[llvm] r310636 - [gold-plugin] Avoid race condition when creating temporary files.

[Benjamin Kramer via llvm-commits]

Author: d0k
Date: Thu Aug 10 10:38:41 2017
New Revision: 310636

URL: http://llvm.org/viewvc/llvm-project?rev=310636&view=rev
Log:
[gold-plugin] Avoid race condition when creating temporary files.

This is both a potential security issue and a potential functionality
issue because we create temporary files from multiple threads. Use
the safe version of createTemporaryFile instead.

Modified:
    llvm/trunk/tools/gold/gold-plugin.cpp

Modified: llvm/trunk/tools/gold/gold-plugin.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/gold/gold-plugin.cpp?rev=310636&r1=310635&r2=310636&view=diff
==============================================================================
--- llvm/trunk/tools/gold/gold-plugin.cpp (original)
+++ llvm/trunk/tools/gold/gold-plugin.cpp Thu Aug 10 10:38:41 2017
@@ -699,11 +699,12 @@ static void recordFile(std::string Filen
 /// Return the desired output filename given a base input name, a flag
 /// indicating whether a temp file should be generated, and an optional task id.
 /// The new filename generated is returned in \p NewFilename.
-static void getOutputFileName(SmallString<128> InFilename, bool TempOutFile,
-                              SmallString<128> &NewFilename, int TaskID) {
+static int getOutputFileName(SmallString<128> InFilename, bool TempOutFile,
+                             SmallString<128> &NewFilename, int TaskID) {
+  int FD = -1;
   if (TempOutFile) {
     std::error_code EC =
-        sys::fs::createTemporaryFile("lto-llvm", "o", NewFilename);
+        sys::fs::createTemporaryFile("lto-llvm", "o", FD, NewFilename);
     if (EC)
       message(LDPL_FATAL, "Could not create temporary file: %s",
               EC.message().c_str());
@@ -711,7 +712,13 @@ static void getOutputFileName(SmallStrin
     NewFilename = InFilename;
     if (TaskID > 0)
       NewFilename += utostr(TaskID);
+    std::error_code EC =
+        sys::fs::openFileForWrite(NewFilename, FD, sys::fs::F_None);
+    if (EC)
+      message(LDPL_FATAL, "Could not open file %s: %s", NewFilename.c_str(),
+              EC.message().c_str());
   }
+  return FD;
 }
 
 static CodeGenOpt::Level getCGOptLevel() {
@@ -899,14 +906,8 @@ static ld_plugin_status allSymbolsReadHo
   auto AddStream =
       [&](size_t Task) -> std::unique_ptr<lto::NativeObjectStream> {
     IsTemporary[Task] = !SaveTemps;
-    getOutputFileName(Filename, /*TempOutFile=*/!SaveTemps, Filenames[Task],
-                      Task);
-    int FD;
-    std::error_code EC =
-        sys::fs::openFileForWrite(Filenames[Task], FD, sys::fs::F_None);
-    if (EC)
-      message(LDPL_FATAL, "Could not open file %s: %s", Filenames[Task].c_str(),
-              EC.message().c_str());
+    int FD = getOutputFileName(Filename, /*TempOutFile=*/!SaveTemps,
+                               Filenames[Task], Task);
     return llvm::make_unique<lto::NativeObjectStream>(
         llvm::make_unique<llvm::raw_fd_ostream>(FD, true));
   };