vfs_oss: implement 'SNDCTL_DSP_SETTRIGGER' command

Fixes #4579

repos/libports/src/lib/libc/vfs_plugin.cc

@@ -1682,7 +1682,41 @@ Libc::Vfs_plugin::_ioctl_sndctl(File_descriptor *fd, unsigned long request, char
 
 		if (!argp) return { true, EINVAL };
 
-		/* dummy implementation */
+		int mask = *(int *)argp;
+
+		if (((fd->flags & O_ACCMODE) == O_RDONLY) ||
+		    ((fd->flags & O_ACCMODE) == O_RDWR)) {
+
+			char enable_input_string[2];
+
+			::snprintf(enable_input_string, sizeof(enable_input_string),
+			           "%u", (mask & PCM_ENABLE_INPUT) ? 1 : 0);
+
+			Absolute_path enable_input_path = ioctl_dir(*fd);
+			enable_input_path.append_element("enable_input");
+			File_descriptor *enable_input_fd = open(enable_input_path.base(), O_WRONLY);
+			if (!enable_input_fd)
+				return { true, ENOTSUP };
+			write(enable_input_fd, enable_input_string, sizeof(enable_input_string));
+			close(enable_input_fd);
+		}
+
+		if (((fd->flags & O_ACCMODE) == O_WRONLY) ||
+		    ((fd->flags & O_ACCMODE) == O_RDWR)) {
+
+			char enable_output_string[2];
+
+			::snprintf(enable_output_string, sizeof(enable_output_string),
+			           "%u", (mask & PCM_ENABLE_OUTPUT) ? 1 : 0);
+
+			Absolute_path enable_output_path = ioctl_dir(*fd);
+			enable_output_path.append_element("enable_output");
+			File_descriptor *enable_output_fd = open(enable_output_path.base(), O_WRONLY);
+			if (!enable_output_fd)
+				return { true, ENOTSUP };
+			write(enable_output_fd, enable_output_string, sizeof(enable_output_string));
+			close(enable_output_fd);
+		}
 
 		handled = true;
 

repos/libports/src/lib/vfs/oss/README

@@ -71,6 +71,14 @@ presents all files:
   * halt_output (wo): writing anything into this file halts output processing.
     Corresponding OSS commands: SNDCTL_DSP_HALT
 
+  * enable_input (rw): writing 1 or 0 into this file enables or disables
+    input processing.
+    Corresponding OSS commands: SNDCTL_DSP_SETTRIGGER
+
+  * enable_output (rw): writing 1 or 0 into this file enables or disables
+    output processing.
+    Corresponding OSS commands: SNDCTL_DSP_SETTRIGGER
+
 In its current state the plugin is merely enough to use simple applications requiring
 nothing more than a minimal set of the OSSv4 API. It does not allow altering
 of all parameters and will only work when 44100Hz/s16le is used.

repos/libports/src/lib/vfs/oss/vfs_oss.cc

@@ -193,6 +193,9 @@ struct Vfs::Oss_file_system::Audio
 		Audio(Audio const &);
 		Audio &operator = (Audio const &);
 
+		bool _audio_out_enabled { true };
+		bool _audio_in_enabled  { true };
+
 		bool _audio_out_started { false };
 		bool _audio_in_started  { false };
 
@@ -208,6 +211,23 @@ struct Vfs::Oss_file_system::Audio
 		size_t _read_sample_offset  { 0 };
 		size_t _write_sample_offset { 0 };
 
+		void _start_input()
+		{
+			if (!_audio_in_started && _audio_in_enabled) {
+				_in->start();
+				_audio_in_started = true;
+			}
+		}
+
+		void _start_output()
+		{
+			if (!_audio_out_started && _audio_out_enabled) {
+				_out[0]->start();
+				_out[1]->start();
+				_audio_out_started = true;
+			}
+		}
+
 	public:
 
 		Audio(Genode::Env &env,
@@ -302,6 +322,28 @@ struct Vfs::Oss_file_system::Audio
 			}
 		}
 
+		void enable_input(bool enable)
+		{
+			if (enable) {
+				_audio_in_enabled = true;
+				_start_input();
+			} else {
+				halt_input();
+				_audio_in_enabled = false;
+			}
+		}
+
+		void enable_output(bool enable)
+		{
+			if (enable) {
+				_audio_out_enabled = true;
+				_start_output();
+			} else {
+				halt_output();
+				_audio_out_enabled = false;
+			}
+		}
+
 		/*
 		 * Handle Audio_out progress signal.
 		 *
@@ -404,10 +446,7 @@ struct Vfs::Oss_file_system::Audio
 		{
 			out_size = 0;
 
-			if (!_audio_in_started) {
+			_start_input();
-				_in->start();
-				_audio_in_started = true;
-			}
 
 			if (_info.ifrag_bytes == 0) {
 				/* block */
@@ -493,11 +532,7 @@ struct Vfs::Oss_file_system::Audio
 				return false;
 			}
 
-			if (!_audio_out_started) {
+			_start_output();
-				_audio_out_started = true;
-				_out[0]->start();
-				_out[1]->start();
-			}
 
 			unsigned stream_samples_written = 0;
 
@@ -756,6 +791,8 @@ struct Vfs::Oss_file_system::Local_factory : File_system_factory
 	Readonly_value_file_system<long long> _optr_samples_fs      { "optr_samples", 0LL };
 	Readonly_value_file_system<unsigned>  _optr_fifo_samples_fs { "optr_fifo_samples", 0U };
 	Value_file_system<unsigned>           _play_underruns_fs    { "play_underruns", 0U };
+	Value_file_system<unsigned>           _enable_input_fs      { "enable_input", 1U };
+	Value_file_system<unsigned>           _enable_output_fs     { "enable_output", 1U };
 
 	/* WO files */
 	Value_file_system<unsigned>           _halt_input_fs        { "halt_input", 0U };
@@ -773,6 +810,18 @@ struct Vfs::Oss_file_system::Local_factory : File_system_factory
 
 	Audio _audio { _env.env(), _info, _info_fs };
 
+	Genode::Watch_handler<Vfs::Oss_file_system::Local_factory> _enable_input_handler {
+		_enable_input_fs, "/enable_input",
+		_env.alloc(),
+		*this,
+		&Vfs::Oss_file_system::Local_factory::_enable_input_changed };
+
+	Genode::Watch_handler<Vfs::Oss_file_system::Local_factory> _enable_output_handler {
+		_enable_output_fs, "/enable_output",
+		_env.alloc(),
+		*this,
+		&Vfs::Oss_file_system::Local_factory::_enable_output_changed };
+
 	Genode::Watch_handler<Vfs::Oss_file_system::Local_factory> _halt_input_handler {
 		_halt_input_fs, "/halt_input",
 		_env.alloc(),
@@ -829,6 +878,18 @@ struct Vfs::Oss_file_system::Local_factory : File_system_factory
 	 ** Watch handlers **
 	 ********************/
 
+	void _enable_input_changed()
+	{
+		bool enable = (bool)_enable_input_fs.value();
+		_audio.enable_input(enable);
+	}
+
+	void _enable_output_changed()
+	{
+		bool enable = (bool)_enable_output_fs.value();
+		_audio.enable_output(enable);
+	}
+
 	void _halt_input_changed()
 	{
 		_audio.halt_input();
@@ -988,6 +1049,14 @@ struct Vfs::Oss_file_system::Local_factory : File_system_factory
 
 		if (node.has_type(Value_file_system<unsigned>::type_name())) {
 
+			if (_enable_input_fs.matches(node)) {
+				return &_enable_input_fs;
+			}
+
+			if (_enable_output_fs.matches(node)) {
+				return &_enable_output_fs;
+			}
+
 			if (_halt_input_fs.matches(node)) {
 				return &_halt_input_fs;
 			}
@@ -1060,6 +1129,14 @@ class Vfs::Oss_file_system::Compound_file_system : private Local_factory,
 						xml.attribute("name", "format");
 					});
 
+					xml.node("value", [&] {
+						xml.attribute("name", "enable_input");
+					});
+
+					xml.node("value", [&] {
+						xml.attribute("name", "enable_output");
+					});
+
 					xml.node("value", [&] {
 						xml.attribute("name", "halt_input");
 					});