From 8178d44ec070f9369fc90d2c79219241544a68ac Mon Sep 17 00:00:00 2001
From: hyung-hwan <hyunghwan.chung@gmail.com>
Date: Sun, 24 May 2020 19:29:35 +0000
Subject: [PATCH] fixed the premature EOF reporting caused by a file descriptor
 added without intention of input/output watching. as EPOLLHUP is always
 waited for, it caused early EOF reporting

---
 mio/lib/mio.c     |  5 +--
 mio/lib/mio.h     |  3 +-
 mio/lib/sys-mux.c | 81 ++++++++++++++++++++++++++++++++++++++++-------
 mio/lib/sys-prv.h |  2 +-
 4 files changed, 76 insertions(+), 15 deletions(-)

diff --git a/mio/lib/mio.c b/mio/lib/mio.c
index 6c4249c..3495958 100644
--- a/mio/lib/mio.c
+++ b/mio/lib/mio.c
@@ -1045,7 +1045,7 @@ int mio_dev_watch (mio_dev_t* dev, mio_dev_watch_cmd_t cmd, int events)
 	if (dev->dev_cap & MIO_DEV_CAP_VIRTUAL) return 0;
 
 	/*ev.data.ptr = dev;*/
-	dev_cap = dev->dev_cap & ~(DEV_CAP_ALL_WATCHED);
+	dev_cap = dev->dev_cap & ~(DEV_CAP_ALL_WATCHED | MIO_DEV_CAP_WATCH_SUSPENDED); /* UGLY to use MIO_DEV_CAP_WATCH_SUSPENDED here */
 
 	switch (cmd)
 	{
@@ -1116,7 +1116,8 @@ int mio_dev_watch (mio_dev_t* dev, mio_dev_watch_cmd_t cmd, int events)
 		if (mio_sys_ctrlmux(mio, mux_cmd, dev, dev_cap) <= -1) return -1;
 	}
 
-	dev->dev_cap = dev_cap;
+	/* UGLY. MIO_DEV_CAP_WATCH_SUSPENDED may be set/unset by mio_sys_ctrlmux. I need this to reflect it */
+	dev->dev_cap = dev_cap | (dev->dev_cap & MIO_DEV_CAP_WATCH_SUSPENDED);
 	return 0;
 }
 
diff --git a/mio/lib/mio.h b/mio/lib/mio.h
index 30a53de..7a71f68 100644
--- a/mio/lib/mio.h
+++ b/mio/lib/mio.h
@@ -390,7 +390,8 @@ enum mio_dev_cap_t
 	MIO_DEV_CAP_HALTED          = (1 << 16),
 	MIO_DEV_CAP_ZOMBIE          = (1 << 17),
 	MIO_DEV_CAP_RENEW_REQUIRED  = (1 << 18),
-	MIO_DEV_CAP_WATCH_STARTED   = (1 << 19)
+	MIO_DEV_CAP_WATCH_STARTED   = (1 << 19),
+	MIO_DEV_CAP_WATCH_SUSPENDED = (1 << 20)
 };
 typedef enum mio_dev_cap_t mio_dev_cap_t;
 
diff --git a/mio/lib/sys-mux.c b/mio/lib/sys-mux.c
index d3dbe78..6f78744 100644
--- a/mio/lib/sys-mux.c
+++ b/mio/lib/sys-mux.c
@@ -186,7 +186,7 @@ int mio_sys_ctrlmux (mio_t* mio, mio_sys_mux_cmd_t cmd, mio_dev_t* dev, int dev_
 
 			MIO_ASSERT (mio, mux->pd.dptr[idx] == dev);
 			mux->pd.pfd[idx].events = events;
-			
+
 			return 0;
 		}
 
@@ -235,26 +235,85 @@ int mio_sys_ctrlmux (mio_t* mio, mio_sys_mux_cmd_t cmd, mio_dev_t* dev, int dev_
 	}
 #elif defined(USE_EPOLL)
 	mio_sys_mux_t* mux = &mio->sysdep->mux;
-	static int epoll_cmd[] = { EPOLL_CTL_ADD, EPOLL_CTL_MOD, EPOLL_CTL_DEL };
 	struct epoll_event ev;
+	mio_syshnd_t hnd;
+	mio_uint32_t events;
+	int x;
 
 	MIO_ASSERT (mio, mio == dev->mio);
+	hnd = dev->dev_mth->getsyshnd(dev);
 
-	ev.data.ptr = dev;
-	ev.events = EPOLLHUP | EPOLLERR /*| EPOLLET*/;
-
+	events = 0;
 	if (dev_cap & MIO_DEV_CAP_IN_WATCHED) 
 	{
-		ev.events |= EPOLLIN;
+		events |= EPOLLIN;
 	#if defined(EPOLLRDHUP)
-		ev.events |= EPOLLRDHUP;
+		events |= EPOLLRDHUP;
 	#endif
-		if (dev_cap & MIO_DEV_CAP_PRI_WATCHED) ev.events |= EPOLLPRI;
+		if (dev_cap & MIO_DEV_CAP_PRI_WATCHED) events |= EPOLLPRI;
+	}
+	if (dev_cap & MIO_DEV_CAP_OUT_WATCHED) events |= EPOLLOUT;
+
+	ev.events = events | EPOLLHUP | EPOLLERR /*| EPOLLET*/;
+	ev.data.ptr = dev;
+
+	switch (cmd)
+	{
+		case MIO_SYS_MUX_CMD_INSERT:
+			if (MIO_UNLIKELY(dev->dev_cap & MIO_DEV_CAP_WATCH_SUSPENDED))
+			{
+				mio_seterrnum (mio, MIO_EEXIST);
+				return -1;
+			}
+
+			x = epoll_ctl(mux->hnd, EPOLL_CTL_ADD, hnd, &ev);
+			break;
+
+		case MIO_SYS_MUX_CMD_UPDATE:
+			if (MIO_UNLIKELY(!events))
+			{
+				if (dev->dev_cap & MIO_DEV_CAP_WATCH_SUSPENDED)
+				{
+					/* no change. keep suspended */
+					return 0;
+				}
+				else
+				{
+					x = epoll_ctl(mux->hnd, EPOLL_CTL_DEL, hnd, &ev);
+					if (x >= 0) dev->dev_cap |= MIO_DEV_CAP_WATCH_SUSPENDED;
+				}
+			}
+			else
+			{
+				if (dev->dev_cap & MIO_DEV_CAP_WATCH_SUSPENDED)
+				{
+					x = epoll_ctl(mux->hnd, EPOLL_CTL_ADD, hnd, &ev);
+					if (x >= 0) dev->dev_cap &= ~MIO_DEV_CAP_WATCH_SUSPENDED;
+				}
+				else
+				{
+					x = epoll_ctl(mux->hnd, EPOLL_CTL_MOD, hnd, &ev);
+				}
+			}
+			break;
+
+		case MIO_SYS_MUX_CMD_DELETE:
+			if (dev->dev_cap & MIO_DEV_CAP_WATCH_SUSPENDED) 
+			{
+				/* clear the SUSPENDED bit because it's a normal deletion */
+				dev->dev_cap &= ~MIO_DEV_CAP_WATCH_SUSPENDED;
+				return 0;
+			}
+
+			x = epoll_ctl(mux->hnd, EPOLL_CTL_DEL, hnd, &ev);
+			break;
+
+		default:
+			mio_seterrnum (mio, MIO_EINVAL);
+			return -1;
 	}
 
-	if (dev_cap & MIO_DEV_CAP_OUT_WATCHED) ev.events |= EPOLLOUT;
-
-	if (epoll_ctl(mux->hnd, epoll_cmd[cmd], dev->dev_mth->getsyshnd(dev), &ev) == -1)
+	if (x == -1)
 	{
 		mio_seterrwithsyserr (mio, 0, errno);
 		return -1;
diff --git a/mio/lib/sys-prv.h b/mio/lib/sys-prv.h
index 7d1dde6..d1c946a 100644
--- a/mio/lib/sys-prv.h
+++ b/mio/lib/sys-prv.h
@@ -68,7 +68,7 @@ struct mio_sys_mux_t
 struct mio_sys_mux_t
 {
 	int hnd;
-	struct epoll_event revs[100]; /* TODO: is it a good size? */
+	struct epoll_event revs[128]; /* TODO: is it a good size? */
 };
 
 #endif