1 files changed, 121 insertions, 0 deletions
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp
new file mode 100644
index 00000000000..e34bc844bd2
--- /dev/null
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp
@@ -0,0 +1,121 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <fstream>
+
+// int_type underflow();
+
+// This test is not entirely portable
+
+#include <fstream>
+#include <cassert>
+
+#include "platform_support.h" // locale name macros
+
+template <class CharT>
+struct test_buf
+    : public std::basic_filebuf<CharT>
+{
+    typedef std::basic_filebuf<CharT> base;
+    typedef typename base::char_type  char_type;
+    typedef typename base::int_type   int_type;
+
+    char_type* eback() const {return base::eback();}
+    char_type* gptr()  const {return base::gptr();}
+    char_type* egptr() const {return base::egptr();}
+    void gbump(int n) {base::gbump(n);}
+
+    virtual int_type underflow() {return base::underflow();}
+};
+
+int main()
+{
+    {
+        test_buf<char> f;
+        assert(f.open("underflow.dat", std::ios_base::in) != 0);
+        assert(f.is_open());
+        assert(f.eback() == 0);
+        assert(f.gptr() == 0);
+        assert(f.egptr() == 0);
+        assert(f.underflow() == '1');
+        assert(f.eback() != 0);
+        assert(f.eback() == f.gptr());
+        assert(*f.gptr() == '1');
+        assert(f.egptr() - f.eback() == 9);
+    }
+    {
+        test_buf<char> f;
+        assert(f.open("underflow.dat", std::ios_base::in) != 0);
+        assert(f.pubsetbuf(0, 0));
+        assert(f.is_open());
+        assert(f.eback() == 0);
+        assert(f.gptr() == 0);
+        assert(f.egptr() == 0);
+        assert(f.underflow() == '1');
+        assert(f.eback() != 0);
+        assert(f.eback() == f.gptr());
+        assert(*f.gptr() == '1');
+        assert(f.egptr() - f.eback() == 8);
+        f.gbump(8);
+        assert(f.sgetc() == '9');
+        assert(f.eback()[0] == '5');
+        assert(f.eback()[1] == '6');
+        assert(f.eback()[2] == '7');
+        assert(f.eback()[3] == '8');
+        assert(f.gptr() - f.eback() == 4);
+        assert(*f.gptr() == '9');
+        assert(f.egptr() - f.gptr() == 1);
+    }
+    {
+        test_buf<wchar_t> f;
+        assert(f.open("underflow.dat", std::ios_base::in) != 0);
+        assert(f.is_open());
+        assert(f.eback() == 0);
+        assert(f.gptr() == 0);
+        assert(f.egptr() == 0);
+        assert(f.underflow() == L'1');
+        assert(f.eback() != 0);
+        assert(f.eback() == f.gptr());
+        assert(*f.gptr() == L'1');
+        assert(f.egptr() - f.eback() == 9);
+    }
+    {
+        test_buf<wchar_t> f;
+        assert(f.pubsetbuf(0, 0));
+        assert(f.open("underflow.dat", std::ios_base::in) != 0);
+        assert(f.is_open());
+        assert(f.eback() == 0);
+        assert(f.gptr() == 0);
+        assert(f.egptr() == 0);
+        assert(f.underflow() == L'1');
+        assert(f.eback() != 0);
+        assert(f.eback() == f.gptr());
+        assert(*f.gptr() == L'1');
+        assert(f.egptr() - f.eback() == 8);
+        f.gbump(8);
+        assert(f.sgetc() == L'9');
+        assert(f.eback()[0] == L'5');
+        assert(f.eback()[1] == L'6');
+        assert(f.eback()[2] == L'7');
+        assert(f.eback()[3] == L'8');
+        assert(f.gptr() - f.eback() == 4);
+        assert(*f.gptr() == L'9');
+        assert(f.egptr() - f.gptr() == 1);
+    }
+    {
+        test_buf<wchar_t> f;
+        f.pubimbue(std::locale(LOCALE_en_US_UTF_8));
+        assert(f.open("underflow_utf8.dat", std::ios_base::in) != 0);
+        assert(f.is_open());
+        assert(f.sbumpc() == 0x4E51);
+        assert(f.sbumpc() == 0x4E52);
+        assert(f.sbumpc() == 0x4E53);
+        assert(f.sbumpc() == -1);
+    }
+}