Static analysis at Mozilla

[Ali Çehreli]

Sean Kelly wrote:
 > bearophile Wrote:
 >
 >> C++ Static Analysis as done on the large Mozilla codebase:
 >> http://blog.ezyang.com/2010/06/static-analysis-mozilla/
 >> It shows that it's important to have a more powerful static 
reflection in D. It works well with scoped user-defined attributes too.
 >
 > As much as I like static analysis, it still has a long way to go. 
For example, here's some C code that a static analysis tool recently 
flagged as broken:
 >
 >     size_t fn( char** pdst, char* src, size_t srclen ) {
 >         __thread static char* dst      = NULL;
 >         __thread static size_t dstcap = 0;
 >         if( dstcap < srclen ) {
 >             dstcap = srclen;
 >             dst      = realloc( dst, dstcap );
 >         }
 >         memcpy( dst, src, srclen ); // Purify: ERROR - uninitialized 
write
 >         *pdst = dst;
 >         return srclen;
 >     }
 >
 > Basically, it wasn't smart enough to realize that dst would
 > always be non-NULL when the memcpy occurred, let alone that it
 > would also always be large enough.  For such false positives,
 > it's generally necessary to insert pointless code simply to
 > silence the error, thus complicating the function and
 > increasing the cost of maintenance.  I still believe that the
 > benefits of static analysis vastly outweigh the cost, but I'd
 > love to see more intelligence in branch analysis if nothing
 > else.

realloc may return NULL. Perhaps they are catching that condition?

Ali