From: Nadav Har'El <n...@scylladb.com>
Committer: Nadav Har'El <n...@scylladb.com>
Branch: master
epoll: test polling of /proc file
This test reproduces issue #971, and verifies that we fixed it in the
previous patches.
It epolls a file from /proc - Linux doesn't allow epolling an ext4 file,
but does allow to do that on /proc files. It then verifies that epoll
doesn't crash even with unorthodox request bits (as happened in #971).
The test can now be run on both Linux and OSv, and succeds on both.
Signed-off-by: Nadav Har'El <n...@scylladb.com>
---
diff --git a/tests/tst-epoll.cc b/tests/tst-epoll.cc
--- a/tests/tst-epoll.cc
+++ b/tests/tst-epoll.cc
@@ -9,7 +9,12 @@
#include <sys/poll.h>
#include <unistd.h>
#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#ifdef __OSV__
#include <osv/latch.hh>
+#endif
#include <string>
#include <iostream>
@@ -79,6 +84,38 @@ static void test_epolloneshot()
report(r == 0, "epoll_ctl DEL");
}
+// Test epoll on a VFS file. It's not a very interesting case, and Linux
+// doesn't even support epoll on disk filesystems (like ext4), but it
+// turns out that on the /proc filesystem, it does work on Linux. In OSv,
+// polling a VFS file (disk file or /proc file) uses the trivial
poll_no_poll()
+// which previously (see issue #971) caused crashes if it got unexpected
+// request flags.
+static void test_epoll_file()
+{
+ constexpr int MAXEVENTS = 1024;
+ struct epoll_event events[MAXEVENTS];
+
+ int ep = epoll_create(1);
+ report(ep >= 0, "epoll_create");
+
+ int fd = open("/proc/sys/kernel/hostname", O_RDONLY);
+ report(fd >= 0, "open file");
+
+ struct epoll_event event;
+ // Some extra flags, which caused issue #971
+ event.events = EPOLLIN | EPOLLRDHUP | EPOLLONESHOT | EPOLLET;
+ event.data.u32 = 123;
+
+ int r = epoll_ctl(ep, EPOLL_CTL_ADD, fd, &event);
+ report(r == 0, "epoll_ctl ADD");
+ r = epoll_wait(ep, events, MAXEVENTS, 0);
+ report(r == 1, "epoll_wait");
+
+ r = epoll_ctl(ep, EPOLL_CTL_DEL, fd, &event);
+ report(r == 0, "epoll_ctl DEL");
+ close(fd);
+}
+
int main(int ac, char** av)
{
int ep = epoll_create(1);
@@ -154,6 +191,7 @@ int main(int ac, char** av)
"epoll timeout");
////////////////////////////////////////////////////////////////////////////
+#ifdef __OSV__
event.events = EPOLLIN | EPOLLET;
r = epoll_ctl(ep, EPOLL_CTL_MOD, s[0], &event);
report(r == 0, "epoll_ctl_mod");
@@ -174,6 +212,7 @@ int main(int ac, char** av)
r = epoll_ctl(ep, EPOLL_CTL_MOD, s[0], &event);
report(r == 0, "epoll_ctl_mod");
t2.join();
+#endif
////////////////////////////////////////////////////////////////////////////
// Test EPOLLET (edge-triggered event notification)
@@ -229,6 +268,7 @@ int main(int ac, char** av)
report(r == -1 && errno == EEXIST, "EEXIST");
test_epolloneshot();
+ test_epoll_file();
std::cout << "SUMMARY: " << tests << ", " << fails << " failures\n";
return !!fails;
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