Hi,

I would like to request if it would make sense to provide a function
equivalent to g_file_set_contents() but which accepts a file mode to
be passed to mkstemp_full(), instead of the fixed 0666 used currently.

At the moment if one wants to use g_file_set_contents() to create a
file with more restricted permission it's necessary to use umask() but
this has some disadvantages, like not being thread-safe and being
ineffective in case the parent directory has a default ACL set (since
the default ACL overrides the umask).

For example, in NetworkManager we call umask() before
g_file_set_contents() to create the connection files (restricted to
root), but we received reports that this doesn't work well with ACLs;
in my opinion it would be really helpful to have in GLib a function
like:

 gboolean
 g_file_set_contents_mode (const gchar *filename,
                           const gchar *contents,
                           gssize length,
                           mode_t mode
                           GError **error)

Any thoughts?