[LTP] [PATCH 3/5] syscalls/fanotify09: Read variable length events

[Amir Goldstein <amir73il@gmail.com>]

In preparation of testing events with filename info, teach the
how to read variable length events and parse the name info.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 .../kernel/syscalls/fanotify/fanotify09.c     | 88 +++++++++++++------
 1 file changed, 60 insertions(+), 28 deletions(-)

diff --git a/testcases/kernel/syscalls/fanotify/fanotify09.c b/testcases/kernel/syscalls/fanotify/fanotify09.c
index daeb712d2..7bb901cf3 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify09.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify09.c
@@ -138,42 +138,73 @@ static void cleanup_fanotify_groups(void)
 }
 
 static void event_res(int ttype, int group,
-		      struct fanotify_event_metadata *event)
+		      struct fanotify_event_metadata *event,
+		      const char *filename)
 {
-	int len;
-	sprintf(symlnk, "/proc/self/fd/%d", event->fd);
-	len = readlink(symlnk, fdpath, sizeof(fdpath));
-	if (len < 0)
-		len = 0;
-	fdpath[len] = 0;
-	tst_res(ttype, "group %d got event: mask %llx pid=%u fd=%d path=%s",
+	if (event->fd != FAN_NOFD) {
+		int len = 0;
+		sprintf(symlnk, "/proc/self/fd/%d", event->fd);
+		len = readlink(symlnk, fdpath, sizeof(fdpath));
+		if (len < 0)
+			len = 0;
+		fdpath[len] = 0;
+		filename = fdpath;
+	}
+	tst_res(ttype, "group %d got event: mask %llx pid=%u fd=%d filename=%s",
 		group, (unsigned long long)event->mask,
-		(unsigned)event->pid, event->fd, fdpath);
+		(unsigned)event->pid, event->fd, filename);
+}
+
+static const char *event_filename(struct fanotify_event_metadata *event)
+{
+	struct fanotify_event_info_fid *event_fid;
+	struct file_handle *file_handle;
+	const char *filename, *end;
+
+	if (event->event_len <= FAN_EVENT_METADATA_LEN)
+		return "";
+
+	event_fid = (struct fanotify_event_info_fid *)(event + 1);
+	file_handle = (struct file_handle *)event_fid->handle;
+	filename = (char *)file_handle->f_handle + file_handle->handle_bytes;
+	end = (char *)event_fid + event_fid->hdr.len;
+
+	/* End of event_fid could have name, zero padding, both or none */
+	return (filename == end) ? "" : filename;
 }
 
 static void verify_event(int group, struct fanotify_event_metadata *event,
-			 uint32_t expect)
+			 uint32_t expect, const char *expect_filename)
 {
+	const char *filename = event_filename(event);
+
 	if (event->mask != expect) {
 		tst_res(TFAIL, "group %d got event: mask %llx (expected %llx) "
-			"pid=%u fd=%d", group, (unsigned long long)event->mask,
+			"pid=%u fd=%d filename=%s", group, (unsigned long long)event->mask,
 			(unsigned long long)expect,
-			(unsigned)event->pid, event->fd);
+			(unsigned)event->pid, event->fd, filename);
 	} else if (event->pid != getpid()) {
 		tst_res(TFAIL, "group %d got event: mask %llx pid=%u "
-			"(expected %u) fd=%d", group,
+			"(expected %u) fd=%d filename=%s", group,
 			(unsigned long long)event->mask, (unsigned)event->pid,
-			(unsigned)getpid(), event->fd);
+			(unsigned)getpid(), event->fd, filename);
+	} else if (strcmp(filename, expect_filename)) {
+		tst_res(TFAIL, "group %d got event: mask %llx pid=%u "
+			"fd=%d filename='%s' (expected '%s')", group,
+			(unsigned long long)event->mask, (unsigned)event->pid,
+			event->fd, filename, expect_filename);
 	} else {
-		event_res(TPASS, group, event);
+		event_res(TPASS, group, event, filename);
 	}
+	if (event->fd != FAN_NOFD)
+		SAFE_CLOSE(event->fd);
 }
 
 static void test_fanotify(unsigned int n)
 {
 	int ret, dirfd;
 	unsigned int i;
-	struct fanotify_event_metadata *event, *ev;
+	struct fanotify_event_metadata *event;
 	struct tcase *tc = &tcases[n];
 
 	tst_res(TINFO, "Test #%d: %s", n, tc->tname);
@@ -210,20 +241,21 @@ static void test_fanotify(unsigned int n)
 			ret, tc->nevents * (int)FAN_EVENT_METADATA_LEN);
 	}
 	event = (struct fanotify_event_metadata *)event_buf;
-	verify_event(0, event, FAN_MODIFY);
-	if (tc->ondir)
-		verify_event(0, event + 1, FAN_CLOSE_NOWRITE);
-	if (ret > tc->nevents * (int)FAN_EVENT_METADATA_LEN) {
+	verify_event(0, event, FAN_MODIFY, "");
+	event = FAN_EVENT_NEXT(event, ret);
+	if (tc->ondir) {
+		verify_event(0, event, FAN_CLOSE_NOWRITE, "");
+		event = FAN_EVENT_NEXT(event, ret);
+	}
+	if (ret > 0) {
 		tst_res(TFAIL,
-			"first group got more than %d events (%d > %d)",
-			tc->nevents, ret,
-			tc->nevents * (int)FAN_EVENT_METADATA_LEN);
+			"first group got more than %d events (%d bytes)",
+			tc->nevents, ret);
 	}
 	/* Close all file descriptors of read events */
-	for (ev = event; ret >= (int)FAN_EVENT_METADATA_LEN; ev++) {
-		if (ev->fd != FAN_NOFD)
-			SAFE_CLOSE(ev->fd);
-		ret -= (int)FAN_EVENT_METADATA_LEN;
+	for (; FAN_EVENT_OK(event, ret); FAN_EVENT_NEXT(event, ret)) {
+		if (event->fd != FAN_NOFD)
+			SAFE_CLOSE(event->fd);
 	}
 
 	/*
@@ -233,7 +265,7 @@ static void test_fanotify(unsigned int n)
 	for (i = 1; i < NUM_GROUPS; i++) {
 		ret = read(fd_notify[i], event_buf, FAN_EVENT_METADATA_LEN);
 		if (ret > 0) {
-			event_res(TFAIL, i, event);
+			event_res(TFAIL, i, event, "");
 			if (event->fd != FAN_NOFD)
 				SAFE_CLOSE(event->fd);
 			continue;
-- 
2.25.1