Justin Cormack <justin@street-vision.com> writes:

Here is a small patch to add epoll support to uclibc.

The only thing I am not sure about is what needs to be done (if anything)
to make it work on 2.4/2.2 kernels (are the syscall numbers defined but
give errors when called or not?).

Tested on 2.6, though some other issues prevent more extensive testing at
the minute.

Mike Frysinger:
cleaned up patch and added checks to make sure that the syscall actually
exists, returning ENOSYS in cases where it doesn't.

include/sys/epoll.h

@@ -0,0 +1,107 @@
+/* Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef	_SYS_EPOLL_H
+#define	_SYS_EPOLL_H	1
+
+#include <stdint.h>
+#include <sys/types.h>
+
+
+enum EPOLL_EVENTS
+  {
+    EPOLLIN = 0x001,
+#define EPOLLIN EPOLLIN
+    EPOLLPRI = 0x002,
+#define EPOLLPRI EPOLLPRI
+    EPOLLOUT = 0x004,
+#define EPOLLOUT EPOLLOUT
+    EPOLLRDNORM = 0x040,
+#define EPOLLRDNORM EPOLLRDNORM
+    EPOLLRDBAND = 0x080,
+#define EPOLLRDBAND EPOLLRDBAND
+    EPOLLWRNORM = 0x100,
+#define EPOLLWRNORM EPOLLWRNORM
+    EPOLLWRBAND = 0x200,
+#define EPOLLWRBAND EPOLLWRBAND
+    EPOLLMSG = 0x400,
+#define EPOLLMSG EPOLLMSG
+    EPOLLERR = 0x008,
+#define EPOLLERR EPOLLERR
+    EPOLLHUP = 0x010,
+#define EPOLLHUP EPOLLHUP
+    EPOLLONESHOT = (1 << 30),
+#define EPOLLONESHOT EPOLLONESHOT
+    EPOLLET = (1 << 31)
+#define EPOLLET EPOLLET
+  };
+
+
+/* Valid opcodes ( "op" parameter ) to issue to epoll_ctl().  */
+#define EPOLL_CTL_ADD 1	/* Add a file decriptor to the interface.  */
+#define EPOLL_CTL_DEL 2	/* Remove a file decriptor from the interface.  */
+#define EPOLL_CTL_MOD 3	/* Change file decriptor epoll_event structure.  */
+
+
+typedef union epoll_data
+{
+  void *ptr;
+  int fd;
+  uint32_t u32;
+  uint64_t u64;
+} epoll_data_t;
+
+struct epoll_event
+{
+  uint32_t events;	/* Epoll events */
+  epoll_data_t data;	/* User data variable */
+} __attribute__ ((__packed__));
+
+
+__BEGIN_DECLS
+
+/* Creates an epoll instance.  Returns an fd for the new instance.
+   The "size" parameter is a hint specifying the number of file
+   descriptors to be associated with the new instance.  The fd
+   returned by epoll_create() should be closed with close().  */
+extern int epoll_create (int __size) __THROW;
+
+
+/* Manipulate an epoll instance "epfd". Returns 0 in case of success,
+   -1 in case of error ( the "errno" variable will contain the
+   specific error code ) The "op" parameter is one of the EPOLL_CTL_*
+   constants defined above. The "fd" parameter is the target of the
+   operation. The "event" parameter describes which events the caller
+   is interested in and any associated user data.  */
+extern int epoll_ctl (int __epfd, int __op, int __fd,
+		      struct epoll_event *__event) __THROW;
+
+
+/* Wait for events on an epoll instance "epfd". Returns the number of
+   triggered events returned in "events" buffer. Or -1 in case of
+   error with the "errno" variable set to the specific error code. The
+   "events" parameter is a buffer that will contain triggered
+   events. The "maxevents" is the maximum number of events to be
+   returned ( usually size of "events" ). The "timeout" parameter
+   specifies the maximum wait time in milliseconds (-1 == infinite).  */
+extern int epoll_wait (int __epfd, struct epoll_event *__events,
+		       int __maxevents, int __timeout) __THROW;
+
+__END_DECLS
+
+#endif /* sys/epoll.h */

libc/sysdeps/linux/common/Makefile

@@ -24,7 +24,7 @@ CSRC=	__rt_sigtimedwait.c __socketcall.c __syscall_fcntl.c \
 	__syscall_sigaction.c _exit.c access.c acct.c adjtimex.c alarm.c \
 	bdflush.c capget.c capset.c chdir.c chmod.c chown.c chroot.c \
 	close.c cmsg_nxthdr.c creat64.c create_module.c delete_module.c \
-	dup.c dup2.c execve.c fchdir.c fchmod.c fchown.c fdatasync.c \
+	dup.c dup2.c epoll.c execve.c fchdir.c fchmod.c fchown.c fdatasync.c \
 	flock.c fork.c fstat.c fstat64.c fstatfs.c fsync.c ftruncate.c \
 	ftruncate64.c get_kernel_syms.c getcwd.c getdents.c getdents64.c \
 	getdirname.c getdnnm.c getdtablesize.c getegid.c geteuid.c \

libc/sysdeps/linux/common/epoll.c

@@ -0,0 +1,65 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * epoll_create() / epoll_ctl() / epoll_wait() for uClibc
+ *
+ * Copyright (C) 2005 by Erik Andersen <andersen@codepoet.org>
+ *
+ * GNU Library General Public License (LGPL) version 2 or later.
+ */
+
+#include "syscalls.h"
+#include <sys/epoll.h>
+
+/*
+ * epoll_create()
+ */
+#ifdef __NR_epoll_create
+#define __NR___syscall_epoll_create __NR_epoll_create
+static inline _syscall1(int, __syscall_epoll_create, int, size);
+#endif
+
+int epoll_create(int size)
+{
+#ifdef __NR_epoll_create
+	return (__syscall_epoll_create(size));
+#else
+    __set_errno(ENOSYS);
+    return -1;
+#endif
+}
+
+/*
+ * epoll_ctl()
+ */
+#ifdef __NR_epoll_ctl
+#define __NR___syscall_epoll_ctl __NR_epoll_ctl
+static inline _syscall4(int, __syscall_epoll_ctl, int, epfd, int, op, int, fd, struct epoll_event *, event);
+#endif
+
+int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event)
+{
+#ifdef __NR_epoll_ctl
+	return (__syscall_epoll_ctl(epfd, op, fd, event));
+#else
+	__set_errno(ENOSYS);
+	return -1;
+#endif
+}
+
+/*
+ * epoll_wait()
+ */
+#ifdef __NR_epoll_wait
+#define __NR___syscall_epoll_wait __NR_epoll_wait
+static inline _syscall4(int, __syscall_epoll_wait, int, epfd, struct epoll_event *, events, int, maxevents, int, timeout);
+#endif
+
+int epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout)
+{
+#ifdef __NR_epoll_wait
+	return (__syscall_epoll_wait(epfd, events, maxevents, timeout));
+#else
+	__set_errno(ENOSYS);
+	return -1;
+#endif
+}