java: add the skeleton of a java vm program

This program loads the given class and determines whether a main method is
present.

Signed-off-by: Vegard Nossum <[email protected]>

CMakeLists.txt

@@ -15,9 +15,11 @@ add_library (cafebabe SHARED
 )
 
 add_executable (dump src/dump.c)
-
 target_link_libraries (dump cafebabe)
 
+add_executable (java src/java.c)
+target_link_libraries (java cafebabe)
+
 set (LIB_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/lib
 	CACHE PATH "Installation prefix for user executables" FORCE)
 set (INCLUDE_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/include

src/java.c

@@ -0,0 +1,87 @@
+/*
+ * cafebabe - the class loader library in C
+ * Copyright (C) 2008  Vegard Nossum <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "cafebabe/access.h"
+#include "cafebabe/attribute_info.h"
+#include "cafebabe/class.h"
+#include "cafebabe/constant_pool.h"
+#include "cafebabe/error.h"
+#include "cafebabe/field_info.h"
+#include "cafebabe/method_info.h"
+#include "cafebabe/stream.h"
+
+int
+main(int argc, char *argv[])
+{
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s CLASS\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	const char *classname = argv[1];
+	char *filename;
+	if (asprintf(&filename, "%s.class", classname) == -1) {
+		fprintf(stderr, "error: %s\n", strerror(errno));
+		goto out;
+	}
+
+	struct cafebabe_stream stream;
+	if (cafebabe_stream_open(&stream, filename)) {
+		fprintf(stderr, "error: %s: %s\n", filename,
+			cafebabe_stream_error(&stream));
+		goto out_filename;
+	}
+
+	struct cafebabe_class class;
+	if (cafebabe_class_init(&class, &stream)) {
+		fprintf(stderr, "error: %s:%d/%d: %s\n", filename,
+			stream.virtual_i, stream.virtual_n,
+			cafebabe_stream_error(&stream));
+		goto out_stream;
+	}
+
+	struct cafebabe_method_info *main_method;
+	if (cafebabe_class_get_method(&class,
+		"main", "([Ljava/lang/String;)V", &main_method))
+	{
+		fprintf(stderr, "error: %s: no main method\n", classname);
+		goto out_class;
+	}
+
+	cafebabe_class_deinit(&class);
+	cafebabe_stream_close(&stream);
+
+	return EXIT_SUCCESS;
+
+out_class:
+	cafebabe_class_deinit(&class);
+out_stream:
+	cafebabe_stream_close(&stream);
+out_filename:
+	free(filename);
+out:
+	return EXIT_FAILURE;
+}