Add s6_svc_lock_take() and s6_svc_lock_release()

 Allows fixing a race condition in s6-rc-init.
 s6-supervise also creates event/ before supervise/ so that
locking the servicedir ensures event/ can be used.

9 files changed, 53 insertions, 5 deletions

diff --git a/NEWS b/NEWS
index fafb9c6..e352e5e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,12 @@
 Changelog for s6.
 
+In 2.6.0.1
+----------
+ - Bugfixes.
+ - Addition of the s6_svc_lock_take() and s6_svc_lock_release()
+functions, to fix a race condition in s6-rc.
+
+
 In 2.6.0.0
 ----------
 
diff --git a/doc/index.html b/doc/index.html
index 636d015..8f15a5e 100644
--- a/doc/index.html
+++ b/doc/index.html
@@ -100,7 +100,7 @@ library. </li>
 <h3> Download </h3>
 
 <ul>
- <li> The current released version of s6 is <a href="s6-2.6.0.0.tar.gz">2.6.0.0</a>. </li>
+ <li> The current released version of s6 is <a href="s6-2.6.0.1.tar.gz">2.6.0.1</a>. </li>
  <li> Alternatively, you can checkout a copy of the
 <a href="//git.skarnet.org/cgi-bin/cgit.cgi/s6/">s6
 git repository</a>:
diff --git a/doc/upgrade.html b/doc/upgrade.html
index df5cb3b..0b599c1 100644
--- a/doc/upgrade.html
+++ b/doc/upgrade.html
@@ -18,6 +18,13 @@
 
 <h1> What has changed in s6 </h1>
 
+<h2> in 2.6.0.1 </h2>
+
+<ul>
+ <li> No functional changes. Additions of a few interfaces to libs6
+in order to fix a race condition in s6-rc. </li>
+</ul>
+
 <h2> in 2.6.0.0 </h2>
 
 <ul>
diff --git a/package/deps.mak b/package/deps.mak
index 8d485ca..82fcc61 100644
--- a/package/deps.mak
+++ b/package/deps.mak
@@ -89,6 +89,7 @@ src/libs6/s6_fdholder_store.o src/libs6/s6_fdholder_store.lo: src/libs6/s6_fdhol
 src/libs6/s6_fdholder_store_async.o src/libs6/s6_fdholder_store_async.lo: src/libs6/s6_fdholder_store_async.c src/include/s6/s6-fdholder.h
 src/libs6/s6_supervise_lock.o src/libs6/s6_supervise_lock.lo: src/libs6/s6_supervise_lock.c src/include/s6/s6-supervise.h
 src/libs6/s6_supervise_lock_mode.o src/libs6/s6_supervise_lock_mode.lo: src/libs6/s6_supervise_lock_mode.c src/include/s6/s6-supervise.h
+src/libs6/s6_svc_lock_take.o src/libs6/s6_svc_lock_take.lo: src/libs6/s6_svc_lock_take.c src/include/s6/s6-supervise.h
 src/libs6/s6_svc_ok.o src/libs6/s6_svc_ok.lo: src/libs6/s6_svc_ok.c src/include/s6/s6-supervise.h
 src/libs6/s6_svc_write.o src/libs6/s6_svc_write.lo: src/libs6/s6_svc_write.c src/include/s6/s6-supervise.h
 src/libs6/s6_svc_writectl.o src/libs6/s6_svc_writectl.lo: src/libs6/s6_svc_writectl.c src/include/s6/s6-supervise.h
@@ -206,9 +207,9 @@ s6-fdholder-transferdumpc: EXTRA_LIBS := ${SOCKET_LIB} ${TAINNOW_LIB}
 s6-fdholder-transferdumpc: src/fdholder/s6-fdholder-transferdumpc.o ${LIBS6} -lskarnet
 s6-fdholderd: EXTRA_LIBS := ${SOCKET_LIB} ${TAINNOW_LIB}
 s6-fdholderd: src/fdholder/s6-fdholderd.o ${LIBS6} -lskarnet
-libs6.a.xyzzy: src/libs6/ftrigr1_zero.o src/libs6/ftrigr_check.o src/libs6/ftrigr_checksa.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_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_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_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_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_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_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_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_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_store.o src/libs6/s6_fdholder_store_async.o
 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_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_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_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_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_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_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_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_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_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_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/package/info b/package/info
index 4cc1ef8..5eddbcd 100644
--- a/package/info
+++ b/package/info
@@ -1,4 +1,4 @@
 package=s6
-version=2.6.0.0
+version=2.6.0.1
 category=admin
 package_macro_name=S6
diff --git a/src/include/s6/s6-supervise.h b/src/include/s6/s6-supervise.h
index f0b08e7..541c30d 100644
--- a/src/include/s6/s6-supervise.h
+++ b/src/include/s6/s6-supervise.h
@@ -5,6 +5,7 @@
 
 #include <sys/types.h>
 #include <skalibs/tai.h>
+#include <skalibs/djbunix.h>
 
 #define S6_SUPERVISE_CTLDIR "supervise"
 #define S6_SUPERVISE_EVENTDIR "event"
@@ -17,6 +18,9 @@ extern int s6_svc_write (char const *, char const *, size_t) ;
 extern int s6_svc_writectl (char const *, char const *, char const *, size_t) ;
 extern int s6_svc_main (int, char const *const *, char const *, char const *, char const *) ;
 
+extern int s6_svc_lock_take (char const *) ;
+#define s6_svc_lock_release(fdlock) lock_un(fdlock)
+
 typedef struct s6_svstatus_s s6_svstatus_t, *s6_svstatus_t_ref ;
 struct s6_svstatus_s
 {
diff --git a/src/libs6/deps-lib/s6 b/src/libs6/deps-lib/s6
index ace5a05..5acb672 100644
--- a/src/libs6/deps-lib/s6
+++ b/src/libs6/deps-lib/s6
@@ -26,6 +26,7 @@ s6_accessrules_uidgid_cdb.o
 s6_accessrules_uidgid_fs.o
 s6_supervise_lock.o
 s6_supervise_lock_mode.o
+s6_svc_lock_take.o
 s6_svc_ok.o
 s6_svc_write.o
 s6_svc_writectl.o
diff --git a/src/libs6/s6_svc_lock_take.c b/src/libs6/s6_svc_lock_take.c
new file mode 100644
index 0000000..57830c0
--- /dev/null
+++ b/src/libs6/s6_svc_lock_take.c
@@ -0,0 +1,28 @@
+/* ISC license. */
+
+#include <sys/stat.h>
+#include <string.h>
+#include <errno.h>
+#include <skalibs/djbunix.h>
+#include <s6/s6-supervise.h>
+
+int s6_svc_lock_take (char const *dir)
+{
+  size_t dirlen = strlen(dir) ;
+  int fdlock ;
+  char lock[dirlen + sizeof(S6_SUPERVISE_CTLDIR) + 6] ;
+  memcpy(lock, dir, dirlen) ;
+  memcpy(lock + dirlen, "/" S6_SUPERVISE_CTLDIR, sizeof(S6_SUPERVISE_CTLDIR) + 1) ;
+  if ((mkdir(lock, S_IRWXU) < 0) && (errno != EEXIST)) return -1 ;
+  memcpy(lock + dirlen + sizeof(S6_SUPERVISE_CTLDIR), "/lock", 6) ;
+  fdlock = open_create(lock) ;
+  if (fdlock < 0) return -1 ;
+  if (coe(fdlock) < 0 || lock_ex(fdlock) < 0)
+  {
+    int e = errno ;
+    fd_close(fdlock) ;
+    errno = e ;
+    return -1 ;
+  }
+  return fdlock ;
+}
diff --git a/src/supervision/s6-supervise.c b/src/supervision/s6-supervise.c
index 7527668..71f247e 100644
--- a/src/supervision/s6-supervise.c
+++ b/src/supervision/s6-supervise.c
@@ -599,9 +599,9 @@ int main (int argc, char const *const *argv)
     memcpy(progname + proglen + 1, argv[1], namelen + 1) ;
     PROG = progname ;
     if (!fd_sanitize()) strerr_diefu1sys(111, "sanitize stdin and stdout") ;
-    x[1].fd = s6_supervise_lock(S6_SUPERVISE_CTLDIR) ;
     if (!ftrigw_fifodir_make(S6_SUPERVISE_EVENTDIR, getegid(), 0))
       strerr_diefu2sys(111, "mkfifodir ", S6_SUPERVISE_EVENTDIR) ;
+    x[1].fd = s6_supervise_lock(S6_SUPERVISE_CTLDIR) ;
     x[0].fd = selfpipe_init() ;
     if (x[0].fd == -1) strerr_diefu1sys(111, "init selfpipe") ;
     if (sig_ignore(SIGPIPE) < 0) strerr_diefu1sys(111, "ignore SIGPIPE") ;