1 files changed, 100 insertions, 0 deletions
diff --git a/src/libs6ps/s6ps_otree.c b/src/libs6ps/s6ps_otree.c
new file mode 100644
index 0000000..c3bd202
--- /dev/null
+++ b/src/libs6ps/s6ps_otree.c
@@ -0,0 +1,100 @@
+/* ISC license. */
+
+#include <errno.h>
+
+#include <skalibs/avltreen.h>
+
+#include "s6ps.h"
+
+typedef struct ptreeiter_s ptreeiter_t, *ptreeiter_t_ref ;
+struct ptreeiter_s
+{
+  unsigned int *childlist ;
+  unsigned int const *childindex ;
+  unsigned int const *ppindex ;
+  unsigned int *cpos ;
+} ;
+
+typedef struct pstuff_s pstuff_t, *pstuff_t_ref ;
+struct pstuff_s
+{
+  unsigned int *orderedlist ;
+  pscan_t *p ;
+  unsigned int const *childlist ;
+  unsigned int const *childindex ;
+  unsigned int const *nchild ;
+} ;
+
+static int fillchildlist (unsigned int i, unsigned int h, void *x)
+{
+  ptreeiter_t *pt = x ;
+  unsigned int j = pt->ppindex[i] ;
+  pt->childlist[pt->childindex[j] + pt->cpos[j]++] = i ;
+  (void)h ;
+  return 1 ;
+}
+
+static void fillo_tree_rec (pstuff_t *blah, unsigned int root, signed int h)
+{
+  static unsigned int j = 0 ;
+  unsigned int i = !blah->p[root].pid ;
+  if (blah->p[root].pid == 1) h = -1 ;
+  blah->p[root].height = (h > 0) ? h : 0 ;
+  blah->orderedlist[j++] = root ;
+  for (; i < blah->nchild[root] ; i++)
+    fillo_tree_rec(blah, blah->childlist[blah->childindex[root] + i], h+1) ;
+}
+
+ /*
+    Fills up orderedlist with the right indices to print a process tree.
+    O(n log n) time, O(n) space, all in the stack.
+ */
+
+void s6ps_otree (pscan_t *p, unsigned int n, avltreen *pidtree, unsigned int *orderedlist)
+{
+  unsigned int childlist[n] ;
+  unsigned int childindex[n] ;
+  unsigned int nchild[n] ;
+  unsigned int i = 0 ;
+  for (; i < n ; i++) nchild[i] = 0 ;
+
+ /* Compute the ppid tree */
+  for (i = 0 ; i < n ; i++)
+  {
+    uint32_t k ;
+    if (!avltreen_search(pidtree, &p[i].ppid, &k)) k = n-1 ;
+    orderedlist[i] = k ; /* using orderedlist as ppindex */
+    nchild[k]++ ;
+  }
+  {
+    unsigned int j = 0 ;
+    for (i = 0 ; i < n ; i++)
+    {
+      childindex[i] = j ;
+      j += nchild[i] ;
+    }
+  }
+
+ /* Fill the childlist by increasing pids so it is sorted */
+  {
+    unsigned int cpos[n] ;
+    ptreeiter_t blah = { .childlist = childlist, .childindex = childindex, .ppindex = orderedlist, .cpos = cpos } ;
+    for (i = 0 ; i < n ; i++) cpos[i] = 0 ;
+    avltreen_iter_nocancel(pidtree, avltreen_totalsize(pidtree), &fillchildlist, &blah) ;
+  }
+
+ /* If we have init, make it the last in the orphan list */
+  if (n > 1 && p[childlist[childindex[n-1]+1]].pid == 1)
+  {
+    unsigned int pos1 = childlist[childindex[n-1] + 1] ;
+    for (i = 2 ; i < nchild[n-1] ; i++)
+      childlist[childindex[n-1]+i-1] = childlist[childindex[n-1]+i] ;
+    childlist[childindex[n-1]+nchild[n-1]-1] = pos1 ;
+  } 
+
+ /* Finally, fill orderedlist by walking the childindex tree. */
+  {
+    pstuff_t blah = { .orderedlist = orderedlist, .p = p, .childlist = childlist, .childindex = childindex, .nchild = nchild } ;
+    fillo_tree_rec(&blah, n-1, -1) ;
+  }
+}