Function svn_io_set_file_read_write 

pub unsafe extern "C" fn svn_io_set_file_read_write(
    path: *const c_char,
    ignore_enoent: svn_boolean_t,
    pool: *mut apr_pool_t,
) -> *mut svn_error_t

Make a file as writable as the operating system allows. @a path is the utf8-encoded path to the file. If @a ignore_enoent is @c TRUE, don’t fail if the target file doesn’t exist. @warning On Unix this function will do the equivalent of chmod a+w path. If this is not what you want you should not use this function, but rather use apr_file_perms_set().

If @a path is a symlink, do nothing.

@note If @a path is a directory, act on it as though it were a file, as described above, but note that you probably don’t want to call this function on directories. We have left it effective on directories for compatibility reasons, but as its name implies, it should be used only for files.