From: Clement Calmels <clement.calmels@fr.ibm.com>
Date: Wed, 13 Jan 2010 17:51:16 +0000 (+0100)
Subject: Don't mess descr->ev
X-Git-Tag: lxc-0.6.5~30
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5df6b18f0e5f1ebb86167efa4c43436e01740e79;p=thirdparty%2Flxc.git

Don't mess descr->ev

A simple test program to show up the issue:

-8<---
#include <stdio.h>
#include <unistd.h>

#include "mainloop.h"

struct lxc_epoll_descr loop;

int cb1(int fd, void *data, struct lxc_epoll_descr *descr)
{
	fprintf(stderr, "cb1\n");
        return 1;
}

int cb2(int fd, void *data, struct lxc_epoll_descr *descr)
{
	fprintf(stderr, "cb2\n");
        return 1;
}

int main(int argc, char *argv[])
{
        int ret;
        int fds[2];

        ret = pipe(fds);
        if (ret) {
                perror("pipe:");
                return -1;
        }

        ret = lxc_mainloop_open(&loop);
        if (ret) {
                fprintf(stderr, "lxc_mainloop_open: %d\n", ret);
                return -1;
        }

        ret = lxc_mainloop_add_handler(&loop, fds[1], cb1, NULL);
        if (ret) {
                fprintf(stderr, "lxc_mainloop_add_handler(fds[1]): %d\n", ret);
                return -1;
        }

        ret = lxc_mainloop_add_handler(&loop, fds[0], cb2, NULL);
        if (ret) {
                fprintf(stderr, "lxc_mainloop_add_handler(fds[0]): %d\n", ret);
                return -1;
        }

        write(fds[1], &ret, sizeof(ret));

        ret = lxc_mainloop(&loop);
        if (ret) {
	        fprintf(stderr, "lxc_mainloop: %d\n", ret);
				return -1;
        }

        ret = lxc_mainloop_close(&loop);
        if (ret) {
                fprintf(stderr, "lxc_mainloop_close: %d\n", ret);
                return -1;
        }

        return 0;
}

Compile and run:
$ gcc test.c -o test -I ./src/lxc/ ./src/lxc/liblxc_so-mainloop.o && ./test
cb2
---

diff --git a/src/lxc/mainloop.c b/src/lxc/mainloop.c
index 03d178f9e..6b656d13f 100644
--- a/src/lxc/mainloop.c
+++ b/src/lxc/mainloop.c
@@ -35,40 +35,32 @@ struct mainloop_handler {
 	void *data;
 };
 
+#define MAX_EVENTS 10
+
 int lxc_mainloop(struct lxc_epoll_descr *descr)
 {
-	int i, nfds, triggered;
+	int i, nfds;
 	struct mainloop_handler *handler;
+	struct epoll_event events[MAX_EVENTS];
 
 	for (;;) {
 
-		triggered = 0;
-
-		nfds = epoll_wait(descr->epfd, descr->ev, descr->nfds, -1);
+		nfds = epoll_wait(descr->epfd, events, MAX_EVENTS, -1);
 		if (nfds < 0) {
 			if (errno == EINTR)
 				continue;
 			return -1;
 		}
 
-		for (i = 0; i < descr->nfds; i++) {
-
-			if (!(descr->ev[i].events & EPOLLIN) &&
-			    !(descr->ev[i].events & EPOLLHUP))
-				continue;
-
-			triggered++;
+		for (i = 0; i < nfds; i++) {
 			handler =
-			  (struct mainloop_handler *) descr->ev[i].data.ptr;
+				(struct mainloop_handler *) events[i].data.ptr;
 
 			/* If the handler returns a positive value, exit
 			   the mainloop */
 			if (handler->callback(handler->fd, handler->data, 
 					      descr) > 0)
 				return 0;
-
-			if (triggered == nfds)
-				break;
 		}
 
 		if (!descr->nfds)