From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 20 Jun 2018 10:32:30 +0000 (+0300)
Subject: Add signature detection for sound files
X-Git-Url: http://git.tdb.fi/?p=libs%2Fal.git;a=commitdiff_plain;h=d035e638b940f25cb5d46a049a00b34dc60dc5e0

Add signature detection for sound files
---

diff --git a/source/oggdecoder.cpp b/source/oggdecoder.cpp
index efea1f6..d287342 100644
--- a/source/oggdecoder.cpp
+++ b/source/oggdecoder.cpp
@@ -107,6 +107,14 @@ OggDecoder::~OggDecoder()
 	delete priv;
 }
 
+bool OggDecoder::detect(const std::string &sig)
+{
+	static const char ogg_sig[] = { 'O', 'g', 'g', 'S' };
+	if(sig.size()<sizeof(ogg_sig))
+		return false;
+	return !sig.compare(0, sizeof(ogg_sig), ogg_sig);
+}
+
 void OggDecoder::rewind()
 {
 	ov_pcm_seek(&priv->ovfile, 0);
diff --git a/source/oggdecoder.h b/source/oggdecoder.h
index 49cadbb..aab8f5c 100644
--- a/source/oggdecoder.h
+++ b/source/oggdecoder.h
@@ -29,6 +29,8 @@ public:
 	OggDecoder(IO::Seekable &);
 	~OggDecoder();
 
+	static bool detect(const std::string &);
+
 	virtual void rewind();
 	virtual unsigned read(char *, unsigned);
 };
diff --git a/source/sounddecoder.cpp b/source/sounddecoder.cpp
index 138117f..a2cd51a 100644
--- a/source/sounddecoder.cpp
+++ b/source/sounddecoder.cpp
@@ -1,5 +1,6 @@
 #include <msp/core/refptr.h>
 #include <msp/io/file.h>
+#include <msp/strings/format.h>
 #include "oggdecoder.h"
 #include "sounddecoder.h"
 
@@ -29,14 +30,29 @@ SoundDecoder::~SoundDecoder()
 SoundDecoder *SoundDecoder::open_file(const string &fn)
 {
 	RefPtr<IO::BufferedFile> file = new IO::BufferedFile(fn);
-	SoundDecoder *decoder = new OggDecoder(*file);
+	SoundDecoder *decoder = open_io(*file);
 	decoder->source = file.release();
 	return decoder;
 }
 
 SoundDecoder *SoundDecoder::open_io(IO::Seekable &io)
 {
-	return new OggDecoder(io);
+	char sig_buf[8];
+	io.read(sig_buf, sizeof(sig_buf));
+	string signature(sig_buf, sizeof(sig_buf));
+	if(OggDecoder::detect(signature))
+		return new OggDecoder(io);
+	else
+	{
+		string sig_hex;
+		for(unsigned i=0; i<sizeof(sig_buf); ++i)
+		{
+			if(i)
+				sig_hex += ' ';
+			sig_hex += Msp::format("%02X", static_cast<unsigned char>(sig_buf[i]));
+		}
+		throw unsupported_sound(sig_hex);
+	}
 }
 
 } // namespace AL