From e2dc7122774e5d8de07731f3abe15ec0a9ffa643 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 30 May 2012 19:28:12 +0000
Subject: [PATCH] Add support for capturing output in ExternalTask

---
 source/externaltask.cpp | 63 +++++++++++++++++++++++++++++++++++++++--
 source/externaltask.h   | 18 ++++++++++++
 2 files changed, 78 insertions(+), 3 deletions(-)

diff --git a/source/externaltask.cpp b/source/externaltask.cpp
index 6ff6a3e..0da81e5 100644
--- a/source/externaltask.cpp
+++ b/source/externaltask.cpp
@@ -2,7 +2,10 @@
 #include <unistd.h>
 #include <sys/wait.h>
 #include <msp/fs/dir.h>
+#include <msp/io/console.h>
+#include <msp/io/file.h>
 #include <msp/io/print.h>
+#include <msp/time/units.h>
 #include "externaltask.h"
 
 using namespace std;
@@ -12,9 +15,17 @@ ExternalTask::ExternalTask(const vector<string> &a, const FS::Path &wd):
 	argv(a),
 	work_dir(wd),
 	pid(-1),
-	exit_code(-1)
+	exit_code(-1),
+	stdout_dest(PASSTHROUGH),
+	stderr_dest(PASSTHROUGH),
+	capture_pipe(0)
 { }
 
+ExternalTask::~ExternalTask()
+{
+	delete capture_pipe;
+}
+
 string ExternalTask::get_command() const
 {
 	string cmd;
@@ -36,6 +47,9 @@ string ExternalTask::get_command() const
 
 void ExternalTask::start()
 {
+	if(stdout_dest==CAPTURE || stderr_dest==CAPTURE)
+		capture_pipe = new IO::Pipe;
+
 	if((pid = fork()))
 	{
 		if(pid==-1)
@@ -50,6 +64,24 @@ void ExternalTask::start()
 			cargv[i] = argv[i].c_str();
 		cargv.back() = 0;
 
+		if(stdout_dest==IGNORE || stderr_dest==IGNORE)
+		{
+			IO::File devnull("/dev/null", IO::M_WRITE);
+			if(stdout_dest==IGNORE)
+				IO::cout.redirect(devnull);
+			if(stderr_dest==IGNORE)
+				IO::cerr.redirect(devnull);
+		}
+
+		if(capture_pipe)
+		{
+			if(stdout_dest==CAPTURE)
+				IO::cout.redirect(*capture_pipe);
+			if(stderr_dest==CAPTURE)
+				IO::cerr.redirect(*capture_pipe);
+			delete capture_pipe;
+		}
+
 		if(!work_dir.empty())
 			FS::chdir(work_dir);
 		execvp(cargv.front(), const_cast<char *const *>(&cargv.front()));
@@ -62,6 +94,7 @@ Task::Status ExternalTask::check()
 {
 	if(pid>0)
 	{
+		// XXX This is sub-optimal, should have support for a blocking wait
 		int status;
 		if(waitpid(pid, &status, WNOHANG)==pid)
 		{
@@ -72,12 +105,36 @@ Task::Status ExternalTask::check()
 			else
 				exit_code = 1025;
 			pid = 0;
+		}
 
-			signal_finished.emit(!exit_code);
+		// Do this after waiting to avoid a race condition
+		if(capture_pipe)
+		{
+			while(IO::poll(*capture_pipe, IO::P_INPUT, Time::zero))
+			{
+				char buf[1024];
+				unsigned len = capture_pipe->read(buf, sizeof(buf));
+				output.append(buf, len);
+				if(len<sizeof(buf))
+					break;
+			}
 		}
-		else
+
+		if(pid>0)
 			return RUNNING;
+		else
+			signal_finished.emit(!exit_code);
 	}
 
 	return exit_code ? ERROR : SUCCESS;
 }
+
+void ExternalTask::set_stdout(Destination d)
+{
+	stdout_dest = d;
+}
+
+void ExternalTask::set_stderr(Destination d)
+{
+	stderr_dest = d;
+}
diff --git a/source/externaltask.h b/source/externaltask.h
index 0bd108e..b23bb66 100644
--- a/source/externaltask.h
+++ b/source/externaltask.h
@@ -4,22 +4,40 @@
 #include <string>
 #include <vector>
 #include <msp/fs/path.h>
+#include <msp/io/pipe.h>
 #include "task.h"
 
 class ExternalTask: public Task
 {
+public:
+	enum Destination
+	{
+		PASSTHROUGH,
+		CAPTURE,
+		IGNORE
+	};
+
 private:
 	std::vector<std::string> argv;
 	Msp::FS::Path work_dir;
 	int pid;
 	int exit_code;
+	Destination stdout_dest;
+	Destination stderr_dest;
+	Msp::IO::Pipe *capture_pipe;
+	std::string output;
 
 public:
 	ExternalTask(const std::vector<std::string> &, const Msp::FS::Path &);
+	virtual ~ExternalTask();
 
 	virtual std::string get_command() const;
 	virtual void start();
 	virtual Status check();
+
+	void set_stdout(Destination);
+	void set_stderr(Destination);
+	const std::string &get_output() const { return output; }
 };
 
 #endif
-- 
2.43.0