From 22c4fb20d407f464813ce1031308bc4c6db13bb4 Mon Sep 17 00:00:00 2001
From: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Date: Wed, 14 Apr 2010 06:55:55 +0200
Subject: win32: add poll()

Only works for pipes, as commented in the source code.
---
 include/mingw.h |  2 +-
 win32/mingw.c   | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/include/mingw.h b/include/mingw.h
index d41580da7..c2c0c7816 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -61,7 +61,7 @@ typedef unsigned long nfds_t;
 #define POLLIN 1
 #define POLLHUP 2
 
-NOIMPL(poll,struct pollfd *ufds UNUSED_PARAM, unsigned int nfds UNUSED_PARAM, int timeout UNUSED_PARAM);
+int poll(struct pollfd *ufds, unsigned int nfds, int timeout);
 
 /*
  * pwd.h
diff --git a/win32/mingw.c b/win32/mingw.c
index adf2d161e..0376c9b13 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -176,6 +176,75 @@ int pipe(int filedes[2])
 	return 0;
 }
 
+int poll(struct pollfd *ufds, unsigned int nfds, int timeout)
+{
+	int i, pending;
+
+	if (timeout >= 0) {
+		if (nfds == 0) {
+			Sleep(timeout);
+			return 0;
+		}
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* When there is only one fd to wait for, then we pretend that
+	 * input is available and let the actual wait happen when the
+	 * caller invokes read().
+	 */
+	if (nfds == 1) {
+		if (!(ufds[0].events & POLLIN)) {
+			errno = EINVAL;
+			return -1;
+		}
+		ufds[0].revents = POLLIN;
+		return 0;
+	}
+
+repeat:
+	pending = 0;
+	for (i = 0; i < nfds; i++) {
+		DWORD avail = 0;
+		HANDLE h = (HANDLE) _get_osfhandle(ufds[i].fd);
+		if (h == INVALID_HANDLE_VALUE)
+			return -1;	/* errno was set */
+
+		if (!(ufds[i].events & POLLIN)) {
+			errno = EINVAL;
+			return -1;
+		}
+
+		/* this emulation works only for pipes */
+		if (!PeekNamedPipe(h, NULL, 0, NULL, &avail, NULL)) {
+			int err = GetLastError();
+			if (err == ERROR_BROKEN_PIPE) {
+				ufds[i].revents = POLLHUP;
+				pending++;
+			} else {
+				errno = EINVAL;
+				return -1;
+			}
+		} else if (avail) {
+			ufds[i].revents = POLLIN;
+			pending++;
+		} else
+			ufds[i].revents = 0;
+	}
+	if (!pending) {
+		/* The only times that we spin here is when the process
+		 * that is connected through the pipes is waiting for
+		 * its own input data to become available. But since
+		 * the process (pack-objects) is itself CPU intensive,
+		 * it will happily pick up the time slice that we are
+		 * relinguishing here.
+		 */
+		Sleep(0);
+		goto repeat;
+	}
+	return 0;
+}
+
 struct tm *gmtime_r(const time_t *timep, struct tm *result)
 {
 	/* gmtime() in MSVCRT.DLL is thread-safe, but not reentrant */
-- 
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