trans: fix the creation of files in fakeroot

Previously, fakeroot failed to create files in certain circumstances,
e. g. assuming /tmp is a tmpfs and /tmp/some_file does not exist:

% cd /tmp && fakeroot-hurd /bin/sh -c ':>/tmp/some_file'
/bin/sh: 1: cannot create /tmp/some_file: Is a directory

Fix this by sanitizing the flags value not to contain O_WRITE if we're
not at the last path component.

* trans/fakeroot.c (netfs_S_dir_lookup): Strip O_WRITE from flags when
  looking up all but the last path component.

1 files changed, 4 insertions, 0 deletions

diff --git a/trans/fakeroot.c b/trans/fakeroot.c
index 679e4765..b6938dce 100644
--- a/trans/fakeroot.c
+++ b/trans/fakeroot.c
@@ -307,6 +307,10 @@ netfs_S_dir_lookup (struct protid *diruser,
 	      /* We already know about this node.  */
 	      mach_port_deallocate (mach_task_self (), idport);
 	      pthread_mutex_lock (&np->lock);
+	      if (retry_name[0] != '\0')
+		/* This was not the last component, remove O_WRITE to
+		   avoid opening directories with it.  */
+		flags &= ~O_WRITE;
 	      err = check_openmodes (np->nn, (flags & (O_RDWR|O_EXEC)), file);
 	      if (!err)
 		netfs_nref (np);