[llvm-commits] [llvm] r108110 - /llvm/trunk/lib/System/Unix/Path.inc

[Chris Lattner]

Author: lattner
Date: Sun Jul 11 19:09:55 2010
New Revision: 108110

URL: http://llvm.org/viewvc/llvm-project?rev=108110&view=rev
Log:
improve Path::makeUnique when mkstemp/mktemp are not available
patch by Lasse Kärkkäinen in PR7404.

Modified:
    llvm/trunk/lib/System/Unix/Path.inc

Modified: llvm/trunk/lib/System/Unix/Path.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/System/Unix/Path.inc?rev=108110&r1=108109&r2=108110&view=diff
==============================================================================
--- llvm/trunk/lib/System/Unix/Path.inc (original)
+++ llvm/trunk/lib/System/Unix/Path.inc Sun Jul 11 19:09:55 2010
@@ -888,14 +888,19 @@
 #else
   // Okay, looks like we have to do it all by our lonesome.
   static unsigned FCounter = 0;
-  unsigned offset = path.size() + 1;
-  while ( FCounter < 999999 && exists()) {
-    sprintf(FNBuffer+offset,"%06u",++FCounter);
+  // Try to initialize with unique value.
+  if (FCounter == 0) FCounter = ((unsigned)getpid() & 0xFFFF) << 8;
+  char* pos = strstr(FNBuffer, "XXXXXX");
+  do {
+    if (++FCounter > 0xFFFFFF) {
+      return MakeErrMsg(ErrMsg,
+        path + ": can't make unique filename: too many files");
+    }
+    sprintf(pos, "%06X", FCounter);
     path = FNBuffer;
-  }
-  if (FCounter > 999999)
-    return MakeErrMsg(ErrMsg,
-      path + ": can't make unique filename: too many files");
+  } while (exists());
+  // POSSIBLE SECURITY BUG: An attacker can easily guess the name and exploit
+  // LLVM.
 #endif
   return false;
 }