examples/nitro: Add more required arguments

Add more arguments for customizing the nitro enclaves example. These
arguments include

- Enclave rootfs.
- Number of vCPUs for enclave.
- Amount of RAM (in MiB) allocated to enclave.

Signed-off-by: Tyler Fanelli <tfanelli@redhat.com>

Author: tylerfanelli

examples/nitro.c

@@ -33,11 +33,14 @@
 static void print_help(char *const name)
 {
     fprintf(stderr,
-        "Usage: %s EIF_FILE [COMMAND_ARGS...]\n"
+        "Usage: %s ENCLAVE_IMAGE NEWROOT NUM_VCPUS RAM_MIB\n"
         "OPTIONS: \n"
         "        -h    --help                Show help\n"
         "\n"
         "ENCLAVE_IMAGE:     The enclave image to run\n",
+        "NEWROOT:           The root directory of the enclave\n",
+        "NUM_VCPUS:         The amount of vCPUs for running the enclave\n",
+        "RAM_MIB:           The amount of RAM (MiB) allocated for enclave\n",
         name
     );
 }
@@ -50,6 +53,9 @@ static const struct option long_options[] = {
 struct cmdline {
     bool show_help;
     const char *eif_path;
+    const char *new_root;
+    unsigned int num_vcpus;
+    unsigned int ram_mib;
 };
 
 bool parse_cmdline(int argc, char *const argv[], struct cmdline *cmdline)
@@ -78,11 +84,22 @@ bool parse_cmdline(int argc, char *const argv[], struct cmdline *cmdline)
         }
     }
 
-    if (optind < argc) {
+    if (optind < argc - 3) {
         cmdline->eif_path = argv[optind];
+        cmdline->new_root = argv[optind + 1];
+        cmdline->num_vcpus = strtoul(argv[optind + 2], NULL, 10);
+        cmdline->ram_mib = strtoul(argv[optind + 3], NULL, 10);
         return true;
-    } else
-        fprintf(stderr, "Missing EIF_FILE argument");
+    }
+
+    if (optind >= argc - 3)
+        fprintf(stderr, "Missing RAM_MIB argument\n");
+    if (optind >= argc - 2)
+        fprintf(stderr, "Missing NUM_VCPUS argument\n");
+    if (optind >= argc - 1)
+        fprintf(stderr, "Missing NEWROOT argument\n");
+    if (optind == argc)
+        fprintf(stderr, "Missing ENCLAVE_IMAGE argument\n");
 
     return false;
 }