module-gsettings: new module to store configuration using gsettings

GConf is deprecated, and distributions are removing it. paprefs depends
on GConf, so in order to avoid paprefs getting removed as well, paprefs
has to be changed to use something else than GConf. GSettings is the
easiest alternative to migrate to, although it has the same problems
that GConf had: no support for system mode or networking.

This patch takes the non-GConf specific code from module-gconf and puts
it in stdin-util.[ch], which is then reused by module-gsettings.
module-gsettings is designed to be very similar to module-gconf.

Migration is expected to happen as follows: Distributions update
PulseAudio and paprefs at the same time, or first PulseAudio and then
paprefs. paprefs depends on module-gsettings, and module-gsettings
conflicts with module-gconf. Therefore module-gconf gets automatically
removed during the paprefs update. After the update an old PulseAudio is
likely to be running with module-gconf loaded. If the user tries to use
paprefs during this period, whatever the user does in paprefs won't have
any effect until PulseAudio is restarted (probably by a reboot or
relogin). This is not ideal, but will have to do.

When module-gsettings is loaded, it runs gsettings-data-convert
(implemented in a later patch). That will copy the settings from GConf
to GSettings. If gsettings-data-convert is not available (it's part of
GConf, so it may have already been uninstalled), then any previous
paprefs settings are lost.

src/modules/stdin-util.h

@@ -0,0 +1,89 @@
+#ifndef foostdinutilhfoo
+#define foostdinutilhfoo
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2009 Lennart Poettering
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <errno.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <pulsecore/module.h>
+#include <pulsecore/typedefs.h>
+
+#define MAX_MODULES 10
+#define BUF_MAX 2048
+
+struct userdata;
+
+struct module_item {
+    char *name;
+    char *args;
+    uint32_t index;
+};
+
+struct pa_module_info {
+    struct userdata *userdata;
+    char *name;
+
+    struct module_item items[MAX_MODULES];
+    unsigned n_items;
+};
+
+struct userdata {
+    pa_core *core;
+    pa_module *module;
+
+    pa_hashmap *module_infos;
+
+    pid_t pid;
+
+    int fd;
+    int fd_type;
+    pa_io_event *io_event;
+
+    char buf[BUF_MAX];
+    size_t buf_fill;
+};
+
+int fill_buf(struct userdata *u);
+int read_byte(struct userdata *u);
+char *read_string(struct userdata *u);
+void unload_one_module(struct pa_module_info *m, unsigned i);
+void unload_all_modules(struct pa_module_info *m);
+void load_module(
+  struct pa_module_info *m,
+  unsigned i,
+  const char *name,
+  const char *args,
+  bool is_new);
+void module_info_free(void *p);
+int handle_event(struct userdata *u);
+void io_event_cb(
+  pa_mainloop_api*a,
+  pa_io_event* e,
+  int fd,
+  pa_io_event_flags_t events,
+  void *userdata);
+
+#endif