client: splitted client.c into several pieces

Makefile.am

@@ -204,6 +204,15 @@ src_mpd_SOURCES = \
 	src/filter_registry.c \
 	src/update.c \
 	src/client.c \
+	src/client_event.c \
+	src/client_expire.c \
+	src/client_global.c \
+	src/client_idle.c \
+	src/client_list.c \
+	src/client_new.c \
+	src/client_process.c \
+	src/client_read.c \
+	src/client_write.c \
 	src/listen.c \
 	src/log.c \
 	src/ls.c \

src/client_event.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+#include "main.h"
+
+#include <assert.h>
+
+static gboolean
+client_out_event(G_GNUC_UNUSED GIOChannel *source, GIOCondition condition,
+		 gpointer data)
+{
+	struct client *client = data;
+
+	assert(!client_is_expired(client));
+
+	if (condition != G_IO_OUT) {
+		client_set_expired(client);
+		return false;
+	}
+
+	client_write_deferred(client);
+
+	if (client_is_expired(client)) {
+		client_close(client);
+		return false;
+	}
+
+	g_timer_start(client->last_activity);
+
+	if (g_queue_is_empty(client->deferred_send)) {
+		/* done sending deferred buffers exist: schedule
+		   read */
+		client->source_id = g_io_add_watch(client->channel,
+						   G_IO_IN|G_IO_ERR|G_IO_HUP,
+						   client_in_event, client);
+		return false;
+	}
+
+	/* write more */
+	return true;
+}
+
+gboolean
+client_in_event(G_GNUC_UNUSED GIOChannel *source, GIOCondition condition,
+		gpointer data)
+{
+	struct client *client = data;
+	enum command_return ret;
+
+	assert(!client_is_expired(client));
+
+	if (condition != G_IO_IN) {
+		client_set_expired(client);
+		return false;
+	}
+
+	g_timer_start(client->last_activity);
+
+	ret = client_read(client);
+	switch (ret) {
+	case COMMAND_RETURN_OK:
+	case COMMAND_RETURN_ERROR:
+		break;
+
+	case COMMAND_RETURN_KILL:
+		client_close(client);
+		g_main_loop_quit(main_loop);
+		return false;
+
+	case COMMAND_RETURN_CLOSE:
+		client_close(client);
+		return false;
+	}
+
+	if (client_is_expired(client)) {
+		client_close(client);
+		return false;
+	}
+
+	if (!g_queue_is_empty(client->deferred_send)) {
+		/* deferred buffers exist: schedule write */
+		client->source_id = g_io_add_watch(client->channel,
+						   G_IO_OUT|G_IO_ERR|G_IO_HUP,
+						   client_out_event, client);
+		return false;
+	}
+
+	/* read more */
+	return true;
+}

src/client_expire.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+
+static guint expire_source_id;
+
+void
+client_set_expired(struct client *client)
+{
+	if (!client_is_expired(client))
+		client_schedule_expire();
+
+	if (client->source_id != 0) {
+		g_source_remove(client->source_id);
+		client->source_id = 0;
+	}
+
+	if (client->channel != NULL) {
+		g_io_channel_unref(client->channel);
+		client->channel = NULL;
+	}
+}
+
+static void
+client_check_expired_callback(gpointer data, G_GNUC_UNUSED gpointer user_data)
+{
+	struct client *client = data;
+
+	if (client_is_expired(client)) {
+		g_debug("[%u] expired", client->num);
+		client_close(client);
+	} else if (!client->idle_waiting && /* idle clients
+					       never expire */
+		   (int)g_timer_elapsed(client->last_activity, NULL) >
+		   client_timeout) {
+		g_debug("[%u] timeout", client->num);
+		client_close(client);
+	}
+}
+
+static void
+client_manager_expire(void)
+{
+	client_list_foreach(client_check_expired_callback, NULL);
+}
+
+/**
+ * An idle event which calls client_manager_expire().
+ */
+static gboolean
+client_manager_expire_event(G_GNUC_UNUSED gpointer data)
+{
+	expire_source_id = 0;
+	client_manager_expire();
+	return false;
+}
+
+void
+client_schedule_expire(void)
+{
+	if (expire_source_id == 0)
+		/* delayed deletion */
+		expire_source_id = g_idle_add(client_manager_expire_event,
+					      NULL);
+}
+
+void
+client_deinit_expire(void)
+{
+	if (expire_source_id != 0)
+		g_source_remove(expire_source_id);
+}

src/client_global.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+#include "conf.h"
+
+#include <assert.h>
+
+#define CLIENT_TIMEOUT_DEFAULT			(60)
+#define CLIENT_MAX_CONNECTIONS_DEFAULT		(10)
+#define CLIENT_MAX_COMMAND_LIST_DEFAULT		(2048*1024)
+#define CLIENT_MAX_OUTPUT_BUFFER_SIZE_DEFAULT	(8192*1024)
+
+/* set this to zero to indicate we have no possible clients */
+unsigned int client_max_connections;
+int client_timeout;
+size_t client_max_command_list_size;
+size_t client_max_output_buffer_size;
+
+void client_manager_init(void)
+{
+	client_timeout = config_get_positive(CONF_CONN_TIMEOUT,
+					     CLIENT_TIMEOUT_DEFAULT);
+	client_max_connections =
+		config_get_positive(CONF_MAX_CONN,
+				    CLIENT_MAX_CONNECTIONS_DEFAULT);
+	client_max_command_list_size =
+		config_get_positive(CONF_MAX_COMMAND_LIST_SIZE,
+				    CLIENT_MAX_COMMAND_LIST_DEFAULT / 1024)
+		* 1024;
+
+	client_max_output_buffer_size =
+		config_get_positive(CONF_MAX_OUTPUT_BUFFER_SIZE,
+				    CLIENT_MAX_OUTPUT_BUFFER_SIZE_DEFAULT / 1024)
+		* 1024;
+}
+
+static void client_close_all(void)
+{
+	while (!client_list_is_empty()) {
+		struct client *client = client_list_get_first();
+
+		client_close(client);
+	}
+
+	assert(client_list_is_empty());
+}
+
+void client_manager_deinit(void)
+{
+	client_close_all();
+
+	client_max_connections = 0;
+
+	client_deinit_expire();
+}

src/client_idle.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+#include "idle.h"
+
+#include <assert.h>
+
+/**
+ * Send "idle" response to this client.
+ */
+static void
+client_idle_notify(struct client *client)
+{
+	unsigned flags, i;
+	const char *const* idle_names;
+
+	assert(client->idle_waiting);
+	assert(client->idle_flags != 0);
+
+	flags = client->idle_flags;
+	client->idle_flags = 0;
+	client->idle_waiting = false;
+
+	idle_names = idle_get_names();
+	for (i = 0; idle_names[i]; ++i) {
+		if (flags & (1 << i) & client->idle_subscriptions)
+			client_printf(client, "changed: %s\n",
+				      idle_names[i]);
+	}
+
+	client_puts(client, "OK\n");
+	g_timer_start(client->last_activity);
+}
+
+static void
+client_idle_callback(gpointer data, gpointer user_data)
+{
+	struct client *client = data;
+	unsigned flags = GPOINTER_TO_UINT(user_data);
+
+	if (client_is_expired(client))
+		return;
+
+	client->idle_flags |= flags;
+	if (client->idle_waiting
+	    && (client->idle_flags & client->idle_subscriptions)) {
+		client_idle_notify(client);
+		client_write_output(client);
+	}
+}
+
+void client_manager_idle_add(unsigned flags)
+{
+	assert(flags != 0);
+
+	client_list_foreach(client_idle_callback, GUINT_TO_POINTER(flags));
+}
+
+bool client_idle_wait(struct client *client, unsigned flags)
+{
+	assert(!client->idle_waiting);
+
+	client->idle_waiting = true;
+	client->idle_subscriptions = flags;
+
+	if (client->idle_flags & client->idle_subscriptions) {
+		client_idle_notify(client);
+		return true;
+	} else
+		return false;
+}

src/client_internal.h

@@ -21,6 +21,10 @@
 #define MPD_CLIENT_INTERNAL_H
 
 #include "client.h"
+#include "command.h"
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "client"
 
 struct deferred_buffer {
 	size_t size;
@@ -65,4 +69,77 @@ struct client {
 	unsigned idle_subscriptions;
 };
 
+extern unsigned int client_max_connections;
+extern int client_timeout;
+extern size_t client_max_command_list_size;
+extern size_t client_max_output_buffer_size;
+
+bool
+client_list_is_empty(void);
+
+bool
+client_list_is_full(void);
+
+struct client *
+client_list_get_first(void);
+
+void
+client_list_add(struct client *client);
+
+void
+client_list_foreach(GFunc func, gpointer user_data);
+
+void
+client_list_remove(struct client *client);
+
+void
+client_close(struct client *client);
+
+static inline void
+new_cmd_list_ptr(struct client *client, const char *s)
+{
+	client->cmd_list = g_slist_prepend(client->cmd_list, g_strdup(s));
+}
+
+static inline void
+free_cmd_list(GSList *list)
+{
+	for (GSList *tmp = list; tmp != NULL; tmp = g_slist_next(tmp))
+		g_free(tmp->data);
+
+	g_slist_free(list);
+}
+
+void
+client_set_expired(struct client *client);
+
+/**
+ * Schedule an "expired" check for all clients: permanently delete
+ * clients which have been set "expired" with client_set_expired().
+ */
+void
+client_schedule_expire(void);
+
+/**
+ * Removes a scheduled "expired" check.
+ */
+void
+client_deinit_expire(void);
+
+enum command_return
+client_read(struct client *client);
+
+enum command_return
+client_process_line(struct client *client, char *line);
+
+void
+client_write_deferred(struct client *client);
+
+void
+client_write_output(struct client *client);
+
+gboolean
+client_in_event(GIOChannel *source, GIOCondition condition,
+		gpointer data);
+
 #endif

src/client_list.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+
+#include <assert.h>
+
+static GList *clients;
+static unsigned num_clients;
+
+bool
+client_list_is_empty(void)
+{
+	return num_clients == 0;
+}
+
+bool
+client_list_is_full(void)
+{
+	return num_clients >= client_max_connections;
+}
+
+struct client *
+client_list_get_first(void)
+{
+	assert(clients != NULL);
+
+	return clients->data;
+}
+
+void
+client_list_add(struct client *client)
+{
+	clients = g_list_prepend(clients, client);
+	++num_clients;
+}
+
+void
+client_list_foreach(GFunc func, gpointer user_data)
+{
+	g_list_foreach(clients, func, user_data);
+}
+
+void
+client_list_remove(struct client *client)
+{
+	assert(num_clients > 0);
+	assert(clients != NULL);
+
+	clients = g_list_remove(clients, client);
+	--num_clients;
+}

src/client_new.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+#include "fifo_buffer.h"
+#include "socket_util.h"
+#include "permission.h"
+#include "config.h"
+
+#include <assert.h>
+#include <unistd.h>
+
+#define LOG_LEVEL_SECURE G_LOG_LEVEL_INFO
+
+static const char GREETING[] = "OK MPD " PROTOCOL_VERSION "\n";
+
+void client_new(int fd, const struct sockaddr *sa, size_t sa_length, int uid)
+{
+	static unsigned int next_client_num;
+	struct client *client;
+	char *remote;
+
+	assert(fd >= 0);
+
+	if (client_list_is_full()) {
+		g_warning("Max Connections Reached!");
+		close(fd);
+		return;
+	}
+
+	client = g_new0(struct client, 1);
+
+#ifndef G_OS_WIN32
+	client->channel = g_io_channel_unix_new(fd);
+#else
+	client->channel = g_io_channel_win32_new_socket(fd);
+#endif
+	/* GLib is responsible for closing the file descriptor */
+	g_io_channel_set_close_on_unref(client->channel, true);
+	/* NULL encoding means the stream is binary safe; the MPD
+	   protocol is UTF-8 only, but we are doing this call anyway
+	   to prevent GLib from messing around with the stream */
+	g_io_channel_set_encoding(client->channel, NULL, NULL);
+	/* we prefer to do buffering */
+	g_io_channel_set_buffered(client->channel, false);
+
+	client->source_id = g_io_add_watch(client->channel,
+					   G_IO_IN|G_IO_ERR|G_IO_HUP,
+					   client_in_event, client);
+
+	client->input = fifo_buffer_new(4096);
+
+	client->permission = getDefaultPermissions();
+	client->uid = uid;
+
+	client->last_activity = g_timer_new();
+
+	client->cmd_list = NULL;
+	client->cmd_list_OK = -1;
+	client->cmd_list_size = 0;
+
+	client->deferred_send = g_queue_new();
+	client->deferred_bytes = 0;
+	client->num = next_client_num++;
+
+	client->send_buf_used = 0;
+
+	(void)write(fd, GREETING, sizeof(GREETING) - 1);
+
+	client_list_add(client);
+
+	remote = sockaddr_to_string(sa, sa_length, NULL);
+	g_log(G_LOG_DOMAIN, LOG_LEVEL_SECURE,
+	      "[%u] opened from %s", client->num, remote);
+	g_free(remote);
+}
+
+static void
+deferred_buffer_free(gpointer data, G_GNUC_UNUSED gpointer user_data)
+{
+	struct deferred_buffer *buffer = data;
+	g_free(buffer);
+}
+
+void
+client_close(struct client *client)
+{
+	client_list_remove(client);
+
+	client_set_expired(client);
+
+	g_timer_destroy(client->last_activity);
+
+	if (client->cmd_list) {
+		free_cmd_list(client->cmd_list);
+		client->cmd_list = NULL;
+	}
+
+	g_queue_foreach(client->deferred_send, deferred_buffer_free, NULL);
+	g_queue_free(client->deferred_send);
+
+	fifo_buffer_free(client->input);
+
+	g_log(G_LOG_DOMAIN, LOG_LEVEL_SECURE,
+	      "[%u] closed", client->num);
+	g_free(client);
+}

src/client_process.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+
+#include <string.h>
+
+#define CLIENT_LIST_MODE_BEGIN "command_list_begin"
+#define CLIENT_LIST_OK_MODE_BEGIN "command_list_ok_begin"
+#define CLIENT_LIST_MODE_END "command_list_end"
+
+enum command_return
+client_process_line(struct client *client, char *line)
+{
+	enum command_return ret;
+
+	if (strcmp(line, "noidle") == 0) {
+		if (client->idle_waiting) {
+			/* send empty idle response and leave idle mode */
+			client->idle_waiting = false;
+			command_success(client);
+			client_write_output(client);
+		}
+
+		/* do nothing if the client wasn't idling: the client
+		   has already received the full idle response from
+		   client_idle_notify(), which he can now evaluate */
+
+		return COMMAND_RETURN_OK;
+	} else if (client->idle_waiting) {
+		/* during idle mode, clients must not send anything
+		   except "noidle" */
+		g_warning("[%u] command \"%s\" during idle",
+			  client->num, line);
+		return COMMAND_RETURN_CLOSE;
+	}
+
+	if (client->cmd_list_OK >= 0) {
+		if (strcmp(line, CLIENT_LIST_MODE_END) == 0) {
+			g_debug("[%u] process command list",
+				client->num);
+
+			/* for scalability reasons, we have prepended
+			   each new command; now we have to reverse it
+			   to restore the correct order */
+			client->cmd_list = g_slist_reverse(client->cmd_list);
+
+			ret = command_process_list(client,
+						   client->cmd_list_OK,
+						   client->cmd_list);
+			g_debug("[%u] process command "
+				"list returned %i", client->num, ret);
+
+			if (ret == COMMAND_RETURN_CLOSE ||
+			    client_is_expired(client))
+				return COMMAND_RETURN_CLOSE;
+
+			if (ret == COMMAND_RETURN_OK)
+				command_success(client);
+
+			client_write_output(client);
+			free_cmd_list(client->cmd_list);
+			client->cmd_list = NULL;
+			client->cmd_list_OK = -1;
+		} else {
+			size_t len = strlen(line) + 1;
+			client->cmd_list_size += len;
+			if (client->cmd_list_size >
+			    client_max_command_list_size) {
+				g_warning("[%u] command list size (%lu) "
+					  "is larger than the max (%lu)",
+					  client->num,
+					  (unsigned long)client->cmd_list_size,
+					  (unsigned long)client_max_command_list_size);
+				return COMMAND_RETURN_CLOSE;
+			}
+
+			new_cmd_list_ptr(client, line);
+			ret = COMMAND_RETURN_OK;
+		}
+	} else {
+		if (strcmp(line, CLIENT_LIST_MODE_BEGIN) == 0) {
+			client->cmd_list_OK = 0;
+			ret = COMMAND_RETURN_OK;
+		} else if (strcmp(line, CLIENT_LIST_OK_MODE_BEGIN) == 0) {
+			client->cmd_list_OK = 1;
+			ret = COMMAND_RETURN_OK;
+		} else {
+			g_debug("[%u] process command \"%s\"",
+				client->num, line);
+			ret = command_process(client, line);
+			g_debug("[%u] command returned %i",
+				client->num, ret);
+
+			if (ret == COMMAND_RETURN_CLOSE ||
+			    client_is_expired(client))
+				return COMMAND_RETURN_CLOSE;
+
+			if (ret == COMMAND_RETURN_OK)
+				command_success(client);
+
+			client_write_output(client);
+		}
+	}
+
+	return ret;
+}

src/client_read.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+#include "fifo_buffer.h"
+
+#include <assert.h>
+#include <string.h>
+
+static char *
+client_read_line(struct client *client)
+{
+	const char *p, *newline;
+	size_t length;
+	char *line;
+
+	p = fifo_buffer_read(client->input, &length);
+	if (p == NULL)
+		return NULL;
+
+	newline = memchr(p, '\n', length);
+	if (newline == NULL)
+		return NULL;
+
+	line = g_strndup(p, newline - p);
+	fifo_buffer_consume(client->input, newline - p + 1);
+
+	return g_strchomp(line);
+}
+
+static enum command_return
+client_input_received(struct client *client, size_t bytesRead)
+{
+	char *line;
+
+	fifo_buffer_append(client->input, bytesRead);
+
+	/* process all lines */
+
+	while ((line = client_read_line(client)) != NULL) {
+		enum command_return ret = client_process_line(client, line);
+		g_free(line);
+
+		if (ret == COMMAND_RETURN_KILL ||
+		    ret == COMMAND_RETURN_CLOSE)
+			return ret;
+		if (client_is_expired(client))
+			return COMMAND_RETURN_CLOSE;
+	}
+
+	return COMMAND_RETURN_OK;
+}
+
+enum command_return
+client_read(struct client *client)
+{
+	char *p;
+	size_t max_length;
+	GError *error = NULL;
+	GIOStatus status;
+	gsize bytes_read;
+
+	assert(client != NULL);
+	assert(client->channel != NULL);
+
+	p = fifo_buffer_write(client->input, &max_length);
+	if (p == NULL) {
+		g_warning("[%u] buffer overflow", client->num);
+		return COMMAND_RETURN_CLOSE;
+	}
+
+	status = g_io_channel_read_chars(client->channel, p, max_length,
+					 &bytes_read, &error);
+	switch (status) {
+	case G_IO_STATUS_NORMAL:
+		return client_input_received(client, bytes_read);
+
+	case G_IO_STATUS_AGAIN:
+		/* try again later, after select() */
+		return COMMAND_RETURN_OK;
+
+	case G_IO_STATUS_EOF:
+		/* peer disconnected */
+		return COMMAND_RETURN_CLOSE;
+
+	case G_IO_STATUS_ERROR:
+		/* I/O error */
+		g_warning("failed to read from client %d: %s",
+			  client->num, error->message);
+		g_error_free(error);
+		return COMMAND_RETURN_CLOSE;
+	}
+
+	/* unreachable */
+	return COMMAND_RETURN_CLOSE;
+}

src/client_write.c

+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "client_internal.h"
+
+#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+
+static size_t
+client_write_deferred_buffer(struct client *client,
+			     const struct deferred_buffer *buffer)
+{
+	GError *error = NULL;
+	GIOStatus status;
+	gsize bytes_written;
+
+	assert(client != NULL);
+	assert(client->channel != NULL);
+	assert(buffer != NULL);
+
+	status = g_io_channel_write_chars
+		(client->channel, buffer->data, buffer->size,
+		 &bytes_written, &error);
+	switch (status) {
+	case G_IO_STATUS_NORMAL:
+		return bytes_written;
+
+	case G_IO_STATUS_AGAIN:
+		return 0;
+
+	case G_IO_STATUS_EOF:
+		/* client has disconnected */
+
+		client_set_expired(client);
+		return 0;
+
+	case G_IO_STATUS_ERROR:
+		/* I/O error */
+
+		client_set_expired(client);
+		g_warning("failed to flush buffer for %i: %s",
+			  client->num, error->message);
+		g_error_free(error);
+		return 0;
+	}
+
+	/* unreachable */
+	return 0;
+}
+
+void
+client_write_deferred(struct client *client)
+{
+	size_t ret;
+
+	while (!g_queue_is_empty(client->deferred_send)) {
+		struct deferred_buffer *buf =
+			g_queue_peek_head(client->deferred_send);
+
+		assert(buf->size > 0);
+		assert(buf->size <= client->deferred_bytes);
+
+		ret = client_write_deferred_buffer(client, buf);
+		if (ret == 0)
+			break;
+
+		if (ret < buf->size) {
+			assert(client->deferred_bytes >= (size_t)ret);
+			client->deferred_bytes -= ret;
+			buf->size -= ret;
+			memmove(buf->data, buf->data + ret, buf->size);
+			break;
+		} else {
+			size_t decr = sizeof(*buf) -
+				sizeof(buf->data) + buf->size;
+
+			assert(client->deferred_bytes >= decr);
+			client->deferred_bytes -= decr;
+			g_free(buf);
+			g_queue_pop_head(client->deferred_send);
+		}
+
+		g_timer_start(client->last_activity);
+	}
+
+	if (g_queue_is_empty(client->deferred_send)) {
+		g_debug("[%u] buffer empty %lu", client->num,
+			(unsigned long)client->deferred_bytes);
+		assert(client->deferred_bytes == 0);
+	}
+}
+
+static void client_defer_output(struct client *client,
+				const void *data, size_t length)
+{
+	size_t alloc;
+	struct deferred_buffer *buf;
+
+	assert(length > 0);
+
+	alloc = sizeof(*buf) - sizeof(buf->data) + length;
+	client->deferred_bytes += alloc;
+	if (client->deferred_bytes > client_max_output_buffer_size) {
+		g_warning("[%u] output buffer size (%lu) is "
+			  "larger than the max (%lu)",
+			  client->num,
+			  (unsigned long)client->deferred_bytes,
+			  (unsigned long)client_max_output_buffer_size);
+		/* cause client to close */
+		client_set_expired(client);
+		return;
+	}
+
+	buf = g_malloc(alloc);
+	buf->size = length;
+	memcpy(buf->data, data, length);
+
+	g_queue_push_tail(client->deferred_send, buf);
+}
+
+static void client_write_direct(struct client *client,
+				const char *data, size_t length)
+{
+	GError *error = NULL;
+	GIOStatus status;
+	gsize bytes_written;
+
+	assert(client != NULL);
+	assert(client->channel != NULL);
+	assert(data != NULL);
+	assert(length > 0);
+	assert(g_queue_is_empty(client->deferred_send));
+
+	status = g_io_channel_write_chars(client->channel, data, length,
+					  &bytes_written, &error);
+	switch (status) {
+	case G_IO_STATUS_NORMAL:
+	case G_IO_STATUS_AGAIN:
+		break;
+
+	case G_IO_STATUS_EOF:
+		/* client has disconnected */
+
+		client_set_expired(client);
+		return;
+
+	case G_IO_STATUS_ERROR:
+		/* I/O error */
+
+		client_set_expired(client);
+		g_warning("failed to write to %i: %s",
+			  client->num, error->message);
+		g_error_free(error);
+		return;
+	}
+
+	if (bytes_written < length)
+		client_defer_output(client, data + bytes_written,
+				    length - bytes_written);
+
+	if (!g_queue_is_empty(client->deferred_send))
+		g_debug("[%u] buffer created", client->num);
+}
+
+void
+client_write_output(struct client *client)
+{
+	if (client_is_expired(client) || !client->send_buf_used)
+		return;
+
+	if (!g_queue_is_empty(client->deferred_send)) {
+		client_defer_output(client, client->send_buf,
+				    client->send_buf_used);
+
+		if (client_is_expired(client))
+			return;
+
+		/* try to flush the deferred buffers now; the current
+		   server command may take too long to finish, and
+		   meanwhile try to feed output to the client,
+		   otherwise it will time out.  One reason why
+		   deferring is slow might be that currently each
+		   client_write() allocates a new deferred buffer.
+		   This should be optimized after MPD 0.14. */
+		client_write_deferred(client);
+	} else
+		client_write_direct(client, client->send_buf,
+				    client->send_buf_used);
+
+	client->send_buf_used = 0;
+}
+
+/**
+ * Write a block of data to the client.
+ */
+static void client_write(struct client *client, const char *buffer, size_t buflen)
+{
+	/* if the client is going to be closed, do nothing */
+	if (client_is_expired(client))
+		return;
+
+	while (buflen > 0 && !client_is_expired(client)) {
+		size_t copylen;
+
+		assert(client->send_buf_used < sizeof(client->send_buf));
+
+		copylen = sizeof(client->send_buf) - client->send_buf_used;
+		if (copylen > buflen)
+			copylen = buflen;
+
+		memcpy(client->send_buf + client->send_buf_used, buffer,
+		       copylen);
+		buflen -= copylen;
+		client->send_buf_used += copylen;
+		buffer += copylen;
+		if (client->send_buf_used >= sizeof(client->send_buf))
+			client_write_output(client);
+	}
+}
+
+void client_puts(struct client *client, const char *s)
+{
+	client_write(client, s, strlen(s));
+}
+
+void client_vprintf(struct client *client, const char *fmt, va_list args)
+{
+	va_list tmp;
+	int length;
+	char *buffer;
+
+	va_copy(tmp, args);
+	length = vsnprintf(NULL, 0, fmt, tmp);
+	va_end(tmp);
+
+	if (length <= 0)
+		/* wtf.. */
+		return;
+
+	buffer = g_malloc(length + 1);
+	vsnprintf(buffer, length + 1, fmt, args);
+	client_write(client, buffer, length);
+	g_free(buffer);
+}
+
+G_GNUC_PRINTF(2, 3) void client_printf(struct client *client, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	client_vprintf(client, fmt, args);
+	va_end(args);
+}