1 files changed, 111 insertions, 0 deletions
diff --git a/src/util/fifo_listen.c b/src/util/fifo_listen.c
new file mode 100644
index 0000000..9ad3440
--- /dev/null
+++ b/src/util/fifo_listen.c
@@ -0,0 +1,111 @@
+/*++
+/* NAME
+/*	fifo_listen 3
+/* SUMMARY
+/*	start fifo listener
+/* SYNOPSIS
+/*	#include <listen.h>
+/*
+/*	int	fifo_listen(path, permissions, block_mode)
+/*	const char *path;
+/*	int	permissions;
+/*	int	block_mode;
+/* DESCRIPTION
+/*	The \fBfifo_listen\fR routine creates the specified named pipe with
+/*	the specified permissions, opens the FIFO read-write or read-only,
+/*	depending on the host operating system, and returns the resulting
+/*	file descriptor.
+/*	The \fIblock_mode\fR argument is either NON_BLOCKING for
+/*	a non-blocking socket, or BLOCKING for blocking mode.
+/* DIAGNOSTICS
+/*	Fatal errors: all system call failures.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System interfaces. */
+
+#include <sys_defs.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/* Utility library. */
+
+#include "msg.h"
+#include "iostuff.h"
+#include "listen.h"
+#include "warn_stat.h"
+
+#define BUF_LEN	100
+
+/* fifo_listen - create fifo listener */
+
+int     fifo_listen(const char *path, int permissions, int block_mode)
+{
+    char    buf[BUF_LEN];
+    static int open_mode = 0;
+    const char *myname = "fifo_listen";
+    struct stat st;
+    int     fd;
+    int     count;
+
+    /*
+     * Create a named pipe (fifo). Do whatever we can so we don't run into
+     * trouble when this process is restarted after crash.  Make sure that we
+     * open a fifo and not something else, then change permissions to what we
+     * wanted them to be, because mkfifo() is subject to umask settings.
+     * Instead we could zero the umask temporarily before creating the FIFO,
+     * but that would cost even more system calls. Figure out if the fifo
+     * needs to be opened O_RDWR or O_RDONLY. Some systems need one, some
+     * need the other. If we choose the wrong mode, the fifo will stay
+     * readable, causing the program to go into a loop.
+     */
+    if (unlink(path) && errno != ENOENT)
+	msg_fatal("%s: remove %s: %m", myname, path);
+    if (mkfifo(path, permissions) < 0)
+	msg_fatal("%s: create fifo %s: %m", myname, path);
+    switch (open_mode) {
+    case 0:
+	if ((fd = open(path, O_RDWR | O_NONBLOCK, 0)) < 0)
+	    msg_fatal("%s: open %s: %m", myname, path);
+	if (readable(fd) == 0) {
+	    open_mode = O_RDWR | O_NONBLOCK;
+	    break;
+	} else {
+	    open_mode = O_RDONLY | O_NONBLOCK;
+	    if (msg_verbose)
+		msg_info("open O_RDWR makes fifo readable - trying O_RDONLY");
+	    (void) close(fd);
+	    /* FALLTRHOUGH */
+	}
+    default:
+	if ((fd = open(path, open_mode, 0)) < 0)
+	    msg_fatal("%s: open %s: %m", myname, path);
+	break;
+    }
+
+    /*
+     * Make sure we opened a FIFO and skip any cruft that might have
+     * accumulated before we opened it.
+     */
+    if (fstat(fd, &st) < 0)
+	msg_fatal("%s: fstat %s: %m", myname, path);
+    if (S_ISFIFO(st.st_mode) == 0)
+	msg_fatal("%s: not a fifo: %s", myname, path);
+    if (fchmod(fd, permissions) < 0)
+	msg_fatal("%s: fchmod %s: %m", myname, path);
+    non_blocking(fd, block_mode);
+    while ((count = peekfd(fd)) > 0
+	   && read(fd, buf, BUF_LEN < count ? BUF_LEN : count) > 0)
+	 /* void */ ;
+    return (fd);
+}