1 //===----------------------------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 // <ostream>
11 
12 // template <class charT, class traits = char_traits<charT> >
13 //   class basic_ostream;
14 
15 // basic_ostream<charT,traits>& seekp(off_type off, ios_base::seekdir dir);
16 
17 #include <ostream>
18 #include <cassert>
19 
20 int seekoff_called = 0;
21 
22 template <class CharT>
23 struct testbuf
24     : public std::basic_streambuf<CharT>
25 {
26     typedef std::basic_streambuf<CharT> base;
testbuftestbuf27     testbuf() {}
28 
29 protected:
30 
31     typename base::pos_type
seekofftestbuf32     seekoff(typename base::off_type off, std::ios_base::seekdir way,
33                                          std::ios_base::openmode which)
34     {
35         ++seekoff_called;
36         assert(way == std::ios_base::beg);
37         assert(which == std::ios_base::out);
38         return off;
39     }
40 };
41 
main()42 int main()
43 {
44     {
45         seekoff_called = 0;
46         std::ostream os((std::streambuf*)0);
47         assert(&os.seekp(5, std::ios_base::beg) == &os);
48         assert(seekoff_called == 0);
49     }
50     {
51         seekoff_called = 0;
52         testbuf<char> sb;
53         std::ostream os(&sb);
54         assert(&os.seekp(10, std::ios_base::beg) == &os);
55         assert(seekoff_called == 1);
56         assert(os.good());
57         assert(&os.seekp(-1, std::ios_base::beg) == &os);
58         assert(seekoff_called == 2);
59         assert(os.fail());
60     }
61     { // See https://llvm.org/bugs/show_bug.cgi?id=21361
62         seekoff_called = 0;
63         testbuf<char> sb;
64         std::ostream os(&sb);
65         os.setstate(std::ios_base::eofbit);
66         assert(&os.seekp(10, std::ios_base::beg) == &os);
67         assert(seekoff_called == 1);
68         assert(os.rdstate() == std::ios_base::eofbit);
69     }
70 }
71