[llvm] r234619 - Remember if lseek works in this FD.

[Rafael Espindola]

Author: rafael
Date: Fri Apr 10 13:15:51 2015
New Revision: 234619

URL: http://llvm.org/viewvc/llvm-project?rev=234619&view=rev
Log:
Remember if lseek works in this FD.

It will be used in clang in a sec.

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

Modified: llvm/trunk/include/llvm/Support/raw_ostream.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/raw_ostream.h?rev=234619&r1=234618&r2=234619&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/raw_ostream.h (original)
+++ llvm/trunk/include/llvm/Support/raw_ostream.h Fri Apr 10 13:15:51 2015
@@ -333,6 +333,8 @@ class raw_fd_ostream : public raw_ostrea
 
   uint64_t pos;
 
+  bool SupportsSeeking;
+
   /// See raw_ostream::write_impl.
   void write_impl(const char *Ptr, size_t Size) override;
 
@@ -370,6 +372,8 @@ public:
   /// fsync.
   void close();
 
+  bool supportsSeeking() { return SupportsSeeking; }
+
   /// Flushes the stream and repositions the underlying file descriptor position
   /// to the offset specified from the beginning of the file.
   uint64_t seek(uint64_t off);

Modified: llvm/trunk/lib/Support/raw_ostream.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=234619&r1=234618&r2=234619&view=diff
==============================================================================
--- llvm/trunk/lib/Support/raw_ostream.cpp (original)
+++ llvm/trunk/lib/Support/raw_ostream.cpp Fri Apr 10 13:15:51 2015
@@ -525,7 +525,8 @@ raw_fd_ostream::raw_fd_ostream(int fd, b
 
   // Get the starting position.
   off_t loc = ::lseek(FD, 0, SEEK_CUR);
-  if (loc == (off_t)-1)
+  SupportsSeeking = loc != (off_t)-1;
+  if (!SupportsSeeking)
     pos = 0;
   else
     pos = static_cast<uint64_t>(loc);