libuuu: sdp: SDPBootCmd: add barebox autodetection

We do already support the -barebox switch, so the user can force the
barebox image handling. Add a autodetection mechanism to make it even
more user friendly. The autodetection is based on the fact, that barebox
does add an "barebox" string at offset 0x20 to the image. If this string
is found we can assume that user provided file is an barebox image.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>

libuuu/sdp.cpp

@@ -243,6 +243,25 @@ SDPBootCmd::SDPBootCmd(char *p) : SDPCmdBase(p)
 	insert_param_info("-barebox", &m_barebox, Param::Type::e_bool);
 }
 
+# define BAREBOX_MAGIC_OFFSET	0x20
+
+bool SDPBootCmd::is_barebox_img(void)
+{
+	shared_ptr<FileBuffer> fbuf= get_file_buffer(m_filename, true);
+	if (fbuf == nullptr)
+		return false;
+
+	string barebox_magic ("barebox");
+
+	shared_ptr<DataBuffer> dbuf = fbuf->request_data(0, BAREBOX_MAGIC_OFFSET + barebox_magic.length());
+	if (dbuf == nullptr)
+		return false;
+
+	string img ((const char *)&dbuf->at(BAREBOX_MAGIC_OFFSET), barebox_magic.length());
+
+	return img.compare(barebox_magic) == 0 ? true : false;
+}
+
 int SDPBootCmd::load_barebox(CmdCtx *ctx)
 {
 	const ROM_INFO *rom = search_rom_info(ctx->m_config_item);
@@ -341,7 +360,7 @@ int SDPBootCmd::run(CmdCtx *ctx)
 		if (jmp.run(ctx)) return -1;
 	}
 
-	if (m_barebox)
+	if (m_barebox || is_barebox_img())
 	{
 		if (load_barebox(ctx)) return -1;
 	}

libuuu/sdp.h

@@ -213,6 +213,7 @@ class SDPBootCmd : public SDPCmdBase
 	int run(CmdCtx *p) override;
 
 private:
+	bool is_barebox_img(void);
 	int load_barebox(CmdCtx *ctx);
 
 	bool m_clear_dcd = false;