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From: "Boris Schaeling" <boriss AT web DOT de>
To: "Corinna Vinschen" <cygwin AT cygwin DOT com>
Subject: AW: poll() bugs and patch
Date: Wed, 13 Mar 2002 22:20:30 +0100
Message-ID: <LOBBKDBPKEGJJFKNFHKBCEPEGJAA.boriss@web.de>
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> -----Ursprüngliche Nachricht-----
> Von: cygwin-owner AT cygwin DOT com [mailto:cygwin-owner AT cygwin DOT com]Im Auftrag
> von Corinna Vinschen
> Gesendet: Mittwoch, 13. März 2002 18:14
> An: cygwin AT cygwin DOT com
> Betreff: Re: poll() bugs and patch

> [...]
> > Actually, I'm inclined to just let this one in.  There isn't a lot of
> > new code, it's mainly just rearranged.
>
> Ok with me.  However, I'll not take that patch w/o a ChangeLog entry.
> Please create one, Boris.

Here they are:
- change.log
- poll.patch
- newpoll.cc (new implementation)
- polltest.c (testcase)

HTH,
Boris

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2002-03-13  Boris Schaeling  <boriss AT web DOT de> =0A=
=0A=
	* poll.cc: variable open_fds removed, rearranged =0A=
	and added code to fix settings of revents 
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	name="poll.patch"
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	filename="poll.patch"

--- poll.cc	Sun Mar 10 21:52:26 2002=0A=
+++ newpoll.cc	Tue Mar 12 00:53:20 2002=0A=
@@ -26,7 +26,7 @@ int=0A=
 poll (struct pollfd *fds, unsigned int nfds, int timeout)=0A=
 {=0A=
   int max_fd =3D 0;=0A=
-  fd_set *open_fds, *read_fds, *write_fds, *except_fds;=0A=
+  fd_set *read_fds, *write_fds, *except_fds;=0A=
   struct timeval tv =3D { timeout / 1000, (timeout % 1000) * 1000 };=0A=
   sigframe thisframe (mainthread);=0A=
 =0A=
@@ -36,63 +36,55 @@ poll (struct pollfd *fds, unsigned int n=0A=
 =0A=
   size_t fds_size =3D howmany(max_fd + 1, NFDBITS) * sizeof (fd_mask);=0A=
 =0A=
-  open_fds =3D (fd_set *) alloca (fds_size);=0A=
   read_fds =3D (fd_set *) alloca (fds_size);=0A=
   write_fds =3D (fd_set *) alloca (fds_size);=0A=
   except_fds =3D (fd_set *) alloca (fds_size);=0A=
 =0A=
-  if (!open_fds || !read_fds || !write_fds || !except_fds)=0A=
+  if (!read_fds || !write_fds || !except_fds)=0A=
     {=0A=
       set_errno (ENOMEM);=0A=
       return -1;=0A=
     }=0A=
 =0A=
-  memset (open_fds, 0, fds_size);=0A=
   memset (read_fds, 0, fds_size);=0A=
   memset (write_fds, 0, fds_size);=0A=
   memset (except_fds, 0, fds_size);=0A=
 =0A=
-  bool valid_fds =3D false;=0A=
-  for (unsigned int i =3D 0; i < nfds; ++i)=0A=
-    if (!cygheap->fdtab.not_open (fds[i].fd))=0A=
-      {=0A=
-	valid_fds =3D true;=0A=
-	fds[i].revents =3D 0;=0A=
-	FD_SET (fds[i].fd, open_fds);=0A=
-	if (fds[i].events & POLLIN)=0A=
-	  FD_SET (fds[i].fd, read_fds);=0A=
-	if (fds[i].events & POLLOUT)=0A=
-	  FD_SET (fds[i].fd, write_fds);=0A=
-	if (fds[i].events & POLLPRI)=0A=
-	  FD_SET (fds[i].fd, except_fds);=0A=
-      }=0A=
-      else=0A=
-	fds[i].revents =3D POLLNVAL;=0A=
-=0A=
-  int ret =3D 0;=0A=
-  if (valid_fds)=0A=
-    ret =3D cygwin_select (max_fd + 1, read_fds, write_fds, except_fds,=0A=
-			 timeout < 0 ? NULL : &tv);=0A=
-=0A=
-  for (unsigned int i =3D 0; i < nfds; ++i)=0A=
-    {=0A=
-      if (fds[i].revents =3D=3D POLLNVAL && ret >=3D 0)=0A=
-	ret++;=0A=
-      else if (cygheap->fdtab.not_open(fds[i].fd))=0A=
-	fds[i].revents =3D POLLHUP;=0A=
-      else if (ret < 0)=0A=
-	fds[i].revents =3D POLLERR;=0A=
-      else=0A=
-	{=0A=
-	  fds[i].revents =3D 0;=0A=
-	  if (FD_ISSET (fds[i].fd, read_fds))=0A=
-	    fds[i].revents |=3D POLLIN;=0A=
-	  if (FD_ISSET (fds[i].fd, write_fds))=0A=
-	    fds[i].revents |=3D POLLOUT;=0A=
-	  if (FD_ISSET (fds[i].fd, except_fds))=0A=
-	    fds[i].revents |=3D POLLPRI;=0A=
-	}=0A=
-    }=0A=
+  for (unsigned int i =3D 0; i < nfds; ++i) =0A=
+  { =0A=
+    fds[i].revents =3D 0; =0A=
+    if (!cygheap->fdtab.not_open(fds[i].fd)) =0A=
+    { =0A=
+      if (fds[i].events & POLLIN) =0A=
+        FD_SET(fds[i].fd, read_fds); =0A=
+      if (fds[i].events & POLLOUT) =0A=
+        FD_SET(fds[i].fd, write_fds); =0A=
+      if (fds[i].events & POLLPRI) =0A=
+        FD_SET(fds[i].fd, except_fds); =0A=
+    } =0A=
+  } =0A=
+=0A=
+  int ret =3D cygwin_select (max_fd + 1, read_fds, write_fds, =
except_fds, timeout < 0 ? NULL : &tv);=0A=
+=0A=
+  if (ret > 0) =0A=
+    for (unsigned int i =3D 0; i < nfds; ++i) =0A=
+    { =0A=
+      if (fds[i].fd < 0) =0A=
+        fds[i].revents =3D POLLNVAL; =0A=
+      else if (cygheap->fdtab.not_open(fds[i].fd)) =0A=
+        fds[i].revents =3D POLLHUP; =0A=
+      else =0A=
+      { =0A=
+        if (FD_ISSET(fds[i].fd, read_fds)) =0A=
+	  fds[i].revents |=3D POLLIN; =0A=
+	if (FD_ISSET(fds[i].fd, write_fds)) =0A=
+	  fds[i].revents |=3D POLLOUT; =0A=
+	if (FD_ISSET(fds[i].fd, read_fds) && FD_ISSET(fds[i].fd, write_fds)) =0A=
+	  fds[i].revents |=3D POLLERR; =0A=
+	if (FD_ISSET(fds[i].fd, except_fds)) =0A=
+	  fds[i].revents |=3D POLLPRI; =0A=
+      } =0A=
+    } =0A=
 =0A=
-  return ret;=0A=
-}=0A=
+  return ret; =0A=
+} =0A=
\ No newline at end of file=0A=

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/* gcc -opolltest polltest.c */=20

#include <stdio.h>=20
#include <string.h>=20
#include <poll.h>=20
#include <signal.h>=20
#include <unistd.h>=20

void callback_alarm(int sig) { return; }=20

int main()=20
{=20
	struct pollfd p[3];=20

	memset(p, 0, sizeof(struct pollfd) * 3);=20

	p[0].fd =3D -1;=20
	p[1].fd =3D -1;=20
	p[2].fd =3D -1;=20

	printf("no descriptor is valid - poll() must wait for 2 seconds\n");=20
	poll(p, 3, 2000);=20
	printf("no descriptor is valid - revents for any descriptor must be 0: =
%d, %d, %d\n", p[0].revents, p[1].revents, p[2].revents);=20

	p[2].fd =3D 0;=20
	printf("no descriptor is ready - poll() must return 0: %d\n", poll(p, =
3, 500));=20
	printf("no descriptor is ready - revents for any descriptor must be 0: =
%d, %d, %d\n", p[0].revents, p[1].revents, p[2].revents);=20

	signal(SIGALRM, callback_alarm);=20

	alarm(1);=20

	printf("SIGALRM - poll() must return -1: %d\n", poll(p, 3, 1500));=20
	printf("SIGALRM - revents for any descriptor must be 0: %d, %d, %d\n", =
p[0].revents, p[1].revents, p[2].revents);=20
} 
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/* poll.cc. Implements poll(2) via usage of select(2) call.=0A=
=0A=
   Copyright 2000, 2001 Red Hat, Inc.=0A=
=0A=
   This file is part of Cygwin.=0A=
=0A=
   This software is a copyrighted work licensed under the terms of the=0A=
   Cygwin license.  Please consult the file "CYGWIN_LICENSE" for=0A=
   details. */=0A=
=0A=
#include "winsup.h"=0A=
#include <sys/time.h>=0A=
#include <sys/poll.h>=0A=
#include <errno.h>=0A=
#include <stdlib.h>=0A=
#include "security.h"=0A=
#include "fhandler.h"=0A=
#include "path.h"=0A=
#include "dtable.h"=0A=
#include "cygerrno.h"=0A=
#include "cygheap.h"=0A=
#include "sigproc.h"=0A=
=0A=
extern "C"=0A=
int=0A=
poll (struct pollfd *fds, unsigned int nfds, int timeout)=0A=
{=0A=
  int max_fd =3D 0;=0A=
  fd_set *read_fds, *write_fds, *except_fds;=0A=
  struct timeval tv =3D { timeout / 1000, (timeout % 1000) * 1000 };=0A=
  sigframe thisframe (mainthread);=0A=
=0A=
  for (unsigned int i =3D 0; i < nfds; ++i)=0A=
    if (fds[i].fd > max_fd)=0A=
      max_fd =3D fds[i].fd;=0A=
=0A=
  size_t fds_size =3D howmany(max_fd + 1, NFDBITS) * sizeof (fd_mask);=0A=
=0A=
  read_fds =3D (fd_set *) alloca (fds_size);=0A=
  write_fds =3D (fd_set *) alloca (fds_size);=0A=
  except_fds =3D (fd_set *) alloca (fds_size);=0A=
=0A=
  if (!read_fds || !write_fds || !except_fds)=0A=
    {=0A=
      set_errno (ENOMEM);=0A=
      return -1;=0A=
    }=0A=
=0A=
  memset (read_fds, 0, fds_size);=0A=
  memset (write_fds, 0, fds_size);=0A=
  memset (except_fds, 0, fds_size);=0A=
=0A=
  for (unsigned int i =3D 0; i < nfds; ++i) =0A=
  { =0A=
    fds[i].revents =3D 0; =0A=
    if (!cygheap->fdtab.not_open(fds[i].fd)) =0A=
    { =0A=
      if (fds[i].events & POLLIN) =0A=
        FD_SET(fds[i].fd, read_fds); =0A=
      if (fds[i].events & POLLOUT) =0A=
        FD_SET(fds[i].fd, write_fds); =0A=
      if (fds[i].events & POLLPRI) =0A=
        FD_SET(fds[i].fd, except_fds); =0A=
    } =0A=
  } =0A=
=0A=
  int ret =3D cygwin_select (max_fd + 1, read_fds, write_fds, =
except_fds, timeout < 0 ? NULL : &tv);=0A=
=0A=
  if (ret > 0) =0A=
    for (unsigned int i =3D 0; i < nfds; ++i) =0A=
    { =0A=
      if (fds[i].fd < 0) =0A=
        fds[i].revents =3D POLLNVAL; =0A=
      else if (cygheap->fdtab.not_open(fds[i].fd)) =0A=
        fds[i].revents =3D POLLHUP; =0A=
      else =0A=
      { =0A=
        if (FD_ISSET(fds[i].fd, read_fds)) =0A=
          fds[i].revents |=3D POLLIN; =0A=
        if (FD_ISSET(fds[i].fd, write_fds)) =0A=
          fds[i].revents |=3D POLLOUT; =0A=
        if (FD_ISSET(fds[i].fd, read_fds) && FD_ISSET(fds[i].fd, =
write_fds)) =0A=
          fds[i].revents |=3D POLLERR; =0A=
        if (FD_ISSET(fds[i].fd, except_fds)) =0A=
          fds[i].revents |=3D POLLPRI; =0A=
      } =0A=
    } =0A=
=0A=
  return ret; =0A=
} 

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