Move system_exec from gtk2_ardour/ to libs/pbd/

1 files changed, 201 insertions, 0 deletions

diff --git a/libs/pbd/pbd/system_exec.h b/libs/pbd/pbd/system_exec.h
new file mode 100644
index 0000000000..cf8518f547
--- /dev/null
+++ b/libs/pbd/pbd/system_exec.h
@@ -0,0 +1,201 @@
+/*
+    Copyright (C) 2010 Paul Davis
+    Author: Robin Gareus <robin@gareus.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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+#ifndef __ardour_system_exec_h__
+#define __ardour_system_exec_h__
+
+#ifndef STDIN_FILENO
+#define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+#define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+#define STDERR_FILENO 2
+#endif
+
+#include <string>
+#include <pthread.h>
+#include <signal.h>
+#ifdef NOPBD  /* outside ardour */
+#include <sigc++/bind.h>
+#include <sigc++/signal.h>
+#else
+#include <pbd/signals.h>
+#endif
+
+/** @class: SystemExec
+ *  @brief execute an external command
+ *
+ * This class allows launche an external command-line application
+ * opening a full-duplex connection to its standard I/O.
+ *
+ * In Ardour context it is used to launch xjadeo and ffmpeg.
+ *
+ * The \ref write_to_stdin function provides for injecting data into STDIN
+ * of the child-application while output of the program to STDOUT/STDERR is
+ * forwarded using the \ref ReadStdout signal.
+ * \ref Terminated is sent if the child application exits.
+ *
+ */
+class SystemExec
+{
+	public:
+		/** prepare execution of a program with 'execve'
+		 *
+		 * This function takes over the existing environment variable and provides
+		 * an easy way to speciy command-line arguments for the new process.
+		 *
+		 * Note: The argument parser does not interpret quotation-marks and splits
+		 * arugments on whitespace. The argument string can be empty.
+		 * The alternative constructor below allows to specify quoted parameters
+		 * incl. whitespace.
+		 *
+		 * @param c program pathname that identifies the new process image file.
+		 * @param a string of commandline-arguments to be passed to the new program.
+		 */
+		SystemExec (std::string c, std::string a = "");
+		/** similar to \ref SystemExec but allows to specify custom arguments
+		 *
+		 * @param c program pathname that identifies the new process image file.
+		 * @param a array of argument strings passed to the new program as 'argv'.
+		 *          it must be terminated by a null pointer (see the 'evecve'
+		 *          POSIX-C documentation for more information)
+		 *          The array must be dynamically allocated using malloc or strdup.
+		 *          Unless they're NULL, the array itself and each of its content
+		 *          memory is freed() in the destructor.
+		 *
+		 */
+		SystemExec (std::string c, char ** a);
+		virtual ~SystemExec ();
+
+		/** fork and execute the given program
+		 *
+		 * @param stderr_mode select what to do with program's standard error
+		 * output:
+		 * '0': keep STDERR; mix it with parent-process' STDERR
+		 * '1': ignore STDERR of child-program
+		 * '2': merge STDERR into STDOUT and send it with the
+		 *      ReadStdout signal.
+		 * @return If the process is already running or was launched successfully
+		 * the function returns zero (0). A negative number indicates an error.
+		 */
+		int start (int stderr_mode = 1);
+		/** kill running child-process
+		 *
+		 * if a child process exists trt to shut it down by closing its STDIN.
+		 * if the program dies not react try SIGTERM and eventually SIGKILL
+		 */
+		void terminate ();
+		/** check if the child programm is (still) running.
+		 *
+		 * This function calls waitpid(WNOHANG) to check the state of the
+		 * child-process.
+		 * @return true if the program is (still) running.
+		 */
+		bool is_running ();
+		/** call the waitpid system-call with the pid of the child-program
+		 *
+		 * Basically what \ref terminate uses internally.
+		 *
+		 * This function is only useful if you want to control application
+		 * termination yourself (eg timeouts or progress-dialog).
+		 * @param option flags - see waitpid manual
+		 * @return status info from waitpid call (not waitpid's return value)
+		 * or -1 if the child-program is not running.
+		 */
+		int wait (int options=0);
+		/** closes both STDIN and STDOUT connections to/from
+		 * the child-program.
+		 * With the output-interposer thread gone, the program
+		 * should terminate.
+		 * used by \ref terminate()
+		 */
+		void close_stdin ();
+		/** write into child-program's STDIN
+		 * @param d data to write
+		 * @param len length of data to write, if it is 0 (zero), d.length() is
+		 * used to determine the number of bytes to transmit.
+		 * @return number of bytes written.
+		 */
+		int write_to_stdin (std::string d, size_t len=0);
+
+		/** The ReadStdout signal is emitted when the application writes to STDOUT.
+		 * it passes the written data and its length in bytes as arguments to the bound
+		 * slot(s).
+		 */
+#ifdef NOPBD  /* outside ardour */
+		sigc::signal<void, std::string,size_t> ReadStdout;
+#else
+		PBD::Signal2<void, std::string,size_t> ReadStdout;
+#endif
+
+		/** The Terminated signal is emitted when application terminates. */
+#ifdef NOPBD  /* outside ardour */
+		sigc::signal<void> Terminated;
+#else
+		PBD::Signal0<void> Terminated;
+#endif
+
+		/** interposer to emit signal for writes to STDOUT/ERR.
+		 *
+		 * Thread that reads the stdout of the forked
+		 * process and signal-sends it to the main thread.
+		 * It also emits the Terminated() signal once
+		 * the the forked process closes it's stdout.
+		 *
+		 * Note: it's actually 'private' function but used
+		 * by the internal pthread, which only has a pointer
+		 * to this instance and thus can only access public fn.
+		 */
+		void output_interposer ();
+
+	protected:
+		std::string cmd; ///< path to command - set when creating the class
+		int nicelevel; ///< process nice level - defaults to 0
+
+		void make_argp(std::string);
+		void make_envp();
+
+		char **argp;
+		char **envp;
+
+	private:
+#ifdef __WIN32__
+		PROCESS_INFORMATION *pid;
+		HANDLE stdinP[2];
+		HANDLE stdoutP[2];
+		HANDLE stderrP[2];
+		char *w_args;
+		void make_wargs(char **);
+#else
+		pid_t pid;
+#endif
+		pthread_mutex_t write_lock;
+
+		int fdin; ///< file-descriptor for writing to child's STDIN. This variable is identical to pin[1] but also used as status check if the stdin pipe is open: <0 means closed.
+		int pok[2];
+		int pin[2];
+		int pout[2];
+
+		pthread_t      thread_id_tt;
+		bool           thread_active;
+};
+
+#endif /* __ardour_system_exec_h__ */