Fix for bug #2664460: Various SeekableReadStream::seek() implementations (as well as our unit tests, ouch) handled SEEK_END incorrectly (using -offset instead of offset), contrary to what the docs said and what fseek does. Hopefully I found and fixed all affected parts, but still watch out for regressions

svn-id: r39135

3 files changed, 65 insertions, 4 deletions

diff --git a/test/common/bufferedseekablereadstream.h b/test/common/bufferedseekablereadstream.h
index f039acd2a8..b91a27d221 100644
--- a/test/common/bufferedseekablereadstream.h
+++ b/test/common/bufferedseekablereadstream.h
@@ -56,13 +56,13 @@ class BufferedSeekableReadStreamTestSuite : public CxxTest::TestSuite {
 		b = ssrs.readByte();
 		TS_ASSERT( ssrs.eos() );
 
-		ssrs.seek(3, SEEK_END);
+		ssrs.seek(-3, SEEK_END);
 		TS_ASSERT( !ssrs.eos() );
 		TS_ASSERT_EQUALS( ssrs.pos(), 7 );
 		b = ssrs.readByte();
 		TS_ASSERT_EQUALS( b, 7 );
 
-		ssrs.seek(8, SEEK_END);
+		ssrs.seek(-8, SEEK_END);
 		TS_ASSERT_EQUALS( ssrs.pos(), 2 );
 		b = ssrs.readByte();
 		TS_ASSERT_EQUALS( b, 2 );
diff --git a/test/common/memoryreadstream.h b/test/common/memoryreadstream.h
new file mode 100644
index 0000000000..2cec073ad5
--- /dev/null
+++ b/test/common/memoryreadstream.h
@@ -0,0 +1,61 @@
+#include <cxxtest/TestSuite.h>
+
+#include "common/stream.h"
+
+class MemoryReadStreamTestSuite : public CxxTest::TestSuite {
+	public:
+	void test_seek_set(void) {
+		byte contents[] = { 'a', 'b', '\n', '\n', 'c', '\n' };
+		Common::MemoryReadStream ms(contents, sizeof(contents));
+
+		ms.seek(0, SEEK_SET);
+		TS_ASSERT_EQUALS(ms.pos(), 0);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(1, SEEK_SET);
+		TS_ASSERT_EQUALS(ms.pos(), 1);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(5, SEEK_SET);
+		TS_ASSERT_EQUALS(ms.pos(), 5);
+		TS_ASSERT(!ms.eos());
+	}
+
+	void test_seek_cur(void) {
+		byte contents[] = { 'a', 'b', '\n', '\n', 'c' };
+		Common::MemoryReadStream ms(contents, sizeof(contents));
+
+		ms.seek(3, SEEK_CUR);
+		TS_ASSERT_EQUALS(ms.pos(), 3);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(-1, SEEK_CUR);
+		TS_ASSERT_EQUALS(ms.pos(), 2);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(3, SEEK_CUR);
+		TS_ASSERT_EQUALS(ms.pos(), 5);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(-1, SEEK_CUR);
+		TS_ASSERT_EQUALS(ms.pos(), 4);
+		TS_ASSERT(!ms.eos());
+	}
+
+	void test_seek_end(void) {
+		byte contents[] = { 'a', 'b', '\n', '\n', 'c' };
+		Common::MemoryReadStream ms(contents, sizeof(contents));
+
+		ms.seek(0, SEEK_END);
+		TS_ASSERT_EQUALS(ms.pos(), 5);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(-1, SEEK_END);
+		TS_ASSERT_EQUALS(ms.pos(), 4);
+		TS_ASSERT(!ms.eos());
+
+		ms.seek(-5, SEEK_END);
+		TS_ASSERT_EQUALS(ms.pos(), 0);
+		TS_ASSERT(!ms.eos());
+	}
+};
diff --git a/test/common/seekablesubreadstream.h b/test/common/seekablesubreadstream.h
index 68febc7fd6..354e2dd5c1 100644
--- a/test/common/seekablesubreadstream.h
+++ b/test/common/seekablesubreadstream.h
@@ -58,13 +58,13 @@ class SeekableSubReadStreamTestSuite : public CxxTest::TestSuite {
 		b = ssrs.readByte();
 		TS_ASSERT( ssrs.eos() );
 
-		ssrs.seek(3, SEEK_END);
+		ssrs.seek(-3, SEEK_END);
 		TS_ASSERT( !ssrs.eos() );
 		TS_ASSERT_EQUALS( ssrs.pos(), 5 );
 		b = ssrs.readByte();
 		TS_ASSERT_EQUALS( b, 6 );
 
-		ssrs.seek(8, SEEK_END);
+		ssrs.seek(-8, SEEK_END);
 		TS_ASSERT_EQUALS( ssrs.pos(), 0 );
 		b = ssrs.readByte();
 		TS_ASSERT_EQUALS( b, 1 );