From 3960919efe4ce383dce6192f8026eec368959e72 Mon Sep 17 00:00:00 2001
From: Dan Snyder <snyderdan46@gmail.com>
Date: Tue, 14 Jan 2025 19:24:12 -0500
Subject: [PATCH] reworked linking logic to be a little clearer, added 'kernel'
 node

---
 src/process.h |  1 -
 src/server.c  | 92 ++++++++++++++++++++++++++++++---------------------
 2 files changed, 54 insertions(+), 39 deletions(-)

diff --git a/src/process.h b/src/process.h
index 33fd6bf..eb8309e 100644
--- a/src/process.h
+++ b/src/process.h
@@ -6,7 +6,6 @@
 typedef struct st_process {
     // For our own purposes
     struct st_process *next;    // next process in order we read them
-    struct st_process *prev;    // previous process read
     struct st_process *parent;  // parent process
     struct st_process *child;   // pointer to first child
     struct st_process *sibling; // pointer to next sibling
diff --git a/src/server.c b/src/server.c
index e841d4d..05d86ce 100644
--- a/src/server.c
+++ b/src/server.c
@@ -95,33 +95,6 @@ int parseIOFile(Process *proc, char *filedata) {
   return 0;
 }
 
-void linkFamily(Process *head) {
-  int orphans = 1;
-
-  while (orphans) {
-    orphans = 0;
-    Process *current = head;
-    // while on an actual process node, and it has a parent link or doesn't need a parent link
-    while (current != NULL && (current->parent != NULL || current->ppid <= 0)) current = current->next;
-    if (current == NULL) break;
-    orphans = 1;
-    
-    Process *parent = head;
-    while (parent != NULL && parent->pid != current->ppid) parent = parent->next;
-    if (parent == NULL) {
-      printf("Found orphan process: %d\n", current->pid);
-      current->ppid = -1;
-      continue;
-    }
-
-    // We have a parent and a child ready to be united
-    current->parent = parent;
-    Process **placement = &(parent->child);
-    while ((*placement) != NULL) placement = &((*placement)->sibling);
-    *placement = current;
-  }
-}
-
 int resetVisits(Process *head) {
   Process *current = head;
   int processCount = 0;
@@ -135,6 +108,37 @@ int resetVisits(Process *head) {
   return processCount;
 }
 
+
+void linkFamily(Process *head) {
+  int orphans = resetVisits(head);
+
+  while (orphans) {
+    Process *cur, *parent = head;
+    // get next unvisited node
+    while (parent != NULL && parent->visited) parent = parent->next;
+    
+    if (parent == NULL) {    // sanity check
+      printf("Error: Found %d orphan process(es):\n", orphans);
+      break;
+    }
+
+    parent->visited = 1;
+
+    // Search for children
+    for (cur = head; cur != NULL; cur = cur->next) {
+      if (cur->ppid != parent->pid) continue;
+
+      // We have a parent and child ready to be united
+      orphans--;
+      cur->parent = parent;
+      // place child amongst siblings, if any are present
+      Process **placement = &(parent->child);
+      while ((*placement) != NULL) placement = &((*placement)->sibling);
+      *placement = cur;
+    }
+  }
+}
+
 void printFamilyTree(Process *head) {
   int processCount = resetVisits(head);
   int visited = 0;
@@ -253,13 +257,27 @@ char *readProcesses(char *procdir) {
   char first;
   FILE *file;
 
-  Process *cur = calloc(1, sizeof(Process));
-  Process *head = cur;
+  Process *head = calloc(1, sizeof(Process));
+  Process *cur = head;
+  Process *prev = NULL;
   lxcinfo *lxcs = NULL;
 
+  // First process node is the kernel
+  strcpy(cur->label, "kernel");
+  cur->lxc = -1;
+  cur->visited = 1;
+
   while ((pDirent = readdir(pDir)) != NULL) {
     first = pDirent->d_name[0];
     if (first < '0' || first > '9') continue;
+
+    if (cur->visited) {
+      // get new process node if necessary
+      prev = cur;
+      cur->next = calloc(1, sizeof(Process));
+      cur = cur->next;
+    }
+
     sprintf(fname, "/proc/%s/status", pDirent->d_name);
     file = fopen(fname, "rb");
     if (file == NULL) continue;
@@ -299,21 +317,19 @@ char *readProcesses(char *procdir) {
       sscanf(cur->cpuset, "/lxc/%d/ns", &cur->lxc);
       if (getLXCInfo(&lxcs, cur->lxc) == NULL) 
         printf("Failed to read LXC config <%d>\n", cur->lxc);
-
     } else {
       cur->lxc = -1;
     }
 
-  nextProcess:
-    cur->next = calloc(1, sizeof(Process));
-    cur->next->prev = cur;
-    cur = cur->next;
+nextProcess:
+    cur->visited = 1;
   }
 
-  // clean up unused last node
-  cur = cur->prev;
-  free(cur->next);
-  cur->next = NULL;
+  if (!cur->visited) {
+    // if there's an unused node, remove it
+    prev->next = NULL;
+    free(cur);
+  }
   
   linkFamily(head);
   aggregateStats(head);