1 files changed, 79 insertions, 0 deletions
diff --git a/ramfs/src/ptree.c b/ramfs/src/ptree.c
new file mode 100644
index 0000000..2773140
--- /dev/null
+++ b/ramfs/src/ptree.c
@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+
+#define __NR_ptree 313
+
+struct prinfo {
+	long state;
+	pid_t pid;
+	pid_t parent_pid;
+	pid_t first_child_pid;
+	pid_t next_sibling_pid;
+	long uid;
+	char comm[64];
+};
+
+static inline int ptree(struct prinfo *processes, unsigned int *count)
+{
+	return syscall(__NR_ptree, processes, count);
+}
+
+static pid_t find_parent(struct prinfo *processes, unsigned int count, pid_t pid)
+{
+	int i;
+	for (i = 0; i < count; ++i) {
+		if (processes[i].pid == pid)
+			return processes[i].parent_pid;
+	}
+	return 0;
+}
+
+static int hilariously_inefficient_method_of_finding_indentation_level(struct prinfo *processes, unsigned int count, pid_t pid)
+{
+	int indentation = 0;
+	while((pid = find_parent(processes, count, pid)))
+		++indentation;
+	return indentation;
+
+	/* Bonus points if you can find a reasonable _looking_
+	 * algorithm that is even more inefficient. */
+}
+
+int main(int argc, char *argv[])
+{
+	struct prinfo *processes;
+	unsigned int count, indentation, i, j;
+	pid_t last_ppid;
+
+	indentation = 0;
+
+	count = 32768;
+	processes = malloc(sizeof(struct prinfo) * count);
+	if (!processes) {
+		perror("processes");
+		return EXIT_FAILURE;
+	}
+
+	memset(processes, 0, sizeof(struct prinfo) * count);
+
+	if (ptree(processes, &count)) {
+		perror("ptree");
+		return EXIT_FAILURE;
+	}
+
+	for (i = 0; i < count; ++i) {
+		indentation = hilariously_inefficient_method_of_finding_indentation_level(processes, count, processes[i].pid);
+		for (j = 0; j < indentation; ++j)
+			putchar('\t');
+		printf("%s,%d,%ld,%d,%d,%d,%ld\n", processes[i].comm, processes[i].pid,
+			processes[i].state, processes[i].parent_pid, processes[i].first_child_pid,
+			processes[i].next_sibling_pid, processes[i].uid);
+	}
+
+	printf("%d processes\n", count);
+
+	return EXIT_SUCCESS;
+}