Fix llvm-extract's "writing bitcode to a terminal" warning, which wasn't
working. To support this, add an is_displayed() function to raw_ostream,
and generalize Process::StandardOutIsDisplayed and friends in order to
support it.

Also, call RemoveFileOnSignal before creating a file instead of after, so
that the file isn't left behind if the program is interrupted between when
the file is created and RemoveFileOnSignal is called.

While here, add a -S to llvm-extract and port it to IRReader so that it
supports assembly input.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81568 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/SystemUtils.cpp b/lib/Support/SystemUtils.cpp
index 3d3649e..299032f 100644
--- a/lib/Support/SystemUtils.cpp
+++ b/lib/Support/SystemUtils.cpp
@@ -20,8 +20,7 @@
 
 bool llvm::CheckBitcodeOutputToConsole(raw_ostream &stream_to_check,
                                        bool print_warning) {
-  if (&stream_to_check == &outs() &&
-      sys::Process::StandardOutIsDisplayed()) {
+  if (stream_to_check.is_displayed()) {
     if (print_warning) {
       errs() << "WARNING: You're attempting to print out a bitcode file.\n"
              << "This is inadvisable as it may cause display problems. If\n"
diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index a229efd..2cb3771 100644
--- a/lib/Support/raw_ostream.cpp
+++ b/lib/Support/raw_ostream.cpp
@@ -454,6 +454,10 @@
   return *this;
 }
 
+bool raw_fd_ostream::is_displayed() const {
+  return sys::Process::FileDescriptorIsDisplayed(FD);
+}
+
 //===----------------------------------------------------------------------===//
 //  raw_stdout/err_ostream
 //===----------------------------------------------------------------------===//
diff --git a/lib/System/Unix/Process.inc b/lib/System/Unix/Process.inc
index 774783f..d715585 100644
--- a/lib/System/Unix/Process.inc
+++ b/lib/System/Unix/Process.inc
@@ -179,26 +179,20 @@
 }
 
 bool Process::StandardInIsUserInput() {
-#if HAVE_ISATTY
-  return isatty(0);
-#else
-  // If we don't have isatty, just return false.
-  return false;
-#endif
+  return FileDescriptorIsDisplayed(STDIN_FILENO);
 }
 
 bool Process::StandardOutIsDisplayed() {
-#if HAVE_ISATTY
-  return isatty(1);
-#else
-  // If we don't have isatty, just return false.
-  return false;
-#endif
+  return FileDescriptorIsDisplayed(STDOUT_FILENO);
 }
 
 bool Process::StandardErrIsDisplayed() {
+  return FileDescriptorIsDisplayed(STDERR_FILENO);
+}
+
+bool Process::FileDescriptorIsDisplayed(int fd) {
 #if HAVE_ISATTY
-  return isatty(2);
+  return isatty(fd);
 #else
   // If we don't have isatty, just return false.
   return false;
diff --git a/lib/System/Win32/Process.inc b/lib/System/Win32/Process.inc
index cfbe33c..feb0806 100644
--- a/lib/System/Win32/Process.inc
+++ b/lib/System/Win32/Process.inc
@@ -120,15 +120,19 @@
 }
 
 bool Process::StandardInIsUserInput() {
-  return GetFileType((HANDLE)_get_osfhandle(0)) == FILE_TYPE_CHAR;
+  return FileDescriptorIsDisplayed(0);
 }
 
 bool Process::StandardOutIsDisplayed() {
-  return GetFileType((HANDLE)_get_osfhandle(1)) == FILE_TYPE_CHAR;
+  return FileDescriptorIsDisplayed(1);
 }
 
 bool Process::StandardErrIsDisplayed() {
-  return GetFileType((HANDLE)_get_osfhandle(2)) == FILE_TYPE_CHAR;
+  return FileDescriptorIsDisplayed(2);
+}
+
+bool Process::FileDescriptorIsDisplayed(int fd) {
+  return GetFileType((HANDLE)_get_osfhandle(fd)) == FILE_TYPE_CHAR;
 }
 
 unsigned Process::StandardOutColumns() {