[llvm] r176226 - [PathV2] In llvm::sys::fs::unique_file, make sure it doesn't fall into an infinite loop by constantly trying

[Aaron Ballman]

Can we fall into the same trap in the Windows version of this code too?

~Aaron

On Wed, Feb 27, 2013 at 7:38 PM, Argyrios Kyrtzidis <akyrtzi at gmail.com> wrote:
> Author: akirtzidis
> Date: Wed Feb 27 18:38:19 2013
> New Revision: 176226
>
> URL: http://llvm.org/viewvc/llvm-project?rev=176226&view=rev
> Log:
> [PathV2] In llvm::sys::fs::unique_file, make sure it doesn't fall into an infinite loop by constantly trying
> to create the parent path.
>
> This can happen if the path is a relative filename and the current directory was removed.
> Thanks to Daniel D. for the hint in fixing it.
>
> Modified:
>     llvm/trunk/lib/Support/Unix/PathV2.inc
>
> Modified: llvm/trunk/lib/Support/Unix/PathV2.inc
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/PathV2.inc?rev=176226&r1=176225&r2=176226&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/Unix/PathV2.inc (original)
> +++ llvm/trunk/lib/Support/Unix/PathV2.inc Wed Feb 27 18:38:19 2013
> @@ -417,6 +417,10 @@ retry_random_path:
>        RandomPath[i] = "0123456789abcdef"[sys::Process::GetRandomNumber() & 15];
>    }
>
> +  // Make sure we don't fall into an infinite loop by constantly trying
> +  // to create the parent path.
> +  bool TriedToCreateParent = false;
> +
>    // Try to open + create the file.
>  rety_open_create:
>    int RandomFD = ::open(RandomPath.c_str(), O_RDWR | O_CREAT | O_EXCL, mode);
> @@ -427,7 +431,9 @@ rety_open_create:
>        goto retry_random_path;
>      // If path prefix doesn't exist, try to create it.
>      if (SavedErrno == errc::no_such_file_or_directory &&
> -        !exists(path::parent_path(RandomPath))) {
> +        !exists(path::parent_path(RandomPath)) &&
> +        !TriedToCreateParent) {
> +      TriedToCreateParent = true;
>        StringRef p(RandomPath);
>        SmallString<64> dir_to_create;
>        for (path::const_iterator i = path::begin(p),
>
>
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