From f261251a9bcee1acc233e7fb96f841a60bb83b2a Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Thu, 28 Jan 2010 10:03:54 +0100
Subject: [PATCH] Add perm option to SHM driver

---
 chrony.texi    | 8 ++++++--
 refclock_shm.c | 7 +++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/chrony.texi b/chrony.texi
index b0235cd..3f7c9b6 100644
--- a/chrony.texi
+++ b/chrony.texi
@@ -2242,14 +2242,18 @@ refclock PPS /dev/pps0
 
 @item SHM
 NTP shared memory driver.  The parameter is the number of the
-shared memory segment that should be used to read timestamps, usually
+shared memory segment that should be used for receiving timestamps, usually
 0, 1, 2 or 3.  For example:
 
 @example
 refclock SHM 1 poll 3 refid GPS1
 @end example
 
-Software that can be used as a source of timestamps includes
+A driver option in form @code{:perm=NNN} can be appended to the
+segment number to create the segment with permissions other than the
+default @code{0600}. 
+
+Software that can be used as a source of reference time includes
 @code{gpsd} and @code{shmpps}.
 @item SOCK
 Unix domain socket driver.  The parameter is a path to the socket
diff --git a/refclock_shm.c b/refclock_shm.c
index b3b689b..ed0c3d0 100644
--- a/refclock_shm.c
+++ b/refclock_shm.c
@@ -56,12 +56,15 @@ struct shmTime {
 };
 
 static int shm_initialise(RCL_Instance instance) {
-  int id, param;
+  int id, param, perm;
+  char *s;
   struct shmTime *shm;
 
   param = atoi(RCL_GetDriverParameter(instance));
+  s = RCL_GetDriverOption(instance, "perm");
+  perm = s ? strtol(s, NULL, 8) : 0600;
 
-  id = shmget(SHMKEY + param, sizeof (struct shmTime), IPC_CREAT | 0700);
+  id = shmget(SHMKEY + param, sizeof (struct shmTime), IPC_CREAT | perm);
   if (id == -1) {
     LOG_FATAL(LOGF_Refclock, "shmget() failed");
     return 0;