Add a higher level createTemporaryFile function.

This function is inspired by clang's Driver::GetTemporaryPath. It hides the
pattern used for uniquing and requires simple file names that are always
placed in the system temporary directory.

llvm-svn: 185716

include/llvm/Support/FileSystem.h

@@ -575,6 +575,22 @@ error_code unique_file(const Twine &model, int &result_fd,
 error_code unique_file(const Twine &Model, SmallVectorImpl<char> &ResultPath,
                        bool MakeAbsolute = true);
 
+/// @brief Create a file in the system temporary directory.
+///
+/// The filename is of the form prefix-random_chars.suffix. Since the directory
+/// is not know to the caller, Prefix and Suffix cannot have path separators.
+/// The files are created with mode 0600.
+///
+/// This should be used for things like a temporary .s that is removed after
+/// running the assembler.
+error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
+                               int &ResultFD,
+                               SmallVectorImpl<char> &ResultPath);
+
+/// @brief Simpler version for clients that don't want an open file.
+error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
+                               SmallVectorImpl<char> &ResultPath);
+
 error_code createUniqueDirectory(const Twine &Prefix,
                                  SmallVectorImpl<char> &ResultPath);
 

lib/Support/Path.cpp

@@ -654,6 +654,40 @@ error_code unique_file(const Twine &Model, SmallVectorImpl<char> &ResultPath,
   return createUniqueEntity(Model, Dummy, ResultPath, MakeAbsolute, 0, FS_Name);
 }
 
+static error_code createTemporaryFile(const Twine &Model, int &ResultFD,
+                                      llvm::SmallVectorImpl<char> &ResultPath,
+                                      FSEntity Type) {
+  SmallString<128> Storage;
+  StringRef P = Model.toNullTerminatedStringRef(Storage);
+  assert(P.find_first_of(separators) == StringRef::npos &&
+         "Model must be a simple filename.");
+  // Use P.begin() so that createUniqueEntity doesn't need to recreate Storage.
+  return createUniqueEntity(P.begin(), ResultFD, ResultPath,
+                            true, owner_read | owner_write, Type);
+}
+
+static error_code
+createTemporaryFile(const Twine &Prefix, StringRef Suffix, int &ResultFD,
+                    llvm::SmallVectorImpl<char> &ResultPath,
+                    FSEntity Type) {
+  return createTemporaryFile(Prefix + "-%%%%%%." + Suffix, ResultFD, ResultPath,
+                             Type);
+}
+
+
+error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
+                               int &ResultFD,
+                               SmallVectorImpl<char> &ResultPath) {
+  return createTemporaryFile(Prefix, Suffix, ResultFD, ResultPath, FS_File);
+}
+
+error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
+                               SmallVectorImpl<char> &ResultPath) {
+  int Dummy;
+  return createTemporaryFile(Prefix, Suffix, Dummy, ResultPath, FS_Name);
+}
+
+
 // This is a mkdtemp with a different pattern. We use createUniqueEntity mostly
 // for consistency. We should try using mkdtemp.
 error_code createUniqueDirectory(const Twine &Prefix,