[FileSystem] Split up the OpenFlags enumeration.

This breaks the OpenFlags enumeration into two separate
enumerations: OpenFlags and CreationDisposition.  The first
controls the behavior of the API depending on whether or not
the target file already exists, and is not a flags-based
enum.  The second controls more flags-like values.

This yields a more easy to understand API, while also allowing
flags to be passed to the openForRead api, where most of the
values didn't make sense before.  This also makes the apis more
testable as it becomes easy to enumerate all the configurations
which make sense, so I've added many new tests to exercise all
the different values.

llvm-svn: 334221

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index fe04bb6fb57..d8cc853f2a8 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -244,7 +244,7 @@ static ErrorOr<std::unique_ptr<MB>>
 getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize,
            uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile) {
   int FD;
-  std::error_code EC = sys::fs::openFileForRead(Filename, FD);
+  std::error_code EC = sys::fs::openFileForRead(Filename, FD, sys::fs::OF_None);
 
   if (EC)
     return EC;
@@ -364,8 +364,8 @@ static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
 getReadWriteFile(const Twine &Filename, uint64_t FileSize, uint64_t MapSize,
                  uint64_t Offset) {
   int FD;
-  std::error_code EC = sys::fs::openFileForWrite(
-      Filename, FD, sys::fs::F_RW | sys::fs::F_NoTrunc);
+  std::error_code EC = sys::fs::openFileForReadWrite(
+      Filename, FD, sys::fs::CD_OpenExisting, sys::fs::OF_None);
 
   if (EC)
     return EC;
@@ -518,7 +518,7 @@ ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() {
 ErrorOr<std::unique_ptr<MemoryBuffer>>
 MemoryBuffer::getFileAsStream(const Twine &Filename) {
   int FD;
-  std::error_code EC = sys::fs::openFileForRead(Filename, FD);
+  std::error_code EC = sys::fs::openFileForRead(Filename, FD, sys::fs::OF_None);
   if (EC)
     return EC;
   ErrorOr<std::unique_ptr<MemoryBuffer>> Ret =