From 8a412367448c55916380ce7040ddbd0a75fa722e Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 2 Nov 2021 11:57:28 +0200
Subject: [PATCH] Add a function to detect raw data signature

---
 source/rawdata.cpp | 10 +++++++++-
 source/rawdata.h   |  4 ++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/source/rawdata.cpp b/source/rawdata.cpp
index 7a90c9d..b912a56 100644
--- a/source/rawdata.cpp
+++ b/source/rawdata.cpp
@@ -1,3 +1,4 @@
+#include <cstring>
 #include <stdexcept>
 #include <msp/io/zlibcompressed.h>
 #include "collection.h"
@@ -9,6 +10,8 @@ using namespace std;
 namespace Msp {
 namespace DataFile {
 
+const char RawData::signature[4] = { 'M', 'D', 'R', 1 };
+
 RawData::~RawData()
 {
 	delete owned_data;
@@ -17,6 +20,11 @@ RawData::~RawData()
 		delete in;
 }
 
+bool RawData::detect_signature(const std::string &sig)
+{
+	return !sig.compare(0, string::npos, signature, sizeof(signature));
+}
+
 void RawData::open_file(Collection &coll, const string &fn)
 {
 	if(in)
@@ -40,7 +48,7 @@ void RawData::open_io(IO::Base &i, const string &fn)
 	unsigned len = i.read(header, sizeof(header));
 	if(len!=sizeof(header))
 		throw data_error(fn, 0, "Missing header");
-	if(header[0]!='M' || header[1]!='D' || header[2]!='R' || header[3]!=1)
+	if(memcmp(header, signature, sizeof(signature)))
 		throw data_error(fn, 0, "Bad header");
 
 	size = 0;
diff --git a/source/rawdata.h b/source/rawdata.h
index 2db390b..2744744 100644
--- a/source/rawdata.h
+++ b/source/rawdata.h
@@ -26,9 +26,13 @@ private:
 	char *data = nullptr;
 	char *owned_data = nullptr;
 
+	static const char signature[4];
+
 public:
 	~RawData();
 
+	static bool detect_signature(const std::string &);
+
 	void open_file(Collection &, const std::string &);
 	void open_io(IO::Base &, const std::string &);
 	void load();
-- 
2.45.2