1 files changed, 29 insertions, 0 deletions
diff --git a/src/serverlib/s6rc_db_check_revdeps.c b/src/serverlib/s6rc_db_check_revdeps.c
new file mode 100644
index 0000000..0097d06
--- /dev/null
+++ b/src/serverlib/s6rc_db_check_revdeps.c
@@ -0,0 +1,29 @@
+/* ISC license. */
+
+#include <string.h>
+#include <skalibs/bitarray.h>
+#include <s6-rc/s6rc-db.h>
+
+int s6rc_db_check_revdeps (s6rc_db_t const *db)
+{
+  size_t n = db->nshort + db->nlong ;
+  size_t m = bitarray_div8(n) ;
+  unsigned char matrix[n * m] ;
+  unsigned int i = n ;
+  unsigned char const *p = matrix ;
+  memset(matrix, 0, n * m) ;
+  while (i--)
+  {
+    unsigned int j = db->services[i].ndeps[1] ;
+    while (j--) bitarray_not(matrix + m * i, db->deps[db->ndeps + db->services[i].deps[1] + j], 1) ;
+  }
+  i = n ;
+  while (i--)
+  {
+    unsigned int j = db->services[i].ndeps[0] ;
+    while (j--) bitarray_not(matrix + m * db->deps[db->services[i].deps[0] + j], i, 1) ;
+  }
+  n *= m ;
+  while (n--) if (*p++) return 1 ;
+  return 0 ;
+}