apps: cam: Print an error when outputting DNG and DNG support is missing

When DNG support is missing, the cam application ignores the .dng suffix
of the file pattern and writes raw binary data instead, without
notifying the user. This leads to confusion. Fix it by printing an error
message.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

src/apps/cam/camera_session.cpp

@@ -256,11 +256,16 @@ int CameraSession::start()
 #endif
 
 	if (options_.isSet(OptFile)) {
-		if (!options_[OptFile].toString().empty())
-			sink_ = std::make_unique<FileSink>(camera_.get(), streamNames_,
-							   options_[OptFile]);
-		else
-			sink_ = std::make_unique<FileSink>(camera_.get(), streamNames_);
+		std::unique_ptr<FileSink> sink =
+			std::make_unique<FileSink>(camera_.get(), streamNames_);
+
+		if (!options_[OptFile].toString().empty()) {
+			ret = sink->setFilePattern(options_[OptFile]);
+			if (ret)
+				return ret;
+		}
+
+		sink_ = std::move(sink);
 	}
 
 	if (sink_) {

src/apps/cam/file_sink.cpp

@@ -5,6 +5,7 @@
  * File Sink
  */
 
+#include <array>
 #include <assert.h>
 #include <fcntl.h>
 #include <iomanip>
@@ -12,6 +13,7 @@
 #include <sstream>
 #include <string.h>
 #include <unistd.h>
+#include <utility>
 
 #include <libcamera/camera.h>
 
@@ -24,13 +26,13 @@
 using namespace libcamera;
 
 FileSink::FileSink([[maybe_unused]] const libcamera::Camera *camera,
-		   const std::map<const libcamera::Stream *, std::string> &streamNames,
-		   const std::string &pattern)
+		   const std::map<const libcamera::Stream *, std::string> &streamNames)
 	:
 #ifdef HAVE_TIFF
 	  camera_(camera),
 #endif
-	  streamNames_(streamNames), pattern_(pattern)
+	  pattern_(kDefaultFilePattern), fileType_(FileType::Binary),
+	  streamNames_(streamNames)
 {
 }
 
@@ -38,6 +40,41 @@ FileSink::~FileSink()
 {
 }
 
+int FileSink::setFilePattern(const std::string &pattern)
+{
+	static const std::array<std::pair<std::string, FileType>, 2> types{{
+		{ ".dng", FileType::Dng },
+		{ ".ppm", FileType::Ppm },
+	}};
+
+	pattern_ = pattern;
+
+	if (pattern_.empty() || pattern_.back() == '/')
+		pattern_ += kDefaultFilePattern;
+
+	fileType_ = FileType::Binary;
+
+	for (const auto &type : types) {
+		if (pattern_.size() < type.first.size())
+			continue;
+
+		if (pattern_.find(type.first, pattern_.size() - type.first.size()) !=
+		    std::string::npos) {
+			fileType_ = type.second;
+			break;
+		}
+	}
+
+#ifndef HAVE_TIFF
+	if (fileType_ == FileType::Dng) {
+		std::cerr << "DNG support not available" << std::endl;
+		return -EINVAL;
+	}
+#endif /* HAVE_TIFF */
+
+	return 0;
+}
+
 int FileSink::configure(const libcamera::CameraConfiguration &config)
 {
 	int ret = FrameSink::configure(config);
@@ -67,21 +104,10 @@ bool FileSink::processRequest(Request *request)
 void FileSink::writeBuffer(const Stream *stream, FrameBuffer *buffer,
 			   [[maybe_unused]] const ControlList &metadata)
 {
-	std::string filename;
+	std::string filename = pattern_;
 	size_t pos;
 	int fd, ret = 0;
 
-	if (!pattern_.empty())
-		filename = pattern_;
-
-#ifdef HAVE_TIFF
-	bool dng = filename.find(".dng", filename.size() - 4) != std::string::npos;
-#endif /* HAVE_TIFF */
-	bool ppm = filename.find(".ppm", filename.size() - 4) != std::string::npos;
-
-	if (filename.empty() || filename.back() == '/')
-		filename += "frame-#.bin";
-
 	pos = filename.find_first_of('#');
 	if (pos != std::string::npos) {
 		std::stringstream ss;
@@ -93,7 +119,7 @@ void FileSink::writeBuffer(const Stream *stream, FrameBuffer *buffer,
 	Image *image = mappedBuffers_[buffer].get();
 
 #ifdef HAVE_TIFF
-	if (dng) {
+	if (fileType_ == FileType::Dng) {
 		ret = DNGWriter::write(filename.c_str(), camera_,
 				       stream->configuration(), metadata,
 				       buffer, image->data(0).data());
@@ -104,7 +130,7 @@ void FileSink::writeBuffer(const Stream *stream, FrameBuffer *buffer,
 		return;
 	}
 #endif /* HAVE_TIFF */
-	if (ppm) {
+	if (fileType_ == FileType::Ppm) {
 		ret = PPMWriter::write(filename.c_str(), stream->configuration(),
 				       image->data(0));
 		if (ret < 0)

src/apps/cam/file_sink.h

@@ -21,10 +21,11 @@ class FileSink : public FrameSink
 {
 public:
 	FileSink(const libcamera::Camera *camera,
-		 const std::map<const libcamera::Stream *, std::string> &streamNames,
-		 const std::string &pattern = "");
+		 const std::map<const libcamera::Stream *, std::string> &streamNames);
 	~FileSink();
 
+	int setFilePattern(const std::string &pattern);
+
 	int configure(const libcamera::CameraConfiguration &config) override;
 
 	void mapBuffer(libcamera::FrameBuffer *buffer) override;
@@ -32,6 +33,14 @@ public:
 	bool processRequest(libcamera::Request *request) override;
 
 private:
+	static constexpr const char *kDefaultFilePattern = "frame-#.bin";
+
+	enum class FileType {
+		Binary,
+		Dng,
+		Ppm,
+	};
+
 	void writeBuffer(const libcamera::Stream *stream,
 			 libcamera::FrameBuffer *buffer,
 			 const libcamera::ControlList &metadata);
@@ -39,7 +48,10 @@ private:
 #ifdef HAVE_TIFF
 	const libcamera::Camera *camera_;
 #endif
-	std::map<const libcamera::Stream *, std::string> streamNames_;
+
 	std::string pattern_;
+	FileType fileType_;
+
+	std::map<const libcamera::Stream *, std::string> streamNames_;
 	std::map<libcamera::FrameBuffer *, std::unique_ptr<Image>> mappedBuffers_;
 };