Re: [Boost-build] build engine crashes when GLOBing paths with forward slashes on windows

Subject: Re: [Boost-build] build engine crashes when GLOBing paths with forward slashes on windows
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2012-02-23 10:17:27

AMDG

On 02/23/2012 03:21 AM, Marc Dürner wrote:
> However the code still looks a bit strange. there is a tricky
> recursion. Please review if the following can still happen:
> 

This can't happen because ShortPathToLongPath
strips off the last path element before calling
path_write_key.  The result is that given the
path: "C:\Users\Steven\Documents"

We end up calling

ShortPathToLongPath("C:\Users\Steven\Documents")
 -> path_write_key("C:\Users\Steven")
   -> ShortPathToLongPath("C:\Users\Steven")
     -> path_write_key("C:\Users")
       -> ShortPathToLongPath("C:\Users")
         -> path_write_key("C:\")
           -> ShortPathToLongPath("C:\") - base case

> static void path_write_key( char * path_, string * out )
> {
>     struct path_key_entry e, *result = &e;
>     OBJECT * path = object_new( path_ );
> 
>     /* This is only called by path_as_key, which initializes the cache. */
>     assert( path_key_cache );
> 
>     result->path = path;
> 1:  if ( hashenter( path_key_cache, (HASHDATA * *)&result ) )
>     {
>         /* path_ is already normalized. */
> 2:     ShortPathToLongPath( path_, out );
> 3:     result->key = object_new( out->value );
>     }
>     else
>     {
>         object_free( path );
> 4:     string_append( out, object_str( result->key ) );
>     }
> }
> 
> Lets assume we enter path_write_key() with a path that is not in the
> cache yet. The function hashenter() will return true if a new element
> was added [1]. Eventually we reach [2] and enter
> ShortPathToLongPath(), which calls path_write_key() again, in my case
> protentially with the same path.The function hashenter will return
> false in the following invokation of path_write_key(), because the
> element is already in the cache. But it wasn't initialized yet,
> because that happens at [3]. So we access uninitialized data in [4].
> 

In Christ,
Steven Watanabe