[gnome-applets/wip/muktupavels/async-command] command: add GaCommand

[Alberts Muktupāvels <muktupavels src gnome org>]

commit e77692b44faab1fd21b1deeeb7f19014e91230ea
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Tue Nov 27 01:27:09 2018 +0200

    command: add GaCommand
    
    It will be used to asynchronously run command in next commits.

 command/src/Makefile.am  |   2 +
 command/src/command.c    |   5 +-
 command/src/ga-command.c | 399 +++++++++++++++++++++++++++++++++++++++++++++++
 command/src/ga-command.h |  43 +++++
 4 files changed, 446 insertions(+), 3 deletions(-)
---
diff --git a/command/src/Makefile.am b/command/src/Makefile.am
index 72b8a25dc..a5e2cb324 100644
--- a/command/src/Makefile.am
+++ b/command/src/Makefile.am
@@ -20,6 +20,8 @@ libcommand_applet_la_CFLAGS = \
 
 libcommand_applet_la_SOURCES = \
        command.c \
+       ga-command.h \
+       ga-command.c \
        $(NULL)
 
 libcommand_applet_la_LDFLAGS = \
diff --git a/command/src/command.c b/command/src/command.c
index a74fe8983..8a05f6230 100644
--- a/command/src/command.c
+++ b/command/src/command.c
@@ -22,9 +22,8 @@
  *      Stefano Karapetsas <stefano karapetsas com>
  */
 
-#ifdef HAVE_CONFIG_H
-#  include <config.h>
-#endif
+#include "config.h"
+#include "ga-command.h"
 
 #include <glib.h>
 #include <glib/gi18n.h>
diff --git a/command/src/ga-command.c b/command/src/ga-command.c
new file mode 100644
index 000000000..25a7edde7
--- /dev/null
+++ b/command/src/ga-command.c
@@ -0,0 +1,399 @@
+/*
+ * Copyright (C) 2018 Alberts Muktupāvels
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include "ga-command.h"
+
+#define BUFFER_SIZE 64
+
+struct _GaCommand
+{
+  GObject   parent;
+
+  gchar    *command;
+  gchar   **argv;
+};
+
+typedef struct
+{
+  GPid        pid;
+
+  GIOChannel *channel;
+
+  GString    *input;
+
+  guint       io_watch_id;
+  guint       child_watch_id;
+} CommandData;
+
+enum
+{
+  PROP_0,
+
+  PROP_COMMAND,
+
+  LAST_PROP
+};
+
+static GParamSpec *command_properties[LAST_PROP] = { NULL };
+
+static void initable_iface_init (GInitableIface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (GaCommand, ga_command, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
+                                                initable_iface_init))
+
+static gboolean
+read_cb (GIOChannel   *source,
+         GIOCondition  condition,
+         gpointer      user_data)
+{
+  GTask *task;
+  CommandData *data;
+  gchar buffer[BUFFER_SIZE];
+  gsize bytes_read;
+  GError *error;
+  GIOStatus status;
+
+  task = (GTask *) user_data;
+  data = g_task_get_task_data (task);
+
+  if (g_task_return_error_if_cancelled (task))
+    {
+      g_object_unref (task);
+
+      data->io_watch_id = 0;
+
+      return G_SOURCE_REMOVE;
+    }
+
+  error = NULL;
+  status = g_io_channel_read_chars (source, buffer, BUFFER_SIZE,
+                                    &bytes_read, &error);
+
+  if (status == G_IO_STATUS_AGAIN)
+    {
+      g_clear_error (&error);
+
+      return G_SOURCE_CONTINUE;
+    }
+  else if (status != G_IO_STATUS_NORMAL)
+    {
+      if (error != NULL)
+        {
+          g_task_return_error (task, error);
+          g_object_unref (task);
+        }
+
+      data->io_watch_id = 0;
+
+      return G_SOURCE_REMOVE;
+    }
+
+  g_string_append_len (data->input, buffer, bytes_read);
+
+  return G_SOURCE_CONTINUE;
+}
+
+static void
+child_watch_cb (GPid     pid,
+                gint     status,
+                gpointer user_data)
+{
+  GTask *task;
+  CommandData *data;
+
+  task = (GTask *) user_data;
+  data = g_task_get_task_data (task);
+
+  g_task_return_pointer (task, g_strdup (data->input->str), g_free);
+  g_object_unref (task);
+}
+
+static void
+cancelled_cb (GCancellable *cancellable,
+              gpointer      user_data)
+{
+  GTask *task;
+
+  task = G_TASK (user_data);
+
+  g_object_unref (task);
+}
+
+static void
+command_data_free (gpointer user_data)
+{
+  CommandData *data;
+
+  data = (CommandData *) user_data;
+
+  if (data->pid != 0)
+    {
+      g_spawn_close_pid (data->pid);
+      data->pid = 0;
+    }
+
+  if (data->channel != NULL)
+    {
+      g_io_channel_unref (data->channel);
+      data->channel = NULL;
+    }
+
+  if (data->input != NULL)
+    {
+      g_string_free (data->input, TRUE);
+      data->input = NULL;
+    }
+
+  if (data->io_watch_id != 0)
+    {
+      g_source_remove (data->io_watch_id);
+      data->io_watch_id = 0;
+    }
+
+  if (data->child_watch_id != 0)
+    {
+      g_source_remove (data->child_watch_id);
+      data->child_watch_id = 0;
+    }
+
+  g_free (data);
+}
+
+static gboolean
+ga_command_initable_init (GInitable     *initable,
+                          GCancellable  *cancellable,
+                          GError       **error)
+{
+  GaCommand *command;
+
+  command = GA_COMMAND (initable);
+
+  if (command->command == NULL || *command->command == '\0')
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_DATA,
+                   "Empty command");
+
+      return FALSE;
+    }
+
+  if (!g_shell_parse_argv (command->command, NULL, &command->argv, error))
+    return FALSE;
+
+  return TRUE;
+}
+
+static void
+initable_iface_init (GInitableIface *iface)
+{
+  iface->init = ga_command_initable_init;
+}
+
+static void
+ga_command_finalize (GObject *object)
+{
+  GaCommand *command;
+
+  command = GA_COMMAND (object);
+
+  g_clear_pointer (&command->command, g_free);
+  g_clear_pointer (&command->argv, g_strfreev);
+
+  G_OBJECT_CLASS (ga_command_parent_class)->finalize (object);
+}
+
+static void
+ga_command_set_property (GObject      *object,
+                         guint         property_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GaCommand *command;
+
+  command = GA_COMMAND (object);
+
+  switch (property_id)
+    {
+      case PROP_COMMAND:
+        g_assert (command->command == NULL);
+        command->command = g_value_dup_string (value);
+        break;
+
+      default:
+        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+        break;
+    }
+}
+
+static void
+install_properties (GObjectClass *object_class)
+{
+  command_properties[PROP_COMMAND] =
+    g_param_spec_string ("command", "command", "command",
+                         NULL,
+                         G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE |
+                         G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, LAST_PROP,
+                                     command_properties);
+}
+
+static void
+ga_command_class_init (GaCommandClass *command_class)
+{
+  GObjectClass *object_class;
+
+  object_class = G_OBJECT_CLASS (command_class);
+
+  object_class->finalize = ga_command_finalize;
+  object_class->set_property = ga_command_set_property;
+
+  install_properties (object_class);
+}
+
+static void
+ga_command_init (GaCommand *command)
+{
+}
+
+/**
+ * ga_command_new:
+ * @command: a command
+ * @error: (nullable): return location for an error, or %NULL
+ *
+ * Creates a new #GaCommand.
+ *
+ * Returns: (nullable): a newly allocated #GaCommand
+ */
+GaCommand *
+ga_command_new (const gchar  *command,
+                GError      **error)
+{
+  return g_initable_new (GA_TYPE_COMMAND, NULL, error,
+                         "command", command,
+                         NULL);
+}
+
+/**
+ * ga_command_run_async:
+ * @command: a #GaCommand
+ * @cancellable: (nullable): a #GCancellable or %NULL
+ * @callback: a #GAsyncReadyCallback to call when the request is satisfied
+ * @user_data: the data to pass to @callback
+ *
+ * Request an asynchronous read of output from command that was passed
+ * to ga_command_new().
+ */
+void
+ga_command_run_async (GaCommand           *command,
+                      GCancellable        *cancellable,
+                      GAsyncReadyCallback  callback,
+                      gpointer             user_data)
+{
+  GTask *task;
+  CommandData *data;
+  GSpawnFlags spawn_flags;
+  gint command_stdout;
+  GError *error;
+  GIOChannel *channel;
+  GIOStatus status;
+  GIOCondition condition;
+
+  g_return_if_fail (GA_IS_COMMAND (command));
+  g_return_if_fail (callback != NULL);
+
+  task = g_task_new (command, cancellable, callback, user_data);
+  g_task_set_source_tag (task, ga_command_run_async);
+
+  if (cancellable)
+    {
+      g_signal_connect_object (cancellable, "cancelled",
+                               G_CALLBACK (cancelled_cb), task,
+                               G_CONNECT_AFTER);
+    }
+
+  data = g_new0 (CommandData, 1);
+  g_task_set_task_data (task, data, command_data_free);
+
+  spawn_flags = G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD;
+  error = NULL;
+
+  if (!g_spawn_async_with_pipes (NULL, command->argv, NULL, spawn_flags,
+                                 NULL, NULL, &data->pid, NULL, &command_stdout,
+                                 NULL, &error))
+    {
+      g_task_return_error (task, error);
+      g_object_unref (task);
+
+      return;
+    }
+
+  channel = data->channel = g_io_channel_unix_new (command_stdout);
+  g_io_channel_set_close_on_unref (channel, TRUE);
+
+  g_assert (error == NULL);
+  status = g_io_channel_set_encoding (channel, NULL, &error);
+
+  if (status != G_IO_STATUS_NORMAL)
+    {
+      g_task_return_error (task, error);
+      g_object_unref (task);
+
+      return;
+    }
+
+  g_assert (error == NULL);
+  status = g_io_channel_set_flags (channel, G_IO_FLAG_NONBLOCK, &error);
+
+  if (status != G_IO_STATUS_NORMAL)
+    {
+      g_task_return_error (task, error);
+      g_object_unref (task);
+
+      return;
+    }
+
+  data->input = g_string_new (NULL);
+
+  condition = G_IO_IN | G_IO_PRI | G_IO_ERR | G_IO_HUP;
+  data->io_watch_id = g_io_add_watch (channel, condition, read_cb, task);
+
+  data->child_watch_id = g_child_watch_add (data->pid, child_watch_cb, task);
+}
+
+/**
+ * ga_command_run_finish:
+ * @command: a #GaCommand
+ * @result: a #GAsyncResult
+ * @error: (nullable): return location for an error, or %NULL
+ *
+ * Finishes an operation started with ga_command_run_async().
+ *
+ * Returns: %NULL if @error is set, otherwise output from command
+ */
+gchar *
+ga_command_run_finish (GaCommand     *command,
+                       GAsyncResult  *result,
+                       GError       **error)
+{
+  g_return_val_if_fail (GA_IS_COMMAND (command), NULL);
+  g_return_val_if_fail (g_task_is_valid (result, command), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  return g_task_propagate_pointer (G_TASK (result), error);
+}
diff --git a/command/src/ga-command.h b/command/src/ga-command.h
new file mode 100644
index 000000000..0d6f0f7c5
--- /dev/null
+++ b/command/src/ga-command.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2018 Alberts Muktupāvels
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef GA_COMMAND_H
+#define GA_COMMAND_H
+
+#include <gio/gio.h>
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+#define GA_TYPE_COMMAND (ga_command_get_type ())
+G_DECLARE_FINAL_TYPE (GaCommand, ga_command, GA, COMMAND, GObject)
+
+GaCommand *ga_command_new        (const gchar          *command,
+                                  GError              **error);
+
+void       ga_command_run_async  (GaCommand            *command,
+                                  GCancellable         *cancellable,
+                                  GAsyncReadyCallback   callback,
+                                  gpointer              user_data);
+
+gchar     *ga_command_run_finish (GaCommand            *command,
+                                  GAsyncResult         *result,
+                                  GError              **error);
+
+G_END_DECLS
+
+#endif