Re: [Valgrind-developers] What is the correct way to intercept new function in memcheck ?

[Julian S. <js...@ac...>]

Dmitry,

Do you have some examples of the false errors that this solves?
It would be good to see some examples.

> And i have questions:
> 1. Will such addition be accepted? Or there are caveats with WCHAR
> functions?

Depends on correctness, lack of bad side effects, and presence of
test cases.  Especially the last one; memcheck/tests/str_tester.c
is the right place to add them.

> 2. Is mc_replace_strmem.c the correct file for such addition?

Yes
 
> 3. Will it be correct to use 20360 20370 20380 and 20390 for
> wcscmp/wscncmp/wsclen/wcsnlen?
> Comment in mc_replace_strmem.c say
> -- begin --
> Assignment of behavioural equivalence class tags: 2NNNP is intended
>    to be reserved for Memcheck.  Current usage:
> 
>    20010 STRRCHR
> ...skip...
>    20350 STRCASESTR
> -- end --

Yes fine.  Just don't re-use any existing numbers.

> Naive implementation for wcscmp() works under Fedora16/x64/gcc-4.6.3 (at
> least it looks so :) )
> 
> #include <wchar.h>
> #define WCSCMP(soname, fnname) \
>    int VG_REPLACE_FUNCTION_EZU(20360,soname,fnname) \
>           ( const wchar_t* s1, const wchar_t* s2 ); \
>    int VG_REPLACE_FUNCTION_EZU(20360,soname,fnname) \
>           ( const wchar_t* s1, const wchar_t* s2 ) \
>    { \
>       register wchar_t c1; \
>       register wchar_t c2; \
>       while (True) { \
>          c1 = *(wchar_t *)s1; \
>          c2 = *(wchar_t *)s2; \
>          if (c1 != c2) break; \
>          if (c1 == 0) break; \
>          s1++; s2++; \
>       } \
>       if ((wchar_t)c1 < (wchar_t)c2) return -1; \
>       if ((wchar_t)c1 > (wchar_t)c2) return 1; \
>       return 0; \
>    }
> 
> #if defined(VGO_linux)
>  WCSCMP(VG_Z_LIBC_SONAME,          wcscmp)
>  WCSCMP(VG_Z_LIBC_SONAME,          __GI_wcscmp)
> #elif defined(VGO_darwin)
> //  WCSCMP(VG_Z_LIBC_SONAME,          wcscmp)
> #endif

Looks OK.  It's just a clone of strcmp, yes?

Do wide character comparisons involve locale stuff?  That has
caused problems in the past.  Or are they locale independent?

J