[llvm] r299098 - Following r297661, disable dup workaround to disable duplicate STDOUT fd closing and instead directly prevent closing of STD* file descriptors.

[Yaron Keren via llvm-commits]

Author: yrnkrn
Date: Thu Mar 30 14:30:51 2017
New Revision: 299098

URL: http://llvm.org/viewvc/llvm-project?rev=299098&view=rev
Log:
Following r297661, disable dup workaround to disable duplicate STDOUT fd closing and instead directly prevent closing of STD* file descriptors. 

We do not want to close STDOUT as there may have been several uses of it
such as the case: llc %s -o=- -pass-remarks-output=- -filetype=asm
which cause multiple closes of STDOUT_FILENO and/or use-after-close of it.
Using dup() in getFD doesn't work as we end up with original STDOUT_FILENO
open anyhow.

reviewed by Rafael Espindola

Differential Revision: https://reviews.llvm.org/D31505


Modified:
    llvm/trunk/lib/Support/raw_ostream.cpp

Modified: llvm/trunk/lib/Support/raw_ostream.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=299098&r1=299097&r2=299098&view=diff
==============================================================================
--- llvm/trunk/lib/Support/raw_ostream.cpp (original)
+++ llvm/trunk/lib/Support/raw_ostream.cpp Thu Mar 30 14:30:51 2017
@@ -473,7 +473,7 @@ static int getFD(StringRef Filename, std
     // possible.
     if (!(Flags & sys::fs::F_Text))
       sys::ChangeStdoutToBinary();
-    return dup(STDOUT_FILENO);
+    return STDOUT_FILENO;
   }
 
   int FD;
@@ -497,6 +497,13 @@ raw_fd_ostream::raw_fd_ostream(int fd, b
     ShouldClose = false;
     return;
   }
+  // We do not want to close STDOUT as there may have been several uses of it
+  // such as the case: llc %s -o=- -pass-remarks-output=- -filetype=asm
+  // which cause multiple closes of STDOUT_FILENO and/or use-after-close of it.
+  // Using dup() in getFD doesn't work as we end up with original STDOUT_FILENO
+  // open anyhow.
+  if (FD <= STDERR_FILENO)
+    ShouldClose = false;
 
   // Get the starting position.
   off_t loc = ::lseek(FD, 0, SEEK_CUR);