Use getopt to parse command line options

src/includes/common-includes.h

@@ -11,6 +11,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <unistd.h>
+#include <getopt.h>
 #include <sys/reboot.h>
 
 #define U_DISABLE_CURL

src/runtime-config.c

@@ -11,18 +11,86 @@ struct config
 extern struct config config;
 struct config config;
 
+void print_usage()
+{
+    printf("Usage:\n");
+    printf("  cryptops-api --root-device=DEV --crypt-name=LABEL "
+        " [--notify-command=COMMAND]\n");
+}
+
 void set_config_from_arguments(int argc, char ** argv)
 {
-    if (argc < 4)
+    // Set defaults.
+    char * crypt_name = NULL;
+    char * notify_command = "";
+    char * root_device = NULL;
+
+    int c;
+    while (true)
+    {
+        static struct option long_options[] =
+        {
+            {"crypt-name"    ,  required_argument, 0, 'c'},
+            {"notify-command",  required_argument, 0, 'n'},
+            {"root-device"   ,  required_argument, 0, 'r'},
+            {0, 0, 0, 0}
+        };
+        int option_index = 0;
+
+        c = getopt_long(argc, argv, "c:n:r:", long_options, &option_index);
+
+        // Check if we have dealt with all options.
+        if (c == -1)
+        {
+            break;
+        }
+
+        switch (c)
+        {
+            case 'c':
+                crypt_name = optarg;
+                break;
+            case 'n':
+                notify_command = optarg;
+                break;
+            case 'r':
+                root_device = optarg;
+                break;
+            case '?':
+                // getopt_long already printed an error message.
+                break;
+            default:
+                abort();
+        }
+    }
+
+    // Print any remaining command line arguments (not options).
+    if (optind < argc)
+    {
+        printf("non-option ARGV-elements: ");
+        while (optind < argc)
+        {
+            printf("%s ", argv[optind++]);
+        }
+        putchar('\n');
+    }
+
+    if (root_device == NULL)
+    {
+        printf("Required option --root-device missing.\n");
+        print_usage();
+        exit(1);
+    }
+    if (crypt_name == NULL)
     {
-        printf("Not enough arguments. Usage:\n");
-        printf("  cryptops-api ROOTDEV CRYPTNAME NOTIFY_COMMAND\n");
+        printf("Required option --crypt-name missing.\n");
+        print_usage();
         exit(1);
     }
 
-    config.root_device = argv[1];
-    config.mapped_device_name = argv[2];
-    config.notify_command = argv[3];
+    config.root_device = root_device;
+    config.mapped_device_name = crypt_name;
+    config.notify_command = notify_command;
 
     asprintf(&config.info_partition_device, "%s1", config.root_device);
     asprintf(&config.data_partition_device, "%s2", config.root_device);