From 05f48c6a3c9bb49c4977dde0dc57cb88c2bb63df Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Tue, 26 Jul 2016 16:07:44 -0400
Subject: [PATCH] implement pipe.

---
 command.cpp | 39 ++++++++++++++++++++++++++++++++++-----
 fdset.h     |  4 ++++
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/command.cpp b/command.cpp
index 95db807..608b4d7 100644
--- a/command.cpp
+++ b/command.cpp
@@ -417,11 +417,13 @@ int or_command::execute(Environment &e, const fdmask &fds, bool throwup) {
 		if (rv == 0) return rv;
 	}
 
-	return e.status(rv);
+	return e.status(rv, throwup);
 }
 
 int and_command::execute(Environment &e, const fdmask &fds, bool throwup) {
 
+	// mpw - false && true -> no exit
+	// mpw - true && false -> exit
 	int rv = 0;
 	for (auto &c : children) {
 		if (!c) continue;
@@ -429,16 +431,43 @@ int and_command::execute(Environment &e, const fdmask &fds, bool throwup) {
 		if (rv != 0) return rv;
 	}
 
-	return rv;
+	return e.status(rv, throwup);
 }
 
 
 int pipe_command::execute(Environment &e, const fdmask &fds, bool throwup) {
 	// not yet supported!
-	fputs( "### MPW Shell - Pipes are not yet supported.\n", stderr);
-	return e.status(1, throwup);
-}
+	//fputs( "### MPW Shell - Pipes are not yet supported.\n", stderr);
+	//return e.status(1, throwup);
 
+	if (children[0] && children[1]) {
+		int fd;
+		int rv = 0;
+		char temp[32] = "/tmp/mpw-shell-XXXXXXXX";
+		fdset pipe_fd;
+
+		fd = mkstemp(temp);
+		pipe_fd.set(1, fd);
+
+		try {
+
+			rv = children[0]->execute(e, pipe_fd | fds, throwup);
+
+			// fdset will close the fd ...
+			pipe_fd.swap_in_out();
+			lseek(fd, 0, SEEK_SET);
+
+			rv = children[1]->execute(e, pipe_fd | fds, throwup);
+
+		} catch(std::exception &ex) {
+			unlink(temp);
+			throw;
+		}
+	}
+	if (children[0]) return children[0]->execute(e, fds, throwup);
+	if (children[1]) return children[1]->execute(e, fds, throwup);
+	return e.status(0, throwup);
+}
 
 int vector_command::execute(Environment &e, const fdmask &fds, bool throwup) {
 
diff --git a/fdset.h b/fdset.h
index 8bbcfc3..4143fe0 100644
--- a/fdset.h
+++ b/fdset.h
@@ -132,6 +132,10 @@ class fdset {
 		return fdmask(_fds);
 	}
 
+	void swap_in_out() {
+		std::swap(_fds[0], _fds[1]);
+	}
+
 	private:
 
 	void reset() {