From 2d9a6cf1b0123e5962d5558b57f74c1faf33bf0b Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 1 Dec 2017 13:03:46 +0200
Subject: [PATCH] Improve ExternalTask::run_and_capture_output

Redirect input from /dev/null and allow stderr to be captured as well.
---
 source/externaltask.cpp | 17 +++++++++++------
 source/externaltask.h   |  7 ++++---
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/source/externaltask.cpp b/source/externaltask.cpp
index 257d131..e4dfdc2 100644
--- a/source/externaltask.cpp
+++ b/source/externaltask.cpp
@@ -16,6 +16,7 @@ ExternalTask::ExternalTask(const Arguments &a, const FS::Path &wd):
 	work_dir(wd),
 	process(0),
 	exit_code(-1),
+	stdin_action(PASSTHROUGH),
 	stdout_action(PASSTHROUGH),
 	stderr_action(PASSTHROUGH),
 	capture_pipe(0)
@@ -45,7 +46,7 @@ string ExternalTask::get_command() const
 		}
 	}
 
-	if(!stdin_file.empty())
+	if(stdin_action==REDIRECT)
 	{
 		cmd += " <";
 		cmd += stdin_file.str();
@@ -70,9 +71,11 @@ void ExternalTask::start()
 
 	process = new Process;
 
-	if(stdout_action==IGNORE || stderr_action==IGNORE)
+	if(stdin_action==IGNORE || stdout_action==IGNORE || stderr_action==IGNORE)
 	{
-		devnull = new IO::File("/dev/null", IO::M_WRITE);
+		devnull = new IO::File("/dev/null", IO::M_RDWR);
+		if(stdin_action==IGNORE)
+			process->redirect_cin(*devnull);
 		if(stdout_action==IGNORE)
 			process->redirect_cout(*devnull);
 		if(stderr_action==IGNORE)
@@ -94,7 +97,7 @@ void ExternalTask::start()
 			process->redirect_cerr(*capture_pipe);
 	}
 
-	if(!stdin_file.empty())
+	if(stdin_action==REDIRECT)
 	{
 		infile = new IO::File((work_dir/stdin_file).str());
 		process->redirect_cin(*infile);
@@ -156,6 +159,7 @@ Task::Status ExternalTask::do_wait(bool block)
 
 void ExternalTask::set_stdin(const FS::Path &f)
 {
+	stdin_action = REDIRECT;
 	stdin_file = f;
 }
 
@@ -179,11 +183,12 @@ void ExternalTask::set_stderr(StreamAction a)
 	stderr_action = a;
 }
 
-string ExternalTask::run_and_capture_output(const Arguments &argv, const FS::Path &wd)
+string ExternalTask::run_and_capture_output(const Arguments &argv, const FS::Path &wd, bool capture_stderr)
 {
 	ExternalTask task(argv, wd);
+	task.stdin_action = IGNORE;
 	task.set_stdout(CAPTURE);
-	task.set_stderr(IGNORE);
+	task.set_stderr(capture_stderr ? CAPTURE : IGNORE);
 	task.start();
 	if(task.wait()!=SUCCESS)
 		throw runtime_error(format("%s failed", argv.front()));
diff --git a/source/externaltask.h b/source/externaltask.h
index 00465f3..26a6aca 100644
--- a/source/externaltask.h
+++ b/source/externaltask.h
@@ -31,6 +31,7 @@ private:
 	Msp::FS::Path work_dir;
 	Msp::Process *process;
 	int exit_code;
+	StreamAction stdin_action;
 	Msp::FS::Path stdin_file;
 	StreamAction stdout_action;
 	Msp::FS::Path stdout_file;
@@ -70,9 +71,9 @@ public:
 	still running, but it will always return all output. */
 	const std::string &get_output() const { return output; }
 
-	/** Executes a command and captures its output.  Stderr is ignored, but if
-	the command exits with a nonzero status, an exception is thrown. */
-	static std::string run_and_capture_output(const Arguments &, const Msp::FS::Path & = Msp::FS::Path());
+	/** Executes a command and captures its output.  If the command exits with
+	a nonzero status, an exception is thrown. */
+	static std::string run_and_capture_output(const Arguments &, const Msp::FS::Path & = Msp::FS::Path(), bool = false);
 };
 
 #endif
-- 
2.43.0