Don't wait on locks by default (fail instead); add a -b option to get the waiting behaviour

 Also fix a few types in s6-rc-compile (unsigned int -> uint32_t for avltree indices)

9 files changed, 78 insertions, 57 deletions

diff --git a/src/include/s6-rc/s6rc-utils.h b/src/include/s6-rc/s6rc-utils.h
index 4eb65f5..22d8324 100644
--- a/src/include/s6-rc/s6rc-utils.h
+++ b/src/include/s6-rc/s6rc-utils.h
@@ -8,7 +8,7 @@
 #include <s6-rc/s6rc-db.h>
 
 extern void s6rc_graph_closure (s6rc_db_t const *, unsigned char *, unsigned int, int) ;
-extern int s6rc_lock (char const *, int, int *, char const *, int, int *) ;
+extern int s6rc_lock (char const *, int, int *, char const *, int, int *, int) ;
 extern int s6rc_read_uint (char const *, unsigned int *) ;
 extern int s6rc_sanitize_dir (stralloc *, char const *, size_t *) ;
 
diff --git a/src/libs6rc/s6rc_lock.c b/src/libs6rc/s6rc_lock.c
index dab3035..2a623d0 100644
--- a/src/libs6rc/s6rc_lock.c
+++ b/src/libs6rc/s6rc_lock.c
@@ -5,7 +5,17 @@
 #include <skalibs/djbunix.h>
 #include <s6-rc/s6rc-utils.h>
 
-int s6rc_lock (char const *live, int lwhat, int *llfd, char const *compiled, int cwhat, int *ccfd)
+static inline int lockex (int fd, int blocking)
+{
+  return blocking ? lock_ex(fd) : lock_exnb(fd) ;
+}
+
+static inline int locksh (int fd, int blocking)
+{
+  return blocking ? lock_sh(fd) : lock_shnb(fd) ;
+}
+
+int s6rc_lock (char const *live, int lwhat, int *llfd, char const *compiled, int cwhat, int *ccfd, int blocking)
 {
   int e = 0 ;
   int lfd = -1, cfd = -1 ;
@@ -18,7 +28,7 @@ int s6rc_lock (char const *live, int lwhat, int *llfd, char const *compiled, int
     memcpy(lfn + llen, "/lock", 6) ;
     lfd = open_create(lfn) ;
     if (lfd < 0) return 0 ;
-    if ((lwhat > 1 ? lock_ex(lfd) : lock_sh(lfd)) < 0) { e = errno ; goto lerr ; }
+    if ((lwhat > 1 ? lockex(lfd, blocking) : locksh(lfd, blocking)) < 0) { e = errno ; goto lerr ; }
   }
 
   if (cwhat)
@@ -31,7 +41,7 @@ int s6rc_lock (char const *live, int lwhat, int *llfd, char const *compiled, int
     if (cfd < 0)
       if (cwhat > 1 || errno != EROFS) { e = errno ; goto lerr ; }
       else cfd = -errno ;
-    else if ((cwhat > 1 ? lock_ex(cfd) : lock_sh(cfd)) < 0) { e = errno ; goto cerr ; }
+    else if ((cwhat > 1 ? lockex(cfd, blocking) : locksh(cfd, blocking)) < 0) { e = errno ; goto cerr ; }
   }
 
   if (lwhat) *llfd = lfd ;
diff --git a/src/s6-rc/s6-rc-bundle.c b/src/s6-rc/s6-rc-bundle.c
index 78bfcbe..837d3b9 100644
--- a/src/s6-rc/s6-rc-bundle.c
+++ b/src/s6-rc/s6-rc-bundle.c
@@ -18,7 +18,7 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc-bundle [ -l live ] [ -c compiled ] command... (use s6-rc-bundle help for more information)"
+#define USAGE "s6-rc-bundle [ -l live ] [ -c compiled ] [ -b ] command... (use s6-rc-bundle help for more information)"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 static void cleanup (char const *compiled)
@@ -259,18 +259,20 @@ int main (int argc, char const **argv)
   char const *compiled = 0 ;
   unsigned int what ;
   int force = 0 ;
+  int blocking = 0 ;
   PROG = "s6-rc-bundle" ;
   {
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "fl:c:", &l) ;
+      int opt = subgetopt_r(argc, argv, "fl:c:b", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
         case 'f' : force = 1 ; break ;
         case 'l' : live = l.arg ; break ;
         case 'c' : compiled = l.arg ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -301,7 +303,7 @@ int main (int argc, char const **argv)
       compiled = compiledblob ;
     }
 
-    if (!s6rc_lock(0, 0, 0, compiled, 2, &compiledlock))
+    if (!s6rc_lock(0, 0, 0, compiled, 2, &compiledlock, blocking))
       strerr_diefu2sys(111, "take lock on ", compiled) ;
     fdcompiled = open_readb(compiled) ;
     if (fdcompiled < 0)
diff --git a/src/s6-rc/s6-rc-compile.c b/src/s6-rc/s6-rc-compile.c
index fdf2602..60bae6b 100644
--- a/src/s6-rc/s6-rc-compile.c
+++ b/src/s6-rc/s6-rc-compile.c
@@ -26,22 +26,12 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc-compile [ -v verbosity ] [ -u okuid,okuid... ] [ -g okgid,okgid... ] [ -h fdholder_user ] destdir sources..."
+#define USAGE "s6-rc-compile [ -v verbosity ] [ -u okuid,okuid... ] [ -g okgid,okgid... ] [ -h fdholder_user ] [ -b ] destdir sources..."
 #define dieusage() strerr_dieusage(100, USAGE)
 #define dienomem() strerr_dief1x(111, "out of memory") ;
 
 #define S6RC_INTERNALS "s6-rc-compile internals"
 
-#define S6RC_ONESHOT_RUNNER_RUNSCRIPT \
-"#!" EXECLINE_SHEBANGPREFIX "execlineb -P\n" \
-EXECLINE_EXTBINPREFIX "fdmove -c 2 1\n" \
-EXECLINE_EXTBINPREFIX "fdmove 1 3\n" \
-S6_EXTBINPREFIX "s6-ipcserver-socketbinder -- s\n" \
-S6_EXTBINPREFIX "s6-ipcserverd -1 --\n" \
-S6_EXTBINPREFIX "s6-ipcserver-access -v0 -E -l0 -i data/rules --\n" \
-S6_EXTBINPREFIX "s6-sudod -t 2000 --\n" \
-S6RC_EXTLIBEXECPREFIX "s6-rc-oneshot-run -l ../.. --\n"
-
 static unsigned int verbosity = 1 ;
 static stralloc keep = STRALLOC_ZERO ;
 static stralloc data = STRALLOC_ZERO ;
@@ -56,7 +46,6 @@ enum servicetype_e
 } ;
 
 
-
  /* The names tree */
 
 
@@ -84,7 +73,6 @@ static genalloc nameinfo = GENALLOC_ZERO ; /* nameinfo_t */
 static avltree names_map = AVLTREE_INIT(8, 3, 8, &names_dtok, &names_cmp, &nameinfo) ;
 
 
-
  /* Services before resolution */
 
 
@@ -137,7 +125,6 @@ struct before_s
 #define BEFORE_ZERO { .indices = GENALLOC_ZERO, .oneshots = GENALLOC_ZERO, .longruns = GENALLOC_ZERO, .bundles = GENALLOC_ZERO, .nargvs = 0, .specialdeps = { 0, 0 } } ;
 
 
-
  /* Read all the sources, populate the name map */
 
 
@@ -151,8 +138,7 @@ static char const *typestr (servicetype_t type)
 
 static int add_name_nocheck (before_t *be, char const *srcdir, char const *name, servicetype_t type, unsigned int *pos, unsigned int *kpos)
 {
-  unsigned int id ;
-
+  uint32_t id ;
   if (verbosity >= 4)
     strerr_warnt6x("from ", srcdir, ": adding identifier ", name, " of type ", typestr(type)) ;
 
@@ -211,7 +197,7 @@ static int add_name_nocheck (before_t *be, char const *srcdir, char const *name,
       .type = type
     } ;
     size_t namelen = strlen(name) ;
-    unsigned int i = genalloc_len(nameinfo_t, &nameinfo) ;
+    uint32_t i = genalloc_len(nameinfo_t, &nameinfo) ;
     if (type == SVTYPE_ONESHOT || type == SVTYPE_LONGRUN)
       if (!stralloc_catb(&keep, name, namelen + 1)) dienomem() ;
     if (!stralloc_catb(&data, name, namelen + 1)) dienomem() ;
@@ -528,7 +514,7 @@ static inline void add_pipeline_bundles (before_t *be)
   while (i--) if (longruns[i].pipelinename)
   {
     bundle_t bundle = { .listindex = genalloc_len(unsigned int, &be->indices), .n = 1 } ;
-    unsigned int id ;
+    uint32_t id ;
     nameinfo_t const *info ;
     unsigned int j = i ;
     if (verbosity >= 3) strerr_warni2x("creating bundle for pipeline ", data.s + longruns[i].pipelinename) ;
@@ -554,7 +540,6 @@ static inline void add_pipeline_bundles (before_t *be)
 }
 
 
-
  /* Resolve all names and dependencies */
 
 
@@ -584,7 +569,7 @@ static void resolve_bundle_rec (bundle_recinfo_t *recinfo, unsigned int i)
     recinfo->mark[i] |= 1 ;
     for (; j < me->n ; j++)
     {
-      unsigned int id ;
+      uint32_t id ;
       nameinfo_t const *p ;
       avltree_search(&names_map, data.s + listindex[j], &id) ;
       p = genalloc_s(nameinfo_t, &nameinfo) + id ;
@@ -650,7 +635,7 @@ static void resolve_deps (common_t const *me, unsigned int nlong, unsigned int n
   unsigned int j = 0 ;
   for (; j < me->ndeps ; j++)
   {
-    unsigned int id ;
+    uint32_t id ;
     nameinfo_t const *p ;
     avltree_search(&names_map, data.s + indices[me->depindex + j], &id) ;
     p = genalloc_s(nameinfo_t, &nameinfo) + id ;
@@ -691,7 +676,7 @@ static void resolve_deps (common_t const *me, unsigned int nlong, unsigned int n
 
 static uint32_t resolve_prodcons (longrun_t const *longruns, unsigned int i, int h, uint32_t nlong)
 {
-  unsigned int j ;
+  uint32_t j ;
   nameinfo_t const *p ;
   if (!longruns[i].pipeline[h]) return nlong ;
   avltree_search(&names_map, data.s + longruns[i].pipeline[h], &j) ;
@@ -700,7 +685,7 @@ static uint32_t resolve_prodcons (longrun_t const *longruns, unsigned int i, int
   {
     case SVTYPE_LONGRUN :
     {
-      unsigned int k ;
+      uint32_t k ;
       nameinfo_t const *q ;
       avltree_search(&names_map, data.s + longruns[p->i].pipeline[!h], &k) ;
       q = genalloc_s(nameinfo_t, &nameinfo) + k ;
@@ -808,7 +793,6 @@ static inline void flatlist_services (s6rc_db_t *db, unsigned char const *sarray
 }
 
 
-
  /* Write the compiled database */
 
 
@@ -884,7 +868,7 @@ static inline void init_compiled (char const *compiled)
   int compiledlock ;
   if (mkdir(compiled, 0755) < 0)
     strerr_diefu2sys(111, "mkdir ", compiled) ;
-  if (!s6rc_lock(0, 0, 0, compiled, 2, &compiledlock))
+  if (!s6rc_lock(0, 0, 0, compiled, 2, &compiledlock, 0))
     strerr_diefu2sys(111, "take lock on ", compiled) ;
   auto_dir(compiled, "servicedirs") ;
 }
@@ -926,8 +910,9 @@ static void make_skel (char const *compiled, char const *name, uid_t const *uids
   auto_dir(compiled, fn) ;
 }
 
-static inline void write_oneshot_runner (char const *compiled, uid_t const *uids, size_t uidn, gid_t const *gids, size_t gidn)
+static inline void write_oneshot_runner (char const *compiled, uid_t const *uids, size_t uidn, gid_t const *gids, size_t gidn, int blocking)
 {
+  size_t base = satmp.len ;
   size_t i ;
   char fn[34 + sizeof(S6RC_ONESHOT_RUNNER)] = "servicedirs/" S6RC_ONESHOT_RUNNER "/data/rules/gid/" ;
   make_skel(compiled, S6RC_ONESHOT_RUNNER, uids, uidn, gids, gidn, 3) ;
@@ -953,7 +938,19 @@ static inline void write_oneshot_runner (char const *compiled, uid_t const *uids
     memcpy(fn + 28 + S6RC_ONESHOT_RUNNER_LEN + len, "/allow", 7) ;
     auto_file(compiled, fn, "", 0) ;
   }
-  auto_file(compiled, "servicedirs/" S6RC_ONESHOT_RUNNER "/run", S6RC_ONESHOT_RUNNER_RUNSCRIPT, sizeof(S6RC_ONESHOT_RUNNER_RUNSCRIPT) - 1) ;
+  if (!stralloc_cats(&satmp, "#!"
+    EXECLINE_SHEBANGPREFIX "execlineb -P\n"
+    EXECLINE_EXTBINPREFIX "fdmove -c 2 1\n"
+    EXECLINE_EXTBINPREFIX "fdmove 1 3\n"
+    S6_EXTBINPREFIX "s6-ipcserver-socketbinder -- s\n"
+    S6_EXTBINPREFIX "s6-ipcserverd -1 --\n"
+    S6_EXTBINPREFIX "s6-ipcserver-access -v0 -E -l0 -i data/rules --\n"
+    S6_EXTBINPREFIX "s6-sudod -t 2000 --\n"
+    S6RC_EXTLIBEXECPREFIX "s6-rc-oneshot-run -l ../.. ")
+   || (blocking && !stralloc_cats(&satmp, "-b "))
+   || !stralloc_cats(&satmp, "--\n")) dienomem() ;
+  auto_file(compiled, "servicedirs/" S6RC_ONESHOT_RUNNER "/run", satmp.s + base, satmp.len - base) ;
+  satmp.len = base ;
   auto_rights(compiled, "servicedirs/" S6RC_ONESHOT_RUNNER "/run", 0755) ;
 }
 
@@ -1058,9 +1055,9 @@ static inline void write_fdholder (char const *compiled, s6rc_db_t const *db, ui
   auto_rights(compiled, "servicedirs/" S6RC_FDHOLDER "/run", 0755) ;
 }
 
-static inline void write_specials (char const *compiled, s6rc_db_t const *db, uid_t const *uids, size_t uidn, gid_t const *gids, size_t gidn, char const *fdhuser)
+static inline void write_specials (char const *compiled, s6rc_db_t const *db, uid_t const *uids, size_t uidn, gid_t const *gids, size_t gidn, char const *fdhuser, int blocking)
 {
-  write_oneshot_runner(compiled, uids, uidn, gids, gidn) ;
+  write_oneshot_runner(compiled, uids, uidn, gids, gidn, blocking) ;
   write_fdholder(compiled, db, uids, uidn, gids, gidn, fdhuser) ;
 }
 
@@ -1367,7 +1364,8 @@ static inline void write_compiled (
   size_t uidn,
   gid_t const *gids,
   size_t gidn,
-  char const *fdhuser)
+  char const *fdhuser,
+  int blocking)
 {
   if (verbosity >= 2) strerr_warni2x("writing compiled information to ", compiled) ;
   init_compiled(compiled) ;
@@ -1375,7 +1373,7 @@ static inline void write_compiled (
   write_resolve(compiled, db, bundles, nbundles, bdeps) ;
   stralloc_free(&data) ;
   write_db(compiled, db) ;
-  write_specials(compiled, db, uids, uidn, gids, gidn, fdhuser) ;
+  write_specials(compiled, db, uids, uidn, gids, gidn, fdhuser, blocking) ;
   write_servicedirs(compiled, db, srcdirs) ;
 }
 
@@ -1384,6 +1382,7 @@ int main (int argc, char const *const *argv)
   before_t before = BEFORE_ZERO ;
   char const *compiled ;
   char const *fdhuser = 0 ;
+  int blocking = 0 ;
   size_t uidn = 0, gidn = 0 ;
   uid_t uids[256] ;
   gid_t gids[256] ;
@@ -1392,7 +1391,7 @@ int main (int argc, char const *const *argv)
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "v:u:g:h:", &l) ;
+      int opt = subgetopt_r(argc, argv, "v:u:g:h:b", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
@@ -1400,6 +1399,7 @@ int main (int argc, char const *const *argv)
         case 'u' : if (!uid_scanlist(uids, 255, l.arg, &uidn)) dieusage() ; break ;
         case 'g' : if (!gid_scanlist(gids, 255, l.arg, &gidn)) dieusage() ; break ;
         case 'h' : fdhuser = l.arg ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -1446,7 +1446,7 @@ int main (int argc, char const *const *argv)
       uint32_t deps[db.ndeps << 1] ;
       db.deps = deps ;
       flatlist_services(&db, sarray) ;
-      write_compiled(compiled, &db, srcdirs, bundles, nbundles, bdeps, uids, uidn, gids, gidn, fdhuser) ;
+      write_compiled(compiled, &db, srcdirs, bundles, nbundles, bdeps, uids, uidn, gids, gidn, fdhuser, blocking) ;
     }
   }
 
diff --git a/src/s6-rc/s6-rc-db.c b/src/s6-rc/s6-rc-db.c
index 8e4b92a..ce983dc 100644
--- a/src/s6-rc/s6-rc-db.c
+++ b/src/s6-rc/s6-rc-db.c
@@ -13,7 +13,7 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc-db [ -u | -d ] [ -l live ] [ -c compiled ] command... (use s6-rc-db help for more information)"
+#define USAGE "s6-rc-db [ -u | -d ] [ -l live ] [ -c compiled ] [ -b ] command... (use s6-rc-db help for more information)"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 static char const *compiled = 0 ;
@@ -344,12 +344,13 @@ int main (int argc, char const *const *argv)
   char const *live = S6RC_LIVE_BASE ;
   unsigned int what, subwhat = 0 ;
   int up = 1 ;
+  int blocking = 0 ;
   PROG = "s6-rc-db" ;
   {
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "udl:c:", &l) ;
+      int opt = subgetopt_r(argc, argv, "udl:c:b", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
@@ -357,6 +358,7 @@ int main (int argc, char const *const *argv)
         case 'c' : compiled = l.arg ; break ;
         case 'u' : up = 1 ; break ;
         case 'd' : up = 0 ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -387,7 +389,7 @@ int main (int argc, char const *const *argv)
       compiled = compiledblob ;
     }
 
-    if (!s6rc_lock(0, 0, 0, compiled, 1, &compiledlock))
+    if (!s6rc_lock(0, 0, 0, compiled, 1, &compiledlock, blocking))
       strerr_diefu2sys(111, "take lock on ", compiled) ;
     fdcompiled = open_readb(compiled) ;
     if (fdcompiled < 0)
diff --git a/src/s6-rc/s6-rc-init.c b/src/s6-rc/s6-rc-init.c
index 386fbe7..c749609 100644
--- a/src/s6-rc/s6-rc-init.c
+++ b/src/s6-rc/s6-rc-init.c
@@ -14,7 +14,7 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc-init [ -c compiled ] [ -l live ] [ -t timeout ] scandir"
+#define USAGE "s6-rc-init [ -c compiled ] [ -l live ] [ -t timeout ] [ -b ] scandir"
 #define dieusage() strerr_dieusage(100, USAGE)
 #define dienomem() strerr_diefu1sys(111, "stralloc_catb")
 
@@ -37,19 +37,21 @@ int main (int argc, char const *const *argv)
   size_t dirlen ;
   char const *live = S6RC_LIVE_BASE ;
   char const *compiled = S6RC_COMPILED_BASE ;
+  int blocking = 0 ;
   PROG = "s6-rc-init" ;
   {
     unsigned int t = 0 ;
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "c:l:t:", &l) ;
+      int opt = subgetopt_r(argc, argv, "c:l:t:b", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
         case 'c' : compiled = l.arg ; break ;
         case 'l' : live = l.arg ; break ;
         case 't' : if (!uint0_scan(l.arg, &t)) dieusage() ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -89,7 +91,7 @@ int main (int argc, char const *const *argv)
     unlink(live) ;
     rm_rf(satmp.s) ;
     if (mkdir(satmp.s, 0755) < 0) strerr_diefu2sys(111, "mkdir ", satmp.s) ;
-    if (!s6rc_lock(satmp.s, 2, &fdlock, 0, 0, 0))
+    if (!s6rc_lock(satmp.s, 2, &fdlock, 0, 0, 0, blocking))
     {
       char tmp[satmp.len] ;
       memcpy(tmp, satmp.s, satmp.len) ;
diff --git a/src/s6-rc/s6-rc-oneshot-run.c b/src/s6-rc/s6-rc-oneshot-run.c
index 3bb38a8..01e51ba 100644
--- a/src/s6-rc/s6-rc-oneshot-run.c
+++ b/src/s6-rc/s6-rc-oneshot-run.c
@@ -10,7 +10,7 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc-oneshot-run [ -l live ] up|down servicenumber"
+#define USAGE "s6-rc-oneshot-run [ -l live ] [ -b ] up|down servicenumber"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 int main (int argc, char const *const *argv, char const *const *envp)
@@ -18,16 +18,18 @@ int main (int argc, char const *const *argv, char const *const *envp)
   char const *live = S6RC_LIVE_BASE ;
   unsigned int number ;
   int up ;
+  int blocking = 0 ;
   PROG = "s6-rc-oneshot-run" ;
   {
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "l:", &l) ;
+      int opt = subgetopt_r(argc, argv, "l:b", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
         case 'l' : live = l.arg ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -48,7 +50,7 @@ int main (int argc, char const *const *argv, char const *const *envp)
     memcpy(compiled, live, livelen) ;
     memcpy(compiled + livelen, "/compiled", 10) ;
 
-    if (!s6rc_lock(0, 0, 0, compiled, 1, &compiledlock))
+    if (!s6rc_lock(0, 0, 0, compiled, 1, &compiledlock, blocking))
       strerr_diefu2sys(111, "take lock on ", compiled) ;
     fdcompiled = open_readb(compiled) ;
     if (fdcompiled < 0)
diff --git a/src/s6-rc/s6-rc-update.c b/src/s6-rc/s6-rc-update.c
index 4008388..5f4d25e 100644
--- a/src/s6-rc/s6-rc-update.c
+++ b/src/s6-rc/s6-rc-update.c
@@ -27,7 +27,7 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc-update [ -n ] [ -v verbosity ] [ -t timeout ] [ -l live ] [ -f conversion_file ] newdb"
+#define USAGE "s6-rc-update [ -n ] [ -v verbosity ] [ -t timeout ] [ -l live ] [ -f conversion_file ] [ -b ] newdb"
 #define dieusage() strerr_dieusage(100, USAGE)
 #define dienomem() strerr_diefu1sys(111, "build string") ;
 
@@ -611,13 +611,14 @@ int main (int argc, char const *const *argv, char const *const *envp)
   char const *convfile = "/dev/null" ;
   tain_t deadline ;
   int dryrun = 0 ;
+  int blocking = 0 ;
   PROG = "s6-rc-update" ;
   {
     unsigned int t = 0 ;
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "v:t:nl:f:", &l) ;
+      int opt = subgetopt_r(argc, argv, "v:t:nl:f:b", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
@@ -626,6 +627,7 @@ int main (int argc, char const *const *argv, char const *const *envp)
         case 'n' : dryrun = 1 ; break ;
         case 'l' : live = l.arg ; break ;
         case 'f' : convfile = l.arg ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -658,9 +660,9 @@ int main (int argc, char const *const *argv, char const *const *envp)
 
     memcpy(dbfn, live, livelen) ;
     memcpy(dbfn + livelen, "/compiled", 10) ;
-    if (!s6rc_lock(live, 2, &livelock, dbfn, 1, &oldlock))
+    if (!s6rc_lock(live, 2, &livelock, dbfn, 1, &oldlock, blocking))
       strerr_diefu4sys(111, "take lock on ", live, " and ", dbfn) ;
-    if (!s6rc_lock(0, 0, 0, argv[0], 1, &newlock))
+    if (!s6rc_lock(0, 0, 0, argv[0], 1, &newlock, blocking))
       strerr_diefu2sys(111, "take lock on ", argv[0]) ;
 
 
diff --git a/src/s6-rc/s6-rc.c b/src/s6-rc/s6-rc.c
index f81d38d..615cbf8 100644
--- a/src/s6-rc/s6-rc.c
+++ b/src/s6-rc/s6-rc.c
@@ -21,7 +21,7 @@
 #include <s6-rc/config.h>
 #include <s6-rc/s6rc.h>
 
-#define USAGE "s6-rc [ -v verbosity ] [ -n dryrunthrottle ] [ -t timeout ] [ -l live ] [ -u | -d ] [ -p ] [ -a ] help|list|listall|change [ servicenames... ]"
+#define USAGE "s6-rc [ -v verbosity ] [ -n dryrunthrottle ] [ -t timeout ] [ -l live ] [ -b ] [ -u | -d ] [ -p ] [ -a ] help|list|listall|change [ servicenames... ]"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 typedef struct pidindex_s pidindex_t ;
@@ -374,7 +374,7 @@ static inline void print_help (void)
 
 int main (int argc, char const *const *argv)
 {
-  int up = 1, prune = 0, selectlive = 0, takelocks = 1 ;
+  int up = 1, prune = 0, selectlive = 0, takelocks = 1, blocking = 0 ;
   unsigned int what ;
   PROG = "s6-rc" ;
   {
@@ -382,7 +382,7 @@ int main (int argc, char const *const *argv)
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "v:n:t:l:udpaX", &l) ;
+      int opt = subgetopt_r(argc, argv, "v:n:t:l:udpaXb", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
@@ -401,6 +401,7 @@ int main (int argc, char const *const *argv)
         case 'p' : prune = 1 ; break ;
         case 'a' : selectlive = 1 ; break ;
         case 'X' : takelocks = 0 ; break ;
+        case 'b' : blocking = 1 ; break ;
         default : dieusage() ;
       }
     }
@@ -432,7 +433,7 @@ int main (int argc, char const *const *argv)
     if (takelocks)
     {
       int livelock, compiledlock ;
-      if (!s6rc_lock(live, 1 + (what >= 3), &livelock, dbfn, 1, &compiledlock))
+      if (!s6rc_lock(live, 1 + (what >= 3), &livelock, dbfn, 1, &compiledlock, blocking))
         strerr_diefu1sys(111, "take locks") ;
       if (coe(livelock) < 0)
         strerr_diefu3sys(111, "coe ", live, "/lock") ;