ms = ms%1000;

  timeout.tv_usec = ms * 1000;

  select(0, NULL,  NULL, NULL, &timeout);