implement poll method, handle enomem by closing a 'random' fd

ev.c

@@ -58,6 +58,10 @@
 # define EV_USE_SELECT 1
 #endif
 
+#ifndef EV_USE_POLL
+# define EV_USE_POLL 0 /* poll is usually slower than select, and not as well tested */
+#endif
+
 #ifndef EV_USE_EPOLL
 # define EV_USE_EPOLL 0
 #endif
@@ -279,20 +283,44 @@ fd_change (int fd)
   fdchanges [fdchangecnt - 1] = fd;
 }
 
+static void
+fd_kill (int fd)
+{
+  struct ev_io *w;
+
+  printf ("killing fd %d\n", fd);//D
+  while ((w = anfds [fd].head))
+    {
+      ev_io_stop (w);
+      event ((W)w, EV_ERROR | EV_READ | EV_WRITE);
+    }
+}
+
 /* called on EBADF to verify fds */
 static void
-fd_recheck (void)
+fd_ebadf (void)
 {
   int fd;
 
   for (fd = 0; fd < anfdmax; ++fd)
     if (anfds [fd].events)
       if (fcntl (fd, F_GETFD) == -1 && errno == EBADF)
-        while (anfds [fd].head)
-          {
-            ev_io_stop (anfds [fd].head);
-            event ((W)anfds [fd].head, EV_ERROR | EV_READ | EV_WRITE);
-          }
+        fd_kill (fd);
+}
+
+/* called on ENOMEM in select/poll to kill some fds and retry */
+static void
+fd_enomem (void)
+{
+  int fd = anfdmax;
+
+  while (fd--)
+    if (anfds [fd].events)
+      {
+        close (fd);
+        fd_kill (fd);
+        return;
+      }
 }
 
 /*****************************************************************************/
@@ -456,6 +484,9 @@ childcb (struct ev_signal *sw, int revents)
 #if EV_USE_EPOLL
 # include "ev_epoll.c"
 #endif
+#if EV_USE_POLL
+# include "ev_poll.c"
+#endif
 #if EV_USE_SELECT
 # include "ev_select.c"
 #endif
@@ -472,7 +503,15 @@ ev_version_minor (void)
   return EV_VERSION_MINOR;
 }
 
-int ev_init (int flags)
+/* return true if we are running with elevated privileges and ignore env variables */
+static int
+enable_secure ()
+{
+  return getuid () != geteuid ()
+      || getgid () != getegid ();
+}
+
+int ev_init (int methods)
 {
   if (!ev_method)
     {
@@ -492,12 +531,21 @@ int ev_init (int flags)
       if (pipe (sigpipe))
         return 0;
 
-      ev_method = EVMETHOD_NONE;
+      if (methods == EVMETHOD_AUTO)
+          if (!enable_secure () && getenv ("LIBEV_METHODS"))
+            methods = atoi (getenv ("LIBEV_METHODS"));
+          else
+            methods = EVMETHOD_ANY;
+
+      ev_method = 0;
 #if EV_USE_EPOLL
-      if (ev_method == EVMETHOD_NONE) epoll_init (flags);
+      if (!ev_method && (methods & EVMETHOD_EPOLL )) epoll_init  (methods);
+#endif
+#if EV_USE_POLL
+      if (!ev_method && (methods & EVMETHOD_POLL  )) poll_init   (methods);
 #endif
 #if EV_USE_SELECT
-      if (ev_method == EVMETHOD_NONE) select_init (flags);
+      if (!ev_method && (methods & EVMETHOD_SELECT)) select_init (methods);
 #endif
 
       if (ev_method)

ev.h

@@ -167,12 +167,14 @@ struct ev_child
   int status; /* rw, holds the exit status, use the macros from sys/wait.h */
 };
 
-#define EVMETHOD_NONE   0
+#define EVMETHOD_AUTO   0 /* consults environment */
 #define EVMETHOD_SELECT 1
-#define EVMETHOD_EPOLL  2
+#define EVMETHOD_POLL   2
+#define EVMETHOD_EPOLL  4
+#define EVMETHOD_ANY    ~0 /* any method, do not consult env */
 #if EV_PROTOTYPES
 extern int ev_method;
-int ev_init (int flags); /* returns ev_method */
+int ev_init (int methods); /* returns ev_method */
 int ev_version_major (void);
 int ev_version_minor (void);
 

ev_poll.c

@@ -29,82 +29,80 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/epoll.h>
+#include <poll.h>
 
-static int epoll_fd = -1;
+static struct pollfd *polls;
+static int pollmax, pollcnt;
+static int *pollidxs; /* maps fds into structure indices */
+static int pollidxmax;
 
 static void
-epoll_modify (int fd, int oev, int nev)
+pollidx_init (int *base, int count)
 {
-  int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL;
-
-  struct epoll_event ev;
-  ev.data.fd = fd;
-  ev.events =
-      (nev & EV_READ ? EPOLLIN : 0)
-      | (nev & EV_WRITE ? EPOLLOUT : 0);
-
-  epoll_ctl (epoll_fd, mode, fd, &ev);
+  while (count--)
+    *base++ = -1;
 }
 
 static void
-epoll_postfork_child (void)
+poll_modify (int fd, int oev, int nev)
 {
-  int fd;
+  int idx;
+  array_needsize (pollidxs, pollidxmax, fd + 1, pollidx_init);
 
-  epoll_fd = epoll_create (256);
-  fcntl (epoll_fd, F_SETFD, FD_CLOEXEC);
+  idx = pollidxs [fd];
 
-  /* re-register interest in fds */
-  for (fd = 0; fd < anfdmax; ++fd)
-    if (anfds [fd].events)//D
-      epoll_modify (fd, EV_NONE, anfds [fd].events);
-}
+  if (idx < 0) /* need to allocate a new pollfd */
+    {
+      idx = pollcnt++;
+      array_needsize (polls, pollmax, pollcnt, );
+      polls [idx].fd = fd;
+    }
 
-static struct epoll_event *events;
-static int eventmax;
+  if (nev)
+    polls [idx].events =
+        (nev & EV_READ ? POLLIN : 0)
+        | (nev & EV_WRITE ? POLLOUT : 0);
+  else /* remove pollfd */
+    {
+      if (idx < pollcnt--)
+        {
+          pollidxs [fd] = -1;
+          polls [idx] = polls [pollcnt];
+          pollidxs [polls [idx].fd] = idx;
+        }
+    }
+}
 
 static void
-epoll_poll (ev_tstamp timeout)
+poll_poll (ev_tstamp timeout)
 {
-  int eventcnt = epoll_wait (epoll_fd, events, eventmax, ceil (timeout * 1000.));
-  int i;
-
-  if (eventcnt < 0)
-    return;
+  int res = poll (polls, pollcnt, ceil (timeout * 1000.));
 
-  for (i = 0; i < eventcnt; ++i)
-    fd_event (
-      events [i].data.fd,
-      (events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0)
-      | (events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0)
-    );
-
-  /* if the receive array was full, increase its size */
-  if (expect_false (eventcnt == eventmax))
+  if (res > 0)
+    {
+      int i;
+
+      for (i = 0; i < pollcnt; ++i)
+        fd_event (
+          polls [i].fd,
+          (polls [i].revents & (POLLOUT | POLLERR | POLLHUP) ? EV_WRITE : 0)
+          | (polls [i].revents & (POLLIN | POLLERR | POLLHUP) ? EV_READ : 0)
+        );
+    }
+  else if (res < 0)
     {
-      free (events);
-      eventmax = array_roundsize (events, eventmax << 1);
-      events = malloc (sizeof (struct epoll_event) * eventmax);
+      if (errno == EBADF)
+        fd_ebadf ();
+      else if (errno == ENOMEM)
+        fd_enomem ();
     }
 }
 
 static void
-epoll_init (int flags)
+poll_init (int flags)
 {
-  epoll_fd = epoll_create (256);
-
-  if (epoll_fd < 0)
-    return;
-
-  fcntl (epoll_fd, F_SETFD, FD_CLOEXEC);
-
-  ev_method     = EVMETHOD_EPOLL;
-  method_fudge  = 1e-3; /* needed to compensate for epoll returning early */
-  method_modify = epoll_modify;
-  method_poll   = epoll_poll;
-
-  eventmax = 64; /* intiial number of events receivable per poll */
-  events = malloc (sizeof (struct epoll_event) * eventmax);
+  ev_method     = EVMETHOD_POLL;
+  method_fudge  = 1e-3; /* needed to compensate for select returning early, very conservative */
+  method_modify = poll_modify;
+  method_poll   = poll_poll;
 }
-

ev_select.c

@@ -116,7 +116,9 @@ select_poll (ev_tstamp timeout)
   else if (res < 0)
     {
       if (errno == EBADF)
-        fd_recheck ();
+        fd_ebadf ();
+      else if (errno == ENOMEM)
+        fd_enomem ();
     }
 }