[chrony-dev] [RFC PATCH v1 04/17] configure: Add configuration parameters for auxiliary clock support on Linux

[Christopher S M Hall <christopher.s.hall@xxxxxxxxx>]

Add a new capability (HAVE_CLOCK_ADJTIME) for use of clock_adjtime() rather than adjtimex() or ntp_adjtime().
This is needed to make adjustments to the auxiliary clock on Linux builds. Currently, it only enabled on
Linux builds, but could be added to others.

Add a new feature for auxiliary clocks (FEAT_AUXCLOCK) for Linux builds only. Most of the auxiliary clock
code is contained with #ifdef FEAT_AUXCLOCK... #endif.

Since the auxiliary clock requires clock_adjtime() a check is needed. Add a function to check for
capabilities [get_capabilities] not only features. The get_capabilities and get_features functions use
common code.
---
 configure | 50 ++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 44 insertions(+), 6 deletions(-)

diff --git a/configure b/configure
index 4f4d155..c1a7150 100755
--- a/configure
+++ b/configure
@@ -130,6 +130,8 @@ For better control, use the options below.
   --without-clock-gettime Don't use clock_gettime() even if it is available
   --disable-timestamping Disable support for SW/HW timestamping
   --enable-ntp-signd     Enable support for MS-SNTP authentication in Samba
+  --without-clock-adjtime Don't use clock_adjtime even if it is available
+  --enable-auxclocks     Enable use of Linux auxiliary system clocks
   --with-ntp-era=SECONDS Specify earliest assumed NTP time in seconds
                          since 1970-01-01 [50*365 days ago]
   --with-user=USER       Specify default chronyd user [root]
@@ -185,14 +187,16 @@ add_def () {
   fi
 }
 #}}}
-#{{{ get_features
-get_features () {
+#{{{ get_config
+get_config () {
+  prefix=$1
+  shift
   ff=1
   for f; do
     if [ "$ff" = "0" ]; then
       printf " "
     fi
-    if grep "define FEAT_$f" config.h > /dev/null; then
+    if grep "define ${prefix}_$f" config.h > /dev/null; then
       printf "%s" "+$f"
     else
       printf "%s" "-$f"
@@ -201,7 +205,16 @@ get_features () {
   done
 }
 #}}}
-
+#{{{ get_features
+get_features () {
+  get_config FEAT $@
+}
+#}}}
+#{{{ get_capabilities
+get_capabilities () {
+  get_config HAVE $@
+}
+#}}}
 # ======================================================================
 
 
@@ -256,7 +269,10 @@ default_hwclockfile=""
 default_pidfile="/var/run/chrony/chronyd.pid"
 default_rtcdevice="/dev/rtc"
 mail_program="/usr/lib/sendmail"
-
+feat_clockadjtime=1
+try_clockadjtime=0
+feat_auxclock=0
+try_auxclock=0
 for option
 do
     case "$option" in
@@ -389,6 +405,12 @@ do
     --without-gnutls )
       try_gnutls=0
     ;;
+    --enable-auxclock | --enable-auxclocks )
+      feat_auxclock=1
+    ;;
+    --without-clockadjtime )
+      feat_clockadjtime=0
+    ;;
     --host-system=* )
       OPERATINGSYSTEM=`echo $option | sed -e 's/^.*=//;'`
     ;;
@@ -422,6 +444,8 @@ case $OPERATINGSYSTEM in
         try_lockmem=1
         try_phc=1
         try_arc4random=0
+        try_clockadjtime=1
+        try_auxclock=1
         add_def LINUX
         echo "Configuring for " $SYSTEM
     ;;
@@ -1032,6 +1056,20 @@ if [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
   fi
 fi
 
+if [ $feat_clockadjtime = "1" ] && [ $try_clockadjtime = "1" ] &&
+     test_code 'clock_adjtime()' 'time.h' '' '' \
+     'struct timex timex0; clock_adjtime (CLOCK_REALTIME, &timex0);'; then
+   add_def HAVE_CLOCK_ADJTIME
+fi
+
+if [ $feat_auxclock = "1" ] && [ $try_auxclock = "1" ] &&
+     [ $(get_capabilities CLOCK_ADJTIME | cut -c 1) = '+' ] &&
+     [ $(get_capabilities CLOCK_GETTIME | cut -c 1) = '+' ] &&
+     test_code 'Linux auxiliary clock support' 'linux/time.h assert.h' '' '' \
+     'assert (CLOCK_AUX_LAST == (CLOCK_AUX + MAX_AUX_CLOCKS - 1));'; then
+   add_def FEAT_AUXCLOCK
+fi
+
 SYSCONFDIR=/etc
 if [ "x$SETSYSCONFDIR" != "x" ]; then
   SYSCONFDIR=$SETSYSCONFDIR
@@ -1098,7 +1136,7 @@ add_def MAIL_PROGRAM "\"$mail_program\""
 
 common_features="`get_features SECHASH IPV6 DEBUG`"
 chronyc_features="`get_features READLINE`"
-chronyd_features="`get_features CMDMON REFCLOCK RTC PRIVDROP SCFILTER SIGND NTS`"
+chronyd_features="`get_features AUXCLOCK CMDMON REFCLOCK RTC PRIVDROP SCFILTER SIGND NTS`"
 add_def CHRONYC_FEATURES "\"$chronyc_features $common_features\""
 add_def CHRONYD_FEATURES "\"$chronyd_features $common_features\""
 echo "Features : $chronyd_features $chronyc_features $common_features"
-- 
2.34.1


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