Added print tree function

src/process.h

@@ -10,6 +10,7 @@ typedef struct st_process {
     struct st_process *parent;  // parent process
     struct st_process *child;   // pointer to first child
     struct st_process *sibling; // pointer to next sibling
+    int visited;
     uint32_t flags;
     char cpuset[128];
     int tgid;

src/server.c

@@ -117,6 +117,55 @@ void linkFamily(Process *head) {
   }
 }
 
+int resetVisits(Process *head) {
+  Process *current = head;
+  int processCount = 0;
+
+  while (current != NULL) {
+    current->visited = 0;
+    current = current->next;
+  }
+
+  return processCount;
+}
+
+void printFamilyTree(Process *head) {
+  int processCount = resetVisits(head);
+  int visited = 0;
+  Process *current = head;
+  int depth = 0;
+  
+  while (visited < processCount) {
+    if (current == NULL) {
+      printf("Bad visit count: %d visited of %d processes\n", visited, processCount);
+      break;
+    }
+
+    current->visited = 1;
+    printf("%10d  ", current->pid);
+    // `ps f` style tree
+    for (int i=1; i<depth; i++) puts("    ");
+    if (depth > 0) puts(" \\_ ");
+    printf("%s\n", current->label);
+
+    if (current->child != NULL) {
+      // process children first
+      depth++;
+      current = current->child; 
+    } else if (current->sibling != NULL) {
+      // process siblings next
+      current = current->sibling;
+    } else if (current->parent != NULL) {
+      // return to parent when tree is exhausted
+      depth--;
+      current = current->parent;
+    } else {
+      // no parent - scan for unvisited process
+      while (current != NULL && current->visited == 1) current = current->next;
+    }
+  }
+}
+
 void aggregateStats(Process *head) {
 
 }
@@ -204,6 +253,7 @@ char *readProcesses(char *procdir) {
   cur->next = NULL;
 
   linkFamily(head);
+  printFamilyTree(head);
 
   int clocks = sysconf(_SC_CLK_TCK);
   char *output = malloc(8 * 1024 * 1024);