fuse: diagnostic FLUSH interrupt

We add dummy interrupt handling for the FLUSH
fuse message. It can be enabled by the
"--fuse-flush-handle-interrupt" hidden command line
option, or "-ofuse-flush-handle-interrupt=yes"
mount option.

It serves no other than diagnostic & demonstational
purposes -- to exercise the interrupt handling framework
a bit and to give an usage example.

Documentation is also provided that showcases interrupt
handling via FLUSH.

Change-Id: I522f1e798501d06b74ac3592a5f73c1ab0590c60
updates: #465
Signed-off-by: Csaba Henk <csaba@redhat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/tests/features/open_and_sleep.c b/tests/features/open_and_sleep.c
new file mode 100644
index 00000000000..7d0e22a2503
--- /dev/null
+++ b/tests/features/open_and_sleep.c
@@ -0,0 +1,27 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+int
+main(int argc, char **argv)
+{
+    pid_t pid;
+    int fd;
+
+    if (argc >= 2) {
+        fd = open(argv[1], O_RDWR | O_CREAT, 0644);
+        if (fd == -1) {
+            fprintf(stderr, "cannot open/create %s\n", argv[1]);
+            return 1;
+        }
+    }
+
+    pid = getpid();
+    printf("%d\n", pid);
+    fflush(stdout);
+
+    for (;;)
+        sleep(1);
+
+    return 0;
+}