1 files changed, 104 insertions, 0 deletions
diff --git a/lib/selfpipe.cc b/lib/selfpipe.cc
new file mode 100644
index 0000000..83b390c
--- /dev/null
+++ b/lib/selfpipe.cc
@@ -0,0 +1,104 @@
+// nullmailer -- a simple relay-only MTA
+// Copyright (C) 2017  Bruce Guenter <bruce@untroubled.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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+// You can contact me at <bruce@untroubled.org>.  There is also a mailing list
+// available to discuss this package.  To subscribe, send an email to
+// <nullmailer-subscribe@lists.untroubled.org>.
+
+#include <sys/types.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+#include "selfpipe.h"
+
+static int fds[2] = { -1, -1 };
+
+static int fcntl_fl_on(int fd, int flag)
+{
+  int flags;
+  int newflags;
+  if ((flags = fcntl(fd, F_GETFL, 0)) == -1)
+    return 0;
+  if ((newflags = flags | flag) != flags)
+    if (fcntl(fd, F_SETFL, newflags))
+      return 0;
+  return 1;
+}
+
+selfpipe::selfpipe()
+{
+  if (fds[0] < 0) {
+    if (pipe(fds) != -1) {
+      if (fcntl_fl_on(fds[0], O_NONBLOCK)
+	  && fcntl_fl_on(fds[1], O_NONBLOCK)
+	  && fcntl_fl_on(fds[1], FD_CLOEXEC)
+	  && fcntl_fl_on(fds[1], FD_CLOEXEC))
+	return;
+
+      close(fds[0]);
+      close(fds[1]);
+    }
+    fds[0] = fds[1] = -1;
+  }
+}
+
+selfpipe::operator bool() const
+{
+  return fds[0] >= 0;
+}
+
+static void catcher(int sig)
+{
+  signal(sig, catcher);
+  write(fds[1], &sig, sizeof sig);
+}
+
+void selfpipe::catchsig(int sig)
+{
+  signal(sig, catcher);
+}
+
+int selfpipe::caught()
+{
+  int buf;
+  if (read(fds[0], &buf, sizeof buf) == sizeof buf)
+    return buf;
+  return 0;
+}
+
+int selfpipe::waitsig(int timeout)
+{
+  if (timeout > 0) {
+    fd_set fdset;
+    FD_ZERO(&fdset);
+    FD_SET(fds[0], &fdset);
+    struct timeval tv;
+    tv.tv_sec = timeout;
+    tv.tv_usec = 0;
+    int s;
+    while ((s = select(fds[0] + 1, &fdset, 0, 0,
+		     (timeout <= 0) ? 0 : &tv)) == -1) {
+      if (errno != EINTR)
+        return -1;
+    }
+    if (s != 1)
+      return 0;
+  }
+  return caught();
+}