Relax assert to avoid spurious failures with /dev/null.

llvm-svn: 236106

2 files changed, 36 insertions, 1 deletions

diff --git a/llvm/include/llvm/Support/raw_ostream.h b/llvm/include/llvm/Support/raw_ostream.h
index ed9c8b09ba4..b59317112c4 100644
--- a/llvm/include/llvm/Support/raw_ostream.h
+++ b/llvm/include/llvm/Support/raw_ostream.h
@@ -323,7 +323,13 @@ public:
   explicit raw_pwrite_stream(bool Unbuffered = false)
       : raw_ostream(Unbuffered) {}
   void pwrite(const char *Ptr, size_t Size, uint64_t Offset) {
-    assert(Size + Offset <= tell() && "We don't support extending the stream");
+#ifndef NDBEBUG
+    uint64_t Pos = tell();
+    // /dev/null always reports a pos of 0, so we cannot perform this check
+    // in that case.
+    if (Pos)
+      assert(Size + Offset <= Pos && "We don't support extending the stream");
+#endif
     pwrite_impl(Ptr, Size, Offset);
   }
 };
diff --git a/llvm/unittests/Support/raw_pwrite_stream_test.cpp b/llvm/unittests/Support/raw_pwrite_stream_test.cpp
index 2792f44b605..4e521a04728 100644
--- a/llvm/unittests/Support/raw_pwrite_stream_test.cpp
+++ b/llvm/unittests/Support/raw_pwrite_stream_test.cpp
@@ -9,6 +9,7 @@
 
 #include "gtest/gtest.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -30,4 +31,32 @@ TEST(raw_pwrite_ostreamTest, TestSVector) {
 #endif
 #endif
 }
+
+TEST(raw_pwrite_ostreamTest, TestFD) {
+  SmallString<64> Path;
+  int FD;
+  sys::fs::createTemporaryFile("foo", "bar", FD, Path);
+  raw_fd_ostream OS(FD, true);
+  OS << "abcd";
+  StringRef Test = "test";
+  OS.pwrite(Test.data(), Test.size(), 0);
+  OS.pwrite(Test.data(), Test.size(), 0);
+
+#ifdef GTEST_HAS_DEATH_TEST
+#ifndef NDEBUG
+  EXPECT_DEATH(OS.pwrite("12345", 5, 0),
+               "We don't support extending the stream");
+#endif
+#endif
+}
+
+TEST(raw_pwrite_ostreamTest, TestDevNull) {
+  int FD;
+  sys::fs::openFileForWrite("/dev/null", FD, sys::fs::F_None);
+  raw_fd_ostream OS(FD, true);
+  OS << "abcd";
+  StringRef Test = "test";
+  OS.pwrite(Test.data(), Test.size(), 0);
+  OS.pwrite(Test.data(), Test.size(), 0);
+}
 }