Opens a file for writing in the preferred directory for temporary files (as returned by g_get_tmp_dir()).
tmpl should be a string in the GLib file name encoding containing a sequence of six 'X' characters, as the parameter to g_mkstemp(). However, unlike these functions, the template should only be a basename, no directory components are allowed. If template is NULL, a default template is used.
Note that in contrast to g_mkstemp() (and mkstemp()) tmpl is not modified, and might thus be a read-only literal string.
The actual name used is returned in name_used if non-NULL. This string should be freed with g_free() when not needed any longer. The returned name is in the GLib file name encoding.
| A file handle (as from open()) to the file opened for reading and writing. The file is opened in binary mode on platforms where there is a difference. The file handle should be closed with close(). In case of errors, -1 is returned and error will be set. |