feat(lab2): unix lab2 done

Lab 2 is in fact the first lab in the set of ones we actually do. It's
not particularly hard, but consumed some time for me

OSs/lab2/unix/part-A/son.c

@@ -0,0 +1,47 @@
+/*
+ * "THE CHEESE-WARE LICENSE" (Revision 1):
+ * <ElectronixTM> wrote this file. As long as you retain this notice
+ * you can do whatever you want with this stuff. If we meet some day,
+ * and you think this stuff is worth it, you can buy me some cheese
+ * in return
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "common.h"
+
+#define PROG_PREFIX "son: "
+#define log(fmt, args...) printf(PROG_PREFIX fmt "\n", ##args)
+
+int main(int argc, const char **argv)
+{
+    log("\n"
+        "HEEEEEY, father\n"
+        "There's an endless road to rediscover\n"
+        "HEEEEEY, sister\n"
+        "Do you still belive in love I wonder");
+    if (argc != 2) {
+        log("Ooops, wrong amount of args, %d", argc);
+        return EXIT_FAILURE;
+    }
+    long mode = strtol(argv[1], NULL, 10);
+    log("mode: %ld", mode);
+    switch(mode) {
+    case WAIT_FOR_CHILD:
+        log("pid %d ppid %d", getpid(), getppid());
+        sleep(5);
+        break;
+    case DONT_WAIT_FOR_CHILD:
+        log("before parent die: pid %d ppid %d", getpid(), getppid());
+        sleep(5);
+        log("after parent die: pid %d ppid %d", getpid(), getppid());
+        break;
+    case ZOMBIE_PROCESS:
+        break;
+    default:
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}