Return AVERROR_EOF from the avio_read method when appropriate.

4 files changed, 33 insertions, 18 deletions

diff --git a/src/lib/ffmpeg.cc b/src/lib/ffmpeg.cc
index 6ec368ef6..39abfe2b8 100644
--- a/src/lib/ffmpeg.cc
+++ b/src/lib/ffmpeg.cc
@@ -273,7 +273,11 @@ FFmpeg::subtitle_codec_context () const
 int
 FFmpeg::avio_read (uint8_t* buffer, int const amount)
 {
-	return _file_group.read (buffer, amount);
+	auto result = _file_group.read(buffer, amount);
+	if (result.eof && result.bytes_read == 0) {
+		return AVERROR_EOF;
+	}
+	return result.bytes_read;
 }
 
 
diff --git a/src/lib/file_group.cc b/src/lib/file_group.cc
index 71faacc4c..f4d50028e 100644
--- a/src/lib/file_group.cc
+++ b/src/lib/file_group.cc
@@ -134,9 +134,8 @@ FileGroup::seek (int64_t pos, int whence) const
 /** Try to read some data from the current position into a buffer.
  *  @param buffer Buffer to write data into.
  *  @param amount Number of bytes to read.
- *  @return Number of bytes read.
  */
-int
+FileGroup::Result
 FileGroup::read (uint8_t* buffer, int amount) const
 {
 	DCPOMATIC_ASSERT (_current_file);
@@ -173,13 +172,13 @@ FileGroup::read (uint8_t* buffer, int amount) const
 		if (eof) {
 			/* See if there is another file to use */
 			if ((_current_path + 1) >= _paths.size()) {
-				break;
+				return { read, true };
 			}
 			ensure_open_path (_current_path + 1);
 		}
 	}
 
-	return read;
+	return { read, false };
 }
 
 
diff --git a/src/lib/file_group.h b/src/lib/file_group.h
index 693bf89ba..aac72c228 100644
--- a/src/lib/file_group.h
+++ b/src/lib/file_group.h
@@ -49,8 +49,18 @@ public:
 
 	void set_paths (std::vector<boost::filesystem::path> const &);
 
+	struct Result {
+		Result(int bytes_read_, bool eof_)
+			: bytes_read(bytes_read_)
+			, eof(eof_)
+		{}
+
+		int bytes_read = 0;
+		bool eof = false;
+	};
+
 	int64_t seek (int64_t, int) const;
-	int read (uint8_t*, int) const;
+	Result read (uint8_t*, int) const;
 	int64_t length () const;
 
 private:
diff --git a/test/file_group_test.cc b/test/file_group_test.cc
index f974a3725..3fb31317c 100644
--- a/test/file_group_test.cc
+++ b/test/file_group_test.cc
@@ -79,51 +79,53 @@ BOOST_AUTO_TEST_CASE (file_group_test)
 	int pos = 0;
 
 	/* Basic read from 0 */
-	BOOST_CHECK_EQUAL (fg.read(test, 64), 64);
+	BOOST_CHECK_EQUAL(fg.read(test, 64).bytes_read, 64);
 	BOOST_CHECK_EQUAL (memcmp(data, test, 64), 0);
 	pos += 64;
 
 	/* Another read following the previous */
-	BOOST_CHECK_EQUAL (fg.read(test, 4), 4);
+	BOOST_CHECK_EQUAL(fg.read(test, 4).bytes_read, 4);
 	BOOST_CHECK_EQUAL (memcmp(data + pos, test, 4), 0);
 	pos += 4;
 
 	/* Read overlapping A and B */
-	BOOST_CHECK_EQUAL (fg.read(test, 128), 128);
+	BOOST_CHECK_EQUAL(fg.read(test, 128).bytes_read, 128);
 	BOOST_CHECK_EQUAL (memcmp(data + pos, test, 128), 0);
 	pos += 128;
 
 	/* Read overlapping B/C/D and over-reading by a lot */
-	BOOST_CHECK_EQUAL (fg.read(test, total_length * 3), total_length - pos);
+	BOOST_CHECK_EQUAL(fg.read(test, total_length * 3).bytes_read, total_length - pos);
 	BOOST_CHECK_EQUAL (memcmp(data + pos, test, total_length - pos), 0);
 
 	/* Over-read by a little */
 	BOOST_CHECK_EQUAL (fg.seek(0, SEEK_SET), 0);
-	BOOST_CHECK_EQUAL (fg.read(test, total_length), total_length);
-	BOOST_CHECK_EQUAL (fg.read(test, 1), 0);
+	BOOST_CHECK_EQUAL(fg.read(test, total_length).bytes_read, total_length);
+	BOOST_CHECK_EQUAL(fg.read(test, 1).bytes_read, 0);
 
 	/* Seeking off the end of the file should not give an error */
 	BOOST_CHECK_EQUAL (fg.seek(total_length * 2, SEEK_SET), total_length * 2);
-	/* and attempting to read should return nothing */
-	BOOST_CHECK_EQUAL (fg.read(test, 64), 0);
+	/* and attempting to read should return nothing and EOF */
+	auto result = fg.read(test, 64);
+	BOOST_CHECK_EQUAL(result.bytes_read, 0);
+	BOOST_CHECK(result.eof);
 	/* but the requested seek should be remembered, so if we now go back (relatively) */
 	BOOST_CHECK_EQUAL (fg.seek(-total_length * 2, SEEK_CUR), 0);
 	/* we should be at the start again */
-	BOOST_CHECK_EQUAL (fg.read(test, 64), 64);
+	BOOST_CHECK_EQUAL(fg.read(test, 64).bytes_read, 64);
 	BOOST_CHECK_EQUAL (memcmp(data, test, 64), 0);
 
 	/* SEEK_SET */
 	BOOST_CHECK_EQUAL (fg.seek(999, SEEK_SET), 999);
-	BOOST_CHECK_EQUAL (fg.read(test, 64), 64);
+	BOOST_CHECK_EQUAL(fg.read(test, 64).bytes_read, 64);
 	BOOST_CHECK_EQUAL (memcmp(data + 999, test, 64), 0);
 
 	/* SEEK_CUR */
 	BOOST_CHECK_EQUAL (fg.seek(42, SEEK_CUR), 999 + 64 + 42);
-	BOOST_CHECK_EQUAL (fg.read(test, 64), 64);
+	BOOST_CHECK_EQUAL(fg.read(test, 64).bytes_read, 64);
 	BOOST_CHECK_EQUAL (memcmp(data + 999 + 64 + 42, test, 64), 0);
 
 	/* SEEK_END */
 	BOOST_CHECK_EQUAL (fg.seek(1077, SEEK_END), total_length - 1077);
-	BOOST_CHECK_EQUAL (fg.read(test, 256), 256);
+	BOOST_CHECK_EQUAL(fg.read(test, 256).bytes_read, 256);
 	BOOST_CHECK_EQUAL (memcmp(data + total_length - 1077, test, 256), 0);
 }