[libcamera-devel] [PATCH v2 1/1] Fix Android adaptor thumbnail buffer lifetime

[Harvey Yang]

Previously the thumbnail buffer is destructed before even being used in
Exif. This patch moves the buffer into class Exif, so that the developer
won't need to worry about its lifetime.

Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
---
 src/android/jpeg/exif.cpp                | 13 +++++--------
 src/android/jpeg/exif.h                  |  5 ++++-
 src/android/jpeg/post_processor_jpeg.cpp |  2 +-
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
index 3220b458..6b1d0f1f 100644
--- a/src/android/jpeg/exif.cpp
+++ b/src/android/jpeg/exif.cpp
@@ -430,16 +430,13 @@ void Exif::setOrientation(int orientation)
 	setShort(EXIF_IFD_0, EXIF_TAG_ORIENTATION, value);
 }
 
-/*
- * The thumbnail data should remain valid until the Exif object is destroyed.
- * Failing to do so, might result in no thumbnail data being set even after a
- * call to Exif::setThumbnail().
- */
-void Exif::setThumbnail(Span<const unsigned char> thumbnail,
+void Exif::setThumbnail(std::vector<unsigned char> &&thumbnail,
 			Compression compression)
 {
-	data_->data = const_cast<unsigned char *>(thumbnail.data());
-	data_->size = thumbnail.size();
+	thumbnailData_ = std::move(thumbnail);
+
+	data_->data = thumbnailData_.data();
+	data_->size = thumbnailData_.size();
 
 	setShort(EXIF_IFD_0, EXIF_TAG_COMPRESSION, compression);
 }
diff --git a/src/android/jpeg/exif.h b/src/android/jpeg/exif.h
index 2ff8fb78..e68716f3 100644
--- a/src/android/jpeg/exif.h
+++ b/src/android/jpeg/exif.h
@@ -10,6 +10,7 @@
 #include <chrono>
 #include <string>
 #include <time.h>
+#include <vector>
 
 #include <libexif/exif-data.h>
 
@@ -60,7 +61,7 @@ public:
 
 	void setOrientation(int orientation);
 	void setSize(const libcamera::Size &size);
-	void setThumbnail(libcamera::Span<const unsigned char> thumbnail,
+	void setThumbnail(std::vector<unsigned char> &&thumbnail,
 			  Compression compression);
 	void setTimestamp(time_t timestamp, std::chrono::milliseconds msec);
 
@@ -106,4 +107,6 @@ private:
 
 	unsigned char *exifData_;
 	unsigned int size_;
+
+	std::vector<unsigned char> thumbnailData_;
 };
diff --git a/src/android/jpeg/post_processor_jpeg.cpp b/src/android/jpeg/post_processor_jpeg.cpp
index d72ebc3c..0cf56716 100644
--- a/src/android/jpeg/post_processor_jpeg.cpp
+++ b/src/android/jpeg/post_processor_jpeg.cpp
@@ -166,7 +166,7 @@ void PostProcessorJpeg::process(Camera3RequestDescriptor::StreamBuffer *streamBu
 			std::vector<unsigned char> thumbnail;
 			generateThumbnail(source, thumbnailSize, quality, &thumbnail);
 			if (!thumbnail.empty())
-				exif.setThumbnail(thumbnail, Exif::Compression::JPEG);
+				exif.setThumbnail(std::move(thumbnail), Exif::Compression::JPEG);
 		}
 
 		resultMetadata->addEntry(ANDROID_JPEG_THUMBNAIL_SIZE, data, 2);
-- 
2.37.1.359.gd136c6c3e2-goog