From 2b1f1066aca0f6a3687377636a86086fa2cd222d Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sun, 18 Nov 2007 18:52:28 +0000
Subject: [PATCH] Fix the Linker testcase regressions, by making
 MemoryBuffer::getFileOrSTDIN return a valid but empty buffer if stdin is
 empty.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44219 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/MemoryBuffer.h |  9 +++------
 lib/Support/MemoryBuffer.cpp        | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/include/llvm/Support/MemoryBuffer.h b/include/llvm/Support/MemoryBuffer.h
index aa13bfc65a8..cfef6b1c6cf 100644
--- a/include/llvm/Support/MemoryBuffer.h
+++ b/include/llvm/Support/MemoryBuffer.h
@@ -88,14 +88,11 @@ public:
   
   /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
   /// if the Filename is "-".  If an error occurs, this returns null and fills
-  /// in *ErrStr with a reason.
+  /// in *ErrStr with a reason.  If stdin is empty, this API (unlike getSTDIN)
+  /// returns an empty buffer.
   static MemoryBuffer *getFileOrSTDIN(const char *FilenameStart,unsigned FnSize,
                                       std::string *ErrStr = 0,
-                                      int64_t FileSize = -1) {
-    if (FnSize == 1 && FilenameStart[0] == '-')
-      return getSTDIN();
-    return getFile(FilenameStart, FnSize, ErrStr, FileSize);
-  }
+                                      int64_t FileSize = -1);
   
   /// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
   /// if the Filename is "-".  If an error occurs, this returns null and fills
diff --git a/lib/Support/MemoryBuffer.cpp b/lib/Support/MemoryBuffer.cpp
index f8779e122d5..20003777941 100644
--- a/lib/Support/MemoryBuffer.cpp
+++ b/lib/Support/MemoryBuffer.cpp
@@ -117,6 +117,24 @@ MemoryBuffer *MemoryBuffer::getNewMemBuffer(unsigned Size,
 }
 
 
+/// getFileOrSTDIN - Open the specified file as a MemoryBuffer, or open stdin
+/// if the Filename is "-".  If an error occurs, this returns null and fills
+/// in *ErrStr with a reason.  If stdin is empty, this API (unlike getSTDIN)
+/// returns an empty buffer.
+MemoryBuffer *MemoryBuffer::getFileOrSTDIN(const char *FilenameStart,
+                                           unsigned FnSize,
+                                           std::string *ErrStr,
+                                           int64_t FileSize) {
+  if (FnSize != 1 || FilenameStart[0] != '-')
+    return getFile(FilenameStart, FnSize, ErrStr, FileSize);
+  MemoryBuffer *M = getSTDIN();
+  if (M) return M;
+
+  // If stdin was empty, M is null.  Cons up an empty memory buffer now.
+  const char *EmptyStr = "";
+  return MemoryBuffer::getMemBuffer(EmptyStr, EmptyStr, "<stdin>");
+}
+
 //===----------------------------------------------------------------------===//
 // MemoryBufferMMapFile implementation.
 //===----------------------------------------------------------------------===//