2 files changed, 43 insertions, 0 deletions
diff --git a/src/libs6rc/deps-lib/s6rc b/src/libs6rc/deps-lib/s6rc
index 9f677f7..f1a8370 100644
--- a/src/libs6rc/deps-lib/s6rc
+++ b/src/libs6rc/deps-lib/s6rc
@@ -5,6 +5,7 @@ s6rc_db_read.o
 s6rc_db_read_sizes.o
 s6rc_db_read_uint32.o
 s6rc_graph_closure.o
+s6rc_graph_clean.o
 s6rc_live_state_size.o
 s6rc_live_state_read.o
 s6rc_livedir_canon.o
diff --git a/src/libs6rc/s6rc_graph_clean.c b/src/libs6rc/s6rc_graph_clean.c
new file mode 100644
index 0000000..d450d65
--- /dev/null
+++ b/src/libs6rc/s6rc_graph_clean.c
@@ -0,0 +1,42 @@
+/* ISC license. */
+
+#include <stdint.h>
+
+#include <skalibs/bitarray.h>
+
+#include <s6-rc/s6rc-db.h>
+#include <s6-rc/s6rc-utils.h>
+
+typedef struct recinfo_s recinfo_t, *recinfo_t_ref ;
+struct recinfo_s
+{
+  s6rc_db_t const *db ;
+  unsigned char *bits ;
+  unsigned char statemask ;
+  unsigned char volmask ;
+  unsigned char resmask ;
+} ;
+
+static void s6rc_graph_clean_rec (recinfo_t *info, uint32_t i)
+{
+  if (!(info->bits[i] & info->volmask))
+  {
+    uint32_t j = 0 ;
+    for (; j < info->db->services[i].ndeps[0] ; j++)
+      if (info->bits[j] & info->statemask && !(info->bits[j] & info->resmask)) break ;
+    if (j >= info->db->services[i].ndeps[0])
+    {
+      info->bits[i] |= info->resmask ;
+      for (j = 0 ; j < info->db->services[i].ndeps[1] ; j++)
+        s6rc_graph_clean_rec(info, info->db->deps[info->db->ndeps + info->db->services[i].deps[1] + j]) ;
+    }
+  }
+}
+
+void s6rc_graph_clean (s6rc_db_t const *db, unsigned char *bits, unsigned int statebit, unsigned int volbit, unsigned int resbit)
+{
+  uint32_t n = db->nshort + db->nlong ;
+  recinfo_t info = { .db = db, .bits = bits, .statemask = 1 << statebit, .volmask = 1 << volbit, .resmask = 1 << resbit } ;
+  for (uint32_t i = 0 ; i < n ; i++) bits[i] &= ~info.resmask ;
+  for (uint32_t i = 0 ; i < n ; i++) if (bits[i] & info.statemask) s6rc_graph_clean_rec(&info, i) ;
+}