Add death tally support to s6-supervise, throttling support to s6_svstatus_t

11 files changed, 158 insertions, 5 deletions

diff --git a/doc/servicedir.html b/doc/servicedir.html
index 06b98b1..cad2cb4 100644
--- a/doc/servicedir.html
+++ b/doc/servicedir.html
@@ -143,6 +143,13 @@ milliseconds after which the <tt>./finish</tt> script, if it exists, will
 be killed with a SIGKILL. The default is 5000: finish scripts are killed
 if they're still alive after 5 seconds. A value of 0 allows finish scripts
 to run forever. </li>
+ <li> An optional regular file named <tt>max-death-tally</tt>. If such a file
+exists, it must only contain an unsigned integer, which is the maximum number of
+service death events that s6-supervise will keep track of. If the service dies
+more than this number of times, the oldest events will be forgotten. Tracking
+death events is useful, for instance, when throttling service restarts. The
+value cannot be greater than 4096. If the file does not exist, a default of 20
+is used. </li>
  <li> A <a href="fifodir.html">fifodir</a> named <tt>event</tt>. It is automatically
 created by <a href="s6-supervise.html">s6-supervise</a> if it does not exist.
 <em>foo</em><tt>/event</tt>
diff --git a/package/deps.mak b/package/deps.mak
index 69650dc..ef1cb47 100644
--- a/package/deps.mak
+++ b/package/deps.mak
@@ -77,6 +77,10 @@ src/libs6/s6_accessrules_keycheck_uidgid.o src/libs6/s6_accessrules_keycheck_uid
 src/libs6/s6_accessrules_params_free.o src/libs6/s6_accessrules_params_free.lo: src/libs6/s6_accessrules_params_free.c src/include/s6/accessrules.h
 src/libs6/s6_accessrules_uidgid_cdb.o src/libs6/s6_accessrules_uidgid_cdb.lo: src/libs6/s6_accessrules_uidgid_cdb.c src/include/s6/accessrules.h
 src/libs6/s6_accessrules_uidgid_fs.o src/libs6/s6_accessrules_uidgid_fs.lo: src/libs6/s6_accessrules_uidgid_fs.c src/include/s6/accessrules.h
+src/libs6/s6_dtally_pack.o src/libs6/s6_dtally_pack.lo: src/libs6/s6_dtally_pack.c src/include/s6/s6-supervise.h
+src/libs6/s6_dtally_read.o src/libs6/s6_dtally_read.lo: src/libs6/s6_dtally_read.c src/include/s6/s6-supervise.h
+src/libs6/s6_dtally_unpack.o src/libs6/s6_dtally_unpack.lo: src/libs6/s6_dtally_unpack.c src/include/s6/s6-supervise.h
+src/libs6/s6_dtally_write.o src/libs6/s6_dtally_write.lo: src/libs6/s6_dtally_write.c src/include/s6/s6-supervise.h
 src/libs6/s6_fdholder_delete.o src/libs6/s6_fdholder_delete.lo: src/libs6/s6_fdholder_delete.c src/include/s6/s6-fdholder.h
 src/libs6/s6_fdholder_delete_async.o src/libs6/s6_fdholder_delete_async.lo: src/libs6/s6_fdholder_delete_async.c src/include/s6/s6-fdholder.h
 src/libs6/s6_fdholder_end.o src/libs6/s6_fdholder_end.lo: src/libs6/s6_fdholder_end.c src/include/s6/s6-fdholder.h
@@ -214,12 +218,12 @@ s6-fdholder-transferdumpc: src/fdholder/s6-fdholder-transferdumpc.o ${LIBS6} -ls
 s6-fdholderd: EXTRA_LIBS := ${SOCKET_LIB} ${TAINNOW_LIB}
 s6-fdholderd: src/fdholder/s6-fdholderd.o ${LIBS6} -lskarnet
 ifeq ($(strip $(STATIC_LIBS_ARE_PIC)),)
-libs6.a.xyzzy: src/libs6/ftrigr1_zero.o src/libs6/ftrigr_check.o src/libs6/ftrigr_checksa.o src/libs6/ftrigr_ack.o src/libs6/ftrigr_end.o src/libs6/ftrigr_start.o src/libs6/ftrigr_startf.o src/libs6/ftrigr_subscribe.o src/libs6/ftrigr_unsubscribe.o src/libs6/ftrigr_update.o src/libs6/ftrigr_updateb.o src/libs6/ftrigr_wait_and.o src/libs6/ftrigr_wait_or.o src/libs6/ftrigr_zero.o src/libs6/ftrigw_clean.o src/libs6/ftrigw_fifodir_make.o src/libs6/ftrigw_notify.o src/libs6/ftrigw_notifyb.o src/libs6/ftrigw_notifyb_nosig.o src/libs6/s6_accessrules_backend_cdb.o src/libs6/s6_accessrules_backend_fs.o src/libs6/s6_accessrules_keycheck_ip4.o src/libs6/s6_accessrules_keycheck_ip6.o src/libs6/s6_accessrules_keycheck_reversedns.o src/libs6/s6_accessrules_keycheck_uidgid.o src/libs6/s6_accessrules_params_free.o src/libs6/s6_accessrules_uidgid_cdb.o src/libs6/s6_accessrules_uidgid_fs.o src/libs6/s6_supervise_lock.o src/libs6/s6_supervise_lock_mode.o src/libs6/s6_svc_lock_take.o src/libs6/s6_svc_lock_release.o src/libs6/s6_svc_ok.o src/libs6/s6_svc_write.o src/libs6/s6_svc_writectl.o src/libs6/s6_svstatus_pack.o src/libs6/s6_svstatus_read.o src/libs6/s6_svstatus_unpack.o src/libs6/s6_svstatus_write.o src/libs6/s6lock_acquire.o src/libs6/s6lock_check.o src/libs6/s6lock_end.o src/libs6/s6lock_release.o src/libs6/s6lock_start.o src/libs6/s6lock_startf.o src/libs6/s6lock_update.o src/libs6/s6lock_wait_and.o src/libs6/s6lock_wait_or.o src/libs6/s6lock_zero.o src/libs6/s6_fdholder_delete.o src/libs6/s6_fdholder_delete_async.o src/libs6/s6_fdholder_end.o src/libs6/s6_fdholder_getdump.o src/libs6/s6_fdholder_list.o src/libs6/s6_fdholder_list_async.o src/libs6/s6_fdholder_list_cb.o src/libs6/s6_fdholder_retrieve.o src/libs6/s6_fdholder_retrieve_async.o src/libs6/s6_fdholder_retrieve_cb.o src/libs6/s6_fdholder_setdump.o src/libs6/s6_fdholder_start.o src/libs6/s6_fdholder_store.o src/libs6/s6_fdholder_store_async.o
+libs6.a.xyzzy: src/libs6/ftrigr1_zero.o src/libs6/ftrigr_check.o src/libs6/ftrigr_checksa.o src/libs6/ftrigr_ack.o src/libs6/ftrigr_end.o src/libs6/ftrigr_start.o src/libs6/ftrigr_startf.o src/libs6/ftrigr_subscribe.o src/libs6/ftrigr_unsubscribe.o src/libs6/ftrigr_update.o src/libs6/ftrigr_updateb.o src/libs6/ftrigr_wait_and.o src/libs6/ftrigr_wait_or.o src/libs6/ftrigr_zero.o src/libs6/ftrigw_clean.o src/libs6/ftrigw_fifodir_make.o src/libs6/ftrigw_notify.o src/libs6/ftrigw_notifyb.o src/libs6/ftrigw_notifyb_nosig.o src/libs6/s6_accessrules_backend_cdb.o src/libs6/s6_accessrules_backend_fs.o src/libs6/s6_accessrules_keycheck_ip4.o src/libs6/s6_accessrules_keycheck_ip6.o src/libs6/s6_accessrules_keycheck_reversedns.o src/libs6/s6_accessrules_keycheck_uidgid.o src/libs6/s6_accessrules_params_free.o src/libs6/s6_accessrules_uidgid_cdb.o src/libs6/s6_accessrules_uidgid_fs.o src/libs6/s6_supervise_lock.o src/libs6/s6_supervise_lock_mode.o src/libs6/s6_dtally_pack.o src/libs6/s6_dtally_unpack.o src/libs6/s6_dtally_read.o src/libs6/s6_dtally_write.o src/libs6/s6_svc_lock_take.o src/libs6/s6_svc_lock_release.o src/libs6/s6_svc_ok.o src/libs6/s6_svc_write.o src/libs6/s6_svc_writectl.o src/libs6/s6_svstatus_pack.o src/libs6/s6_svstatus_read.o src/libs6/s6_svstatus_unpack.o src/libs6/s6_svstatus_write.o src/libs6/s6lock_acquire.o src/libs6/s6lock_check.o src/libs6/s6lock_end.o src/libs6/s6lock_release.o src/libs6/s6lock_start.o src/libs6/s6lock_startf.o src/libs6/s6lock_update.o src/libs6/s6lock_wait_and.o src/libs6/s6lock_wait_or.o src/libs6/s6lock_zero.o src/libs6/s6_fdholder_delete.o src/libs6/s6_fdholder_delete_async.o src/libs6/s6_fdholder_end.o src/libs6/s6_fdholder_getdump.o src/libs6/s6_fdholder_list.o src/libs6/s6_fdholder_list_async.o src/libs6/s6_fdholder_list_cb.o src/libs6/s6_fdholder_retrieve.o src/libs6/s6_fdholder_retrieve_async.o src/libs6/s6_fdholder_retrieve_cb.o src/libs6/s6_fdholder_setdump.o src/libs6/s6_fdholder_start.o src/libs6/s6_fdholder_store.o src/libs6/s6_fdholder_store_async.o
 else
-libs6.a.xyzzy: src/libs6/ftrigr1_zero.lo src/libs6/ftrigr_check.lo src/libs6/ftrigr_checksa.lo src/libs6/ftrigr_ack.lo src/libs6/ftrigr_end.lo src/libs6/ftrigr_start.lo src/libs6/ftrigr_startf.lo src/libs6/ftrigr_subscribe.lo src/libs6/ftrigr_unsubscribe.lo src/libs6/ftrigr_update.lo src/libs6/ftrigr_updateb.lo src/libs6/ftrigr_wait_and.lo src/libs6/ftrigr_wait_or.lo src/libs6/ftrigr_zero.lo src/libs6/ftrigw_clean.lo src/libs6/ftrigw_fifodir_make.lo src/libs6/ftrigw_notify.lo src/libs6/ftrigw_notifyb.lo src/libs6/ftrigw_notifyb_nosig.lo src/libs6/s6_accessrules_backend_cdb.lo src/libs6/s6_accessrules_backend_fs.lo src/libs6/s6_accessrules_keycheck_ip4.lo src/libs6/s6_accessrules_keycheck_ip6.lo src/libs6/s6_accessrules_keycheck_reversedns.lo src/libs6/s6_accessrules_keycheck_uidgid.lo src/libs6/s6_accessrules_params_free.lo src/libs6/s6_accessrules_uidgid_cdb.lo src/libs6/s6_accessrules_uidgid_fs.lo src/libs6/s6_supervise_lock.lo src/libs6/s6_supervise_lock_mode.lo src/libs6/s6_svc_lock_take.lo src/libs6/s6_svc_lock_release.lo src/libs6/s6_svc_ok.lo src/libs6/s6_svc_write.lo src/libs6/s6_svc_writectl.lo src/libs6/s6_svstatus_pack.lo src/libs6/s6_svstatus_read.lo src/libs6/s6_svstatus_unpack.lo src/libs6/s6_svstatus_write.lo src/libs6/s6lock_acquire.lo src/libs6/s6lock_check.lo src/libs6/s6lock_end.lo src/libs6/s6lock_release.lo src/libs6/s6lock_start.lo src/libs6/s6lock_startf.lo src/libs6/s6lock_update.lo src/libs6/s6lock_wait_and.lo src/libs6/s6lock_wait_or.lo src/libs6/s6lock_zero.lo src/libs6/s6_fdholder_delete.lo src/libs6/s6_fdholder_delete_async.lo src/libs6/s6_fdholder_end.lo src/libs6/s6_fdholder_getdump.lo src/libs6/s6_fdholder_list.lo src/libs6/s6_fdholder_list_async.lo src/libs6/s6_fdholder_list_cb.lo src/libs6/s6_fdholder_retrieve.lo src/libs6/s6_fdholder_retrieve_async.lo src/libs6/s6_fdholder_retrieve_cb.lo src/libs6/s6_fdholder_setdump.lo src/libs6/s6_fdholder_start.lo src/libs6/s6_fdholder_store.lo src/libs6/s6_fdholder_store_async.lo
+libs6.a.xyzzy: src/libs6/ftrigr1_zero.lo src/libs6/ftrigr_check.lo src/libs6/ftrigr_checksa.lo src/libs6/ftrigr_ack.lo src/libs6/ftrigr_end.lo src/libs6/ftrigr_start.lo src/libs6/ftrigr_startf.lo src/libs6/ftrigr_subscribe.lo src/libs6/ftrigr_unsubscribe.lo src/libs6/ftrigr_update.lo src/libs6/ftrigr_updateb.lo src/libs6/ftrigr_wait_and.lo src/libs6/ftrigr_wait_or.lo src/libs6/ftrigr_zero.lo src/libs6/ftrigw_clean.lo src/libs6/ftrigw_fifodir_make.lo src/libs6/ftrigw_notify.lo src/libs6/ftrigw_notifyb.lo src/libs6/ftrigw_notifyb_nosig.lo src/libs6/s6_accessrules_backend_cdb.lo src/libs6/s6_accessrules_backend_fs.lo src/libs6/s6_accessrules_keycheck_ip4.lo src/libs6/s6_accessrules_keycheck_ip6.lo src/libs6/s6_accessrules_keycheck_reversedns.lo src/libs6/s6_accessrules_keycheck_uidgid.lo src/libs6/s6_accessrules_params_free.lo src/libs6/s6_accessrules_uidgid_cdb.lo src/libs6/s6_accessrules_uidgid_fs.lo src/libs6/s6_supervise_lock.lo src/libs6/s6_supervise_lock_mode.lo src/libs6/s6_dtally_pack.lo src/libs6/s6_dtally_unpack.lo src/libs6/s6_dtally_read.lo src/libs6/s6_dtally_write.lo src/libs6/s6_svc_lock_take.lo src/libs6/s6_svc_lock_release.lo src/libs6/s6_svc_ok.lo src/libs6/s6_svc_write.lo src/libs6/s6_svc_writectl.lo src/libs6/s6_svstatus_pack.lo src/libs6/s6_svstatus_read.lo src/libs6/s6_svstatus_unpack.lo src/libs6/s6_svstatus_write.lo src/libs6/s6lock_acquire.lo src/libs6/s6lock_check.lo src/libs6/s6lock_end.lo src/libs6/s6lock_release.lo src/libs6/s6lock_start.lo src/libs6/s6lock_startf.lo src/libs6/s6lock_update.lo src/libs6/s6lock_wait_and.lo src/libs6/s6lock_wait_or.lo src/libs6/s6lock_zero.lo src/libs6/s6_fdholder_delete.lo src/libs6/s6_fdholder_delete_async.lo src/libs6/s6_fdholder_end.lo src/libs6/s6_fdholder_getdump.lo src/libs6/s6_fdholder_list.lo src/libs6/s6_fdholder_list_async.lo src/libs6/s6_fdholder_list_cb.lo src/libs6/s6_fdholder_retrieve.lo src/libs6/s6_fdholder_retrieve_async.lo src/libs6/s6_fdholder_retrieve_cb.lo src/libs6/s6_fdholder_setdump.lo src/libs6/s6_fdholder_start.lo src/libs6/s6_fdholder_store.lo src/libs6/s6_fdholder_store_async.lo
 endif
 libs6.so.xyzzy: EXTRA_LIBS := -lskarnet
-libs6.so.xyzzy: src/libs6/ftrigr1_zero.lo src/libs6/ftrigr_check.lo src/libs6/ftrigr_checksa.lo src/libs6/ftrigr_ack.lo src/libs6/ftrigr_end.lo src/libs6/ftrigr_start.lo src/libs6/ftrigr_startf.lo src/libs6/ftrigr_subscribe.lo src/libs6/ftrigr_unsubscribe.lo src/libs6/ftrigr_update.lo src/libs6/ftrigr_updateb.lo src/libs6/ftrigr_wait_and.lo src/libs6/ftrigr_wait_or.lo src/libs6/ftrigr_zero.lo src/libs6/ftrigw_clean.lo src/libs6/ftrigw_fifodir_make.lo src/libs6/ftrigw_notify.lo src/libs6/ftrigw_notifyb.lo src/libs6/ftrigw_notifyb_nosig.lo src/libs6/s6_accessrules_backend_cdb.lo src/libs6/s6_accessrules_backend_fs.lo src/libs6/s6_accessrules_keycheck_ip4.lo src/libs6/s6_accessrules_keycheck_ip6.lo src/libs6/s6_accessrules_keycheck_reversedns.lo src/libs6/s6_accessrules_keycheck_uidgid.lo src/libs6/s6_accessrules_params_free.lo src/libs6/s6_accessrules_uidgid_cdb.lo src/libs6/s6_accessrules_uidgid_fs.lo src/libs6/s6_supervise_lock.lo src/libs6/s6_supervise_lock_mode.lo src/libs6/s6_svc_lock_take.lo src/libs6/s6_svc_lock_release.lo src/libs6/s6_svc_ok.lo src/libs6/s6_svc_write.lo src/libs6/s6_svc_writectl.lo src/libs6/s6_svstatus_pack.lo src/libs6/s6_svstatus_read.lo src/libs6/s6_svstatus_unpack.lo src/libs6/s6_svstatus_write.lo src/libs6/s6lock_acquire.lo src/libs6/s6lock_check.lo src/libs6/s6lock_end.lo src/libs6/s6lock_release.lo src/libs6/s6lock_start.lo src/libs6/s6lock_startf.lo src/libs6/s6lock_update.lo src/libs6/s6lock_wait_and.lo src/libs6/s6lock_wait_or.lo src/libs6/s6lock_zero.lo src/libs6/s6_fdholder_delete.lo src/libs6/s6_fdholder_delete_async.lo src/libs6/s6_fdholder_end.lo src/libs6/s6_fdholder_getdump.lo src/libs6/s6_fdholder_list.lo src/libs6/s6_fdholder_list_async.lo src/libs6/s6_fdholder_list_cb.lo src/libs6/s6_fdholder_retrieve.lo src/libs6/s6_fdholder_retrieve_async.lo src/libs6/s6_fdholder_retrieve_cb.lo src/libs6/s6_fdholder_setdump.lo src/libs6/s6_fdholder_start.lo src/libs6/s6_fdholder_store.lo src/libs6/s6_fdholder_store_async.lo
+libs6.so.xyzzy: src/libs6/ftrigr1_zero.lo src/libs6/ftrigr_check.lo src/libs6/ftrigr_checksa.lo src/libs6/ftrigr_ack.lo src/libs6/ftrigr_end.lo src/libs6/ftrigr_start.lo src/libs6/ftrigr_startf.lo src/libs6/ftrigr_subscribe.lo src/libs6/ftrigr_unsubscribe.lo src/libs6/ftrigr_update.lo src/libs6/ftrigr_updateb.lo src/libs6/ftrigr_wait_and.lo src/libs6/ftrigr_wait_or.lo src/libs6/ftrigr_zero.lo src/libs6/ftrigw_clean.lo src/libs6/ftrigw_fifodir_make.lo src/libs6/ftrigw_notify.lo src/libs6/ftrigw_notifyb.lo src/libs6/ftrigw_notifyb_nosig.lo src/libs6/s6_accessrules_backend_cdb.lo src/libs6/s6_accessrules_backend_fs.lo src/libs6/s6_accessrules_keycheck_ip4.lo src/libs6/s6_accessrules_keycheck_ip6.lo src/libs6/s6_accessrules_keycheck_reversedns.lo src/libs6/s6_accessrules_keycheck_uidgid.lo src/libs6/s6_accessrules_params_free.lo src/libs6/s6_accessrules_uidgid_cdb.lo src/libs6/s6_accessrules_uidgid_fs.lo src/libs6/s6_supervise_lock.lo src/libs6/s6_supervise_lock_mode.lo src/libs6/s6_dtally_pack.lo src/libs6/s6_dtally_unpack.lo src/libs6/s6_dtally_read.lo src/libs6/s6_dtally_write.lo src/libs6/s6_svc_lock_take.lo src/libs6/s6_svc_lock_release.lo src/libs6/s6_svc_ok.lo src/libs6/s6_svc_write.lo src/libs6/s6_svc_writectl.lo src/libs6/s6_svstatus_pack.lo src/libs6/s6_svstatus_read.lo src/libs6/s6_svstatus_unpack.lo src/libs6/s6_svstatus_write.lo src/libs6/s6lock_acquire.lo src/libs6/s6lock_check.lo src/libs6/s6lock_end.lo src/libs6/s6lock_release.lo src/libs6/s6lock_start.lo src/libs6/s6lock_startf.lo src/libs6/s6lock_update.lo src/libs6/s6lock_wait_and.lo src/libs6/s6lock_wait_or.lo src/libs6/s6lock_zero.lo src/libs6/s6_fdholder_delete.lo src/libs6/s6_fdholder_delete_async.lo src/libs6/s6_fdholder_end.lo src/libs6/s6_fdholder_getdump.lo src/libs6/s6_fdholder_list.lo src/libs6/s6_fdholder_list_async.lo src/libs6/s6_fdholder_list_cb.lo src/libs6/s6_fdholder_retrieve.lo src/libs6/s6_fdholder_retrieve_async.lo src/libs6/s6_fdholder_retrieve_cb.lo src/libs6/s6_fdholder_setdump.lo src/libs6/s6_fdholder_start.lo src/libs6/s6_fdholder_store.lo src/libs6/s6_fdholder_store_async.lo
 s6-ftrigrd: EXTRA_LIBS := ${SOCKET_LIB} ${TAINNOW_LIB}
 s6-ftrigrd: src/libs6/s6-ftrigrd.o src/libs6/ftrig1_free.o src/libs6/ftrig1_make.o -lskarnet
 s6lockd: EXTRA_LIBS := ${SOCKET_LIB} ${TAINNOW_LIB} ${SPAWN_LIB}
diff --git a/src/include/s6/s6-supervise.h b/src/include/s6/s6-supervise.h
index bbd8539..187bc20 100644
--- a/src/include/s6/s6-supervise.h
+++ b/src/include/s6/s6-supervise.h
@@ -11,6 +11,8 @@
 #define S6_SVSCAN_CTLDIR ".s6-svscan"
 #define S6_SVSTATUS_FILENAME S6_SUPERVISE_CTLDIR "/status"
 #define S6_SVSTATUS_SIZE 35
+#define S6_DTALLY_FILENAME S6_SUPERVISE_CTLDIR "/death_tally"
+#define S6_MAX_DEATH_TALLY 4096
 
 extern int s6_svc_ok (char const *) ;
 extern int s6_svc_write (char const *, char const *, size_t) ;
@@ -32,6 +34,7 @@ struct s6_svstatus_s
   unsigned int flagwant : 1 ; /* unused */
   unsigned int flagwantup : 1 ;
   unsigned int flagready : 1 ;
+  unsigned int flagthrottled : 1 ;
 } ;
 
 #define S6_SVSTATUS_ZERO \
@@ -44,7 +47,8 @@ struct s6_svstatus_s
   .flagfinishing = 0, \
   .flagwant = 1, \
   .flagwantup = 1, \
-  .flagready = 1 \
+  .flagready = 1, \
+  .flagthrottled = 0 \
 }
 
 extern void s6_svstatus_pack (char *, s6_svstatus_t const *) ;
@@ -56,4 +60,20 @@ extern int s6_svstatus_write (char const *, s6_svstatus_t const *) ;
 extern int s6_supervise_lock (char const *) ;
 extern int s6_supervise_lock_mode (char const *, unsigned int, unsigned int) ;
 
+typedef struct s6_dtally_s s6_dtally_t, *s6_dtally_ref ;
+struct s6_dtally_s
+{
+  tain_t stamp ;
+  unsigned char exitcode ;
+  unsigned char sig ;
+} ;
+#define S6_DTALLY_ZERO { .stamp = TAIN_ZERO, .exitcode = 0, .sig = 0 }
+
+#define S6_DTALLY_PACK (TAIN_PACK + 2)
+
+extern void s6_dtally_pack (char *, s6_dtally_t const *) ;
+extern void s6_dtally_unpack (char const *, s6_dtally_t *) ;
+extern ssize_t s6_dtally_read (char const *, s6_dtally_t *, size_t) ;
+extern int s6_dtally_write (char const *, s6_dtally_t const *, size_t) ;
+
 #endif
diff --git a/src/libs6/deps-lib/s6 b/src/libs6/deps-lib/s6
index 47a3335..65612cc 100644
--- a/src/libs6/deps-lib/s6
+++ b/src/libs6/deps-lib/s6
@@ -28,6 +28,10 @@ s6_accessrules_uidgid_cdb.o
 s6_accessrules_uidgid_fs.o
 s6_supervise_lock.o
 s6_supervise_lock_mode.o
+s6_dtally_pack.o
+s6_dtally_unpack.o
+s6_dtally_read.o
+s6_dtally_write.o
 s6_svc_lock_take.o
 s6_svc_lock_release.o
 s6_svc_ok.o
diff --git a/src/libs6/s6_dtally_pack.c b/src/libs6/s6_dtally_pack.c
new file mode 100644
index 0000000..1608e78
--- /dev/null
+++ b/src/libs6/s6_dtally_pack.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#include <skalibs/tai.h>
+#include <s6/s6-supervise.h>
+
+void s6_dtally_pack (char *pack, s6_dtally_t const *d)
+{
+  tain_pack(pack, &d->stamp) ;
+  pack[TAIN_PACK] = d->exitcode ;
+  pack[TAIN_PACK + 1] = d->sig ;
+}
diff --git a/src/libs6/s6_dtally_read.c b/src/libs6/s6_dtally_read.c
new file mode 100644
index 0000000..3906b93
--- /dev/null
+++ b/src/libs6/s6_dtally_read.c
@@ -0,0 +1,51 @@
+/* ISC license. */
+
+#include <sys/stat.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/tai.h>
+#include <skalibs/djbunix.h>
+#include <s6/s6-supervise.h>
+
+static int truncit (char const *s)
+{
+  int fd = open_trunc(s) ;
+  if (fd < 0) return -1 ;
+  fd_close(fd) ;
+  return 0 ;
+}
+
+ssize_t s6_dtally_read (char const *sv, s6_dtally_t *tab, size_t max)
+{
+  size_t len = strlen(sv) ;
+  size_t n ;
+  int fd ;
+  struct stat st ;
+  char fn[len + sizeof(S6_DTALLY_FILENAME) + 1] ;
+  memcpy(fn, sv, len) ;
+  memcpy(fn + len, "/" S6_DTALLY_FILENAME, sizeof(S6_DTALLY_FILENAME) + 1) ;
+  fd = open_read(fn) ;
+  if (fd < 0) return errno == ENOENT ? truncit(fn) : -1 ;
+  if (fstat(fd, &st) < 0) goto err ;
+  if (st.st_size % S6_DTALLY_PACK)
+  {
+    fd_close(fd) ;
+    return truncit(fn) ;
+  }
+  n = st.st_size / S6_DTALLY_PACK ;
+  if (n > max) n = max ;
+  {
+    char tmp[n ? S6_DTALLY_PACK * n : 1] ;
+    if (lseek(fd, -(off_t)(n * S6_DTALLY_PACK), SEEK_END) < 0) goto err ;
+    if (allread(fd, tmp, n * S6_DTALLY_PACK) < n * S6_DTALLY_PACK) goto err ;
+    fd_close(fd) ;
+    for (size_t i = 0 ; i < n ; i++) s6_dtally_unpack(tmp + i * S6_DTALLY_PACK, tab + i) ;
+  }
+  return n ;
+
+ err:
+  fd_close(fd) ;
+  return -1 ;
+}
diff --git a/src/libs6/s6_dtally_unpack.c b/src/libs6/s6_dtally_unpack.c
new file mode 100644
index 0000000..8fca787
--- /dev/null
+++ b/src/libs6/s6_dtally_unpack.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#include <skalibs/tai.h>
+#include <s6/s6-supervise.h>
+
+void s6_dtally_unpack (char const *pack, s6_dtally_t *d)
+{
+  tain_unpack(pack, &d->stamp) ;
+  d->exitcode = pack[TAIN_PACK] ;
+  d->sig = pack[TAIN_PACK + 1] ;
+}
diff --git a/src/libs6/s6_dtally_write.c b/src/libs6/s6_dtally_write.c
new file mode 100644
index 0000000..785376a
--- /dev/null
+++ b/src/libs6/s6_dtally_write.c
@@ -0,0 +1,16 @@
+/* ISC license. */
+
+#include <string.h>
+#include <skalibs/djbunix.h>
+#include <s6/s6-supervise.h>
+
+int s6_dtally_write (char const *sv, s6_dtally_t const *tab, size_t n)
+{
+  size_t len = strlen(sv) ;
+  char fn[len + sizeof(S6_DTALLY_FILENAME) + 1] ;
+  char tmp[n ? S6_DTALLY_PACK * n : 1] ;
+  memcpy(fn, sv, len) ;
+  memcpy(fn + len, "/" S6_DTALLY_FILENAME, sizeof(S6_DTALLY_FILENAME) + 1) ;
+  for (size_t i = 0 ; i < n ; i++) s6_dtally_pack(tmp + i * S6_DTALLY_PACK, tab + i) ;
+  return openwritenclose_suffix(fn, tmp, n * S6_DTALLY_PACK, ".new") ;
+}
diff --git a/src/libs6/s6_svstatus_pack.c b/src/libs6/s6_svstatus_pack.c
index fbce109..ef2d5bd 100644
--- a/src/libs6/s6_svstatus_pack.c
+++ b/src/libs6/s6_svstatus_pack.c
@@ -17,5 +17,6 @@ void s6_svstatus_pack (char *pack, s6_svstatus_t const *sv)
     (sv->flagfinishing << 1) |
     (sv->flagwant << 2) |
     (sv->flagwantup << 3) |
-    (sv->flagready << 4) ;
+    (sv->flagready << 4) |
+    (sv->flagthrottled << 5) ;
 }
diff --git a/src/libs6/s6_svstatus_unpack.c b/src/libs6/s6_svstatus_unpack.c
index dc358d3..b641c8c 100644
--- a/src/libs6/s6_svstatus_unpack.c
+++ b/src/libs6/s6_svstatus_unpack.c
@@ -21,4 +21,5 @@ void s6_svstatus_unpack (char const *pack, s6_svstatus_t *sv)
   sv->flagwant = !!(pack[34] & 4) ;
   sv->flagwantup = !!(pack[34] & 8) ;
   sv->flagready = !!(pack[34] & 16) ;
+  sv->flagthrottled = !!(pack[34] & 32) ;
 }
diff --git a/src/supervision/s6-supervise.c b/src/supervision/s6-supervise.c
index 71f247e..00c2358 100644
--- a/src/supervision/s6-supervise.c
+++ b/src/supervision/s6-supervise.c
@@ -332,6 +332,7 @@ static int uplastup_z (void)
   status.wstat = (int)status.pid ;
   status.flagpaused = 0 ;
   status.flagready = 0 ;
+  status.flagthrottled = 0 ;
   flagdying = 0 ;
   tain_copynow(&status.stamp) ;
   if (notifyfd >= 0)
@@ -339,6 +340,27 @@ static int uplastup_z (void)
     fd_close(notifyfd) ;
     notifyfd = -1 ;
   }
+
+  {
+    unsigned int n ;
+    if (!read_uint("max-death-tally", &n)) n = 20 ;
+    if (n > S6_MAX_DEATH_TALLY) n = S6_MAX_DEATH_TALLY ;
+    if (n)
+    {
+      s6_dtally_t tab[n+1] ;
+      ssize_t m = s6_dtally_read(".", tab, n) ;
+      if (m < 0) strerr_warnwu2sys("read ", S6_DTALLY_FILENAME) ;
+      else
+      {
+        tab[m].stamp = status.stamp ;
+        tab[m].sig = WIFSIGNALED(status.wstat) ? WTERMSIG(status.wstat) : 0 ;
+        tab[m].exitcode = WIFSIGNALED(status.wstat) ? 128 + WTERMSIG(status.wstat) : WEXITSTATUS(status.wstat) ;
+        if (m >= n ? s6_dtally_write(".", tab+1, n) : s6_dtally_write(".", tab, m+1))
+          strerr_warnwu2sys("write ", S6_DTALLY_FILENAME) ;
+      }
+    }
+  }
+
   status.pid = fork() ;
   if (status.pid < 0)
   {
@@ -617,6 +639,11 @@ int main (int argc, char const *const *argv)
     
     if (!ftrigw_clean(S6_SUPERVISE_EVENTDIR))
       strerr_warnwu2sys("ftrigw_clean ", S6_SUPERVISE_EVENTDIR) ;
+    {
+      int fd = open_trunc(S6_DTALLY_FILENAME) ;
+      if (fd < 0) strerr_diefu2sys(111, "truncate ", S6_DTALLY_FILENAME) ;
+      fd_close(fd) ;
+    }
 
     if (access("down", F_OK) == 0) status.flagwantup = 0 ;
     else if (errno != ENOENT)