Re: [PATCH setup] Avoid stringop-overflow warning with gcc8

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Oct 12 16:43, Jon Turney wrote:
> desktop.cc: In function 'void start_menu(const string&, const string&, const string&, const string&)':
> desktop.cc:110:11: error: 'char* strncat(char*, const char*, size_t)' specified bound 260 equals destination size [-Werror=stringop-overflow=]
> 
> I think strlcat() was meant here, which MinGW doesn't have.  In it's
> absence, open-code it's equivalent.
> 
> (SHGetSpecialFolderLocation() returns a pathname of length at most MAX_PATH,
> and make_link() is limited to accepting a pathname of length MAX_PATH, so we
> want to append our folder name, while truncating the result to MAX_PATH.)
> ---
>  desktop.cc | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/desktop.cc b/desktop.cc
> index 927c02f..d003e91 100644
> --- a/desktop.cc
> +++ b/desktop.cc
> @@ -107,7 +107,8 @@ start_menu (const std::string& title, const std::string& target,
>  			      issystem ? CSIDL_COMMON_PROGRAMS :
>  			      CSIDL_PROGRAMS, &id);
>    SHGetPathFromIDList (id, path);
> -  strncat (path, "/Cygwin", MAX_PATH);
> +  strncat (path, "/Cygwin", MAX_PATH - strlen(path));

Shouldn't that be

     strncat (path, "/Cygwin", MAX_PATH - strlen(path) - 1);

?

"If src contains n or more bytes, strncat() writes n+1 bytes to dest  (n
 from  src plus the terminating null byte).  Therefore, the size of dest
 must be at least strlen(dest)+n+1."


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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