vsprintf(NULL, format, paramList); is not NULL dereference but standard way how to get final string size.

[Jaroslav Fojtik]

size = vsprintf(NULL, format, paramList);
is not NULL dereference but standard way how to get final string size.

#include <stdarg.h>
#include <stdio.h>
int string::printf(const char* format, ...)
{
  va_list paramList;
  va_start(paramList, format);
 #ifdef _HAVE_VSNPRINTF
  size = vsnprintf(0, 0, format, paramList);
#else
  size = vsprintf(NULL, format, paramList);
#endif

  if(size)
    {
    resize(size);
#ifdef _HAVE_VSNPRINTF
    size = vsnprintf(ch, maxlen, format, paramList);
#else
    size = vsprintf(ch, format, paramList);
#endif
    }
  else
    erase();

  va_end(paramList);
  return size;
}

[Jaroslav Fojtik]

Look at here: http://libslack.org/manpages/snprintf.3.html

If size is zero, nothing is written and str may be null.

[Daniel Marjamäki]

I guess we need to update the configuration.. could you review it?

[Jaroslav Fojtik]

Where to find configuration? I did not develop cppcheck yet.

[Daniel Marjamäki]

The configuration is fine as far as I see:
https://github.com/danmar/cppcheck/blob/master/cfg/std.cfg#L5923

I can't reproduce the FP. Which version do you use?

[Jaroslav Fojtik]

I am using the latest one 1.89.

There are two functions vsnprintf and vsprintf. May be that one of them is not defined same way and requires not NULL argument.

Whole source code is attached.

[Jaroslav Fojtik]

The error is still reported on the line:
size = vsprintf(NULL, format, paramList);

And the header file:

[Jaroslav Fojtik]

Please note when your system supports vsprintf only, it is much more neccessary to call with NULL first to check space to allocate.

<function name="vsprintf,std::vsprintf">
<returnvalue type="int">
<noreturn>false</noreturn>
<leak-ignore>
<arg nr="1" direction="out">
<not-null></not-null> <<<<<!!!!!!!
</arg>
<arg nr="2" direction="in">
<not-null>
<not-uninit>
<formatstr>
</formatstr></not-uninit></not-null></arg>
<arg nr="3">
</arg></leak-ignore></returnvalue></function>

[Daniel Marjamäki]

Do you want to send a github pull request? I would suggest that we replace <not-null/> with <not-uninit/>.

[Jaroslav Fojtik]

Pull request means to duplicate git repository. I can do this, but for this minor change it is not neccessary to have right to push backwards. You know better what to do with my report ;).

[Daniel Marjamäki]

ok.. I fix it myself..