Remove timeouts from remote communication loop.

The select() now blocks until there's work to do instead of relying on a
small timeout value which can cause unproductive use of cpu cycles.

src/Pipe.cc

@@ -0,0 +1,79 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#include "Pipe.h"
+#include "Reporter.h"
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <cstdio>
+
+using namespace bro;
+
+static void pipe_fail(int eno)
+	{
+	char tmp[256];
+	strerror_r(eno, tmp, sizeof(tmp));
+	reporter->FatalError("Pipe failure: %s", tmp);
+	}
+
+static void set_flags(int fd, int flags)
+	{
+	if ( flags )
+		fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | flags);
+	}
+
+static void set_status_flags(int fd, int flags)
+	{
+	if ( flags )
+		fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | flags);
+	}
+
+static int dup_or_fail(int fd, int flags)
+	{
+	int rval = dup(fd);
+
+	if ( rval < 0 )
+		pipe_fail(errno);
+
+	set_flags(fd, flags);
+	return rval;
+	}
+
+Pipe::Pipe(int flags0, int flags1, int status_flags0, int status_flags1)
+	{
+	// pipe2 can set flags atomically, but not yet available everywhere.
+	if ( ::pipe(fds) )
+		pipe_fail(errno);
+
+	flags[0] = flags0;
+	flags[1] = flags1;
+
+	set_flags(fds[0], flags[0]);
+	set_flags(fds[1], flags[1]);
+	set_status_flags(fds[0], status_flags0);
+	set_status_flags(fds[1], status_flags1);
+	}
+
+Pipe::~Pipe()
+	{
+	close(fds[0]);
+	close(fds[1]);
+	}
+
+Pipe::Pipe(const Pipe& other)
+	{
+	fds[0] = dup_or_fail(other.fds[0], other.flags[0]);
+	fds[1] = dup_or_fail(other.fds[1], other.flags[1]);
+	}
+
+Pipe& Pipe::operator=(const Pipe& other)
+	{
+	if ( this == &other )
+		return *this;
+
+	close(fds[0]);
+	close(fds[1]);
+	fds[0] = dup_or_fail(other.fds[0], other.flags[0]);
+	fds[1] = dup_or_fail(other.fds[1], other.flags[1]);
+	return *this;
+	}