fs-util: add new CHASE_TRAIL_SLASH flag for chase_symlinks()

This rearranges chase_symlinks() a bit: if no special flags are
specified it will now revert to behaviour before
b12d25a8d631af00b200e7aa9dbba6ba4a4a59ff. However, if the new
CHASE_TRAIL_SLASH flag is specified it will follow the behaviour
introduced by that commit.

I wasn't sure which one to make the beaviour that requires specification
of a flag to enable. I opted to make the "append trailing slash"
behaviour the one to enable by a flag, following the thinking that the
function should primarily be used to generate a normalized path, and I
am pretty sure a path without trailing slash is the more "normalized"
one, as the trailing slash is not really a part of it, but merely a
"decorator" that tells various system calls to generate ENOTDIR if the
path doesn't refer to a path.

Or to say this differently: if the slash was part of normalization then
we really should add it in all cases when the final path is a directory,
not just when the user originally specified it.

Fixes: #8544
Replaces: #8545

1 files changed, 7 insertions, 4 deletions

diff --git a/src/basic/mount-util.c b/src/basic/mount-util.c
index b74d51a26..751702d33 100644
--- a/src/basic/mount-util.c
+++ b/src/basic/mount-util.c
@@ -81,8 +81,10 @@ int name_to_handle_at_loop(
 
                 if (name_to_handle_at(fd, path, h, &mnt_id, flags) >= 0) {
 
-                        if (ret_handle)
-                                *ret_handle = TAKE_PTR(h);
+                        if (ret_handle) {
+                                *ret_handle = h;
+                                h = NULL;
+                        }
 
                         if (ret_mnt_id)
                                 *ret_mnt_id = mnt_id;
@@ -294,7 +296,7 @@ int path_is_mount_point(const char *t, const char *root, int flags) {
          * /bin -> /usr/bin/ and /usr is a mount point, then the parent that we
          * look at needs to be /usr, not /. */
         if (flags & AT_SYMLINK_FOLLOW) {
-                r = chase_symlinks(t, root, 0, &canonical);
+                r = chase_symlinks(t, root, CHASE_TRAIL_SLASH, &canonical);
                 if (r < 0)
                         return r;
 
@@ -954,7 +956,8 @@ int mount_option_mangle(
         }
 
         *ret_mount_flags = mount_flags;
-        *ret_remaining_options = TAKE_PTR(ret);
+        *ret_remaining_options = ret;
+        ret = NULL;
 
         return 0;
 }