Re: [Wireshark-commits] rev 35975: /trunk/epan/dfilter/ /trunk/epan/dfilter/: dfilter-macro.c dfilter.c

[Gerald Combs <gerald () wireshark org>]

On 2/17/11 1:23 AM, Guy Harris wrote:

> To correct this warning, examine the pointer for null value as shown in the following code:
>
>       #include <malloc.h>
>       void f( )
>       {
>         char *p = ( char * )malloc ( 10 );
>         if ( p ) 
>         {
>           *p = '\0';
>           // code ...
>     
>           free( p );
>         }
>       }
> "
>
> (not "if ( p != NULL )", just "if ( p )").

That doesn't produce any errors with "/analyze". The following tests
compile without errors as well:

--------
#include <malloc.h>

void f( )
{
  char *p;

  if (p = ( char * ) malloc( 10 )) {
    *p = '\0';
   free( p );
  }
}
--------

--------
#include <malloc.h>
#include <stdlib.h>

void f( )
{
  char *p;
  int testval = 1;

  if (((p = ( char * ) malloc( 10 )) != NULL) && testval) {
    *p = '\0';
   free( p );
  }
}
--------

However this produces an error:

--------
#include <malloc.h>

void f( )
{
  char *p;
  int testval = 1;

  if ((p = ( char * ) malloc( 10 )) && testval) {
    *p = '\0';
   free( p );
  }
}
--------

test.c(9) : warning C6011: Dereferencing NULL pointer 'p': Lines: 5, 6, 8, 9



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