[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, 8 insertions, 7 deletions

diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index a592ed286fe..32c19a0515b 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -169,7 +169,7 @@ static std::error_code
 createUniqueEntity(const Twine &Model, int &ResultFD,
                    SmallVectorImpl<char> &ResultPath, bool MakeAbsolute,
                    unsigned Mode, FSEntity Type,
-                   sys::fs::OpenFlags Flags = sys::fs::F_RW) {
+                   sys::fs::OpenFlags Flags = sys::fs::OF_None) {
   SmallString<128> ModelStorage;
   Model.toVector(ModelStorage);
 
@@ -201,8 +201,8 @@ retry_random_path:
   switch (Type) {
   case FS_File: {
     if (std::error_code EC =
-            sys::fs::openFileForWrite(Twine(ResultPath.begin()), ResultFD,
-                                      Flags | sys::fs::F_Excl, Mode)) {
+            sys::fs::openFileForReadWrite(Twine(ResultPath.begin()), ResultFD,
+                                          sys::fs::CD_CreateNew, Flags, Mode)) {
       if (EC == errc::file_exists)
         goto retry_random_path;
       return EC;
@@ -929,9 +929,10 @@ std::error_code create_directories(const Twine &Path, bool IgnoreExisting,
 
 std::error_code copy_file(const Twine &From, const Twine &To) {
   int ReadFD, WriteFD;
-  if (std::error_code EC = openFileForRead(From, ReadFD))
+  if (std::error_code EC = openFileForRead(From, ReadFD, OF_None))
     return EC;
-  if (std::error_code EC = openFileForWrite(To, WriteFD, F_None)) {
+  if (std::error_code EC =
+          openFileForWrite(To, WriteFD, CD_CreateAlways, OF_None)) {
     close(ReadFD);
     return EC;
   }
@@ -983,7 +984,7 @@ ErrorOr<MD5::MD5Result> md5_contents(int FD) {
 
 ErrorOr<MD5::MD5Result> md5_contents(const Twine &Path) {
   int FD;
-  if (auto EC = openFileForRead(Path, FD))
+  if (auto EC = openFileForRead(Path, FD, OF_None))
     return EC;
 
   auto Result = md5_contents(FD);
@@ -1180,7 +1181,7 @@ Expected<TempFile> TempFile::create(const Twine &Model, unsigned Mode) {
   int FD;
   SmallString<128> ResultPath;
   if (std::error_code EC =
-          createUniqueFile(Model, FD, ResultPath, Mode, F_Delete | F_RW))
+          createUniqueFile(Model, FD, ResultPath, Mode, OF_Delete))
     return errorCodeToError(EC);
 
   TempFile Ret(ResultPath, FD);