From d23dbe914d68c21f67e2fd75243ae72314295e62 Mon Sep 17 00:00:00 2001
From: cptpcrd <31829097+cptpcrd@users.noreply.github.com>
Date: Tue, 13 Apr 2021 20:52:11 -0400
Subject: [PATCH 1/2] main: tv_sec -> tv_nsec

As specified in utimensat(2), *tv_nsec*, not *tv_sec*, should be set to
UTIME_NOW or UTIME_OMIT.

The way this bug manifests is that if utimensat() is called with
one of the timestamps set to UTIME_OMIT, fuse-overlayfs will
accidentally reset the timestamp to 1073741822, which is 2004-01-10
13:37:02 UTC.
---
 main.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/main.c b/main.c
index 14ac260..6936894 100644
--- a/main.c
+++ b/main.c
@@ -3947,19 +3947,19 @@ ovl_setattr (fuse_req_t req, fuse_ino_t ino, struct stat *attr, int to_set, stru
   l = release_big_lock ();
 
   memset (times, 0, sizeof (times));
-  times[0].tv_sec = UTIME_OMIT;
-  times[1].tv_sec = UTIME_OMIT;
+  times[0].tv_nsec = UTIME_OMIT;
+  times[1].tv_nsec = UTIME_OMIT;
   if (to_set & FUSE_SET_ATTR_ATIME)
     times[0] = attr->st_atim;
   else if (to_set & FUSE_SET_ATTR_ATIME_NOW)
-    times[0].tv_sec = UTIME_NOW;
+    times[0].tv_nsec = UTIME_NOW;
 
   if (to_set & FUSE_SET_ATTR_MTIME)
     times[1] = attr->st_mtim;
   else if (to_set & FUSE_SET_ATTR_MTIME_NOW)
-    times[1].tv_sec = UTIME_NOW;
+    times[1].tv_nsec = UTIME_NOW;
 
-  if (times[0].tv_sec != UTIME_OMIT || times[1].tv_sec != UTIME_OMIT)
+  if (times[0].tv_nsec != UTIME_OMIT || times[1].tv_nsec != UTIME_OMIT)
     {
       if (fd >= 0)
         ret = futimens (fd, times);

From defd480c0ef020f83338a2214b80efa0d29bdc70 Mon Sep 17 00:00:00 2001
From: cptpcrd <31829097+cptpcrd@users.noreply.github.com>
Date: Tue, 13 Apr 2021 20:58:48 -0400
Subject: [PATCH 2/2] main: improve UTIME_NOW special-casing

FUSE never passes FUSE_SET_ATTR_ATIME_NOW without also passing
FUSE_SET_ATTR_ATIME. Since FUSE_SET_ATTR_ATIME_NOW was only checked if
FUSE_SET_ATTR_ATIME was not set, it would never be triggered.

Note that this is an *improvement*, not a *fix*, because FUSE always
passes the current time in st_atim whenever it sets
FUSE_SET_ATTR_ATIME_NOW. As a result, the previous code works properly,
but it does so differently from the way it was intended to.

(All of the above descriptions of st_atim handling also applies to
st_mtim.)
---
 main.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/main.c b/main.c
index 6936894..4be2c9e 100644
--- a/main.c
+++ b/main.c
@@ -3950,14 +3950,18 @@ ovl_setattr (fuse_req_t req, fuse_ino_t ino, struct stat *attr, int to_set, stru
   times[0].tv_nsec = UTIME_OMIT;
   times[1].tv_nsec = UTIME_OMIT;
   if (to_set & FUSE_SET_ATTR_ATIME)
-    times[0] = attr->st_atim;
-  else if (to_set & FUSE_SET_ATTR_ATIME_NOW)
-    times[0].tv_nsec = UTIME_NOW;
+    {
+      times[0] = attr->st_atim;
+      if (to_set & FUSE_SET_ATTR_ATIME_NOW)
+        times[0].tv_nsec = UTIME_NOW;
+    }
 
   if (to_set & FUSE_SET_ATTR_MTIME)
-    times[1] = attr->st_mtim;
-  else if (to_set & FUSE_SET_ATTR_MTIME_NOW)
-    times[1].tv_nsec = UTIME_NOW;
+    {
+      times[1] = attr->st_mtim;
+      if (to_set & FUSE_SET_ATTR_MTIME_NOW)
+        times[1].tv_nsec = UTIME_NOW;
+    }
 
   if (times[0].tv_nsec != UTIME_OMIT || times[1].tv_nsec != UTIME_OMIT)
     {