Changed createTemporaryFile without FD to actually create a file.

Summary:
This commit changes semantics of createUniqueFile and
createTemporaryFile variants that do not return file descriptors.
Previously they only checked if files exist, therefore being subject
to race conditions. Now they will create an empty file to avoid them.

Functions that do not create a file are now called
getPotentiallyUniqueTempFileName and getPotentiallyUniqueFileName.

Reviewers: klimek, bkramer, krasimir, JDevlieghere, espindola

Reviewed By: klimek

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D36827

llvm-svn: 327851

1 files changed, 32 insertions, 7 deletions

diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index f229f23a4f8..ec8a5ca98e5 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -757,9 +757,15 @@ std::error_code createUniqueFile(const Twine &Model, int &ResultFd,
 }
 
 std::error_code createUniqueFile(const Twine &Model,
-                                 SmallVectorImpl<char> &ResultPath) {
-  int Dummy;
-  return createUniqueEntity(Model, Dummy, ResultPath, false, 0, FS_Name);
+                                 SmallVectorImpl<char> &ResultPath,
+                                 unsigned Mode) {
+  int FD;
+  auto EC = createUniqueFile(Model, FD, ResultPath, Mode);
+  if (EC)
+    return EC;
+  // FD is only needed to avoid race conditions. Close it right away.
+  close(FD);
+  return EC;
 }
 
 static std::error_code
@@ -794,8 +800,13 @@ std::error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
 
 std::error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
                                     SmallVectorImpl<char> &ResultPath) {
-  int Dummy;
-  return createTemporaryFile(Prefix, Suffix, Dummy, ResultPath, FS_Name);
+  int FD;
+  auto EC = createTemporaryFile(Prefix, Suffix, FD, ResultPath);
+  if (EC)
+    return EC;
+  // FD is only needed to avoid race conditions. Close it right away.
+  close(FD);
+  return EC;
 }
 
 
@@ -804,8 +815,22 @@ std::error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
 std::error_code createUniqueDirectory(const Twine &Prefix,
                                       SmallVectorImpl<char> &ResultPath) {
   int Dummy;
-  return createUniqueEntity(Prefix + "-%%%%%%", Dummy, ResultPath,
-                            true, 0, FS_Dir);
+  return createUniqueEntity(Prefix + "-%%%%%%", Dummy, ResultPath, true, 0,
+                            FS_Dir);
+}
+
+std::error_code
+getPotentiallyUniqueFileName(const Twine &Model,
+                             SmallVectorImpl<char> &ResultPath) {
+  int Dummy;
+  return createUniqueEntity(Model, Dummy, ResultPath, false, 0, FS_Name);
+}
+
+std::error_code
+getPotentiallyUniqueTempFileName(const Twine &Prefix, StringRef Suffix,
+                                 SmallVectorImpl<char> &ResultPath) {
+  int Dummy;
+  return createTemporaryFile(Prefix, Suffix, Dummy, ResultPath, FS_Name);
 }
 
 static std::error_code make_absolute(const Twine &current_directory,