[thin_delta] read in the snaps and dev

features/thin_delta.feature

@@ -12,7 +12,7 @@ Feature: thin_delta
     Then it should pass with:
 
     """
-    Usage: thin_delta [options]
+    Usage: thin_delta [options] --snap1 <snap> --snap2 <snap> <device or file>
     Options:
       {-h|--help}
       {-V|--version}
@@ -22,7 +22,7 @@ Feature: thin_delta
     When I run `thin_delta -h`
     Then it should pass with:
     """
-    Usage: thin_delta [options]
+    Usage: thin_delta [options] --snap1 <snap> --snap2 <snap> <device or file>
     Options:
       {-h|--help}
       {-V|--version}
@@ -31,3 +31,24 @@ Feature: thin_delta
   Scenario: Unrecognised option should cause failure
     When I run `thin_delta --unleash-the-hedeghogs`
     Then it should fail
+
+  Scenario: --snap1 must be specified
+    When I run `thin_delta --snap2 45 foo`
+    Then it should fail with:
+    """
+    --snap1 not specified.
+    """
+
+  Scenario: --snap2 must be specified
+    When I run `thin_delta --snap1 45 foo`
+    Then it should fail with:
+    """
+    --snap2 not specified.
+    """
+
+  Scenario: device must be specified
+    When I run `thin_delta --snap1 45 --snap2 50`
+    Then it should fail with:
+    """
+    No input device provided.
+    """

thin-provisioning/thin_delta.cc

@@ -1,3 +1,5 @@
+#include <boost/lexical_cast.hpp>
+#include <boost/optional.hpp>
 #include <getopt.h>
 #include <iostream>
 #include <libgen.h>
@@ -9,41 +11,102 @@ using namespace std;
 //----------------------------------------------------------------
 
 namespace {
-	void usage(ostream &out, string const &cmd) {
-		out << "Usage: " << cmd << " [options]" << endl
+	class application {
+	public:
+		application(string const &cmd)
+		: cmd_(cmd) {
+		}
+
+		void usage(ostream &out) {
+			out << "Usage: " << cmd_ << " [options] --snap1 <snap> --snap2 <snap> <device or file>" << endl
 			    << "Options:" << endl
 			    << "  {-h|--help}" << endl
 			    << "  {-V|--version}" << endl;
 		}
+
+		void die(string const &msg) {
+			cerr << msg << endl;
+			usage(cerr);
+			exit(1);
+		}
+
+		unsigned parse_snap(string const &str) {
+			try {
+				return boost::lexical_cast<unsigned>(str);
+
+			} catch (...) {
+				ostringstream out;
+				out << "Couldn't parse snapshot designator: '" << str << "'";
+				die(out.str());
+			}
+
+			return 0; // never get here
+		}
+
+	private:
+		string cmd_;
+	};
+
+	struct flags {
+		boost::optional<string> dev;
+		boost::optional<unsigned> snap1;
+		boost::optional<unsigned> snap2;
+	};
 }
 
 //----------------------------------------------------------------
 
+// FIXME: add metadata snap switch
+
 int main(int argc, char **argv)
 {
 	int c;
+	flags fs;
+	application app(basename(argv[0]));
+
 	char const shortopts[] = "hV";
 	option const longopts[] = {
 		{ "help", no_argument, NULL, 'h' },
-		{ "version", no_argument, NULL, 'V' }
+		{ "version", no_argument, NULL, 'V' },
+		{ "snap1", required_argument, NULL, 1 },
+		{ "snap2", required_argument, NULL, 2 },
 	};
 
 	while ((c = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
 		switch (c) {
 		case 'h':
-			usage(cout, basename(argv[0]));
+			app.usage(cout);
 			return 0;
 
 		case 'V':
 			cout << THIN_PROVISIONING_TOOLS_VERSION << endl;
 			return 0;
 
+		case 1:
+			fs.snap1 = app.parse_snap(optarg);
+			break;
+
+		case 2:
+			fs.snap2 = app.parse_snap(optarg);
+			break;
+
 		default:
-			usage(cerr, basename(argv[0]));
+			app.usage(cerr);
 			return 1;
 		}
 	}
 
+	if (argc == optind)
+		app.die("No input device provided.");
+	else
+		fs.dev = argv[optind];
+
+	if (!fs.snap1)
+		app.die("--snap1 not specified.");
+
+	if (!fs.snap2)
+		app.die("--snap2 not specified.");
+
 	return 0;
 }