[PATCH libXrandr 1/2] fix: doGetScreenResources() info: redundant null check on calling free()

[Hans de Goede]

Hi,

On 12-08-16 16:09, walter harms wrote:
>
>
> Am 12.08.2016 12:11, schrieb Hans de Goede:
>> Hi,
>>
>> On 28-07-16 19:31, walter harms wrote:
>>>
>>> janitorial patch: remove some unneeded if() before free()
>>
>> This is not free() but Xfree() and "man Xfree" states:
>>
>> "A NULL pointer cannot be passed to this function."
>>
>
> this is wrong.
>
> Xfree is a define for free()
> Xlibint.h:#define Xfree(ptr) free((ptr))

Ah, yes then the man-page is wrong, my bad.

> more over the general use is this way.
>
> I will post a patch for the man-page.
>
> do you thing this is understandable ?

Maybe explicitly state that passing NULL
is allowed and will do nothing ?

e.g. man 3 free has:

"If ptr is NULL, no operation is performed."

Regards,

Hans



>
> --- a/man/XFree.man
> +++ b/man/XFree.man
> @@ -90,8 +90,8 @@ Specifies the data that are to be freed.
>  The
>  .ZN XFree
>  function is a general-purpose Xlib routine that frees the specified data.
> -You must use it to free any objects that were allocated by Xlib,
> -unless an alternate function is explicitly specified for the object.
> -A NULL pointer cannot be passed to this function.
> +It is a alternativ for free(3). You should use it to free any objects that
> +were allocated by Xlib, unless an alternate function is explicitly specified
> +for the object.
>  .SH "SEE ALSO"
>  \fI\*(xL\fP
>
>
>
>> Regards,
>>
>> Hans
>>
>>
>>>
>>>
>>> ---
>>>  src/XrrScreen.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/src/XrrScreen.c b/src/XrrScreen.c
>>> index f29071c..b8ce7e5 100644
>>> --- a/src/XrrScreen.c
>>> +++ b/src/XrrScreen.c
>>> @@ -127,8 +127,8 @@ doGetScreenResources (Display *dpy, Window window,
>>> int poll)
>>>      xrsr = (XRRScreenResources *) Xmalloc(rbytes);
>>>      wire_names = (char *) Xmalloc (rep.nbytesNames);
>>>      if (xrsr == NULL || wire_names == NULL) {
>>> -    if (xrsr) Xfree (xrsr);
>>> -    if (wire_names) Xfree (wire_names);
>>> +    Xfree (xrsr);
>>> +    Xfree (wire_names);
>>>      _XEatDataWords (dpy, rep.length);
>>>      UnlockDisplay (dpy);
>>>      SyncHandle ();
>>>