1 files changed, 82 insertions, 0 deletions
diff --git a/src/global/deliver_flock.c b/src/global/deliver_flock.c
new file mode 100644
index 0000000..35a6bcb
--- /dev/null
+++ b/src/global/deliver_flock.c
@@ -0,0 +1,82 @@
+/*++
+/* NAME
+/*	deliver_flock 3
+/* SUMMARY
+/*	lock open file for mail delivery
+/* SYNOPSIS
+/*	#include <deliver_flock.h>
+/*
+/*	int	deliver_flock(fd, lock_style, why)
+/*	int	fd;
+/*	int	lock_style;
+/*	VSTRING	*why;
+/* DESCRIPTION
+/*	deliver_flock() sets one exclusive kernel lock on an open file,
+/*	for example in order to deliver mail.
+/*	It performs several non-blocking attempts to acquire an exclusive
+/*	lock before giving up.
+/*
+/*	Arguments:
+/* .IP fd
+/*	A file descriptor that is associated with an open file.
+/* .IP lock_style
+/*	A locking style defined in myflock(3).
+/* .IP why
+/*	A null pointer, or storage for diagnostics.
+/* DIAGNOSTICS
+/*	deliver_flock() returns -1 in case of problems, 0 in case
+/*	of success. The reason for failure is returned via the \fIwhy\fR
+/*	parameter.
+/* CONFIGURATION PARAMETERS
+/*	deliver_lock_attempts, number of locking attempts
+/*	deliver_lock_delay, time in seconds between attempts
+/*	sun_mailtool_compatibility, disable kernel locking
+/* 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 library. */
+
+#include "sys_defs.h"
+#include <unistd.h>
+
+/* Utility library. */
+
+#include <vstring.h>
+#include <myflock.h>
+#include <iostuff.h>
+
+/* Global library. */
+
+#include "mail_params.h"
+#include "deliver_flock.h"
+
+/* Application-specific. */
+
+#define MILLION	1000000
+
+/* deliver_flock - lock open file for mail delivery */
+
+int     deliver_flock(int fd, int lock_style, VSTRING *why)
+{
+    int     i;
+
+    for (i = 1; /* void */ ; i++) {
+	if (myflock(fd, lock_style,
+		    MYFLOCK_OP_EXCLUSIVE | MYFLOCK_OP_NOWAIT) == 0)
+	    return (0);
+	if (i >= var_flock_tries)
+	    break;
+	rand_sleep(var_flock_delay * MILLION, var_flock_delay * MILLION / 2);
+    }
+    if (why)
+	vstring_sprintf(why, "unable to lock for exclusive access: %m");
+    return (-1);
+}