[SystemZ][z/OS][Windows] Add new functions that set Text/Binary mode for Stdin and Stdout based on OpenFlags

On Windows, we want to open a file in Binary mode if OF_CRLF bit is not set. On z/OS, we want to open a file in Binary mode if the OF_Text bit is not set.

This patch creates two new functions called ChangeStdinMode and ChangeStdoutMode which will take OpenFlags as an arg to determine which mode to set stdin and stdout to. This will enable patches like https://reviews.llvm.org/D100056 to not affect Windows when setting the OF_Text flag for raw_fd_streams.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D100130

Author: abhina-sree

llvm/include/llvm/Support/Program.h

@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/ErrorOr.h"
+#include "llvm/Support/FileSystem.h"
 #include <chrono>
 #include <system_error>
 
@@ -77,6 +78,12 @@ namespace sys {
   ErrorOr<std::string>
   findProgramByName(StringRef Name, ArrayRef<StringRef> Paths = {});
 
+  // These functions change the specified standard stream (stdin or stdout) mode
+  // based on the Flags. They return errc::success if the specified stream was
+  // changed. Otherwise, a platform dependent error is returned.
+  std::error_code ChangeStdinMode(fs::OpenFlags Flags);
+  std::error_code ChangeStdoutMode(fs::OpenFlags Flags);
+
   // These functions change the specified standard stream (stdin or stdout) to
   // binary mode. They return errc::success if the specified stream
   // was changed. Otherwise a platform dependent error is returned.

llvm/lib/Support/MemoryBuffer.cpp

@@ -512,7 +512,7 @@ ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() {
   //
   // FIXME: That isn't necessarily true, we should try to mmap stdin and
   // fallback if it fails.
-  sys::ChangeStdinToBinary();
+  sys::ChangeStdinMode(sys::fs::OF_Text);
 
   return getMemoryBufferForStream(sys::fs::getStdinHandle(), "<stdin>");
 }

llvm/lib/Support/Unix/Program.inc

@@ -493,6 +493,18 @@ ProcessInfo llvm::sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
   return WaitResult;
 }
 
+std::error_code llvm::sys::ChangeStdinMode(fs::OpenFlags Flags){
+  if (!(Flags & fs::OF_Text))
+    return ChangeStdinToBinary();
+  return std::error_code();
+}
+
+std::error_code llvm::sys::ChangeStdoutMode(fs::OpenFlags Flags){
+  if (!(Flags & fs::OF_Text))
+    return ChangeStdoutToBinary();
+  return std::error_code();
+}
+
 std::error_code llvm::sys::ChangeStdinToBinary() {
   // Do nothing, as Unix doesn't differentiate between text and binary.
   return std::error_code();

llvm/lib/Support/Windows/Program.inc

@@ -488,6 +488,18 @@ ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
   return WaitResult;
 }
 
+std::error_code llvm::sys::ChangeStdinMode(sys::fs::OpenFlags Flags){
+  if (!(Flags & fs::OF_CRLF))
+    return ChangeStdinToBinary();
+  return std::error_code();
+}
+
+std::error_code llvm::sys::ChangeStdoutMode(sys::fs::OpenFlags Flags){
+  if (!(Flags & fs::OF_CRLF))
+    return ChangeStdoutToBinary();
+  return std::error_code();
+}
+
 std::error_code sys::ChangeStdinToBinary() {
   int result = _setmode(_fileno(stdin), _O_BINARY);
   if (result == -1)

llvm/lib/Support/raw_ostream.cpp

@@ -574,10 +574,8 @@ static int getFD(StringRef Filename, std::error_code &EC,
   // the owner of stdout and may set the "binary" flag globally based on Flags.
   if (Filename == "-") {
     EC = std::error_code();
-    // If user requested binary then put stdout into binary mode if
-    // possible.
-    if (!(Flags & sys::fs::OF_Text))
-      sys::ChangeStdoutToBinary();
+    // Change stdout's text/binary mode based on the Flags.
+    sys::ChangeStdoutMode(Flags);
     return STDOUT_FILENO;
   }