From 99f5fc937f1042b24188a92bf2fe40f151d023bb Mon Sep 17 00:00:00 2001
From: Marshall Clow <mclow.lists@gmail.com>
Date: Mon, 22 Jun 2015 15:01:21 +0000
Subject: [PATCH] Make seeking on an ostream that has eofbit set work
 correctly. Fixes PR#21361

llvm-svn: 240286
---
 libcxx/include/ostream                                |  4 ++--
 .../output.streams/ostream.seeks/seekp.pass.cpp       | 11 +++++++++++
 .../output.streams/ostream.seeks/seekp2.pass.cpp      | 11 +++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/libcxx/include/ostream b/libcxx/include/ostream
index a7af2994b6b9..f55fd40856ec 100644
--- a/libcxx/include/ostream
+++ b/libcxx/include/ostream
@@ -1004,7 +1004,7 @@ basic_ostream<_CharT, _Traits>&
 basic_ostream<_CharT, _Traits>::seekp(pos_type __pos)
 {
     sentry __s(*this);
-    if (__s)
+    if (!this->fail())
     {
         if (this->rdbuf()->pubseekpos(__pos, ios_base::out) == pos_type(-1))
             this->setstate(ios_base::failbit);
@@ -1018,7 +1018,7 @@ basic_ostream<_CharT, _Traits>&
 basic_ostream<_CharT, _Traits>::seekp(off_type __off, ios_base::seekdir __dir)
 {
     sentry __s(*this);
-    if (__s)
+    if (!this->fail())
     {
         if (this->rdbuf()->pubseekoff(__off, __dir, ios_base::out) == pos_type(-1))
             this->setstate(ios_base::failbit);
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp
index e09627b29b64..ec3fe48866c7 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp
@@ -40,11 +40,13 @@ protected:
 int main()
 {
     {
+        seekpos_called = 0;
         std::ostream os((std::streambuf*)0);
         assert(&os.seekp(5) == &os);
         assert(seekpos_called == 0);
     }
     {
+        seekpos_called = 0;
         testbuf<char> sb;
         std::ostream os(&sb);
         assert(&os.seekp(10) == &os);
@@ -54,4 +56,13 @@ int main()
         assert(seekpos_called == 2);
         assert(os.fail());
     }
+    { // See https://llvm.org/bugs/show_bug.cgi?id=21361
+        seekpos_called = 0;
+        testbuf<char> sb;
+        std::ostream os(&sb);
+        os.setstate(std::ios_base::eofbit);
+        assert(&os.seekp(10) == &os);
+        assert(seekpos_called == 1);
+        assert(os.rdstate() == std::ios_base::eofbit);
+    }
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp
index 69b26f3a96e8..ebfd24af91d5 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp
@@ -42,11 +42,13 @@ protected:
 int main()
 {
     {
+        seekoff_called = 0;
         std::ostream os((std::streambuf*)0);
         assert(&os.seekp(5, std::ios_base::beg) == &os);
         assert(seekoff_called == 0);
     }
     {
+        seekoff_called = 0;
         testbuf<char> sb;
         std::ostream os(&sb);
         assert(&os.seekp(10, std::ios_base::beg) == &os);
@@ -56,4 +58,13 @@ int main()
         assert(seekoff_called == 2);
         assert(os.fail());
     }
+    { // See https://llvm.org/bugs/show_bug.cgi?id=21361
+        seekoff_called = 0;
+        testbuf<char> sb;
+        std::ostream os(&sb);
+        os.setstate(std::ios_base::eofbit);
+        assert(&os.seekp(10, std::ios_base::beg) == &os);
+        assert(seekoff_called == 1);
+        assert(os.rdstate() == std::ios_base::eofbit);
+    }
 }